| 释义 |
occlusion|əˈkluːʒən|
[ad. L. *occlūsiōn-em, n. of action from occlūd-ĕre, occlūs-: see occlude. So mod.F. occlusion (1808 in Hatz.-Darm.).]
1. The action of occluding or fact of being occluded; stopping up, closing. (Chiefly scientific.)
c1645Howell Lett. I. iii. xxix, By the constriction and occlusion of the orifice of the Matrix. 1746Parsons in Phil. Trans. XLIV. 14 To explain the Manner of the Occlusion of the Eye. 1786H. Lee in Sparks Corr. Amer. Rev. (1853) IV. 137 In agreeing to the occlusion of the navigation of the Mississippi. 1876tr. Wagner's Gen. Pathol. (ed. 6) 165 Anæmia occurs from contraction or occlusion of arteries.
2. Chem. The retention of gases in the pores of metals or other substances.
1866[see occlude 2 b]. Ibid. 426 The occlusion of hydrogen by palladium. 1871Roscoe Elem. Chem. 186 The fact that red-hot platinum and iron are porous for hydrogen may be explained by the absorption (or occlusion) of this gas on the one side of the metallic tube or plate and its evaporation at the other side.
3. Dentistry. The position assumed by the two sets of teeth relative to each other when the mouth is closed; the state of having the jaws closed and the teeth in contact.
1880N. W. Kingsley Treat. Oral Deformities xxi. 525 In extreme pain (except in cases where the patient is suffering from periodontitis, when the occlusion of the jaws intensifies the suffering), the teeth are brought together with great force. 1904V. H. Jackson Orthodontia & Orthopædia of Face 198 The opening of the bite in any manner with apparatus, if continued for a considerable time, is likely to prove detrimental to the occlusion. 1962Blake & Trott Periodontology xv. 156 In the European it is usual to find that during lateral movements to either side molar and pre-molar teeth of one side remain in occlusion, while contact is completely lost on the other side. 1974Harty & Roberts Restorative Procedures Practising Dentist xii. 167 It is very important that the occlusion is studied and corrected before any fixed or removable prosthesis is made.
4. Phonetics. The act of closing, or the period of closure of, the breath passage during the articulation of an orally-released consonant, or of the mouth passage during the articulation of a nasal consonant.
1906Mod. Lang. Rev. I. iv. 346 ‘Occlusion’, was, if I remember aright, used by Wilkins in the seventeenth century, but this hardly justifies the employment of such a pedantic term instead of ‘stoppage’, ‘closure’, or ‘stop’. 1926Germanic Rev. I. i. 58 Here, ‘occlusion’ in the glottis does not mean glottal stop, but the partial occlusion in the articulation of voice sounds. 1935J. S. Kenyon Amer. Pronunc. (ed. 6) 51 This initial contact for any sound that has contact is called the closure, or occlusion, and the end of the contact is called the opening, or release. 1943Amer. Speech XVIII. 39 In pronouncing such phrases as ‘Hello, Pete!’..a British speaker ordinarily articulates the vowel of the final syllable, lifts his tongue to make the closure for the final consonant (applosion), holds it there from eight to twelve hundredths of a second (occlusion), and then breaks the closure with a sharp downward snap of the tongue which produces a clear ‘pop’ (explosion). 1966B. Trnka Phonol. Analysis Present-Day Stand. Eng. (rev. ed.) ii. 11 In producing l, the tip of the tongue forms an occlusion against the alveolar ridge.
5. Chem. A kind of co-precipitation (see quots.); the trapping of foreign material by growing crystals of a precipitate.
1920Chem. Abstr. XIV. 3029 (heading) The occlusion of lime and magnesia by ferric oxide. 1929L. P. Hammett Solutions of Electrolytes i. iii. 40 Analytical separations are..never quite as satisfactory..because of the existence of occlusion. 1932[see co-precipitation]. 1942W. Rieman et al. Quantitative Analysis (ed. 2) xvii. 244 The phenomenon [sc. coprecipitation] has also been called contamination, inclusion, occlusion, and adsorption. The last two terms should not be used as synonyms for coprecipitation because they denote certain mechanisms that apply to some but not all cases of coprecipitation. 1947Jrnl. Chem. Education XXIV. 597/1 The term occlusion has been used to refer to contamination of a precipitate by the incorporation into the body of it during its formation of foreign substances whether or not the latter give rise to mixed crystal formation (solid solution)... It has been used to include both solid solution phenomena and contamination of the precipitate by adsorption..; it has been used to indicate contamination by basic salts and other substances not adsorbed and not in solid solution..; and I have heard a noted analytical chemist reserve the term to indicate the contamination of a precipitate by mechanically trapped solute or solvent ions or molecules. No doubt one could locate other senses in which occlusion has been used; the term is almost omnivorous. 1966E. M. Rattenbury Introd. Titrimetric & Gravimetric Anal. vii. 146 Sometimes water or mother liquor is imprisoned by occlusion. 1969E. S. Gilreath Elem. Quantitative Chem. x. 138 Occlusion is a form of coprecipitation in which impurities are enclosed..within the lattice structure of a crystalline precipitate. Ibid., Contamination by occlusion..can produce serious errors in gravimetric analysis.
6. Ophthalm. The covering of an eye so as to block its sight.
1920Brit. Jrnl. Ophthalm. IV. 146 (heading) The influence of prolonged monocular occlusion in revealing errors of the muscle balance. 1973Nature 26 Jan. 288/2 The technique of monocular occlusion has long been used by ophthalmologists in the therapeutic treatment of such conditions as strabismus (squint) and amblyopia.
7. Meteorol. The overtaking of the warm front of a depression by the cold front, so that the body of warm air between them is forced upwards off the earth's surface by two wedges of cold air; also, the occluded front so formed.
1922Bjerknes & Solberg in Geofysiske Publikationer III. i. 6 No boundary surface results when both branches meet during the occlusion of the cyclone. Ibid., The occlusion then assumes the character of a cold front with a rather narrow rain zone. 1934D. Brunt Physical & Dynamical Meteorol. xviii. 311 The occlusion begins at the centre, where the cold front has a shorter path to cover before overtaking the warm front. Ibid., There will still be a warm sector in the upper air for some time after occlusion has taken place at the surface. 1941B. Haurwitz Dynamic Meteorol. xv. 314 The part of the front where the cold front has caught up is called the occlusion. 1944Hewson & Longley Meteorol. Theoret. & Appl. xvi. 277 The rate of occlusion in several types of frontal depressions may be discussed qualitatively. 1955W. J. Saucier Princ. Meteorol. Analysis ix. 270/1 The cold front overtakes the warm front, resulting in an occluded front (or occlusion). 1974Encycl. Brit. Macropædia V. 394/2 There still is a belt of thick cloud and rain along the line of the old occlusion. |