| 释义 |
ablation|æˈbleɪʃən|
[ad. L. ablātiōn-em a carrying away, n. of action, f. ablāt- ppl. stem of aufer-re: see prec. Cf. Fr. ablation used in sense 2.]
1. The action or process of carrying away or removing; removal. spec. Gradual removal of superficial material (cf. senses 4, 5).
1577–87Harrison England i. ii. i. 37 (1877) The decaies and ablations seene and practised at this present. 1598Hakluyt Voyages I. 148 Marchants haue sustained sundry damages and ablations of their goods. 1677Gale Court of Gent. II. iv. 261 Physic mutation is by Addition or Ablation and Substraction of some real Entitie. 1687H. More App. to Antidote (1712) 227 In the real ablations of Witches and Magicians, when they happen. 1981N.Y. Times 26 Apr. vi. 86/1 It is this ablation of incandescent material from such a meteorite that leaves the traditional fiery trail across the night sky.
†2. Med. The removal or subsidence of the acute symptoms of a disease; cessation, remission. Obs.
1651N. Biggs New Dispens. 76. §120 It doth naturally betoken the ablation of it. 1671Salmon Syn. Medic. iii. xxxvi. 514 If in the ablation of the disease, there be not a..reparation of the strength, the sick may dye. 1831Hooper Med. Dict. 4 Ablation, in some old writings, expresses the interval betwixt two fits of a fever, or the time of remission.
3. Surg. The removing or taking away of any part of the body by mechanical means.
1846J. Miller Pract. of Surg. xxvi. 350 There is safety in nothing short of summary ablation—not only of the nipple itself, but of the mamma also. 1872Cohen Dis. of the Throat 207 [He] succeeded in the ablation of one of these polyps by means of a metallic nail attached to a thimble.
4. a. [In this sense a. F. ablation (L. Agassiz 1842, in Compt. Rend. XV. 285).] Geol. The wearing away or superficial waste of a glacier by surface melting, or of a rock by the action of water. In mod. use, the surface loss of snow or ice as a result of melting and evaporation.
1842Edin. New Philos. Jrnl. XXXIII. 400 M. Agassiz then notices his observations relative to the glacier itself... The ablation of the surface, resulting from the melting and the evaporation, has also been more considerable at the centre than at the edges. 1860Tyndall Glaciers ii. §32. 418 The ablation of the ice must be less than what is generally supposed. 1863J. Ball Guide to West. Alps Introd. 70 The vast amount of ablation, or loss, which a glacier annually undergoes through the melting of the surface. 1942C. A. Cotton Climatic Accidents in Landscape-Making xi. 138 ‘Ice falls’.., often with crowded ridges and pinnacles sharpened by ablation. 1960B. W. Sparks Geomorphol. xii. 267 In these marginal regions, there must be a constant struggle between the tendency of the ice sheet to advance as it is slowly supplied with ice from the highlands, and the tendency for ablation to cause the ice front to recede. 1978Nature 5 Jan. 50/1 An iceberg's underwater shape clearly affects its stability, with most of an iceberg's ablation occurring beneath the waterline.
b. The removal of sand or salt from a surface by the action of the wind.
1961L. D. Stamp Gloss. Geogr. Terms 1/2 Some recent writers refer to ablation of sandy areas by wind. 1962Special Stud. Utah Geol. & Mineral. Survey ii. 3 At the time that the salt reposed in the central part of the basin, the eastern side had risen to the point that it began to suffer wind ablation. 1965A. Holmes Princ. Physical Geol. (ed. 2) xxii. 751 The base-level for wind action is that of the water table, which may be far below sea-level. The ‘pans’ of S. Africa..and the depressions of the N. African and Mongolian deserts, have all been excavated by ablation.
5. Astr. and Astronautics. The loss of surface material from a body as a result of frictional heating as it passes through an atmosphere.
1951Astrophysical Jrnl. CXIV. 460 More direct methods of determining actual surface losses by ablation should be developed. 1958in Amer. Speech (1960) XXXV. 283 Ablation, melting of nose cone materials during reentry of space ships or vehicles into the earth's atmosphere at hypersonic speeds. 1960Nature 29 Oct. 353 Baker has concluded that the australites entered the atmosphere as cold, independent bodies, most of which neither tumbled nor rotated during ablation. 1961New Scientist 4 May 241 The blunt end [of the space capsule] acts as an ‘ablation shield’ for re-entry. 1972Q. Jrnl. R. Astron. Soc. XIII. 88 The abundance of sodium in the high atmosphere—thought to be the result of meteoric ablation. 1977A. Hallam Planet Earth 24 Ablation entirely destroys a high proportion..of a meteoroid entering the atmosphere.
6. Special Combs.: ablation moraine Geol., rock debris which has accumulated as a result of the ablation of the glacier in which it was previously embedded; † a deposit of this; ablation till Geol., ablation moraine.
1909R. S. Tarr in Zeitschr. f. Gletscherkunde III. 85 (heading) The *ablation moraines. Ibid., The material in the ablation moraines does not have an even distribution over the ice surface. 1942C. A. Cotton Climatic Accidents in Landscape-Making xi. 145 Much rock debris that falls on to the surface [of the glacier]..reappears as ‘ablation moraine’. 1970R. J. Small Study of Landforms xi. 383 Towards the margins of the ice..englacial debris will be exposed in large quantities on the surface, thus forming ‘ablation moraine’...With the ultimate disappearance of the ice, a layer of structureless detritus (‘ablation till’) will be left.
1968Embleton & King Glacial & Periglacial Geomorphol. xiii. 301 Lodgement till is sometimes referred to as ground moraine,..and *ablation till as ablation moraine. The use of the term ‘moraine’ is particularly confusing. 1974H. F. Garner Origin of Landscapes viii. 488/2 Ablation till is lowered rather gently to the ground by wasting ice and is generally loose. |