| 释义 |
epi-, prefix
repr. Gr. ἐπι- (before an unaspirated vowel usually ἐπ-, before an aspirated vowel ἐϕ-, represented in Eng. by ep-, eph-), used in prepositional and advb. senses, ‘upon, at, or close upon (a point of space or time), on the ground or occasion of, in addition’.
1. In words derived from compounds which either were, or might legitimately have been, formed already in Greek. Also in mod. scientific terms after the analogy of words derived from Gr.; chiefly with sense ‘placed or resting upon’, as in epicalyx, epicorolline.
2. a. In mod. Chemistry employed in the names epibromhydrin, epichlorhydrin, epicyanhydrin, epiiodohydrin, denoting substances of analogous composition belonging respectively to the bromhydrin, chlorhydrin, etc. series. They contain one equivalent of a salt-radical with 3 of carbon, 5 of hydrogen, and 1 of oxygen.
1857W. A. Miller Elem. Chem. III. 382 Epichlorhydrin (C6H5O2Cl)..is a limpid oil. 1910Encycl. Brit. I. 532/2 It [sc. acrolein] is also produced by the action of sodium on a mixture of epichlorhydrin and methyl iodide. 1956Nature 21 Jan. 122/1 A polymer of repeating unit..which may be prepared from 4,4′-dihydroxydiphenoxyethane and epichlorhydrin in the presence of sodium hydroxide.
b. [a. G. epi- (E. Votoček 1911, in Ber. d. Deut. Chem. Ges. XLIV. 360).] Occas. prefixed to the name of a sugar or sugar derivative to indicate that a second compound, bearing the prefix, is an epimer of the first.
1911[see epimer]. 1932H. Pringsheim Chem. Monosaccharides & Polysaccharides iii. 38 Mannose might be termed ‘epiglucose’. 1963K. Mayer tr. Stanĕk et al. Monosaccharides xviii. 507 The term epi-glucosamine is today reserved for d-mannosamine (2-amino-2-deoxy-d-mannose).
3. In Mineralogy prefixed to the names of certain minerals to form names of other minerals closely resembling them in composition, as in epibouˈlangerite, a sulph-antimonide of lead resulting from the decomposition of boulangerite. epiˈchlorite, a hydrous silicate of aluminium, iron, and magnesium. epiˈdiorite, a mineral differing from diorite in that the hornblende it contains is fibrous. epiˈstilbite, a zeolitic mineral, a hydrous silicate of aluminium, calcium, and sodium.
1872Dana Min., 1st App. 5 Epiboulangerite. 1850Dana Min. 263 Epichlorite..fuses only in thin fibres and with difficulty. 1879Rutley Study Rocks xiii. 245 The viridite (chlorite, epichlorite, or chloritic matter). 1887Dana Manual Min. 482 Epidioryte consists of plagioclase with hornblende, some quartz, a little orthoclase, and some pyroxen. 1826Edin. Jrnl. Sc. IV. 286 The cleavage of epistilbite is quite perfect. |