| 释义 |
radioactive, a.|reɪdɪəʊˈæktɪv|
Also with hyphen.
[f. radio- 2 + active a.]
1. Of an atomic nucleus, a substance, etc.: (capable of) undergoing spontaneous nuclear decay involving emission of ionizing radiation in the form of particles or gamma rays; spec. of an element: consisting of a radioactive isotope.
1898Nature 28 July 312/1 On a new radio-active substance contained in pitchblende. 1900P. Kropotkin in 19th Cent. Dec. 932 Material particles projected from the radio-active bodies. 1904E. Rutherford Radio-Activity v. 161 This increase of activity is due to the continuous production by the radium of the radio-active emanation or gas, which is occluded in the radium compound. 1913Q. Rev. July 117 The disintegration of atom after atom of the radio-active element. 1926R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity i. 4 We now define a substance as being radioactive when the atoms of which it is composed disintegrate spontaneously, and regardless of whether or not the emission of rays can readily be detected in the process. 1935Nature 9 Nov. 754/1 The radio⁓active phosphorus in the urine..was then investigated. 1952New Biol. XIII. 63 The introduction of radio-active iodine (I131) has provided a tool..of the greatest value..to the comparative physiologist. 1955Times 18 Aug. 8/6 Radioactive caesium recovered from waste fission products has been made available to the Royal Marsden Hospital..for treatment of deep-seated cancer. 1957Times Lit. Suppl. 15 Nov. p. iv/3 Death waits for us on the zebra crossing; and tomorrow morning's milk may be radio⁓active. 1959Daily Tel. 10 Mar. 16/3 He also asked the secretary..to advise us of the possibility of any appreciable rise in radioactive content in the river which may result. Ibid. 23 Mar. 18/3 The rate of descent from the stratosphere of radio-active debris, including strontium 90, from nuclear explosions. 1961G. R. Choppin Exper. Nuclear Chem. vi. 77 The average time of existence τ of a radioactive atom before decay is the reciprocal of the decay constant. 1966C. R. Tottle Sci. Engin. Materials i. 23 Almost all elements of atomic number greater than Z = 83 (bismuth) are naturally radioactive. 1969N. W. Pirie Food Resources v. 127 Marine organisms concentrate several of the radioactive isotopes enormously. 1977Nature 14 Apr. 585/1 Any radio⁓active chemical which enters one organism may be transported a considerable distance as it travels through the food chain.
2. Of a process, phenomenon, etc.: of, pertaining to, involving, or produced by radioactivity.
1903Phil. Mag. V. 580 These rays have not yet been sufficiently examined to make any discussion possible of the part they play in radioactive processes. 1906Nature 25 Oct. 634/1 The escape of the emanation causes a radio-active contamination of the laboratory which renders delicate experiments on radio-activity or ionisation very difficult. 1919Phil. Mag. XXXVII. 537 Results showed..that..the H atoms from a glass α-ray tube were a product of radio⁓active disintegration. 1926R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity vii. 78 Ions are produced along the tracks of the radioactive rays. 1938Ibid. (ed. 2) iv. 55 (heading) Absorption measurements with γ-rays as applied to radioactive analysis. 1956A. H. Compton Atomic Quest v. 303 At the instant of the flash there is a burst of radio⁓active rays of enormous magnitude. 1961G. R. Choppin Exper. Nuclear Chem. i. 3 The formation of a more stable nucleus as a result of radioactive decay is accompanied by a release of energy. 1969Bennison & Wright Geol. Hist. Brit. Isles i. 6 Only the limitations of radioactive dating..are here dealt with. 1971Nature 6 Aug. 367/2 The dating of the earlier part of the Pleistocene period still presents considerable problems, but further exploitation of the various ‘radioactive clocks’ should eventually overcome these difficulties. 1977Ibid. 10 Mar. 106/1 Even the most resolute proclaimers of radioactive doom seem to have convinced themselves that fusion power will be gentle and on a homely scale, and that radioactive pollution will be a thing of the past when dirty fission gives way to clean fusion.
3. fig. (Possibly also influenced by radio- 4.)
1905S. Macnaughtan Lame Dog's Diary x. 128 Eliza has found that London is radio-active, hence enjoyable. And Eliza had only been once to the Royal Institution when she said it! 1909A. Bennett Glimpse x. 71 She did not begin to live, socially, till her body was at rest... Then her individuality would be radioactive whereas the individuality of Inez spent itself mildly without ceasing in a persuasive appeal to the sight. 1919D. H. Lawrence in Eng. Rev. June 477 Our plasmic psyche is radio-active, connecting with all things, and having first-knowledge of all things. 1923L. P. Smith S.P.E. Tract xii. 57 This radio-active quality of popular idiom, this power to give out life and never lose it. 1934Punch 5 Sept. 280/2 The invalid son, who ultimately comes out at least all even in the contest with the radio-active Audrey. 1955Koestler Trail of Dinosaur 12 The logic of expediency leads to the atomic disintegration of morality, a kind of radioactive decay of all values. 1974Times 27 May 6/1 His [sc. Byron's] was a radio-active personality that had shattering effects on all who came in contact with him.
4. Special collocations: radioactive constant, the average proportion of nuclei of a given radioactive nuclide which will decay in a given time; now usu. called decay constant; = disintegration constant; radioactive equilibrium, a condition in which the quantities of radioactive daughter nuclides in a material remain constant because each is decaying at the same rate as that at which it is being formed; radioactive indicator = indicator 2 b (ii); radioactive series, a series of radioactive nuclides each member of which decays into the next, together with a non-radioactive end-product; the series of transformations relating such a set of nuclides; (four such series exist among the nuclides heavier than lead: see quot. 1974); radioactive tracer (see tracer1); radioactive waste, waste material that is radioactive, esp. spent nuclear fuel.
1903Rutherford & Soddy in Phil. Mag. V. 581 The law of radioactive change may therefore be expressed in the one statement—the proportional amount of radioactive matter that changes in unit time is a constant... λ may therefore be suitably called the ‘radioactive constant’. 1923Glazebrook Dict. Appl. Physics IV. 574/2 λ, the radioactive constant, represents the average fraction of the number of atoms which break up per unit time. 1942J. D. Stranathan ‘Particles’ of Mod. Physics viii. 325 (heading) Relationships among the several radioactive constants.
1904E. Rutherford Radio-Activity vii. 189 In uranium and thorium compounds there is a continuous production of active matter which keeps the compound in radio-active equilibrium. 1923Glazebrook Dict. Appl. Physics IV. 576/1 If a radioactive mineral is sealed up so that the products of transformation are allowed to accumulate, a stage is ultimately reached in which the amount of each product formed is equal to the amount transformed per unit time throughout the series... Material which has reached this state is said to be in radioactive equilibrium. 1946Physical Rev. LXIX. 672/2 Since the age of the earth is much greater than the life of C14 a radioactive equilibrium must exist in which the rate of disintegration of C14 is equal to the rate of production. 1968Musset & Lloret Conc. Encycl. Atom 95/2 Radioactive equilibrium is also referred to when a radioactive body is produced by nuclear reaction, such as bombarding a target with a beam of particles having a constant intensity. After a certain time, the body formed in the nuclear reaction also acquires a constant radioactivity through the balance of its rates of formation and decay.
1923Biochem. Jrnl. XVII. 439 (heading) A contribution to the application of the method of radioactive indicators in the investigation of the change of substance in plants. 1943Radioactive indicator [see indicator 2 b (ii)].
1923Phil. Mag. XLVI. 647 There are only four complete radio-active series of the type that is known. 1926R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity xxiv. 184 The element thorium is the parent element of a radioactive series. 1956I. Asimov Inside Atom v. 85 The entire set of changes is an example of a radioactive series. This particular one we have been talking about is the uranium-238 series. 1974Encycl. Brit. Micropædia VIII. 378/2 Radioactive series, any of four independent sets of unstable atomic nuclei that decay through a sequence of nuclear transformations until a stable nucleus is achieved... Three of the sets, the thorium series, uranium series, and actinium series..are headed by naturally occurring species of unstable nuclei whose half⁓lives are comparable to the age of the Earth... The fourth set, neptunium series.., came to light after the discovery of induced radioactivity (1934).
1947C. D. Coryell in C. Goodman Sci. & Engin. of Nucl. Power I. vii. 249 In general, radioactive wastes from separation processes must be stored indefinitely in systems free from leaks. 1958Engineering 21 Feb. 236/2 The problem of radioactive waste disposal is finally solved only by the complete natural decay of the constituent fission product activity—a process which may take hundreds of years. 1969N. W. Pirie Food Resources v. 127 Nuclear power stations discharge slightly radioactive waste into the sea near the shore. 1977Nature 10 Mar. 109/2 One of the major obstacles to have arisen to the expanded use of nuclear power has focused on the reprocessing and storage of radioactive waste.
Hence radioˈactively adv., by radioactive decay; with radioactive material; by means of a technique dependent upon radioactivity.
1925J. Joly Surface-Hist. of Earth ix. 147 This method would not be reliable..if the lead was in either case unstable—i.e. ultimately changed radioactively into something else. 1936O. Hahn Appl. Radiochem. vi. 171 In the Kjeldahl determination of nitrogen, the ammonia formed is led into a solution of lead nitrate that has been radio⁓actively activated. 1948Physical Rev. LXXIV. 279/1 Individual atoms of this isotope transform radioactively. 1959Oxf. Univ. Gaz. 16 Mar. 795/2 In the event of nuclear warfare, farm products, particularly milk, obtained from a radio-actively contaminated soil might be positively harmful. 1968R. A. Lyttleton Mysteries Solar Syst. ii. 65 The release of radioactively produced energy means that the internal temperatures of the planets will have risen from their initial values. 1976Nuclear Sci. Internat. Nov. 36/2 Direct measurements of bronchial clearance rates (by inhalation of radioactively labelled dust followed by measurements of radiation from the chest) show little difference between smokers and non-smokers. |