natural purification (자정 작용
| natural language processing | Computer processing of a language with rules that reflect and describe current usage rather than prescribed usage. (12 Dec 1998) |
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| natural mutation | A mutation which occurs by itself without first being affected by a mutagen, for example during the process of DNA replication. Spontaneous mutations arise at a remarkably constant rate. The rate that spontaneous mutations arise has been used as an evolutionary clock to estimate how closely related two (or more) separate species are to each other. (09 Oct 1997) |
| natural passive immunity | Immunity conferred by the mother on the foetus or newborn. (14 Nov 1997) |
| natural pigment | A naturally occurring coloured compound; absorbs light in the visible range of the electromagnetic spectrum. Compare: structural colour. Synonym: biochrome. (05 Mar 2000) |
| natural products | Naturally occurring compounds that are end products of secondary metabolism; often, they are unique compounds for particular organisms or classes of organisms. (05 Mar 2000) |
| natural selection | The hypothesis that genotype environment interactions occurring at the phenotypic level lead to differential reproductive success of individuals and hence to modification of the gene pool of a population. (18 Nov 1997) |
| immunity, natural | The capacity of a normal organism to remain unaffected by microorganisms and their toxins. It results from non-specific mechanisms such as genetic endowment, naturally occurring antiviral and bactericidal substances, phagocytosis, and constitutional factors such as body temperature, oxygen tension, and age. (12 Dec 1998) |
| killer cells, natural | Cells responsible for spontaneous cytotoxicity of a variety of tumour cells without prior immunization. These natural killer cells are found in non-immune humans and experimental animals and are thought by some to be the same as killer cells (killing by antibody-dependent cell cytotoxicity), but they can also kill in the absence of antibody. (12 Dec 1998) |
| bacterial food poisoning | A term commonly used to refer to conditions limited to enteritis or gastroenteritis (excluding the enteric fevers and the dysenteries) caused by bacterial multiplication per se or by a soluble bacterial exotoxin. (05 Mar 2000) |
| health food | A non-medical term defined by the lay public as a food that has little or no preservatives, which has not undergone major processing, enrichment or refinement and which may be grown without pesticides. Health foods have been attributed with the ability to prevent the development of diseases, slow the aging process, and prolong life. (12 Dec 1998) |
| salmonella food poisoning | Poisoning caused by ingestion of food harboring species of salmonella. Conditions of raising, shipping, slaughtering, and marketing of domestic animals contribute to the spread of this bacterium in the food supply. (12 Dec 1998) |
| staphylococcal food poisoning | Poisoning by staphylococcal toxins present in contaminated food. (12 Dec 1998) |
| Staphylococcus food poisoning | Outbreaks commonly caused by staphylococcal enterotoxin and characterised by an abrupt onset of gastroenteritis within several hours after ingestion of the food contaminated with the preformed exotoxin; vomiting is usually more severe and diarrhoea less severe than in infectious forms of bacterial food poisoning. (05 Mar 2000) |
| infant food | Food processed and manufactured for the nutritional health of children in their first year of life. (12 Dec 1998) |
| essential food factors | Those substances required in the diet: certain amino acids and unsaturated fatty acids, vitamins, essential minerals, etc. (05 Mar 2000) |