- 産業: Library & information science
- Number of terms: 152252
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The National Library of Medicine (NLM), on the campus of the National Institutes of Health in Bethesda, Maryland, is the world's largest medical library. The Library collects materials and provides information and research services in all areas of biomedicine and health care.
New chemical species AB, each molecular entity of which is formed by direct combination of two separate molecular entities A and B in such a way that there is change in connectivity, but no loss, of atoms within the moieties A and B.
Note 1: Stoichiometries other than 1:1 are also possible, e.g. a bis-adduct (2:1). An ‘intramolecular adduct’ can be formed when A and B are groups contained within the same molecular entity.
Note 2: This is a general term which, whenever appropriate, should be used in preference to the less explicit term complex. It is also used specifically for products of an addition reaction.
Industry:Biology; Chemistry
Logarithm of the ratio of incident to transmitted radiant power through a sample (excluding the effects of sample cell walls). Depending on the base of the logarithm, a decadic and Napierian absorbance are used. Symbols: A, A10, Ae. This quantity is sometimes called extinction, although the term extinction, better called attenuance, is reserved for the quantity which takes into account the effects of luminescence and scattering as well.
Note: When natural logarithms are used, the Napierian absorbance is the logarithm to the base e of the incident spectral radiant power, essentially monochromatic, divided by the transmitted spectral radiant power, Pλ.
Industry:Biology; Chemistry
1. Transfer in farming and agricultural processing of a component from one system such as soil or feed to another system such as a plant, animal or human being: carry-over is expressed as the concentration of the component in the second system divided by its concentration in the first.
2. Process in analytical studies by which materials are carried into a reaction mixture in which they do not belong.
3. Persistence of a substance in soil, e.g., a pesticide, such that injury may occur subsequently to a new crop.
4. Persistence of a test substance in participants undergoing a cross-over clinical trial study, in which each participant randomly receives the placebo and test substance with an intervening washout period.
Industry:Biology; Chemistry
Breakdown of a substance catalysed by enzymes in vitro or in vivo. This may be characterized for purposes of hazard assessment as:
# Primary. Alteration of the chemical structure of a substance resulting in loss of a specific property of that substance.
# Environmentally acceptable. Biodegradation to such an extent as to remove undesirable properties of the compound. This often corresponds to primary biodegradation but it depends on the circumstances under which the products are discharged into the environment.
# Ultimate. Complete breakdown of a compound to either fully oxidized or reduced simple molecules (such as carbon dioxide/methane, nitrate/ammonium, and water. It should be noted that the products of biodegradation can be more harmful than the substance degraded.
Industry:Biology; Chemistry
1. Ability to produce offspring frequently and in large numbers.
2. In demography, the physiological ability to reproduce.
3. Ability to produce offspring within a given period of time.
Industry:Biology; Chemistry
1. Abnormally low dioxygen content or tension.
2. Deficiency of dioxygen in the inspired air, in blood or in tissues, short of anoxia.
Industry:Biology; Chemistry
1. Act of pouring over or through, especially the passage of a fluid through the vessels of a specific organ.
2. Liquid poured over or through an organ or tissue.
Industry:Biology; Chemistry
1. Action of entering or passing through a cell membrane.
2. Ability or power to enter or pass through a cell membrane.
Industry:Biology; Chemistry
1. Actions taken to prevent or minimize adverse effects to the natural environment.
2. Complex of measures including monitoring of environmental pollution, development and practice of environmental protection principles (legal, technical, and hygienic), including risk assessment, risk management and risk communication.
Industry:Biology; Chemistry
1. Agent that induces a change in a chromosome or gene that leads to the induction of tumors after a second agent, called a promoter, is administered to the tissue.
2. Substance that starts a chain reaction.
Industry:Biology; Chemistry
