| 释义 |
▪ I. screening, vbl. n.|ˈskriːnɪŋ|
[-ing1.]
The action of the vb. screen in various senses.
1. a. The action of sheltering or concealing with or as with a screen.
1788Burke Sp. agst. W. Hastings Wks. XIII. 246 It was done for the screening of his own guilt. 1893Hansard's Parl. Deb. 30 Mar. 1500 The new Order in Council in reference to the screening of side lights in passenger vessels.
attrib.1881Bell tr. C. von Schmidt's Instr. Training Cavalry 231 Four squadrons being placed in 1st line for screening and reconnoitring purposes.
b. The action or practice of shielding from electric and magnetic fields, esp. by means of an enclosing cover of conducting or magnetic material. Freq. attrib.
1840Annals Electr., Magn., & Chem. IV. 293 The screening might, in some way, be connected with an instantaneous current in the plate. Ibid., A certain thickness of metal is..required to produce the screening effect. 1891Electrician 17 Apr. 722/1 Electrostatic screening is of fundamental significance throughout electric theory. 1922Wireless World 1 July 416/1 Magnetic screening from a steady field can be accomplished by surrounding the apparatus by a heavy iron screen. 1929B.B.C. Year-bk. 1930 339 A copper sheet shield may be fixed to the rear of the panel for screening purposes. 1951Good Housek. Home Encycl. 232/2 Most modern refrigerators are provided with suitable screening arrangements to prevent interference with other electrical appliances. 1962A. Nisbett Technique Sound Studio 241 Although it has no screening effect its thickness ensures that the physical separation of successive layers of the magnetic coating is sufficient to maintain printing at a low level. 1970J. Shepherd et al. Higher Electrical Engin. (ed. 2) vii. 225 The object of shielding (or screening) is to prevent a magnetic field from existing at some particular point.
c. The action of an obstruction (such as a hill or a building) in attenuating or blocking broadcast signals.
1907J. Erskine-Murray Handbk. Wireless Telegr. xvii. 231 That the bending of the lines and not their absence is, in part at least, the cause of this apparent screening, is rendered still more probable by the observation that though no signals could be received close to the land, in one instance, they could be obtained at a greater distance from the transmitter by moving the ship away from the land in a straight line. 1920Discovery Apr. 116/1 Mountains..close to a wireless station may produce serious screening in that direction. 1926R. W. Hutchinson Wireless ix. 154 An aerial passing along a passage between the gable ends of two houses..is not efficient owing to the screening effect of the houses. 1967G. J. King Pract. Aerial Handbk. iv. 102 There are invariably pockets of low signal field round the area, due to heavy screening etc. (depending on frequency), where lofty outside aerials are needed to secure the full advantage of the local transmitter.
d. Physics. The reduction of the electric field about an atomic nucleus by the space charge of the surrounding electrons. Also in Comb., as screening constant, the difference between the atomic number of a nucleus and its effective charge, reduced by screening.
1922A. D. Udden tr. Bohr's Theory of Spectra iii. iv. 121 The effect of the presence of the electrons in inner groups upon the motion of the electrons in outer groups as a first approximation may be expected to consist in a simple screening of the nucleus. 1925G. A. Lindsay tr. M. Siegbahn's Spectrosc. of X-Rays vi. 163 These doublets may be roughly explained by the screening of the nuclear charge. Ibid. 166 The screening constants..must depend in general on the quantum number, and on the magnitude and form of the orbit determined by it. 1965Phillips & Williams Inorg. Chem. I. ii. 54 The magnitude of the screening constant indicates the extent to which the full nuclear charge of an element is hidden from the electrons in a particular shell of the core. 1970G. K. Woodgate Elem. Atomic Struct. v. 82 The direct Coulomb interaction e2/r12 raises the degeneracy in l because the amount of screening depends on the eccentricity of the orbit of the outer electron.
e. Physics. = shielding vbl. n. 2 b.
1922F. E. Simpson Radium Therapy vi. 45 It is best to use rather simple and uniform screening until familiarity is obtained with the effects of radium on the tissues.
f. Basketball. Obstruction. See screen n.1 3 g.
1951Sun (Baltimore) 24 Dec. (B ed.) 13/2 In the old American League, the ball changed hands if the referee called screening or blocking.
2. a. A sorting or sifting carried on by means of a ‘screen’.
1725Bradley's Fam. Dict., Skreyn, an Instrument..made of Lath for the Skreening of Earth, Sand, Gravel, &c. 1763Mills Pract. Husb. III. 128 This was then easily separated by proper screening, and the wheat proved so good, that the bakers bought it at the highest market price. 1877Raymond Statist. Mines & Mining 451 Screening through fine screens is, at best, a very imperfect..operation.
b. pl. Material which has passed through the operation of screening; spec., an inferior grade of wheat or polished rice.
1730Wriglesworth Jrnl. of the ‘Lyell’ 23 Sept., This morning put out another Boat Load of our Screenings. 1824‘A. Singleton’ Letters from South & West 111 Their usual fare, is, a peck of corn in the ear a week, which they must break in their hand-mills; and the grit, or refuse, a Rice, like the western screenings of wheat. 1867P. L. Simmonds Commerc. Dict. Trade Products, Screenings, a name in the United States for the inferior wheat that is removed by the screens and fans. 1885Law Times' Rep. LII. 427/2 The footpaths..should be made of good gravel or ballast, or fine stone screenings. 1901Yearbk. U.S. Dept. Agric. 1900 135, 9,400 pounds of screenings, and 3,500 pounds of brewer's rice. 1906Chambers's Jrnl. June 453/1 Tons of rock are..crushed for screenings and ballast. 1923A. Bruttini Uses of Waste Materials ii. ii. 133 By the term screenings are understood the siftings of cereals and other grains. Ibid., Screenings are..made into dog biscuits.
c. Systematic examination of a large number of subjects, esp. for the detection of unwanted attributes or objects.
1944Sun (Baltimore) 8 Jan. 1/1 The preliminary screening physical examination will be discontinued, except for individuals with obvious physical defects. 1946Cancer Res. VI. 490/2 Compounds found in the first screening to possess potency in damaging or killing cells of sarcoma 37..were subjected to further experimentation. 1958New Statesman 6 Sept. 263/3 Some 3,000 Algerians, arrested immediately after the wave of terrorism, were brought there for screening. 1960Guardian 11 Mar. 7/4 Dr. Glover..advocates a psychiatric ‘screening’ of the entire child population in order to detect pathological tendencies to violence. 1964Hueper & Conway Chem. Carcinogenesis & Cancers v. 177 The highest priority for carcinogenic screening should be assigned to those chemicals with which large parts of the general population have contact. 1970Nature 31 Oct. 416/1 Electrophoretic mass screening of blood proteins for new mutations..would be formidable. 1974Times 27 Apr. 5/7 Herr Brandt..said he was generally satisfied with the screening of Federal employees... Herr Guillaume had been thoroughly screened, but not given the highest grade of security clearance. 1974M. C. Gerald Pharmacol. iv. 77 There has been very exhaustive screening of soil samples from almost all parts of the world in an attempt to discover new antibiotics.
d. With out. Cf. screen v. 4 g.
1943Sun (Baltimore) 15 Mar. 5/6 The ‘screening out’ of school children who need medical attention.
3. The posting of an offender's name upon a screen or public notice-board.
1908Westm. Gaz. 28 Mar. 7/1 The Benchers..have imposed the penalty of a reprimand and ‘screening’.
4. The action of screen v.1 8; spec., a particular showing of a film.
1923E. S. Van Zile That Marvel—the Movie 121 Mr. Harding..has suggested the screening of Wells's ‘Outline of History’. Ibid. 198 The actual screening of the story was begun. 1928H. Crane Let. 5 Feb. (1965) 316 We have met some movie actors, attended some studio screenings, etc. 1954Recorder 8 Jan. 1/2 The telegram..‘solemnly protested’ against the screening of a Mass. 1960Guardian 25 Aug. 8/5, I was present ten days prior to its [sc. a film's] screenings at Karlovy-Vary. 1974‘G. Black’ Golden Cockatrice v. 81 The first screening was an old Disney short. 1977Times 23 June 20/4 Many of the journalists who did attend the screenings revealed an uneasiness.
5. Printing. The process of exposing a photosensitive surface or forming an image through a screen (screen n.1 7).
1946[see screen n.1 7]. 1967Karch & Buber Offset Processes v. 168 A device..now permits direct screening of halftone copy that removes the screen dots and reduces the graininess from enlargements. 1973M. Astrua Manual of Colour Reproduction i. 100 For printing continuous tone we have to resort to the optical device of ‘screening’, that is, to the conversion of the various densities of the image..into small dots.
6. attrib. and Comb., as (sense 2 c) screening device, screening experiment, screening method, screening operation, screening procedure, screening process, screening programme, screening technique, screening test; (sense 4) screening room; screening clinic, a clinic at which medical screening is carried out.
1966Listener 4 Aug. 151/1 Last year saw the growth of municipally run screening clinics. In Rotherham and Glasgow there were queues of citizens in the streets waiting to be X-rayed and have other simple examinations. 1977Spare Rib Sept. 19/4 The aim of developing a well woman screening clinic.
1952M. McCarthy Groves of Academe iv. 63 Despite a high tuition and other screening devices..something..had worked to give the college a peculiarly plebeian and subversive tone.
1971J. Anderson in B. de Ferranti Living with Computer vii. 61 New screening experiments are under way at present.
1946Jrnl. Amer. Med. Assoc. 1 June 377/2 [The smear test] can be carried out on a large scale as a screening method. 1950Hansard Commons 7 Nov. 769 Mr Shepherd asked the Prime Minister what inquiries he has made into the efficiency of the screening methods of M.I.5.
1974Times 19 Dec. 4/3 Downing Street refused to say how long the screening operation took.
1964Observer 12 July 4/6 Mammography..is thought by some to be useful as a ‘screening’ procedure for women without symptoms to pick up breast cancer at a very early stage.
1949Cavalier Daily (Univ. of Va.) 22 Oct. 4/2 Applicants could not get their visas approved by the Hungarian government without undergoing a screening process by the American Festival Committee. 1975Language for Life (Dept. Educ. & Sci.) xiv. 215 The screening process might extend across the point of transfer.
1954Cancer VII. 1183/2 A screening program to detect cancer of the cervix.
1974M. Taylor tr. Metz's Film Lang. vi. 156 Inside the screening room. 1978Detroit Free Press 16 Apr. 23 a/1, I absolutely refused to allow ‘Rabbit Test’ to be shown to anyone in a screening room.
1945Amer. Assoc. Adv. Sci. Res. Conf. Cancer 318/2 Utilizing a number of ‘screening’ techniques to evaluate the place of a variety of compounds as to their ability to impair the metabolism of malignant cells.
1942Nation 27 Apr. 41 Since Jan. 1 Selective Service has given only what is called a ‘screening test’. The registrant strips, walks to and away from the doctor and if he has all his limbs and his eyesight and no immediately apparent organic defect, is passed. 1951Jrnl. Amer. Med. Assoc. 11 Aug. 1401/1 The detection center serving..as a laboratory facility to which the physician can refer his patients for screening tests. 1969Times 15 Mar. 7/8 A swift and reliable system is necessary to meet the ideal of offering every woman an annual screening test for signs of cervical cancer.
▪ II. screening, ppl. a.|ˈskriːnɪŋ|
[f. screen v. + -ing2.]
That screens; that hides or protects.
1817D. Hughson Walks through London 395 The screening colonade of the latter will be taken down. 1861Geo. Eliot Silas M. i. ii, He felt hidden even from the heavens by the screening trees and hedge. 1936Practical Wireless 16 May 232/2 Provided that the screening cans are connected to the earth terminal no interaction should be experienced between those components. 1942Electronic Engin. XV. 284/3 Grid 3 is situated between two screening grids maintained at a positive potential of 100 volts. 1943Gloss. Terms Electr. Engin. (B.S.I.) 58 Line choking coil (screening reactor), an inductor connected in series with electrical plant and serving to reduce the effects of high-frequency or steep-fronted surges by absorption or reflection. 1966McGraw-Hill Encycl. Sci. & Technol. XII. 81/2 Military screening smokes. |