Natural Phenomenon or Process

MeSH ID: T070

Related Concepts:

  • Absorption [M0000063]
    The physical or physiological processes by which substances or energy are absorbed.
  • Acetylation [M0000160]
    Formation of an acetyl derivative. (Stedman, 25th ed)
  • Acoustics [M0000244]
    The branch of physics that deals with sound and sound waves. In medicine it is often applied in procedures in speech and hearing studies. With regard to the environment, it refers to the characteristics of a room, auditorium, theatre, building, etc. that determines the audibility or fidelity of sounds in it. (From Random House Unabridged Dictionary, 2d ed)
  • Acylation [M0000333]
    The addition of an organic acid radical into a molecule.
  • Adaptation, Biological [M0000338]
    Changes in biological features that help an organism cope with its ENVIRONMENT. These changes include physiological (ADAPTATION, PHYSIOLOGICAL), phenotypic and genetic changes.
  • Adhesiveness [M0000419]
  • Air Ionization [M0000596]
  • Air Movements [M0000598]
  • Air Pressure [M0000605]
    The force per unit area that the air exerts on any surface in contact with it. Primarily used for articles pertaining to air pressure within a closed environment.
  • Alkylation [M0000722]
    The covalent bonding of an alkyl group to an organic compound. It can occur by a simple addition reaction or by substitution of another functional group.
  • Allostasis [M0488277]
    Biological adaptation, such as the rise of EPINEPHRINE in response to exercise, stress or perceived danger, followed by a fall of epinephrine during RELAXATION. Allostasis is the achievement of stability by turning on and turning off the allostatic systems including the IMMUNE SYSTEM; the AUTONOMIC NERVOUS SYSTEM and NEUROENDOCRINE SYSTEMS.
  • Alpha Particles [M0000774]
    Positively charged particles composed of two protons and two neutrons, i.e., helium nuclei, emitted during disintegration of very heavy isotopes; a beam of alpha particles or an alpha ray has very strong ionizing power, but weak penetrability.
  • Alpha Rays [M0000775]
  • Amination [M0000911]
    The creation of an amine. It can be produced by the addition of an amino group to an organic compound or reduction of a nitro group.
  • Anion Gap [M0000211]
  • Anisotropy [M0025684]
    A physical property showing different values in relation to the direction in or along which the measurement is made. The physical property may be with regard to thermal or electric conductivity or light refraction. In crystallography, it describes crystals whose index of refraction varies with the direction of the incident light. It is also called acolotropy and colotropy. The opposite of anisotropy is isotropy wherein the same values characterize the object when measured along axes in all directions.
  • Anisotropy, Fluorescence [M0008605]
  • Antibiosis [M0001341]
    A property of microorganisms which enables one microorganism to kill, injure, or inhibit the growth of a different microorganism.
  • Antigenic Specificity [M0001404]
  • Atmosphere [M0001915]
    The gaseous envelope surrounding a planet or similar body. (From Random House Unabridged Dictionary, 2d ed)
  • Atmospheric Pressure [M0001917]
    The pressure at any point in an atmosphere due solely to the weight of the atmospheric gases above the point concerned.
  • Background Radiation [M0002116]
    Radiation from sources other than the source of interest. It is due to cosmic rays and natural radioactivity in the environment.
  • Bacterial Physiology [M0027634]
    Physiological processes and activities of bacteria.
  • Bacterial Viability [M0473810]
  • Bacteriolysis [M0002139]
    Rupture of bacterial cells due to mechanical force, chemical action, or the lytic growth of BACTERIOPHAGES.
  • Beta Rays [M0002408]
    A stream of positive or negative electrons ejected with high energy from a disintegrating atomic nucleus; most biomedically used isotopes emit negative particles (electrons or negatrons, rather than positrons). Cathode rays are low-energy negative electrons produced in cathode ray tubes, also called television tubes or oscilloscopes.
  • Biochemical Phenomena [M0002506]
    Biochemical functions, activities, and processes at organic and molecular levels in humans, animals, microorganisms, and plants.
  • Biochemical Phenomena, Metabolism, and Nutrition [M0002507]
  • Biogenesis [M0002517]
    The origin of life. It includes studies of the potential basis for life in organic compounds but excludes studies of the development of altered forms of life through mutation and natural selection, which is EVOLUTION.
  • Biological Phenomena [M0002531]
    Biological functions and activities at the organic and molecular levels in humans, animals, microorganisms, and plants. For biochemical and metabolic processes, BIOCHEMICAL PHENOMENA is available.
  • Biological Phenomena, Cell Phenomena, and Immunity [M0002532]
  • Birefringence [M0002580]
    The property of nonisotropic media, such as crystals, whereby a single incident beam of light traverses the medium as two beams, each plane-polarized, the planes being at right angles to each other. (Cline et al., Dictionary of Visual Science, 4th ed)
  • Bogs [M0496768]
  • Browning Reaction [M0023763]
  • Capillarity [M0003290]
    The action by which the surface of a liquid where it contacts a solid is elevated or depressed, because of the relative attraction of the molecules of the liquid for each other and for those of the solid. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Catalysis [M0003626]
  • Cathode Rays [M0002409]
  • Chemical Actions [M0448593]
  • chemical composition [M0030908]
  • chemical content [M0030909]
  • chemical properties [M0030910]
  • chemical synthesis [M0030321]
    Used for the chemical preparation of molecules in vitro. For the formation of chemical substances in organisms, living cells, or subcellular fractions, "biosynthesis" is used.
  • Chemiluminescence [M0464546]
  • Circular Dichroism [M0004502]
    A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Climate [M0004560]
  • Cold [M0004734]
    An absence of warmth or heat or a temperature notably below an accustomed norm.
  • Cold Climate [M0004735]
  • Color [M0004825]
  • Conception [M0008378]
  • Convection [M0027719]
    Transmission of energy or mass by a medium involving movement of the medium itself. The circulatory movement that occurs in a fluid at a nonuniform temperature owing to the variation of its density and the action of gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed; Webster, 10th ed)
  • Coriolis Acceleration [M0005168]
  • Coriolis Effect [M0005169]
  • Coriolis Force [M0005170]
    The apparent deflection (Coriolis acceleration) of a body in motion with respect to the earth, as seen by an observer on the earth, attributed to a fictitious force (Coriolis force) but actually caused by the rotation of the earth. In a medical context it refers to the physiological effects (nausea, vertigo, dizziness, etc.) felt by a person moving radially in a rotating system, as a rotating space station. (From Random House Unabridged Dictionary, 2d ed & McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Coriolis Stimulation [M0005171]
  • Corrosion [M0005214]
  • Cosmic Radiation [M0005229]
    High-energy radiation or particles from extraterrestrial space that strike the earth, its atmosphere, or spacecraft and may create secondary radiation as a result of collisions with the atmosphere or spacecraft.
  • Crystal Growth [M0498752]
  • Crystallization [M0005403]
    The formation of crystalline substances from solutions or melts. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Cyclization [M0005456]
    Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Darkness [M0005663]
  • Dealkylation [M0005697]
    The removing of alkyl groups from a compound. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Deamination [M0005698]
    The removal of an amino group (NH2) from a chemical compound.
  • Decarboxylation [M0005716]
    The removal of a carboxyl group, usually in the form of carbon dioxide, from a chemical compound.
  • Deceleration [M0005717]
  • Dental Restoration Wear [M0029041]
    Occlusal wear of the surfaces of restorations and surface wear of dentures.
  • Denture Wear [M0029040]
  • Desert Climate [M0006072]
    A type of climate characterized by insufficient moisture to support appreciable plant life. It is a climate of extreme aridity, usually of extreme heat, and of negligible rainfall. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Desiccation [M0006073]
    Removal of moisture from a substance (chemical, food, tissue, etc.).
  • Dialysis [M0006201]
    A process of selective diffusion through a membrane. It is usually used to separate low-molecular-weight solutes which diffuse through the membrane from the colloidal and high-molecular-weight solutes which do not. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Diffusion [M0006364]
    The tendency of a gas or solute to pass from a point of higher pressure or concentration to a point of lower pressure or concentration and to distribute itself throughout the available space; a major mechanism of BIOLOGICAL TRANSPORT.
  • Dimerization [M0028711]
    The process by which two molecules of the same chemical composition form a condensation product or polymer.
  • DNA Denaturation [M0498354]
  • Doppler Effect [M0006762]
    Changes in the observed frequency of waves (as sound, light, or radio waves) due to the relative motion of source and observer. The effect was named for the 19th century Austrian physicist Johann Christian Doppler.
  • Doppler Ultrasound [M0022239]
  • Drought [M0014520]
  • Earthquakes [M0014521]
  • Ecosystem [M0026832]
    A functional system which includes the organisms of a natural community together with their environment. (McGraw Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • EHF Waves [M0013840]
  • Elasticity [M0007150]
    Resistance and recovery from distortion of shape.
  • Electric Resistance [M0025977]
  • Electricity [M0007172]
    A physical phenomenon involving electric charges and their effects when at rest and when in motion. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
  • Electromagnetic Energy [M0393767]
  • Electromagnetic Fields [M0007190]
    Fields representing the joint interplay of electric and magnetic forces.
  • Electromagnetics [M0007191]
    Phenomena involving magnets, electric currents through conductors and the electric and magnetic fields thus produced, as in electric motors.
  • Electroosmosis [M0496885]
    The motion of a liquid through a membrane (or plug or capillary) consequent upon the application of an electric field across the membrane. (Oxford Dictionary of Biochemistry and Molecular Biology, 2001)
  • Electroosmotic Flow [M0496886]
  • Electroplating [M0007219]
    Coating with a metal or alloy by electrolysis.
  • Electrostatics [M0028757]
    The branch of physics dealing with electric phenomena not associated with electricity in motion, electric charges at rest, their electric fields, and potentials. (Random House Unabridged Dictionary, 2d ed; McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Elementary Particle Interactions [M0028963]
    The interactions of particles responsible for their scattering and transformations (decays and reactions). Because of interactions, an isolated particle may decay into other particles. Two particles passing near each other may transform, perhaps into the same particles but with changed momenta (elastic scattering) or into other particles (inelastic scattering). Interactions fall into three groups: strong, electromagnetic, and weak. (From McGraw-Hill Encyclopedia of Science & Technology, 7th ed)
  • Esterification [M0007765]
    The process of converting an acid into an alkyl or aryl derivative. Most frequently the process consists of the reaction of an acid with an alcohol in the presence of a trace of mineral acid as catalyst or the reaction of an acyl chloride with an alcohol. Esterification can also be accomplished by enzymatic processes.
  • Evolution, Molecular [M0028541]
    Evolution at the molecular level of DNA sequences and proteins. (Rieger et al., Glossary of Genetics: Classical and Molecular, 5th ed)
  • Extinction, Biological [M0493472]
    The ceasing of existence of a species or taxonomic groups of organisms.
  • Extinction, Mass [M0493473]
  • Extinction, Species [M0493474]
  • Extraterrestrial Environment [M0008073]
    The environment outside the earth or its atmosphere. The environment may refer to a closed cabin (such as a space shuttle or space station) or to space itself, the moon, or other planets.
  • Fertilization, Delayed [M0008380]
  • Fertilization, Polyspermic [M0008381]
  • Flocculation [M0008561]
  • Floods [M0014522]
  • Fluorescence [M0008603]
    The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
  • Fog [M0022906]
  • Food Browning [M0023761]
  • Food Chain [M0030029]
    The sequence of transfers of matter and energy from organism to organism in the form of FOOD. Food chains intertwine locally into a food web because most organisms consume more than one type of animal or plant. PLANTS, which convert SOLAR ENERGY to food by PHOTOSYNTHESIS, are the primary food source. In a predator chain, a plant-eating animal is eaten by a larger animal. In a parasite chain, a smaller organism consumes part of a larger host and may itself be parasitized by smaller organisms. In a saprophytic chain, microorganisms live on dead organic matter.
  • Food Interactions [M0027828]
  • Food Web [M0030030]
  • Food-Drug Interactions [M0027829]
    The pharmacological result, either desirable or undesirable, of drugs interacting with components of the diet. (From Stedman, 25th ed)
  • Freezing [M0008837]
  • Friction [M0026224]
    Surface resistance to the relative motion of one body against the rubbing, sliding, rolling, or flowing of another with which it is in contact.
  • G Force [M0009628]
  • Gamma Rays [M0008974]
    Very powerful and penetrating, high-energy electromagnetic radiation of shorter wavelength than that of x-rays. They are emitted by a decaying nucleus, usually between 0.01 and 10 MeV. They are also called nuclear x-rays.
  • Gas-Liquid-Solid Phase Transitions [M0445761]
  • Genetic Processes [M0418986]
    Those biological processes that are involved in the transmission of hereditary traits from one organism to another.
  • Genetic Speciation [M0470259]
    The splitting of an ancestral species into daughter species that coexist in time (King, Dictionary of Genetics, 6th ed). Causal factors may include geographic isolation, MUTATION, migration, random GENETIC DRIFT, and HABITAT geometry.
  • Genomic Hybridization [M0015053]
  • Geologic Sediments [M0028394]
    A mass of organic or inorganic solid fragmented material, or the solid fragment itself, that comes from the weathering of rock and is carried by, suspended in, or dropped by air, water, or ice. It refers also to a mass that is accumulated by any other natural agent and that forms in layers on the earth's surface, such as sand, gravel, silt, mud, fill, or loess. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed, p1689)
  • Geothermal Springs [M0449909]
  • Glaciers [M0454316]
  • Glare [M0028957]
    Relatively bright light, or the dazzling sensation of relatively bright light, which produces unpleasantness or discomfort, or which interferes with optimal VISION. (Cline et al., Dictionary of Visual Science, 4th ed)
  • Glycosylation [M0009504]
    The chemical or biochemical addition of carbohydrate or glycosyl groups to other chemicals, especially peptides or proteins. Glycosyl transferases are used in this biochemical reaction.
  • Gravitation [M0009627]
    Acceleration produced by the mutual attraction of two masses, and of magnitude inversely proportional to the square of the distance between the two centers of mass. It is also the force imparted by the earth, moon, or a planet to an object near its surface. (From NASA Thesaurus, 1988)
  • Gravity [M0009630]
  • Grenz Rays [M0023040]
  • Heat [M0009982]
    The form of energy and the sensation of an increase in temperature. Its interest in medicine is largely with reference to its physiological effects, its therapeutic use, and its use in procedures in physics and physical chemistry.
  • Hemagglutination, Viral [M0010025]
    Agglutination of erythrocytes by a virus.
  • Herb-Drug Interactions [M0439215]
    The effect of herbs, other PLANTS, or PLANT EXTRACTS on the activity, metabolism, or toxicity of drugs.
  • High Frequency Waves [M0018398]
  • High-Energy Shock Waves [M0028626]
    Compression waves of large amplitude, across which density, pressure, and particle velocity change drastically. (From McGraw Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Host-Parasite Relations [M0010623]
    The interactions between two organisms, one of which lives at the expense of the other.
  • Hot Springs [M0448422]
    Habitat of hot water naturally heated by underlying geologic processes. Surface hot springs have been used for BALNEOLOGY.
  • Humidity [M0010657]
  • Hurricanes [M0014523]
  • Hydrogen Bonding [M0010717]
    A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.
  • Hydrogenation [M0010727]
    Addition of hydrogen to a compound, especially to an unsaturated fat or fatty acid. (From Stedman, 26th ed)
  • Hydrolysis [M0010729]
    The process of cleaving a chemical compound by the addition of a molecule of water.
  • Hydrostatic Pressure [M0010735]
  • Hydroxylation [M0010769]
    Placing of a hydroxyl group on a compound in a position where one did not exist before. (Stedman, 26th ed)
  • Hypergravity [M0027706]
    Condition wherein the force of gravity is greater than or is increased above that on the surface of the earth. This is expressed as being greater than 1 g.
  • Hypogravity [M0027707]
    Condition wherein the force of gravity is less than or is decreased below that on the surface of the earth. This is expressed as being between 0 and 1 g.
  • HZE Particles [M0005230]
  • Ice Cover [M0454315]
    A thick mass of ICE formed over large regions of land, RIVERS, lakes, ponds, or SEAWATER.
  • Icebergs [M0454318]
  • Incandescence [M0464548]
    Emission of LIGHT by a substance as its temperature is raised. It is sometimes called hot light in contrast to LUMINESCENCE.
  • Infrared Rays [M0011327]
    That portion of the electromagnetic spectrum usually sensed as heat. Infrared wavelengths are longer than those of visible light, extending into the microwave frequencies. They are used therapeutically as heat, and also to warm food in restaurants.
  • Integration, Provirus [M0025393]
  • Interference, Bacterial [M0001342]
  • Intrauterine Device Migration [M0011607]
  • Ion Exchange [M0011675]
    Reversible chemical reaction between a solid, often one of the ION EXCHANGE RESINS, and a fluid whereby ions may be exchanged from one substance to another. This technique is used in water purification, in research, and in industry.
  • Isomerism [M0011770]
    The phenomenon whereby certain chemical compounds have structures that are different although the compounds possess the same elemental composition. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Light [M0012512]
    That portion of the electromagnetic spectrum to which the human eye is sensitive. Light is about 400 to 800 nanometers in wavelength, i.e., between the ultraviolet and infrared spectra.
  • Light, Visible [M0012513]
  • Lightning [M0012516]
  • Lightning Stroke [M0023310]
  • Luminescence [M0464543]
    Emission of LIGHT when ELECTRONS return to the electronic ground state from an excited state and lose the energy as PHOTONS. It is sometimes called cool light in contrast to INCANDESCENCE. LUMINESCENT MEASUREMENTS take advantage of this type of light emitted from LUMINESCENT AGENTS.
  • Lysogeny [M0012840]
    The phenomenon by which a temperate phage incorporates itself into the DNA of a bacterial host, establishing a kind of symbiotic relation between PROPHAGE and bacterium which results in the perpetuation of the prophage in all the descendants of the bacterium. Upon induction (VIRUS ACTIVATION) by various agents, such as ultraviolet radiation, the phage is released, which then becomes virulent and lyses the bacterium.
  • Magnetic Resonance [M0355969]
  • Maillard Reaction [M0023762]
    One of a group of nonenzymatic reactions in which aldehydes, ketones, or reducing sugars react with amino acids, peptides, or proteins. Food browning reactions, such as those that occur with cooking of meats, and also food deterioration reactions, resulting in decreased nutritional value and color changes, are attributed to this reaction type. The Maillard reaction is studied by scientists in the agriculture, food, nutrition, and carbohydrate chemistry fields.
  • Marine Glaciers [M0454317]
  • Marshes [M0496770]
  • Mechanics [M0029052]
    The branch of physics which deals with the motions of material bodies, including kinematics, dynamics, and statics. When the laws of mechanics are applied to living structures, as to the locomotor system, it is referred to as BIOMECHANICS. (From Dorland, 28th ed)
  • Meteorological Factors [M0013532]
    The atmospheric phenomena which pertain to climate and weather.
  • Methylation [M0013618]
    Addition of methyl groups. In histo-chemistry methylation is used to esterify carboxyl groups and remove sulfate groups by treating tissue sections with hot methanol in the presence of hydrochloric acid. (From Stedman, 25th ed)
  • Microbial Inactivation [M0473809]
  • Microbial Viability [M0473808]
    Ability of a microbe to survive under given conditions. This can also be related to a colony's ability to replicate.
  • Microbiologic Phenomena [M0013765]
    Physiological processes and activities of microorganisms, including archaea, bacteria, rickettsia, viruses, protozoa, and fungi.
  • Microclimate [M0013772]
    The climate of a very small area.
  • Microgravity [M0022912]
  • Microwaves [M0013839]
    That portion of the electromagnetic spectrum from the UHF (ultrahigh frequency) radio waves and extending into the INFRARED RAYS frequencies.
  • Motion [M0014099]
    Physical motion, i.e., a change in position of a body or subject as a result of an external force. It is distinguished from MOVEMENT, a process resulting from biological activity.
  • Natural Disasters [M0014524]
    Sudden calamitous events producing great material damage, loss, and distress. They are the result of natural phenomena such as earthquakes, floods, etc.
  • Natural Selection [M0019599]
  • Neutron Diffraction [M0402384]
    The scattering of NEUTRONS by matter, especially crystals, with accompanying variation in intensity due to interference effects. It is useful in CRYSTALLOGRAPHY and POWDER DIFFRACTION.
  • Nuclear Decay [M0018406]
  • Nuclear Energy [M0015026]
    Energy released by nuclear fission or nuclear fusion.
  • Nuclear Fission [M0015031]
    Nuclear reaction in which the nucleus of a heavy atom such as uranium or plutonium is split into two approximately equal parts by a neutron, charged particle, or photon.
  • Nuclear Fusion [M0015032]
    Thermonuclear reaction in which the nuclei of an element of low atomic weight unite under extremely high temperature and pressure to form a nucleus of a heavier atom.
  • Nuclear Magnetic Resonance [M0015034]
  • Nucleic Acid Denaturation [M0015049]
    Disruption of the secondary structure of nucleic acids by heat, extreme pH or chemical treatment. Double strand DNA is "melted" by dissociation of the non-covalent hydrogen bonds and hydrophobic interactions. Denatured DNA appears to be a single-stranded flexible structure. The effects of denaturation on RNA are similar though less pronounced and largely reversible.
  • Nucleic Acid Hybridization [M0015052]
    Widely used technique which exploits the ability of complementary sequences in single-stranded DNAs or RNAs to pair with each other to form a double helix. Hybridization can take place between two complimentary DNA sequences, between a single-stranded DNA and a complementary RNA, or between two RNA sequences. The technique is used to detect and isolate specific sequences, measure homology, or define other characteristics of one or both strands. (Kendrew, Encyclopedia of Molecular Biology, 1994, p503)
  • Nucleic Acid Renaturation [M0015055]
    The reformation of all, or part of, the native conformation of a nucleic acid molecule after the molecule has undergone denaturation.
  • Odors [M0015230]
    The volatile portions of substances perceptible by the sense of smell. (Grant & Hackh's Chemical Dictionary, 5th ed)
  • Ohmic Resistance [M0337369]
  • Optical Rotation [M0015363]
  • Osmosis [M0015496]
    Tendency of fluids (e.g., water) to move from the less concentrated to the more concentrated side of a semipermeable membrane.
  • Osmotic Pressure [M0015499]
    The pressure required to stop osmosis through a semipermeable membrane between a solution and pure solvent. It is proportional to the osmolality of the solution. Osmotic shock is a sudden change in the osmotic pressure to which a cell is subjected, usually in order to cause it to lyse and lose its contents. (Dorland, 28th ed; Stedman, 26th ed)
  • Osmotic Shock [M0015500]
  • Ovulation Inhibition [M0015603]
    Blocking the process leading to OVULATION. Various factors are known to inhibit ovulation, such as neuroendocrine, psychological, and pharmacological agents.
  • Oxidation-Reduction [M0015645]
    A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
  • Parasite Chain [M0030031]
  • Partial Pressure [M0015982]
  • Permeability [M0016368]
    Property of membranes and other structures to permit passage of light, heat, gases, liquids, metabolites, and mineral ions.
  • Pharmacologic Actions [M0029902]
    A broad category of chemical actions and uses that result in the prevention, treatment, cure or diagnosis of disease. Included here are drugs and chemicals that act by altering normal body functions, such as the REPRODUCTIVE CONTROL AGENTS and ANESTHETICS. Effects of chemicals on the environment are also included.
  • Phase Transition [M0444942]
    A change of a substance from one form or state to another.
  • Phosphorylation [M0016733]
    The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.
  • Photobleaching [M0416992]
    Light-induced change in a chromophore, resulting in the loss of its absorption of light of a particular wave length. The photon energy causes a conformational change in the photoreceptor proteins affecting PHOTOTRANSDUCTION. This occurs naturally in the retina (ADAPTATION, OCULAR) on long exposure to bright light. Photobleaching presents problems when occurring in PHOTODYNAMIC THERAPY, and in FLUORESCENCE MICROSCOPY. On the other hand, this phenomenon is exploited in the technique, FLUORESCENCE RECOVERY AFTER PHOTOBLEACHING, allowing measurement of the movements of proteins and LIPIDS in the CELL MEMBRANE.
  • Photolysis [M0016750]
    Chemical decomposition by the action of light and the lysis or solution of cells under the influence of light. (Dorland, 28th ed)
  • Polar Ice Shelf [M0455333]
  • Precipitation [M0017451]
  • Predator Chain [M0030032]
  • Prophage Induction [M0022755]
  • Protein Binding [M0017851]
    The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
  • Protein Glycosylation [M0009505]
  • Radiation [M0018375]
    Emission or propagation of electromagnetic energy (waves/rays), or the waves/rays themselves; a stream of electromagnetic particles (electrons, neutrons, protons, alpha particles) or a mixture of these. The most common source is the sun.
  • Radiation, Ionizing [M0018389]
    Electromagnetic or corpuscular radiation capable of producing ions, directly or indirectly, in its passage through matter. The wavelengths are equal to or smaller than those of short (far) ultraviolet radiation and include gamma and X-rays and high-energy elementary particles.
  • Radiation, Nonionizing [M0018390]
    Electromagnetic radiation which does not produce ions in matter through which it passes. Its wavelengths are generally greater than those of far ultraviolet radiation and range through the longest radio waves.
  • Radio Waves [M0018396]
    Electromagnetic waves with frequencies between about 3 kilohertz (very low frequency - VLF) and 300,000 megahertz (extremely high frequency - EHF). They are used in television and radio broadcasting, land and satellite communications systems, radionavigation, radiolocation, and DIATHERMY. The highest frequency radio waves are MICROWAVES.
  • Radioactivity [M0018405]
  • Rain [M0018460]
    Water particles that fall from the ATMOSPHERE.
  • Raman Scattering [M0496907]
  • Red Tide [M0006483]
  • Remission, Spontaneous [M0018767]
    A spontaneous diminution or abatement of the symptoms of a disease.
  • Rivers [M0448424]
    Large natural streams of FRESH WATER formed by converging tributaries and which empty into a body of water (lake or ocean).
  • RNA Denaturation [M0498355]
  • Saprophytic Chain [M0030033]
  • Scattering, Radiation [M0019471]
    The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
  • Scattering, Small Angle [M0496817]
    Scattering of a beam of electromagnetic or acoustic RADIATION, or particles, at small angles by particles or cavities whose dimensions are many times as large as the wavelength of the radiation or the de Broglie wavelength of the scattered particles. Also know as low angle scattering. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed) Small angle scattering (SAS) techniques, small angle neutron (SANS), X-ray (SAXS), and light (SALS, or just LS) scattering, are used to characterize objects on a nanoscale.
  • Sea Ice Cover [M0454314]
  • Sediments, Marine [M0028393]
  • Shear Strength [M0401864]
    The internal resistance of a material to moving some parts of it parallel to a fixed plane, in contrast to stretching (TENSILE STRENGTH) or compression (COMPRESSIVE STRENGTH). Ionic crystals are brittle because, when subjected to shear, ions of the same charge are brought next to each other, which causes repulsion.
  • Shock Waves, Ultrasonic [M0465120]
  • Short Waves [M0018397]
  • Smog [M0019983]
    A mixture of smoke and fog polluting the atmosphere. (Dorland, 27th ed)
  • Snow [M0019992]
    Frozen water crystals that fall from the ATMOSPHERE.
  • Sol-Gel Phase Transition [M0445760]
  • Solar Activity [M0028933]
    Any type of variation in the appearance of energy output of the sun. (NASA Thesaurus, 1994)
  • Solar Energy [M0020137]
    Energy transmitted from the sun in the form of electromagnetic radiation.
  • Solar Flares [M0028930]
  • Solar Particle Events [M0028931]
  • Sound [M0020178]
  • Space (Astronomy) [M0008074]
  • Species Specificity [M0020221]
    Restriction of a characteristic or response to the members of one species; it usually refers to that property of the immune response which differentiates one species from another on the basis of antigen recognition, but the concept is not limited to immunology and is used loosely at levels higher than the species.
  • Static Electricity [M0028756]
  • Stereoisomerism [M0020475]
    The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
  • Streams [M0448425]
  • Stress, Mechanical [M0020603]
    A purely physical condition which exists within any material because of strain or deformation by external forces or by non-uniform thermal expansion; expressed quantitatively in units of force per unit area.
  • Sunlight [M0020815]
  • Sunspots [M0028932]
  • Surface Properties [M0020855]
  • Surface Tension [M0020856]
  • Sustainable Development [M0005041]
  • Swamps [M0496769]
  • Symbiosis [M0020939]
    The living together of organisms of different species.
  • Tornado [M0014525]
  • Tropical Climate [M0022034]
    A climate which is typical of equatorial and tropical regions, i.e., one with continually high temperatures with considerable precipitation, at least during part of the year. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Ultrahigh Frequency Waves [M0018399]
  • Ultraviolet Rays [M0022240]
    That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.
  • Vacuum [M0022464]
    A space in which the pressure is far below atmospheric pressure so that the remaining gases do not affect processes being carried on in the space.
  • Vaporization [M0022837]
  • Variation (Genetics) [M0022526]
    The phenotypic and genotypic differences among individuals in a population.
  • Very High Frequency Waves [M0018400]
  • Vibration [M0022650]
  • Viral Interference [M0022733]
    A phenomenon in which infection by a first virus results in resistance of cells or tissues to infection by a second, unrelated virus.
  • Viral Physiology [M0027633]
    Biological processes and activities of viruses.
  • Virus Attachment [M0494851]
    The binding of virus particles to receptors on the host cell surface. For enveloped viruses, the virion ligand is usually a surface glycoprotein as is the cellular receptor. For non-enveloped viruses, the virus CAPSID serves as the ligand.
  • Virus Integration [M0025392]
    Insertion of viral DNA into host-cell DNA. This includes integration of phage DNA into bacterial DNA; (LYSOGENY); to form a PROPHAGE or integration of retroviral DNA into cellular DNA to form a PROVIRUS.
  • Virus Internalization [M0494852]
    The entering of cells by viruses following VIRUS ATTACHMENT. This is achieved by ENDOCYTOSIS, by direct MEMBRANE FUSION of the viral membrane with the CELL MEMBRANE, or by translocation of the whole virus across the cell membrane.
  • Virus Membrane Fusion [M0494853]
  • Virus Viability [M0473811]
  • Viscosity [M0022767]
  • Volatilization [M0022836]
  • Volcanic Ash [M0028021]
  • Volcanic Eruption [M0028020]
    The ash, dust, gases, and lava released by volcanic explosion. The gases are volatile matter composed principally of about 90% water vapor, and carbon dioxide, sulfur dioxide, hydrogen, carbon monoxide, and nitrogen. The ash or dust is pyroclastic ejecta and lava is molten extrusive material consisting mainly of magnesium silicate. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • Warm Springs [M0448423]
  • Water Movements [M0022888]
  • Weather [M0022905]
  • Weightlessness [M0022911]
    Condition in which no acceleration, whether due to gravity or any other force, can be detected by an observer within a system. It also means the absence of weight or the absence of the force of gravity acting on a body. Microgravity, gravitational force between 0 and 10 -6 g, is included here. (From NASA Thesaurus, 1988)
  • Wetlands [M0496767]
    Environments or habitats at the interface between truly terrestrial ecosystems and truly aquatic systems making them different from each yet highly dependent on both. Adaptations to low soil oxygen characterize many wetland species.
  • Wind [M0022981]
  • X-Ray Diffraction [M0023036]
    The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
  • X-Rays [M0023041]
    Penetrating electromagnetic radiation emitted when the inner orbital electrons of an atom are excited and release energy - in the same energy range as gamma rays (0.010-10 Mev), but of non-nuclear origin, of shorter wavelength than ultraviolet; soft x-rays or Grenz rays are less penetrating and longer in wavelength than hard x-rays.