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printed circuit

(Encyclopedia)printed circuit, electric circuit in which the conducting paths connecting circuit components are affixed to a flat, insulating base board. The base is typically of plastic, glass, ceramic, or some ot...

antisense

(Encyclopedia)antisense, DNA or RNA manipulated in a laboratory so that its components (nucleotides) form a complementary copy of normal, or “sense,” messenger RNA (mRNA; see nucleic acid). Antisense techniques...

phosgene

(Encyclopedia)phosgene fŏsˈjēn [key], colorless poison gas, first used during World War I by the Germans (1915). When dispersed in air, the gas has the odor of new-mowed hay. The gas is highly toxic; when inhale...

Trail

(Encyclopedia)Trail, city (1991 pop. 7,919), SE British Columbia, Canada, on the Columbia River just N of the Wash. border. It is a metal-smelting center for a mining area that produces lead, zinc, silver, and gold...

ribosome

(Encyclopedia)ribosome: see cell; nucleic acid. ...

aqua fortis

(Encyclopedia)aqua fortis äkˈwə fôrˈtĭs [key]: see nitric acid. ...

urea

(Encyclopedia)CE5 urea yo͝oēˈə [key], organic compound that is the principal end product of nitrogen metabolism in most mammals. Urea was the first animal metabolite to be isolated in crystalline form; its c...

phenylalanine

(Encyclopedia)CE5 phenylalanine fĕnˌəlălˈənēnˌ [key], organic compound, one of the 22 α-amino acids commonly found in animal proteins. Only the l-stereoisomer appears in mammalian protein. It is one of ...

caustic

(Encyclopedia)caustic, any strongly corrosive chemical substance, especially one that attacks organic matter. A caustic alkali is a metal hydroxide, especially that of an alkali metal; caustic soda is sodium hydrox...

saturated fat

(Encyclopedia)saturated fat, any solid fat that is an ester of glycerol and a saturated fatty acid. The molecules of a saturated fat have only single bonds between carbon atoms; if double bonds are present in the f...