| 释义 |
sporadic, a.|spɒˈrædɪk|
Also 7 -ick.
[ad. med.L. sporadic-us (13th c.), a. Gr. σποραδικός, f. σποραδ-, σποράς scattered, dispersed, f. the stem of σπορά, σπόρος sowing: cf. σπείρειν to sow, scatter. So F. sporadique (1690), It. sporadico, Sp. esporadico.]
1. Path. Of diseases: Occurring in isolated instances, or in a few cases only; not epidemic.
a1689Sydenham Wks. (1788) I. i. 6 These I call inter⁓current or sporadic acute diseases, because they happen at all times, when epidemics rage. 1728Chambers Cycl., Sporadic, in Medicine, an Epithet given to such Diseases as have some special or particular Cause, and are dispersed here and there. 1752Phil. Trans. XLVII. 385 The plague..has been mostly sporadic, seldom epidemical. 1843R. J. Graves Syst. Clin. Med. xiv. 152 Other sporadic and epidemic fevers. 1845G. E. Day tr. Simon's Anim. Chem. I. 326 A man who died of sporadic cholera. 1884Manch. Exam. 25 June 5/2 The disease is distinctly sporadic, or due to local causes, and therefore unlikely to spread.
2. a. Scattered or dispersed, occurring singly or in very small numbers, in respect of locality or local distribution.
1813T. Young in Quarterly Rev. Oct. 255 All the Asiatic and European languages..which may be subdivided into five orders, Sporadic, Caucasian, Tartarian, Siberian, and Insular. 1830Lindley Nat. Syst. Bot. 90 About 92 genera..are what are called sporadic, or dispersed over different and widely separated regions. 1856S. P. Woodward Mollusca iii. 350 Those species which characterise particular regions are called ‘endemic’... The others, sometimes called ‘sporadic’, possess great facilities for diffusion. 1865Farrar Chapt. Lang. 29 In various sporadic families, which some would call Turanian. 1877M. Foster Physiol. i. iii. (1878) 89 In the sporadic ganglia the evidence of automatic action seems more clear.
b. Appearing, happening, etc., now and again or at intervals; occasional.
1847H. Bushnell Chr. Nurture viii. (1861) 206 Sporadic cases of sanctification. 1864R. F. Burton Mission to Gelele II. 71 Sporadic heroines..are found in every clime and in all ages. 1877Owen Desp. Wellesley p. xix, A series of sporadic encounters of a petty and inglorious..character. 1882Times 7 Feb., The continuance of sporadic troubles in Basutoland.
c. Of single persons or things: Accidental; isolated.
1821Syd. Smith Wks. (1850) 316 Has any sporadic squire the right to say, that it shall be punished with death? 1875H. James R. Hudson iv. 129 Rowland began to think of the Baden episode as a mere sporadic piece of disorder. 1878Stewart & Tait Unseen Univ. vii. §217. 215 This production was..a sporadic or abrupt act.
d. Astr. Applied to a meteor that is isolated and does not appear to belong to a shower. Also absol., a sporadic meteor.
1929C. Hoffmeister in Astrophysical Jrnl. LXIX. 167, I have developed some methods..to find out..which portion of meteors..may be regarded as ‘sporadic’, i.e., the directions of motions being distributed in an irregular way without indication of radiation in currents... Meteors emanating from a real radiant are mostly of cometary character and sporadic meteors are mostly of interstellar origin. 1954A. C. B. Lovell Meteor Astron. xxi. 429 A good deal of attention has been given..to the problem of the velocity of sporadic meteors, and the conclusion now seems inescapable that they must be contained in the solar system as distinct from the interstellar view which has prevailed for so long. 1961D. W. R. McKinley Meteor Sci. & Engin. i. 3 The number of sporadics greatly outweighs the total number of meteors belonging to the well-known showers. 1978V. F. Buchwald Iron Meteorites I. i. 11/1 It is commonly inferred that all meteors—including the sporadic—are fragments of comets.
3. a. Characterized by occasional or isolated occurrence, appearance, or manifestation.
1842Penny Cycl. XXII. 378/1 The occasional occurrence of diseases..usually epidemic, in a sporadic form. 1852H. Rogers Ecl. Faith (1853) 146 Its manifestation will not be sporadic, but it will be in one race as in another. 1865Carlyle Fredk. Gt. xviii. xiv. V. 368 Meanwhile, the Austrians on front do, in a sporadic way, attack..our batteries. 1881Westcott & Hort Grk. N.T. Introd. §113 All known MSS. shew..traces of sporadic and casual mixture.
b. sporadic E-layer, -region: a discontinuous region of ionization that occurs from time to time in the E-layer of the ionosphere and results in the anomalous reflection back to earth of VHF radio waves. Also ellipt. as sporadic E, sporadic-E, used attrib. and absol.
1937Terrestrial Magnetism XLII. 76 No relation between the sporadic E-region ionizations and magnetic disturbances of widespread character is apparent so far. 1949Nature 2 Apr. 528/2 The usual measure of sporadic E-layer ionization is the so-called ‘critical frequency’, that is, the highest reflected frequency for this layer. 1955Sci. Amer. Sept. 129/1 One of the outstanding mysteries of the ionosphere is a type of irregularity called ‘sporadic E’. 1967Economist 22 July 280/1 UHF is virtually immune to sporadic-E problems which so beset VHF. 1974E. Harnischmacher in F. Verniani Struct. & Dynamics of Upper Atmosphere 272 The Sporadic E layer, Es, is the most irregular and the thinnest layer of the ionosphere.
4. Math. Being a finite simple group that does not fall into any of the infinite classes into which most finite simple groups fall. Also absol. as n.
1968Proc. Nat. Acad. Sci. LXI. 398 (heading) A perfect group of order 8,315,553,613,086,720,000 and the sporadic simple groups. 1968Manifold I. 12 Apart from the Mathieu groups, no other sporadic simple groups were known until Zvonomir Janko discovered one in Australia..in 1965. 1973Amer. Math. Monthly LXXX. 1028 Still, some hardy souls felt a thorn in their side. For the five groups of Mathieu all reason defied; Not An, not twisted, and not Chevalley, They called them sporadic and filed them away. 1980Sci. Amer. May 68/1 There is good reason to believe the number of sporadic groups is finite, and indeed many mathematicians believe the sporadics that have already been identified, a total of 26, complete the list of finite simple groups. |