单词 | pentacyclic |
释义 | > as lemmaspentacyclic pentacyclic adj. Brit. /ˌpɛntəˈsɪklɪk/ , U.S. /ˌpɛn(t)əˈsɪklɪk/ [ < penta- comb. form + ancient Greek κύκλος cycle n.1 + -ic suffix, after German pentacyclisch (1873 in the passage translated in quot. 1875)] (a) Botany (of a flower) having the parts arranged in five whorls (rare); (b) Chemistry having five rings of atoms in the molecule.ΘΚΠ the world > matter > chemistry > organic chemistry > organic compounds > [adjective] > cyclic compounds pentacyclic1875 cyclic1898 1875 A. W. Bennett & W. T. T. Dyer tr. J. von Sachs Text-bk. Bot. 548 The flowers of Gramineæ and Orchideæ can be traced back to the trimerous pentacyclic type. 1899 Jrnl. Chem. Soc. 76 i. 742 It is one of the first cases observed of the conversion of a pentacyclic into a hexacyclic carbon compound. 1945 W. O. Howarth & L. G. G. Warne Lowson's Textbk. Bot. (ed. 9) xiii. 321 Family Saxifragaceae.—Flowers..usually pentacyclic. 1951 H. J. Deuel Lipids I. iv. 391 The β- and α-amyrin groups..are pentacyclic, while the elemi acids contain a tetracyclic group. 1989 Nature 7 Dec. 670/2 Hopanes and other pentacyclic triterpanes are relatively resistant to microbial degradation. < as lemmas |
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