| OAS | old age security; oral allergy syndrome; osmotically active substance |
|---|---|
| OLS | oubain-like substance |
| PGS | peristent gross splenomegaly; Pettigrew syndrome; plant growth substance; postsurgical gastroparesis... |
| PLS | Papillon-Lefevre syndrome; polydactyly-luxation syndrome; preleukemic syndrome; primary lateral scle... |
| PSDA | Patient Self-Determination Act; psychoactive substance abuse and dependence |
| group velocity | <radiobiology> This is derived from the dispersion relation as Vgroup = dw/dk, the group velocity is the rate at which modulations or information within a wave travel through a given medium. (09 Oct 1997) |
|---|---|
| methyl group | A -CH3 group on a larger molecule. A carbon which is single-bonded to three hydrogens, and has one free bond to the rest of the molecule. (09 Oct 1997) |
| middle group of mesenteric lymph nodes | The mesenteric lymph nodes located along the intestinal (jejunal and ileal) branches of the superior mesenteric artery. Synonym: nodi lymphatici superiores centrales, central mesenteric lymph nodes. (05 Mar 2000) |
| phosphate group | <chemistry> A phosphate group on a larger molecule, where the phosphorus is single bonded to each of the four oxygens, and the other bond of one of the oxygens is attached to the rest of the molecule. This means that the entire group has a net negative charge of -3 (from the free second bonds on the oxygen atoms which are only bonded to the phosphorus atom). Often hydrogen atoms will be attached to the oxygens and sometimes double bonds between the phosphorus and an oxygen are present. (31 Dec 1997) |
| clinical cooperative group | A group of medical institutions cooperating to perform clinical research. (16 Dec 1997) |
| collective group | <zoology> An aggregate of related species of which the generic position is uncertain. According to the Code, for the sake of taxonomic convenience, may be treated as a genus. Such a collective group does not require a type species. Assignment to a collective group is a temporary, convenient, identifying label. (09 Jan 1998) |
| collective-group name | 1. A name established expressly for a collective group. 2. A name established for a nominal genus or subgenus and later used for a collective group. (09 Jan 1998) |
| wenlock group | <geology> The middle subdivision of the Upper Silurian in Great Britain; so named from the typical locality in Shropshire. Source: Websters Dictionary (01 Mar 1998) |
| compatibility group | <molecular biology> A group of plasmids (rings of DNA) which is able to coexist in the same cell with another plasmid from a different group. (05 Jan 1998) |
| platinum group | A group of six amphoteric elements: iridium, osmium, palladium, platinum, rhodium, and ruthenium. (05 Mar 2000) |
| connective tissue group | <physiology> A collective name for mucous tissue, dentin, bone, cartilage, and ordinary connective tissue, all derived from the mesenchyme. (05 Mar 2000) |
| control group | A group of subjects participating in the same experiment as another group of subjects, but which is not exposed to the variable under investigation. See: experimental group. (05 Mar 2000) |
| polar group | <chemistry> Any chemical grouping in which the distribution of electrons is uneven enabling it to take part in electrostatic interactions. (18 Nov 1997) |
| portage group | <geology> A subdivision of the Chemung period in American geology. See Chart of Geology. Origin: So called from the township of Portage in New York. Source: Websters Dictionary (01 Mar 1998) |
| posterior group of axillary lymph nodes | Node's of the axillary region located along the subscapular vein and its tributaries; they receive afferent vessels from the dorsal surface of the thorax and scapular region, and send efferent vessels to the central group of lymph nodes. Synonym: nodi lymphatici axillares subscapulares, posterior group of axillary lymph nodes. (05 Mar 2000) |