| 释义 |
accelerator|ækˈsɛləreɪtə(r)|
[f. accelerate v. + -or, as if a. L. *accelerātor, n. of agent f. accelerāre; see accelerate. Accelerater is less in accordance with the usual formation of agent nouns from -ate.]
a. He who or that which accelerates or quickens. Specifically applied to the nerves and muscles that increase the speed of certain organic functions; and also to a light vehicle to convey letter-carriers to their districts, and accelerate the delivery of letters.
1611Cotgr., Avanceur: a forwarder, aduancer, hastener, accelerater. 1841Hor. Smith Moneyed Man III. xi. 325 Steam..that stupendous power which has since become the great accelerator of mind and matter. 1861G. M. Musgrave By-Roads 124 Our red-coated postmen drop out of the accelerators. 1875Wood Therap. (1879) 115 The accelerators of the heart..are of course paralyzed by spinal section.
b. Photogr. A substance used to shorten the duration of development of a negative.
1858Sutton & Worden Dict. Photogr. 3 Accelerators. This name is given to any substances used in photographic processes, with a view to shorten the time of exposure, either in the camera or the printing-frame. c1865J. Wylde's Circ. Sci. I. 157/1 By using the above solutions as accelerators, a rich red rose-colour is produced on the plate. 1898Barnet Bk. Photogr. 24 The alkali sets the reducer in action and is called the accelerator. 1932Hardy & Perrin Princ. Optics xi. 223 The developer usually contains four components: a reducing agent, an accelerator, a preservative, and a restrainer.
c. An apparatus for regulating the speed of the engine in a motor-vehicle, esp. for increasing speed; also attrib. as accelerator pedal, the pedal that controls the ‘throttle’; accelerator valve (see quot. 1901).
1900W. W. Beaumont Motor Vehicles viii. 147 The other governor control is known as the accelerator. 1901Motor-Car World Oct. 272/1 A by-pass throttle or ‘accelerator’ valve, by opening which a full charge of mixture can be admitted at any speed of the engine. 1902A. C. Harmsworth et al. Motors vii. 129 If the driver wishes to slow down..he does not necessarily change his gear, but operates the accelerator. 1904A. B. F. Young Complete Motorist ix. 219 The accelerator pedal..has its uses, notably in changing to a higher speed. 1959Chambers's Encycl. IX. 576/2 The driver moves off by depressing the accelerator having first shifted a miniature gear lever..into the normal operating position. Ibid., The..speeds at which such changes occur are partially dependent upon the use..of the accelerator pedal.
d. A substance used to increase the speed of a chemical or organic process, spec. in the vulcanization of rubber or the curing of a plastic.
1908Proc. Chem. Soc. XXIV. 132 (title) Acids as accelerators in the acetylation of amino-groups. 1912H. E. Potts Chem. Rubber Ind. 91 Calcined magnesia is useful..as an accelerator of vulcanization, particularly for resinous rubbers. 1936Ann. Reg. 1935 ii. 56 In controlling the span and speed of life in fruits in store, ethylene is now used as an accelerator of ripening. 1943R. S. Morrell et al. Synthet. Resins (ed. 2) iv. 180 Reduction in curing time of urea⁓formaldehyde moulding powders can be obtained by using ‘latent’ accelerators. 1956Gloss. Terms Concrete (B.S.I.) 5 Accelerators, additives which, when added to concrete during mixing, will appreciably quicken setting and/or hardening.
e. Physics. An apparatus which imparts high velocities to free electrons or other atomic particles by electrical or magnetic means, esp. linear accelerator (see quot. 1962). Cf. cyclotron.
1931Science XXXVIII. 2030 Focusing occurs along the accelerators and is accomplished quite automatically by the curved electric fields between adjacent cylindrical accelerators. 1935Physical Rev. XLVIII. 495/2 The term ‘magnetic resonance accelerator’ is suggested... The first word is added to distinguish it from the apparatus of Sloane and Lawrence which can be called a ‘linear resonance accelerator’. 1942Pollard & Davidson Appl. Nucl. Physics 55 The simplest type of apparatus utilizing this method is the linear multiple accelerator. 1947L. W. Alvarez et al. in Science CVI. 506/2 (title) Initial Performance of a 32-Mev Proton Linear Accelerator. 1953Lancet 17 Oct. 840/2 An 8-million-volt linear accelerator..the first machine of its kind to be built for X-ray therapy. 1958Engineering 7 Feb. 174/3 The accelerator provides a..source of high-energy electrons. 1962Gloss. Terms Nucl. Sci. (B.S.I.) 6 Among the multiple accelerators distinction is made between linear, in which the particles move in a straight line, and cyclic, in which they move in a circular or spiral orbit. |