首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   232篇
  免费   2篇
化学   164篇
晶体学   1篇
力学   4篇
数学   20篇
物理学   45篇
  2021年   2篇
  2019年   2篇
  2018年   6篇
  2017年   4篇
  2016年   4篇
  2015年   2篇
  2014年   10篇
  2013年   21篇
  2012年   9篇
  2011年   14篇
  2010年   8篇
  2009年   10篇
  2008年   12篇
  2007年   8篇
  2006年   5篇
  2005年   7篇
  2004年   19篇
  2003年   19篇
  2002年   21篇
  2001年   8篇
  2000年   2篇
  1999年   1篇
  1998年   2篇
  1997年   1篇
  1994年   1篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1988年   4篇
  1987年   2篇
  1986年   1篇
  1985年   4篇
  1984年   2篇
  1983年   1篇
  1982年   2篇
  1980年   2篇
  1979年   3篇
  1978年   3篇
  1977年   3篇
  1976年   2篇
  1975年   1篇
  1973年   1篇
  1962年   1篇
排序方式: 共有234条查询结果,搜索用时 140 毫秒
11.
The mobility of fluoride and ammonium ions (180–480 K) in compounds K2? n (NH4)nZrF6 (0.2 ≤ n ≤ 1.70) was investigated by 19F and 1H NMR. Correlations have been found between the composition of the cation sublattice, the character of ion motions, and phase transition temperature in these compounds. The hightemperature modifications with n ≥ 0.85 of the compounds are characterized by translational diffusion of fluoride and ammonium ions and by uniaxial anisotropy of the 19F magnetic shielding tensor. The electrophysical characteristics of these compounds were studied in the temperature range 300–480 K.  相似文献   
12.
The reactions of tetraphenylbismuthonium and -stibonium salts Ph4EX (E = Bi, Sb; X = I, OSO2 (C6H3(CH3)2-2,5), OSO2C6H3(OH-4)(COOH-3)) with bismuth triiodide in acetone afford complexes [Ph4Bi]+[PhBi(C5H5N)I3]-, [(Ph4BiO)2S(O){2,5-(CH3)2C6H3S(O)} [Ph2Bi2I6]2–, [Ph4Sb [Bi4I16]4-·2(CH3)2C=O, and [Ph4Sb] 3+ + [Bi5I18]3-, whose structural units, according to the X-ray diffraction data, are tetraphenylbismuthonium (-stibonium) cations and mono-, di-, tetra-, and pentanuclear anions, respectively.  相似文献   
13.
A method is described for isolating phosphatidylinositol (PI) from a lipid extract of soybean phosphatides. The method includes the separation of the extract with the aid of a Büchner funnel and alumina into two fractions — choline-containing phospholipids and a PI fraction — and the purification of the latter on a column of DEAE-cellulose. As a by-product, phosphatidylethanolamine with a chromatographic purity of 95–96% is obtained from the PI fraction.Institute of Marine Biology, Far Eastern Scientific Center, Academy of the Sciences of the USSR, Vladivostok. Far Eastern State University, Vladivostok. Translated from Khimiya Prirodnykh Soedinenii, No. 1, pp. 35–38, January–February, 1984.  相似文献   
14.
15.
16.
Russian Journal of Coordination Chemistry - Chemisorption synthesis on the basis of the binuclear compound [Bi2{S2CN(C3H7)2}6] (I) and preparative isolation of the ion-polymeric heteronuclear...  相似文献   
17.
Using the conformal-mapping technique, we have found analytical solutions of the current-distribution problem for different configurations of plain conductors.  相似文献   
18.
Effect of electrochemically injected magnesium ions on the process in which carbonate deposits are formed on a corrodible surface of low-carbon steel in water of heat-and-water supply systems was studied. It was found that the anticorrosion efficiency of the deposit, evaluated by the polarization-resistance method and voltammetry, is approximately 1.5 times that of natural deposits formed in the absence of injected magnesium ions. X-ray diffraction analysis with grazing beam incidence, scanning electron microscopy, and energy-dispersive analysis demonstrated that mostly dense polycrystalline calcium carbonate deposits with a structure of aragonite are formed in the presence of magnesium ions. The mechanism by which a protective CaCO3 layer grows on the corrodible surface of low-carbon steel is discussed.  相似文献   
19.
The reaction of [Cd2{S2CN(CH2)6}4] (I) with morpholine gives a crystalline adduct of cadmium N,N-cyclo-hexamethylenedithiocarbamate [Cd{NH(CH2)4O}2{S2CN(CH2)6}2] (II), whose coordination sphere includes two molecules of the donor base. The structural organization and thermal behavior of II is studied by X-ray diffraction analysis and simultaneous thermal analysis in comparison with the original binuclear cadmium complex I. The central cadmium atom (coordination number 6) coordinates two morpholine molecules and two structurally equivalent S,S’-anisobidentate ligands HmDtc to form a chromophore [CdN2S4] with the structure of a distorted octahedron. The thermal destruction of II proceeds in two stages and includes consecutive steps of dissociation of the Cd-N bonds followed by the desorption of morpholine and thermolysis of the dithiocarbamate moiety of the adduct to form CdS as the final product. The structure of binuclear [Cd2{S2CN(CH2)6}4] is refined for a correct refinement of the geometric characteristics of compounds I and II.  相似文献   
20.
Evolution equations for marginal generalized microscopic phase densities are introduced. The evolution equations for average values of microscopic phase densities are derived and a solution of the initial-value problem for the hydrodynamic type hierarchy obtained is constructed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号