| 释义 |
▪ I. Stokes1 Physics.|stəʊks|
The name of Sir George Stokes (1819–1903), Irish-born physicist and mathematician, used in the possessive and attrib. to designate concepts and phenomena discovered by him or arising out of his work: a. Stokes' theorem: the theorem that the line integral of a vector function round a closed path is equal to the surface integral of the curl of the function over any surface bounded by the path.
1893J. J. Thomson Notes Recent Res. Electr. & Magnetism i. 10 Now by Stokes' theorem ∫ (Xdx + Ydy + Zdz) taken round a closed circuit is equal to [etc.]. 1940E. T. Bell Development Math. xviii. 364 Stokes' theorem, its proof, and its generalizations have developed into a thriving industry of modern analysis. 1975R. L. Ferrari Introd. Electromagnetic Fields vi. 109 We have postulated Maxwell's equations in their integral form... Using the vector calculus rule, Stokes' theorem, these can be transformed into differential relationships required to hold everywhere in space.
b. Stokes' law: the statement (not always true) that in fluorescence the wavelength of the emitted radiation is longer than that of the radiation causing it. Also Stokes' line, Stokes' shift, etc., with reference to spectral emission lines at a lower frequency than the stimulating or incident radiation.
[1902Encycl. Brit. XXXII. 124/1 According to the experimental law of Stokes, the wave-lengths of the fluorescent radiation are longer than those of the radiation which excites it.] 1926R. W. Lawson tr. Hevsey & Paneth's Man. Radioactivity v. 57 It is the same condition as that with which we meet in optics in connection with the occurrence of fluorescence according to Stokes' law. 1949P. Pringsheim Fluorescence & Phosphorescence ii. 163 The fourth row of the same table shows..the distances of the first Stokes line from the exciting line. Ibid. vii. 556 Even if the absorption and emission correspond to the same electronic transition,..relatively large Stokes shifts have a great probability [in crystal phosphors]. 1973McGraw-Hill Yearbk. Sci. & Technol. 307/1 Other consequences of the transient nature of the scattering are that the Raman-shifted (Stokes) pulse is both narrowed in time and delayed with respect to the exciting pulse. 1975D. H. Burrin in Williams & Wilson Biologist's Guide to Princ. & Techniques Pract. Biochem. v. 146 The energy emitted from these molecules in regaining the ground state within a period of less than 10—8 s gives rise to a fluorescent peak, showing the Stokes' shift. 1978P. W. Atkins Physical Chem. xvii. 562 (caption) Stokes and anti-Stokes rotational Raman lines.
c. Stokes' law (or Stokes' formula): the statement that the resisting force on a spherical particle moving through a fluid is 6πηVr (where η is the viscosity of the fluid, V the speed of the particle, and r its radius), so that its limiting rate of fall is 2gr2ρ/9η (where g is the acceleration due to gravity and ρ the difference in density between the particle and the fluid).
1910Rep. Brit. Assoc. Adv. Sci. 1909 407 To test Stokes's formula for air, the size, density, and terminal velocity of fall of some spherical spores were determined. 1936Discovery Nov. 349/2 This period [of settlement of dust particles] is dependent on the application of Stokes' law, and hangs on particle size, density, etc. 1968P. A. P. Moran Introd. Probability Theory ix. 431 Assume that the particle, besides being spherical, is large enough for Stokes law to give a good estimate of the resisting force. 1974G. S. Ormsby in P. L. Moore et al. Drilling Practices Manual vi. 158 Since Stokes Law applies in a sand trap, large quantities of barites..may be settled from weighted drilling fluids. 1983Sci. Amer. Apr. 128/2 Many of the grains in Middle Eastern coffee are too large to fall according to Stokes's law.
▪ II. Stokes2|stəʊks|
The name of Sir Wilfrid Stokes (1860–1927), English engineer, used attrib. and absol. to designate a type of trench mortar invented by him.
1915W. S. Churchill Let. 7 Sept. in M. Gilbert Winston S. Churchill (1972) III. Compan. ii. 1167 In the early part of June, Lloyd George and I were shown the Stokes gun in action. 1919[see Lewis3]. 1919Athenæum 25 July 664/1 ‘Stokes’, the name of the inventor of the T.M., has, by metonymy, come to mean the trench mortar gun itself (so ‘Nissen’ = hut; ‘Armstrong’ = 0 hut). 1923Kipling Irish Guards in Gt. War II. 146 Our own two-inch Stokes in the front line strove to cover the noise by separate rapid fire. 1930G. B. Shaw What I really wrote about War (1931) 241 The thermit shower was produced by firing from Stokes guns a cloud of shells packed with it. 1974A. Price Other Paths to Glory i. i. 16 Their dead hanging on the unbroken barbed wire among the dud shells and unexploded Stokes mortar bombs. |