| 释义 |
indicator|ˈɪndɪkeɪtə(r)|
[a. late L. indicātor, agent-noun from indicāre to indicate; cf. F. indicateur (1690 in Hatz.-Darm.).]
1. a. One who or that which points out, or directs attention to, something.
1819(title) The indicator. 1831Carlyle Sart. Res. iii. v, We ourselves, restricted to the duty of Indicator, shall forbear commentary. 1855Singleton Virgil I. 72 O youth, The indicator of the crooked plough. 1879Froude Cæsar ii. 9 Birds..were celestial indicators of the gods' commands. 1907New Pictorial & Descr. Guide to Malvern 56 Many of the more prominent objects and principal sites may be identified by..the help afforded by the Indicator, or Toposcope, erected on the summit of the hill. 1927Glasgow Herald 4 June 9 (headline) Mountain Indicator. Ibid., The indicator..points out over ninety places famous in Border song and story. 1967Listener 10 Aug. 167/2 There's a recent book which displays, at a glance, what's distinctive about the scientific analysis of international affairs. It's the World Handbook of Political and Social Indicators.
b. Anat. The muscle which extends the index or forefinger; the extensor indicis.
1696Phillips, Indicator, one of the Muscles extending the Fore-finger. 1782A. Monro Anat. Bones, Nerves, etc. 191 The tendons of the indicator.
c. In a microscope, A pointer which indicates the position of a special object in the field of view.
1837Goring & Pritchard Microgr. 51 It would perhaps be advisable to have the tire of the wheel made broad enough to admit of four sets of divisions, over which the indicator should extend with a sharp edge. 1883J. Hogg Microsc. 191 Finders and Indicators.
d. Philos. = token-reflexive word; see quots. Also indicator-word.
1951N. Goodman Struct. Appearance xi. 290 Roughly speaking, a word is an indicator if..it names something not named by some replica of the word... Among the commonest indicators are the personal indicators, the spatial indicators, and the temporal indicators. Of the personal indicators, an ‘I’ or ‘me’ normally refers to its own utterer. 1952A. J. Ayer in Mind LXI. 444, I shall refer to predicates instead of properties and to individual signs, to which I shall give the name of indicators, instead of individuals. 1954Mind LXIII. 380 Like Professor Ayer I shall..speak of indicators and predicates rather than of individuals and properties. 1960W. V. Quine Word & Object §21. 101 The indicator words: ‘this’, ‘that’, ‘I’, ‘you’, ‘he’, ‘now’, ‘here’, ‘then’, ‘there’, ‘today’, ‘tomorrow’.
2. a. That which serves to indicate or give a suggestion of something; an indication of.
1666J. Smith Old Age (ed. 2) 73 They are the true indicators of strength. 1760–72H. Brooke Fool of Qual. (1809) II. 98 Our silence and our looks were too sure indicators of the fatal tidings. 1860Tyndall Glac. i. i. 5 The shells became the indicators of an action to which the mass..had been subjected. 1882Froude Carlyle II. 130 They [clothes] were the outward indicators of the inward and spiritual nature.
b. Anything used in a scientific experiment to indicate the presence of a substance or quality, change in a body, etc.; spec. (i) a substance which may be added to a solution to indicate whether the concentration of hydrogen ions or of some other ion in the solution is above or below a particular value, esp. by giving different colours for the two conditions.
1842–3Grove Corr. Phys. Forces (1846) 19 The substance we use as an indicator does not undergo the same physical change as those whose dynamical relations we are examining. c1860Faraday Forces Nat. v. 129 You need be in no want of indicators to discover the presence of this attraction. 1869Roscoe Chem. (1871) 25 Solids expand too little and gases too much to be convenient indicators. 1874Jrnl. Chem. Soc. XXVII. 191 (heading) Alizarin as an indicator in volumetric analysis. 1902Encycl. Brit. XXVIII. 12/2 Para-nitro-phenol has colourless molecules, but an intensely yellow negative ion. In neutral, and still more in acid solutions, the dissociation of the indicator is practically nothing, and the liquid is colourless. 1930Jrnl. Amer. Chem. Soc. LII. 2347 The use of various organic substances..as irreversible oxidation-reduction indicators in the titration of trivalent antimony with ceric sulfate was proposed by Rathsberg. 1938R. E. Oesper tr. Böttger's Newer Methods Volumetric Chem. Analysis i. 19 The fluorescent indicators are related to the ordinary acidimetric color indicators. However, a change of the pH value of the solution produces in them no color change, but a fluorescence appears or disappears. 1939P. J. Durrant Gen. & Inorg. Chem. ix. 214 An indicator may be used for determining the pH value of a solution, or for deciding at what stage during an acid-alkali titration the pH value of a solution has reached a certain value. 1966Ward Lock's Compl. Gardening v. 78 Certain chemical indicators are available for testing a soil in the field as to its approximate pH. 1970R. U. Brumblay First Course Quant. Analysis vi. 83 Adsorption indicators are organic compounds with rather complex molecules which undergo a change in color due to a slight structural change which occurs when they are adsorbed on the surfaces of colloidal particles.
(ii) An isotope (usually a radioactive one) used as a tracer (see tracer1).
1919[see isotopic a. a]. 1926R. W. Lawson tr. Hevesy & Paneth's Man. Radioactivity xv. 122 In problems of this kind, where the radio-element is not the object but the agent of the investigation, we say that the radio-elements serve as ‘indicators’. 1938Ibid. (ed. 2) xviii. 168 In those rare cases in which inactive isotopes are readily accessible they can be used as indicators in fundamentally the same manner, though other methods of measurement must be used... Such experiments have been carried out with deuterium 2D and the oxygen and nitrogen isotopes 17O, and 15N. 1943Thorpe's Dict. Appl. Chem. (ed. 4) VI. 432/1 The hydride of bismuth was discovered by using thorium-C as indicator and causing hydrogen to be generated in an apparatus in which this radioactive indicator had been placed. The gas which escaped was found..to have radioactive properties. 1956E. de B. Barnett Mechanism Org. Chem. Reactions i. 13 The use of an isotopic indicator or tracer often gives useful information as regards mechanism.
c. A geological clue to the presence of gold.
1894R. A. F. Murray in A. W. Howitt Miners' Handbk. 5 Where the gold ceases is usually near and above the line of reef or vein whence it was derived... ‘Indicators’ or small veins of pyrites, ironstone, and often thin bands of peculiar slate, intersected by small quartz veins, should..be carefully looked for. 1943Von Bernewitz & Chellson Handbk. Prospectors (ed. 4) xvii. 200 A lead-bismuth mineral is an indicator in the Quartzburg district of Idaho. The gold is intimately associated with it, yet free.
d. Ecology. A group of plants or animals whose presence acts as a sign of particular environmental conditions. Also attrib.
1906E. W. Hilgard Soils 545 Its [sc. alkali-heath's] perennial, deep-rooting habit of growth, and flexible, somewhat wiry rootstock, which enables it to persist even in cultivated ground, render it a valuable plant as an alkali indicator. 1920F. E. Clements Plant Indicators iv. 112 These [areas of disturbance] furnish an enormous amount of indicator material. 1949W. C. Allee et al. Princ. Animal Ecol. iv. xxix. 567/2 Typical or characteristic organisms..are biotic indicators. 1964J. M. Maclennan tr. Viktorov's Short Guide Geo-Bot. Surveying vi. 122 The composition, structure, and other features of the plant cover may often serve as indicators of various environmental conditions. 1970Nature 25 July 381/1 They [sc. chaetognaths] have also frequently been used as ‘indicator species’ for water masses.
e. A board or device in a railway station used to indicate the times and platform numbers of arriving and departing trains.
1913Ld. Monkswell Railways Gt. Brit. iii. 163 A large indicator showing the platform at which each train will depart, is displayed high up on the side of one of the buildings flanking the concourse. 1914H. M. Hallsworth Elem. Railway Operating iii. 46 Since there are trains for different destinations frequently departing from the same platform at or about the same time passengers are liable to board the wrong train. This is a danger which must be provided for by suitable indicators. 1961Trains Illustr. Jan. 22/2 (caption) The new train indicator board for the Cambridge main line departure platforms. 1972Travelling Winter 43/3 New automatic departure and arrival indicators will be installed. 1973Railway Mag. Mar. 151/2 A new form of train departure indicator is replacing the printed sheets at many stations on BR.
f. In Cryptography (see quot.).
1961Shulman & Weintraub Gloss. Cryptogr., Indicator, a means of showing a change of key or encipherment, usually with a letter of the alphabet agreed upon in advance.
3. techn. A mechanical device or recording instrument which indicates the condition of the apparatus, etc., to which it is attached; e.g.:
a. An instrument which indicates the pressure of steam on the piston of a steam-engine at each portion of its stroke. b. In mines: see quot. 1867. c. In a blast furnace, a gauge which indicates the proper height of a charge (Knight Dict. Mech. 1875). d. The dial and mechanism by which messages are indicated in a dial-telegraph. e. An instrument which indicates the position at any moment of the cage in the shaft of a mine (Raymond Mining Gloss. 1881). f. A contrivance in a lending library for showing what books are out or in.
1839R. S. Robinson Naut. Steam Eng. 153 A most use⁓ful instrument, called an indicator, can be attached to the cylinder, which will point out the exact working state of the engine, how much of the steam is lost between the boiler and cylinder, [etc.]. 1867Morning Star 30 Jan., The barometers in mines are sometimes furnished with an indicator, which tells the furnaceman when it reaches a certain point that he should light up a great fire. 1876R. Routledge Discov. 9 The actual power of a steam engine is ascertained by an instrument called the Indicator. 1876Preece & Sivewright Telegraphy 85 If the pointer in the indicator jumps..the currents are either too strong, or the pointer is too lightly adjusted. 1886Leeds Mercury 20 Jan. 5/4 Causing him to lose sight of the indicator, which would show him the position of the cages in the shaft. 1886T. Greenwood Public Libraries (1891) xix. 392 (Indicators) There are several methods of showing to the public, by means of the devise called the indicator, what books in a lending department are in use or on the shelves. Ibid. 393 [In] 1870..Mr. John Elliot, public librarian of Wolverhampton, brought forward his indicator. 1898Macfarlane Libr. Administr. 208
g. A device fitted to a motor vehicle to indicate an intended change in direction. Cf. direction indicator.
Now usu. consisting of two pairs of lights, one pair placed at the front and the other at the rear of a vehicle, that flash on one side or the other when operated by the driver.
1932[see flashing ppl. a. 1 c]. 1958Observer 17 Aug. 15/6 Triggers under the steering-wheel work the self-cancelling indicators and the headlamp flasher. 1962Which? Car Suppl. Oct. 133/1 All the indicators' flasher times fell within the legal limits. Ibid. 133/2 The rear indicators could be seen from the side. 1973R. Lewis Blood Money vi. 69 A police car..turned into the gateway, indicator flashing.
4. Ornith. A honey-guide, a bird of the genus Indicator, or family Indicatoridæ; esp. the South African species, I. Sparmanni.
First described by Sparrman (1777) who gave it the name of Cuculus indicator (Newton Dict. Birds 429).
1835A. Steedman Wander. S. Afr. ii. v. 189 The little honey⁓sucker, or indicator, kept fluttering before us with its cry of cherr, cherr. Ibid. 190 The trunk of a tree over which the indicator was hovering.
5. Math. [tr. F. indicateur (E. Prouhet 1846, in Nouv. Ann. de Math. V. 176).] = totient.
1919Amer. Math. Monthly XXVI. 290 E. Prouhet..defined the term indicator of n as the number ø(n) of the positive integers less than n and prime to n. 1939H. N. Wright First Course in Theory of Numbers i. 11 Other names for ø(m) are the totient of m and the indicator of m. 1948O. Ore Number Theory v. 110 We shall consider the problem of finding how many of the numbers 1, 2, 3,{ddd}, m—1, m are relatively prime to m. This number is usually denoted by ϕ(m), and it is known as Euler's ϕ-function of m because Euler around 1760 for the first time proposed the question and gave its solution. Other names, for instance, indicator or totient have occasionally been used.
6. attrib. and Comb., as indicator-card, the card on which an indicator-diagram is traced (Webster, 1864); indicator-cylinder, the cylinder of a steam-engine indicator; indicator-diagram, a figure traced by the indicator of a steam-engine, showing the pressure at different points of the stroke (Webster, 1864); indicator lamp, light, a luminous signal indicating operating conditions (see quots. and sense 3 g above); indicator-muscle = indicator 1 b; indicator-pointer, the pointer in a telegraph indicator; indicator switch, a switch for an indicator light; indicator-telegraph, a form of telegraph in which the letters of a message are indicated by a pointer on a dial-plate.
1875Knight Dict. Mech. 1180/2 Near the mid-length of the *indicator-cylinder.
1875R. F. Martin tr. Havrez' Winding Mach. 77 The mean pressure is most easily deduced from the theoretical *indicator diagram of the half stroke.
1961Which? Dec. 313/2 For most cookers, we found that the *indicator light going out gave a satisfactory indication that the oven was nearly at its steady temperature... The Falco Royalty had no *indicator lamp. 1962Ibid. Car Suppl. Oct. 133/2 Both front and rear indicator lights were visible from the side in the VW 1500.
1882Quain Anat. (ed. 9) I. 224 The extensor indicis or *indicator muscle arises from the outer division of the posterior surface of the ulna.
1876Preece & Sivewright Telegraphy 85 If..the *indicator pointer lags behind and drops letters, the currents sent are too weak, or the springs are too stiffly adjusted.
1959Motor Manual (ed. 36) vi. 183 When the *indicator switch is moved, either for a right- or left-hand turn, current is fed to the lamps [etc.].
1875Knight Dict. Mech. 1182/1 Cooke and Wheatstone's *indicator-telegraph. |