| 释义 |
polytype|ˈpɒlɪtaɪp|
[a. mod.F. polytype: see poly- and type.]
1. A cast, or form of stereotype, made from an intaglio matrix obtained by pressing a woodcut or other plate into semi-fluid metal; also, a copy of an engraving, of printed matter, etc. made from such a cast. Also attrib. So ˈpolytypage [F. polytypage], the art of making polytypes; ˈpolytype v. trans. [F. polytyper], to produce by polytypage.
1802Paris as it was II. lxxxiv. 534 note, The learned Camus, in his ‘Historical Sketch of Polytypage and Stereotypage’. 1839T. C. Hansard in Encycl. Brit. (ed. 7) XVIII. 567/1 (heading) Of Polytypage. Ibid. 567/2 Guillot..reported that from one engraving, for the 400 livres assignats, he had struck or polytyped 897 mother-punches and 1487 daughters. Ibid., Didot..issued proposals for printing polytyped editions of the classics. Ibid. 568/1 Professor Wilson of Glasgow..thought it possible to make polytypes of glass from engraved copperplates. 1864Webster, Polytype, a.,..as, a polytype plate. 1888Pall Mall G. 28 Nov. 6/1 A handsome quarto volume with portraits, twenty phototypes, and three polytypes.
2. Cryst. A polytypic form of a substance.
In quot. 1916 rendering G. polytypie polytypism.
1916Chem. Abstr. X. 872 (heading) The various modifications of carborundum and the occurrence of polytypes. 1922Mineral. Abstr. I. 318 Three modifications or polytypes of carborundum crystals are distinguished as types I, II, and III. 1951Phil. Mag. XLII. 1019 Unstable structures will not grow if the supersaturation is small: but probably most of the observed polytypes of carborundum differ in thermodynamic potential by an amount negligible compared with the supersaturation actually occurring. 1972Physics Bull. Dec. 712/1 The difficult areas of x ray crystallography, such as in the study of martensitically transformed materials, mixed polytypes of a mineral or certain nonstoichiometric oxides, can be opened up by an electron microscope technique. 1974Nature 22 Feb. 537/2 The basic structural unit of tin sulphide polytypes consists of two layers of hexagonal close-packed sulphide ions with smaller tin ions nested between them. |
