| alpha-naphthylthiourea | 1-(1-Naphthyl)-2-thiourea;a derivative of thiourea; a highly toxic antithyroid agent, especially to small mammals, causing pulmonary oedema, fatty degeneration of the liver, and low body temperature; used as a rat poison. Acronym: ANTU (05 Mar 2000) |
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| alpha-neoagarooligosaccharide hydrolase | <enzyme> Hydrolyzes the alpha-1,3 linkage of neoagarooligosaccharides; from marine bacterium, vibrio sp.; mw 42 kD; amino acid sequence has been determined Registry number: EC 3.2.1.- Synonym: alpha-naos hydrolase (26 Jun 1999) |
| alpha-oxidation | A form of oxidation of fatty acids in which carbons are removed one at a time in the form of CO2; the alpha-carbon is first hydroxylated and then converted into a carbonyl; a deficiency of this pathway is associated with Refsum's disease. (05 Mar 2000) |
| alpha particle | <physics> A radioactive particle made up of two protons and two neutrons, these particles are created by the decay of a radioactive material or by nuclear bombardment, and they are the same as the nucleus of a helium-4 atom. (09 Oct 1997) |
| alpha particles | Positively charged particles composed of two protons and two neutrons, i.e., helium nuclei, emitted during disintegration of very heavy isotopes; a beam of alpha particles or an alpha ray has very strong ionizing power, but weak penetrability. (12 Dec 1998) |
| alpha-phenoxyethylpenicillin potassium | A penicillin preparation that is stable in gastric acid and is rapidly but only partially absorbed from the gastrointestinal tract. Synonym: alpha-phenoxyethylpenicillin potassium, penicillin B. (05 Mar 2000) |
| alpha-phenoxypropylpenicillin potassium | A semisynthetic acid-stable penicillin that may be more effective than penicillin G. Synonym: alpha-phenoxypropylpenicillin potassium. (05 Mar 2000) |
| alpha-pinene oxide lyase | <enzyme> From nocardia sp. Strain p18.3; catalyses the cleavage of both rings of the bicyclic structure with the formation of 2-methyl-5-isopropylhexa-2,5-dienal Registry number: EC 4.1.2.- Synonym: alpha-pinene oxide lyase (decyclizing) (26 Jun 1999) |
| alpha-prodine hydrochloride | See: alphaprodine. (05 Mar 2000) |
| alpha radiation | <physics, radiobiology> The most easily absorbable type of radiation, it consists of a stream of alpha particles, doubly ionised helium nuclei which are electrically charged and produce intense ionisation in matter. Alpha radiation can be deflected in electromagnetic fields. (09 Oct 1997) |
| alpha ray | <physics> A radioactive particle made up of two protons and two neutrons, these particles are created by the decay of a radioactive material or by nuclear bombardment, and they are the same as the nucleus of a helium-4 atom. (09 Oct 1997) |
| alpha rhythm | Brain waves in the encephalogram which have a frequency of 8 to 13 per second. They are typical of the normal person awake and in a quiet resting state, and occur principally in the occipital region. (12 Dec 1998) |
| alpha-ribazole | 1-alpha-d-ribofuranosyl-5,6-dimethylbenzimidazole;the benzimidazole nucleoside in vitamin B12. (05 Mar 2000) |
| alpha-santonin-1,2-reductase | <enzyme> From pseudomonas cichorii s.; catalyses the reduction of the 1,2-double bond of santonin; NADH or NADPH dependent Registry number: EC 1.3.1.- Synonym: santonin 1,2-reductase (26 Jun 1999) |
| alpha-sarcin | A fungal toxin that acts on the large subunit of rRNA and inactivates the ribosome. (05 Mar 2000) |