| 释义 |
reacˈtivity
[f. reactive a. + -ity, after activity.]
a. The state or power of being reactive.
1888Nature 22 Mar. 503/1 The occurrence of colour..is more frequently than not concomitant with a high degree of reactivity. 1896Allbutt's Syst. Med. I. 558 Our knowledge..of vital reactions and reactivity. 1907Chem. Abstr. I. 1395 Transformation of open chains to cyclic compounds enhances their reactivity. 1934Jrnl. Theol. Stud. XXXV. 402 The author would establish that religion consists in simultaneous reactivity of the affective, conative and cognitive elements of mentality. 1949Brit. Jrnl. Psychol. Dec. 86 When the individual's P.G.R. [psychogalvanic reflex] scores are obtained for a given attitude they must be expressed for each person relative to his own general P.G.R. reactivity. 1950Sci. News XV. 70 Consideration of the chemical reactivity of crystals will obviously be focussed primarily on the surfaces. 1956Nature 10 Mar. 477/2 It is assumed that the reactivity of the anhydride is not increased by adsorption. 1972DePuy & Chapman Molec. Reactions & Photochem. vii. 137 Electronic effects are more important than the steric effects in determining the relative reactivity of dienophiles.
b. The rate of reaction of a coke or coal with (orig.) carbon dioxide, or with oxygen, under specified conditions.
1926Rep. Fuel Res. Board 1925 (Dep. Sci. & Industr. Res.) 23 A method has been designed which gives an empirical figure for reactivity to carbon dioxide. 1930Engineering 22 Aug. 251/4 A convenient distinction has been drawn between the combustibility of a coke, denoting the rate at which it burns in oxygen or air, and its reactivity, meaning the rate at which it reacts with carbon dioxide and produces the reducing atmosphere in which the metallic iron is extracted. 1947G. W. Himus Elem. Fuel Technol. xv. 296 The ‘Reactivity Value’ of coke is defined by the Fuel Research Board as ‘the number of millilitres of carbon monoxide formed from 100 millilitres of carbon dioxide’ under certain definitely specified conditions. 1971Materials & Technol. II. x. 601 Gas coke..has a lower reactivity than most coals and is not suitable for use on open fires. Ibid. 604 The reactivity of coke with respect to oxygen is often measured by the Critical Air Blast (C.A.B.) method.
c. Nuclear Physics. A measure of the extent to which a reactor (or part of it) deviates from a steady critical condition (see quot. 1962).
Orig. in a broader sense.
1945H. D. Smyth Atomic Energy viii. 89 The reactivity of the pile was so far above expectations that it would have been beyond the capacity of the control rods to handle if the remainder of the heavy water had been added. 1947Physical Rev. LXXII. 17/1 The reactivity of a chain-reacting pile depends critically on the balance of neutron production, absorption, and leakage. 1954R. Stephenson Introd. Nuclear Engin. vii. 270 In order to operate at any appreciable power, some excess reactivity must be available to overcome the various factors which act to reduce the ability of the chain reactor to multiply neutrons. 1960Gloss. Atomic Terms (U.K.A.E.A.) 44 At any steady state of operation the reactivity is zero. 1962Gloss. Terms Nuclear Sci. (B.S.I.) 97 Reactivity, the value of the expression (keff-1)/keff, which is a measure of the departure of a reactor from the critical condition... keff is the multiplication constant (effective). 1963B. Fozard Instrumentation Nuclear Reactors xii. 149 A sudden change in reactivity in either direction is liable to produce thermal shock in the fuel elements. 1974Encycl. Brit. Macropædia XIII. 3142 The reactivity of the core increases when the rods..are withdrawn. |