| 单词 | half period |
| 释义 | > as lemmashalf period half period n. (a) the interval taken to complete half a cycle of a periodic physical phenomenon or mathematical function; (b) (Nuclear Physics) the time taken for radioactivity to fall to half the initial level (cf. half-life n. 2a). ΘΠ the world > matter > physics > atomic nucleus > radioactive isotope > radioactive nuclide > [noun] > average duration > time of decrease 1749 R. Smith Harmonics 281 The several dislocations..at the ends of the subsequent short cycles of the octaves and unisons, are equal respectively..throughout their half periods, which are therefore equally harmonious. 1879 A. Cayley Coll. Math. Papers X. 468 The theta-functions have the quarter-periods (1, 1), the half-periods (2, 2), and the whole periods (4, 4). 1905 Nature 13 Apr. 574/1 Different samples gave for the half-period of decay from 52 to 55 seconds. 1942 J. D. Stranathan ‘Particles’ of Mod. Physics xi. 448 One product of the nuclear disruption was a Ba isotope having a half period of 86 minutes. 2017 Jrnl. Coastal Res. 33 1312/1 The tide-dominated regime studied herein prevails during spring tides in absence of wind and resembles, during each half period of the tide, a channel flow. < as lemmas |
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