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quaternary group

См. также в других словарях:

  • Quaternary science — is an inter disciplinary field of study focusing on the Quaternary period, which encompasses the last 2.6 million years. The field studies the last ice age and the recent interstadial the Holocene and uses proxy evidence to reconstruct the past… …   Wikipedia

  • Quaternary ammonium muscle relaxants — are quaternary ammonium salts used as drugs for muscle relaxation, most commonly in anasthesia. It is necessary to prevent spontaneous movement of muscle during surgical operations. Muscle relaxants inhibit neuron transmission to muscle by… …   Wikipedia

  • Quaternary ammonium cation — Quaternary ammonium cations, also known as quats, are positively charged polyatomic ions of the structure NR4+ with R being alkyl groups. Unlike the ammonium ion NH4+ itself and primary, secondary, or tertiary ammonium cations, the quaternary… …   Wikipedia

  • quaternary ammonium compound — n any of numerous strong bases and their salts derived from ammonium by replacement of the hydrogen atoms with organic radicals and important esp. as surface active agents, disinfectants, and drugs called also quat, quaternary * * * an organic… …   Medical dictionary

  • quaternary — /kwot euhr ner ee, kweuh terr neuh ree/, adj., n., pl. quaternaries. adj. 1. consisting of four. 2. arranged in fours. 3. (cap.) Geol. noting or pertaining to the present period of earth history, forming the latter part of the Cenozoic Era,… …   Universalium

  • Quaternary extinction event — Late Pleistocene landscape of northern Eurasia The Quaternary period saw the extinctions of numerous predominantly larger, especially megafaunal, species, many of which occurred during the transition from the Pleistocene to the Holocene epoch.… …   Wikipedia

  • quaternary — I. adjective Etymology: Latin quaternarius, from quaterni four each Date: 1605 1. a. of, relating to, or consisting of four units or members b. of, relating to, or being a number system with a base of four 2. capitalized of, relating to, or being …   New Collegiate Dictionary

  • quaternary — quat•er•nar•y [[t]ˈkwɒt ərˌnɛr i, kwəˈtɜr nə ri[/t]] adj. n. pl. nar•ies 1) consisting of four 2) arranged in fours 3) gel (cap.) of or pertaining to the present period of earth history forming the latter part of the Cenozoic Era, originating… …   From formal English to slang

  • quaternary ammonium — noun An ammonium group in which each hydrogen has been replaced by an alkyl or aryl group …   Wiktionary

  • quaternary — n. group of four; number four; second part of the Cenozoic era, present geologic period (Geology)qua·ter·na·ry || kwÉ‘tÉ™rnerɪ /kwÉ™ tɜːnÉ™rɪ adj. composed of four parts; arranged in quarters; pertaining to the present geological period,… …   English contemporary dictionary

  • quaternary — /kwɒˈtɜnəri / (say kwo ternuhree) adjective 1. consisting of four. 2. arranged in fours. –noun (plural quaternaries) 3. a group of four. 4. the number four. {Middle English, from Latin quaternārius} …  

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