| 释义 |
isometric, a. and n.|aɪsəʊˈmɛtrɪk|
[f. Gr. ἰσοµετρία equality of measure (f. ἴσο-ς + µέτρος) + -ic: in mod.F. isométrique.]
A. adj.
1. Of equal measure or dimensions.
1855Mayne Expos. Lex., Isometric,..of equal measure, or extent. 1879G. B. Prescott Sp. Telephone 547 If an isometric block of metal be drawn out into a wire, its resistance may be indefinitely increased.
2. Applied to a method of projection or perspective, in which the plane of projection is equally inclined to the three principal axes of the object, so that all dimensions parallel to these axes are represented in their actual proportions; used in drawing figures of machines, etc.
1840Penny Cycl. XVII. 492/1 This specific application of projection was termed isometric by the late Professor Farish, who pointed out its practical utility, and the facility of its application to the delineation of engines, etc. Ibid., A scale for determining the lengths of the axes of the isometric projection of a circle.
3. Cryst. Applied to that system of crystalline forms characterized by three equal axes mutually at right angles (also called cubic, tesseral, etc.); belonging to this system.
1868Dana Min. (ed. 5) Introd. 21 The systems of crystallization are..1. Having the axes equal. The Isometric system. Ibid. 22 Some of the simpler isometric forms are represented in figures 1 to 50.
4. Physiol. [ad. G. isometrisch (A. Fick Mech. Arbeit u. Wärmeentwickelung bei d. Muskelthätigkeit (1882) vii. 112).] Of, pertaining to, or designating muscular action in which tension is developed but appreciable shortening of the muscle is prevented.
1891A. D. Waller Introd. Human Physiol. ix. 330 If a muscle contracts against a large resistance..so that it can shorten very little, the curve described by a lever attached to it is termed ‘isometric’. 1895Proc. R. Soc. LVII. 423 The shortening of the muscle is prevented by resistance (isometric contraction of Fick). 1900[see isotonic a. 2]. 1920Jrnl. Physiol. LIV. 85 During the development of tension in an isometric contraction both heat and potential energy are being produced by the muscle. 1951[see isotonic a. 3]. 1969New Yorker 20 Dec. 43/2 He neither drinks nor smokes, and he devotes an hour a day to yoga and isometric exercises. 1971[see isotonic a. 3]. 1973Sci. Amer. Mar. 83 Whereas a machine only performs mechanical work when a force moves through a distance, muscles consume energy when they are in tension but not moving (doing what is sometimes called ‘isometric’ work).
5. Physics. Indicating, or taking place under, conditions of constant volume.
1873J. W. Gibbs in Trans. Connecticut Acad. Arts & Sci. II. 311 The points associated with states of equal volume will form lines, which..we may also call isometric. 1912G. A. Goodenough Princ. Thermodynamics (ed. 2) ii. 22 Lines of constant volume [are called] isometric lines. 1957V. M. Faires Thermodynamics (ed. 3) v. 69 For a reversible steady flow isometric process..we have the energy equation from equation (7 A).
6. Biol. = isogonic a.2
1950J. S. Huxley in Proc. R. Soc. B. CXXXVII. 467 In an isometric organ we find no change in the proportions of its parts with increase in its absolute size.
7. Math. That is an isometry; related by an isometry. Const. to.
1952C. C. Krieger tr. Sierpinski's Gen. Topology vi. 100 Two metric spaces consisting of the same elements but with different metrics may be isometric. 1959L. F. Boron tr. M.A. Naimark's Normed Rings i. 38 Two metric spaces X, X′ are said to be isometric if there exists an isometric mapping of X onto X′. 1966J. H. Cadwell Topics in Recreational Math. xi. 117 A pattern is characterised by the set of isometric motions that bring it into self-coincidence, and this set forms a discrete group. 1968E. T. Copson Metric Spaces iv. 53 If the points a, b of A* correspond to the points a and b of M, we have proved that ρ*(a, b) = ρ(a, b), so that A* is isometric to M.
B. n.
1. Physics. A line in a diagram that corresponds to or represents states of equal volume.
1873[see isopiestic adj. s.v. iso-]. 1936Industr. & Engin. Chem. Feb. 261/2 Not only are the isometrics of the pure substances themselves substantially straight, but the same is also true for mixtures. 1963Obert & Gaggioli Thermodynamics (ed. 2) x. 215 For the real gas, the isometrics are displaced from the origin and are either straight or slightly curved.
2. pl. A system of stationary physical exercises in which muscles are exercised isometrically by pitting one against another or against an unyielding object. orig. U.S.
1962Scholastic Coach Nov. 31/1 This concludes a series of three comprehensive articles on isometrics. 1964Life 17 Apr. 47/1 In 1921 Atlas began preaching the muscle⁓building system he called Dynamic Tension, which pits one muscle against another. Now variations of his system, in which muscles struggle against immobile objects, are the latest U.S. exercise fad. Scientists lump the systems under one fancy word, isometrics. 1970New Scientist 20 Aug. 365/1 Isometrics, but recently hailed as the key to the good life, have also now been condemned for dangerously rocketing the blood pressure. |