| 释义 |
retenˈtivity
[f. as prec. + -ity.]
1. (See quot. 1881); now usu. the strength of the magnetic field that remains in a sample after removal of a saturating inducing field.
1881S. P. Thompson Electr. & Magn. ii. §90 This power of resisting magnetisation or demagnetisation, is sometimes called coercive force; a much better term, due to Lamont, is retentivity. The retentivity of hard-tempered steel is great. 1887Proc. Physic. Soc. Apr. (1888) 120 This experiment was made with a view of ascertaining whether the reglow would occur at a lower temperature the greater the amount of retentivity of the specimen. 1912Brooks & Poyser Magnetism & Electricity xxv. 414 Retentivity is measured by the ‘residual’ or ‘remanent’ magnetism, which persists when the magnetising force is removed. 1924C. R. Underhill Magnets xvi. 291 The retentivity or the residual structural flux density..will be about 9,900 gausses, or about 66 per cent of the induction. 1931S. R. Williams Magnetic Phenomena i. 52 The property of retaining to a greater or less degree a certain amount of magnetization is called the retentivity of the substance. The terminology of magnetism is rather confusing regarding some of these terms... The consensus of opinion among magneticians at present is to reserve the term remanent magnetism for the open-circuit residual magnetism as in the case of a U-shaped permanent magnet with the keeper off. 1939L. F. Bates Mod. Magnetism ii. 58 The specimen is now no longer exposed to a magnetic field, but it still retains a considerable intensity of magnetisation, equal to Ob/4π, which is termed the retentivity of the material and is a measure of the ability to retain magnetism when not subjected to adverse treatment. Some authorities, e.g. Ewing, term the residual induction Ob the retentiveness. 1948Electronic Engin. XX. 351/1 The principal requirements of steels for permanent magnets is that they shall have high remanence (retentivity) and coercive force. 1951R. M. Bozorth Ferromagnetism xi. 499 In strong fields they [sc. the coercive force and the residual induction] approach limiting values called the coercivity and the retentivity, respectively. 1953J. D. Kraus Electromagnetics v. 239 The retentivity of a substance is the maximum value which the residual flux density can attain. 1966McGraw-Hill Encycl. Sci. & Technol. IV. 489/1 The difference between cores of an electromagnet and a permanent magnet is in the retentivity of the material used.
2. Psychol. The capacity or ability to retain learning or to remember.
1909C. S. Myers Exper. Psychol. xiii. 173 Nor is the superior retentivity of the most distributed readings due to the involuntary revival of the syllables by the subject. 1923C. S. Spearman Nature of Intelligence ix. 132 Our second quantitative principle may be called that of retentivity... It appears not to be restricted to cognition, but to extend to mental processes of almost all sorts. It even governs an immense number of purely physical events. 1938Times Lit. Suppl. 19 Mar. 186/1 These are the laws of mental energy and its constancy, of retentivity. 1961Lancet 12 Aug. 361/2 Spearman held that ‘retentivity’ was a factor not closely related to general intelligence.
3. Geol. The property of rocks and minerals of retaining gases, esp. radiogenic ones.
1960Amer. Jrnl. Sci. CCLVIII. 600 The conditions imposed upon phlogopite..in order that its retentivity be greater than 95 per cent for 108 years. 1968Hamilton & Farquhar Radiometric Dating for Geologists i. 19 Chemical alteration which occurs penecontemporaneous with the event to be dated is not pertinent unless it affects the retentivity for argon of the mineral to be dated. Ibid. 22 The retentivities vary greatly within a mineral species. 1975Nature 27 Feb. 704/2 The nature of the gas initially present in the heating apparatus markedly influences trace element retentivity at 1,000°C. |