| 释义 |
isobar Phys. Geog. and Meteorol.|ˈaɪsəʊbɑː(r)|
Also isobare.
[f. Gr. ἰσοβαρή-ς of equal weight, f. ἰσο-, iso- + βαρε-, βάρος weight, βαρύς heavy.]
1. a. A line (drawn on a map or chart, or imaginary) connecting places on the earth's surface at which the barometric pressure is the same (at a given time, or on the average for a given period); an isobaric line.
1864in Webster. 1878Huxley Physiogr. 94 Another isobar [in the Times weather-chart] stretches across Scotland, and indicates a pressure of 29·9 inches. 1880Times 16 Aug. 11/4 In the above chart the dotted lines are ‘isobars’ or lines of equal barometrical pressure. 1880Geikie Phys. Geog. ii. 55 Charts showing, by means of lines of equal pressure called Isobars, the general distribution of atmospheric pressure.
b. A line in a diagram that represents states or conditions of equal pressure.
1892P. Alexander Treat. Thermodynamics v. 39 An isobar is a constant pressure thermogram. 1924A. E. Hill in H. S. Taylor Treat. Physical Chem. I. ix. 383 The isobar ab drawn at 1 atmosphere pressure intersects the curve BO at -78·3°. 1969S. M. Blinder Adv. Physical Chem. viii. 144 In Fig. 8.2, the same data are represented as a series of isobars, plots of V versus t for fixed P.
2. Physics. Each of two or more nuclides which have the same mass number but different atomic numbers (and so are different elements). Orig. † isobare (obs.).
1918A. W. Stewart in Phil. Mag. XXVI. 331 These elements [sc. mesothorium and radiothorium] differ completely from one another in chemical character; but they all possess the same atomic weight. For this reason the name isobares..is here suggested for them. 1928M. Steel Physical Chem. & Biophysics ii. 37 Any product of radioactive change due to the loss of a beta particle..is an isobar of the parent element. 1946Electronic Engin. XVIII. 88/2 Neptunium and plutonium are isobares (same atomic mass but different atomic number). 1952Sci. News XXIII. 37 These nuclei are called isobares. 1954K. Rankama Isotope Geol. xxv. 302 The isotope 40K is the active nuclide in the series of the three neighbouring isobars, 40A{b1}40K{b1}40Ca. 1955R. D. Evans Atomic Nucleus iii. 99 The chemical properties of isobars are generally dissimilar, but their nuclear properties tend to present many parallel features. 1966Phillips & Williams Inorg. Chem. II. xxxv. 621 We shall use the symbol Z for the number of protons in a nucleus (i.e. the atomic number) and N for the number of neutrons, so that A = Z + N, where A is the mass number or ‘rounded’ atomic weight. All nuclei of the same Z are called isotopes, of the same N isotones, and of the same A isobars. |