| 释义 |
proton|ˈprəʊtɒn|
[a. Gr. πρῶτον, neut. sing. of πρῶτος first; but see sense 2 below.]
‖1. Biol. (See quot. 1895.)
1893Nation 11 May 350/2 Mark translates it [Ger. anlage] fundament. Minot adopts it as an English word... Neither seems to have thought of reverting to Aristotle, whose phrases..ἡ πρώτη οὐσία, τό πρῶτον, suggest the short word proton. 1895Buck's Handbk. Med. Sc. IX. 104 (note), This neuter noun [proton] is employed to designate the primitive, undifferentiated mass or rudiment of a part, thus in the sense of Anlage of the German embryologists. 1898Nature 15 Dec. 156/2 Dr. Arthur Willey recently suggested in these columns..the word primordium as an accurate..rendering of Anlage. Prof. B. G. Wilder.. thinks the shorter word proton, already familiar in numerous compounds, and used by many biologists, is a better equivalent.
2. Physics. A stable sub-atomic particle which has a positive charge numerically equal to that of the electron, forms a part (or in the commonest isotope of hydrogen the whole) of all atomic nuclei, and is a baryon with a mass of 938·3 MeV (1836 times that of the electron), spin of ½, and isospin of ½; it is now usu. regarded as a particular state of a nucleon. [Perh. suggested by, if not derived from, the name of William Prout (1785–1850), English chemist and physician, who suggested that hydrogen was a constituent of all the elements.]
1920Engineering 17 Sept. 382/3 Sir Ernest [Rutherford], replying, said that..a clear nomenclature was certainly wanted; the term ‘prouton’ for [read or] ‘proton’ might be suitable for the H nucleus. 1922J. Mills Within Atom ii. 13 The hydrogen atom is composed of only one proton and one electron. 1926Nature 9 Oct. 526/2 Recourse was had to passing fairly large amounts of hydrogen—up to one litre—through heated palladium, in the hope that at the moment of exit a fraction of the protons and electrons would combine to form the helium nucleus. 1942J. D. Stranathan ‘Particles’ Mod. Physics xi. 416 By firing alpha particles through a cloud chamber filled with nitrogen, it has been possible to photograph the track of the proton leaving the nitrogen nucleus. 1955Sci. News Let. 10 Sept. 170/1 The number of protons in the nucleus determines the kind of matter the atom forms, whether hydrogen, uranium, iron, carbon or any other. 1962H. D. Bush Atomic & Nucl. Physics iii. 62 Isotopes will occur where atomic nuclei have the same number of protons but differing numbers of neutrons. 1968,1972[see neutron]. 1979Nature 7 June 483/2 A novel prediction of many such grand unified models is that baryon number is not absolutely conserved; so the proton may actually decay!
3. Special Comb. (all for sense 2): proton accelerator, a particle accelerator designed to accelerate protons; proton acceptor, donor, a substance or species which is able to accept protons from, or give them up to, a substrate; also proton donator; so proton-accepting, proton donating ppl. adjs.; proton gradiometer, a rod with a proton magnetometer at each end, which may be stood on the ground in a vertical position to measure local variations in field strength at ground level due to features just below the surface; proton magnetometer, a magnetometer in which the magnetic field strength is determined from the frequency of the voltage induced by the precession of protons in hydrogen atoms (e.g. in water) following the removal of a stronger magnetic field applied to orient the protons; proton-precession magnetometer = prec.; proton synchrotron, a synchrotron designed to accelerate protons.
1947Proton accelerator [see bevatron]. 1961Livingston & Blewett Particle Accelerators xiii. 438 The synchrocyclotron, which has been so successful as a proton accelerator in the 100- to 700-Mev range, requires a solid⁓core magnet. 1969Times 5 Feb. 13/6 Four new particles of matter have been discovered in two independent experiments using the proton accelerators at Brookhaven..and at the European Nuclear Research Centre.
1925Jrnl. Chem. Soc. CXXVII. i. 1383 All prototropic changes appear to involve..(i) the removal of a proton from one part of a molecule to some outside basic or proton-accepting component of the system, and (ii) the addition to another part of the molecule of a proton..from some acidic or proton-donating component of the system. 1966Gucker & Seifert Physical Chem. xix. 537 Many a neutral molecule is amphiprotic because it has an ionizable proton and a proton-accepting oxygen or nitrogen atom.
1925Jrnl. Chem. Soc. CXXVII. i. 1378 We..regard the acid as a proton donator and the base as a proton acceptor. 1940Glasstone Text-bk. Physical Chem. xii. 958 It is unlikely that free protons exist to any extent in solution, and so the acidic or basic functions of any species cannot become manifest unless the solvent molecules are themselves able to act as proton acceptors or donors, respectively: that is to say, the medium itself must have basic or acidic properties. 1953L. C. Jackson tr. Ketelaar's Chem. Constitution 85 A base, according to Brönsted, is a proton-acceptor just as an acid is a proton-donor. 1973A. W. Adamson Textbk. Physical Chem. xii. 544 NH3 is a much better proton acceptor than is H2O.
1925Proton-donating, donator [see proton-accepting, acceptor above]. 1940,1953Proton donor [see proton acceptor above]. 1977Helmprecht & Friedman Basic Chem. vii. 149 H2SO4 is a more effective proton donor and a stronger acid than HSO4-.
1960M. J. Aitken in Archaeometry III. 38 Previous articles..have described the use of the proton magnetometer for archaeological prospecting. The proton gradiometer is a development which not only has advantages in operation, but is also less complex and therefore cheaper to construct. Ibid. 39 With the two-bottle system of the proton gradiometer all these large-scale effects are avoided for they affect both bottles equally. 1970Oxf. Univ. Gaz. C. Suppl. vi. 25 Comparative surveys using proton gradiometer, pulsed magnetic induction, and soil conductivity meter.
1959Proton magnetometer [see eye n.1 3 g]. 1961Antiquaries' Jrnl. XLI. 44 In an attempt to locate these burials..a survey with proton magnetometer followed by selective excavation was organized. 1975New Yorker 12 May 58/3 With a proton magnetometer, the geologists began aeromagnetic surveys to develop a general view of the region's geological structure. 1976W. M. Telford et al. Appl. Geophysics iii. 136 The important advantages of the proton magnetometer are that it measures absolute field strength and that its sensitivity (∼1γ) is higher than any of the instruments considered so far. The fact that it requires no orientation or levelling makes it very attractive for marine and even more for airborne operations.
1958Jrnl. Geophysical Res. LX. 880 The proton-precession magnetometer has been successfully adapted..for measuring the horizontal and vertical components of the earth's magnetic field. 1971I. G. Gass et al. Understanding Earth xvi. 236/1 Fluxgate and proton-precession magnetometers were developed to measure magnetic fields to one part in 105.
1947Proc. Physical Soc. LIX. 677 (heading) Theory of the proton synchrotron. 1966Daily Tel. 25 Nov. 26/3 Nimrod, a proton-synchrotron, is essentially a circular racetrack, round which bursts of sub-atomic particles are repeatedly accelerated until they approach the speed of light. 1975McGraw-Hill Yearbk. Sci. & Technol. 208/2 The collision of protons of energy 28 GeV from the CERN proton synchrotron with a metal target yielded..charged pions and kaons. |