| densitometry, X-ray | Measurement of the degree of darkening of X-ray film by means of a photocell which measures light transmission through the film. (12 Dec 1998) |
|---|---|
| incident ray | The ray that strikes the surface before reflection. (05 Mar 2000) |
| infrared ray | See: infrared. (05 Mar 2000) |
| fast ray | <microscopy> The fast ray or fast component for a crystal or fibre corresponds to the lower refractive index. (05 Aug 1998) |
| lateral X-ray | An X-ray picture taken from the side. (12 Dec 1998) |
| absolute unit | A unit whose value is constant regardless of place or time and not derived from dependent on gravitation. (05 Mar 2000) |
| alexin unit | The smallest amount (highest dilution) of complement that will cause haemolysis of a unit of red blood cells in the presence of a haemolysin unit. Synonym: alexin unit. (05 Mar 2000) |
| Allen-Doisy unit | The quantity of oestrogen capable of producing in a spayed mouse a characteristic change in the vaginal epithelium, namely, disappearance of leukocytes and appearance of cornified cells, as determined by a vaginal smear; equal approximately to one-half of an estrone unit. Synonym: mouse unit. (05 Mar 2000) |
| amboceptor unit | haemolysin unit |
| androgen unit | The androgenic activity of 100 ug (0.1 mg) of crystalline androsterone as assayed by the comb growth response in capons. (05 Mar 2000) |
| antigen unit | The smallest amount of antigen that, in the presence of specific antiserum, will fix 1 complement unit. (05 Mar 2000) |
| antitoxin unit | A unit expressing the strength or activity of an antitoxin; in general, determined with reference to a preserved standard preparation of antitoxin. See: L doses. (05 Mar 2000) |
| antivenene unit | The amount of antivenum which, injected in the ear vein, will protect 1 g weight of rabbit against a fatal dose of snake venom. (05 Mar 2000) |
| atomic mass unit | <chemistry> One-twelfth the mass of a neutral atom of the most abundant isotope of carbon. (16 Dec 1997) |
| Bethesda unit | A measure of inhibitor activity: the amount of inhibitor that will inactivate 50% or 0.5 unit of a coagulation factor during the incubation period. Origin: Bethesda, MD (05 Mar 2000) |