| specific epithet | The label (or designation) of a particular species in the binomial nomenclature system. For example: coli is the specific epithet of Escherichia coli. (09 Oct 1997) |
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| specific extinction | Absorbance (of light) per unit path length (usually the centimeter) and per unit of mass concentration. Compare: molar absorption coefficient. Synonym: absorbancy index, absorptivity, extinction coefficient, specific extinction. (05 Mar 2000) |
| specific granule | One of the two main classes of granules found in neutrophils: contain lactoferrin, lysozyme, Vitamin B12 binding protein and elastase. Are released more readily than the azurophil (primary) granules which have typical lysosmal contents. (18 Nov 1997) |
| specific gravity | A measure of concentration. It is the weight of a substance, as compared (as a ratio) with that of an equal volume of water. (27 Sep 1997) |
| specific haemolysin | A sensitizing, complement-fixing, haemolytic antibody that reacts totally or completely with red blood cells of the antigenic type used to stimulate the formation of the haemolysin. (05 Mar 2000) |
| specific heat | The amount of energy (measured in calories or joules) needed to raise thetemperature of one gram of a pure substance by one degree C. (09 Oct 1997) |
| specific heat capacity | <chemistry> The amount of energy required to raise the temperature of one gram of a substance by one degree Celsius (or Kelvin). (09 Jan 1998) |
| specific immune globulin | Globulin fraction of pooled serums (or plasma) selected for high titre of antibodies specific for a particular antigen, or from persons specifically immunised. (05 Mar 2000) |
| specific immunity | The immune status in which there is an altered reactivity directed solely against the antigenic determinants (infectious agent or other) that stimulated it. See: acquired immunity. (05 Mar 2000) |
| specific ionisation | <radiobiology> The number of ion pairs formed per unit of distance along the track of an ion passing through matter (16 Dec 1997) |
| specific optical dispersion | <microscopy> The difference between the refractive indices of light of two different wavelengths, both indices measured at the same temperature, the difference being divided by the specific gravity also measured in the same medium at the test temperature. For convenience, the specific dispersion value is multiplied by ten. (05 Aug 1998) |
| specific parasite | A parasite that habitually lives in its present host and is particularly adapted for the host species. (05 Mar 2000) |
| specific passive immunity | See: acquired immunity. (05 Mar 2000) |
| specific pathogen-free organisms | Animals or humans raised in the absence of a particular disease-causing virus or other microorganism. Less frequently plants are cultivated pathogen-free. (12 Dec 1998) |
| specific reaction | The phenomena produced by an agent that is identical with or immunologically related to the one that has already caused an alteration in capacity of the tissue to react. (05 Mar 2000) |