| 释义 |
isopycnic, a. and n.|aɪsəʊˈpɪknɪk|
[f. as prec. + -al.]
A. adj. (Connecting points) of the same density or of constant density; also, in Biochem., used with reference to ultracentrifugal separative techniques which rely on differences in density between the components of a mixture.
1890Webster s.v., An isopycnic line or surface. 1910V. Bjerknes et al. Dynamic Meteorol. & Hydrogr. I. iii. 39 We may represent the distribution of mass by drawing surfaces of constant value of the density, or isopycnic surfaces. 1930N. Shaw Man. Meteorol. III. vi. 262 (caption) The isothermic, isobaric, isopycnic lines. 1955Exper. Cell Res. IX. 457 Isopycnic gradient centrifugation for the stratification and separation of marine egg halves and quarters was first described by the Harveys. 1962Aeroplane CII. 179/1 The isopycnic level at about 25,000 ft., known to meteorologists for its relative constancy, is being suggested as an accurate reference level for shifting safely from pressure instrument to density altimeter set according to the standard atmosphere. 1964Jrnl. Appl. Meteorol. III. 292/2 A thick isopycnic zone might reasonably be said to exist there [in the equatorial region] from about 5–14 km. 1964C. J. O. R. & P. Morris Separation Methods in Biochem. xxi. 807 On the application of the centrifugal field each particle migrates to a position in the gradient corresponding to its own density (the isopycnic point). Particles initially situated below their isopycnic level float upwards to it. Ibid. 809 The apparent density..found from isopycnic measurements. 1971Nature 29 Jan. 299/3 Preparing material entirely uncontaminated by cytoplasmic ribosomes, by isolating the mitochondria by isopycnic centrifugation through sucrose gradients.
B. n. Meteorol. A line (imaginary or on a map) or an imaginary surface connecting points at which the density is the same.
1890Webster, Isopycnic n., a line or surface passing through those points in a medium, at which the density is the same. 1924Q. Jrnl. R. Meteorol. Soc. L. 32 In all probability the concentration of the isopycnics takes place over the antarctic continent. 1930N. Shaw Man. Meteorol. III. vi. 260 (table) Isobars..Isotherms..Isopycnics. |