| 释义 |
picein|ˈpɪ-, ˈpaɪsiːɪn|
[f. L. pice-us pitchy (f. pix pitch n.1) + -in1.]
1. Chem. [ad. F. picéine (Ch. Tanret 1894, in Compt. Rend. CXIX. 80).] A glucoside present in various trees, notably willows and conifers; p-hydroxyacetophenone-β-glucoside, CH3·CO·C6H4·O·C6H11O5.
1894Jrnl. Chem. Soc. LXVI. i. 616 Picein, C14H18O7, whether anhydrous or hydrated, crystallises in silky, prismatic needles, with a bitter taste. 1934C. C. Steele Introd. Plant Biochem. xi. 118 Picein, C14H18O7, salinigrin, or salicinerin, occurs in several species of Salix and Populus. 1968Jrnl. Chromatogr. XXXVI. 28 The collected fraction of pure trimethylsilyl picein also gave a satisfactory infrared spectrum.
2. Also picein wax, and with capital initial. An inert thermoplastic substance composed of hydrocarbons from rubber, shellac, and bitumen and used for sealing joints against air.
1927G. W. C. Kaye High Vacua v. 69 Khotinsky cement..is widely used in the States for vacuum work, while Picein finds extensive application on the Continent. 1936Discovery Sept. 286/1 A plug of picein wax in the capillary is thereby melted and seals up the tube. 1968Chem. Abstr. LXIX. 6796/1 An elec.-insulating material was developed which permitted one to apply fields of up to 2 × 106 w./cm. The material consisted of varying amts. of quartz powder in picein. 1974L. Holland et al. Vacuum Manual i. 65 Picein. This is a classical vacuum wax—sticks well to metal and glass, is resistant to dilute acid and alkalies, is thermoplastic and made from bituminous substances. 1975Sci. Amer. Feb. 110/3 Only prices are missing from this admirable guide to a world of high-technology commerce. String and sealing wax are gone (although not picein wax, quite). |