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   328篇
  免费   1篇
化学   132篇
晶体学   3篇
力学   4篇
数学   65篇
物理学   125篇
  2021年   6篇
  2020年   4篇
  2019年   9篇
  2018年   11篇
  2017年   13篇
  2016年   16篇
  2015年   7篇
  2014年   8篇
  2013年   15篇
  2012年   14篇
  2011年   11篇
  2010年   16篇
  2009年   15篇
  2008年   8篇
  2007年   8篇
  2006年   12篇
  2005年   6篇
  2004年   8篇
  2003年   7篇
  2002年   6篇
  2001年   6篇
  2000年   10篇
  1999年   3篇
  1998年   3篇
  1997年   5篇
  1994年   3篇
  1991年   3篇
  1989年   7篇
  1988年   5篇
  1987年   7篇
  1985年   3篇
  1984年   2篇
  1983年   3篇
  1982年   2篇
  1981年   4篇
  1980年   3篇
  1979年   6篇
  1976年   5篇
  1975年   4篇
  1974年   2篇
  1973年   3篇
  1972年   4篇
  1971年   3篇
  1970年   3篇
  1968年   2篇
  1967年   2篇
  1966年   3篇
  1963年   2篇
  1962年   4篇
  1959年   2篇
排序方式: 共有329条查询结果,搜索用时 15 毫秒
1.
In the article, it is proved that any nonnegative solution of an elliptic quasilinear inequality that vanishes on a subset of positive measure is trivial. __________ Translated from Trudy Seminara imeni I. G. Petrovskogo, No. 25, pp. 112–118, 2005.  相似文献   
2.
Conditions for the preparation of stable aqueous monometallic and bimetallic colloidal solutions (sols) of noble metals (Ru, Rh, Pd, Pt, Ir, Ag, and Au) in the presence of polyoxometalates containing W, Mo, V, and Nb were found. The stability of sols against coagulation at room temperature was studied. The metal/C samples prepared by metal adsorption from sols were studied by powder X-ray diffraction analysis and transmission electron microscopy. The following factors of importance for the preparation of a stable sol are discussed: (1) the formation of a sol of a metal polyhydroxo complex stabilized by a polyoxometalate (preliminary stage) and (2) the formation of polyoxometalate-metal clusters in the course of reduction of polyhydroxo complexes.Translated from Kinetika i Kataliz, Vol. 45, No. 6, 2004, pp. 921–929.Original Russian Text Copyright © 2004 by Maksimova, Chuvilin, Moroz, Likholobov, Matveev.  相似文献   
3.
The direct interaction of 2,6-diphenylpyrylium perchlorate with pyrazoles and pyrazolones led to the synthesis of 4-azolylpyrylium salts, which readily cleave a molecule of perchloric acid in the case of the N-unsubstituted pyrazolones, being converted to pyranylidene derivatives.For Communication 15, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 182–187, February, 1987.  相似文献   
4.
With respect to Co2+, Ni2+, Zn2+,Cd2+, Cu2+, Pd2+, and Sn4+ salts, 1-isopropenyl-substituted imidazole, 2-methylimidazole, and pyrazole behave as monodentate ligands with only one coordination center on the N1 and N2 atoms, respectively; 1-isopropenylpyrazole under complex-formation conditions is dealkylated to form pyrazole complexes. The reaction with HCl leaves the unsaturated substituent in 1-isopropenylimidazole intact and yields corresponding hydrochlorides by the N3 atom of the heterocycle. The least basic 1-isopropenylpyrazole takes up HCl also by the double bond of the alkenyl group.  相似文献   
5.
In this article, the results of calculations of scattering spectra of low-absorptive spherical particles are presented. It was obtained using different approximate and numerical methods. The comparative evaluations of application of single scattering approximation, the average field approximation and of the methods of computer modeling on the basis of Monte-Carlo method on various scattering multiplicity were performed. The comparison demonstrates the good agreement of calculated results with experimental scattering spectra of eye lens. By using the obtained spectral data the colour coordinates are calculated. The regularities of changes in colour characteristics in dependence of disperse system parameters are analyzed.  相似文献   
6.
A chemical sensor for tungstate ions has been developed and implemented in two versions on the basis of the poorly soluble nickel(II) hexatungstonickelate(II) heteropoly compound. The electrode function is linear within the range 10–5–10–1 M tungsten for the film electrode and within the range 10–4–10–1 M tungsten for the coated wire electrode at pH 6–9. The slope of the electrode function is 28–29 mV. The time it takes to attain an equilibrium electrode potential is 1–5 min, depending on the ion concentration to be determined. The selectivity coefficients are found for the tungstate-selective electrode in the presence of chloride, sulfate, nitrate, and perchlorate.  相似文献   
7.
Vibrational spectra of several nitramines in the long-wave region (50–450 cm−1) were studied. The frequencies of intra- and intermolecular vibrations were separated and a tentative assignment of the frequencies of self-associative complexes was performed. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2241–2244, November, 1998.  相似文献   
8.
A calculation is made of the dependences of the coefficient of the tellurium distribution KTe and the electron concentration n in AlxGa1–xSb on the composition of the solid solution and the growth temperature. It is shown that KTe must decrease with increasing x. The dependence of KTe on the temperature is also determined by x. Experimental results were obtained on AlxGa1–x Sb (0 x 0.74) films grown by liquid epitaxy. The electron concentration in the films was measured through the thermoelectric power and the capacitance-voltage characteristics of Schottky barriers. Satisfactory agreement with the results of the calculation was obtained.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 19–25, April, 1980.We thank G. K. Arbuzov for assistance in preparing the surface-barrier structures.  相似文献   
9.
DETECTION OF DNA-PSORALEN PHOTOADDUCTS in situ   总被引:1,自引:0,他引:1  
Abstract— An immunological method, with the use of specific immune serum, has been developed for detection of 8-methoxypsoralen (8-MOP) photoadducts to DNA, formed in situ in cell nuclei, after combined treatment with 8MOP and UV-A irradiation (Zarçbska et al. , 1978). Lymphocytes fixed on slides or in suspension, and cryostat sections of different mammalian tissues, served as antigenic substrate, after treatment with 8-MOP and UV-A in vitro. Specific fluorescence in these substrates was detected in the nuclei after treatment with 30 ˜ 140 kJ/m2 UV-A in the presence of 0.1-0.3 μg/cm2 8-MOP. PHA-stimulated-lymphocytes appeared to be the most sensitive substrate.
However, hairless mice treated with high doses of UV-A in vivo , 70 ˜ 360 kJ/m2 did not reveal a specific fluorescence of epidermal nuclei, unless a high local concentration of 8-MOP was attained.
The apparent discrepancy in the level of photoadduct detection between the in vitro and in vivo treated specimens was explained by the low number of DNA-8-MOP-photoadducts formed in vivo under these experimental conditions. The relevance of these findings to the role of DNA-8-MOP-photoadducts formed during PUVA photochemotherapy is discussed.  相似文献   
10.
The temperature effect on the rate of the decomposition of hydroperoxides and the rate of the formation of free radicals in the oxidation of ethylbenzene with molecular oxygen in the presence of -phenylethyl hydroperoxide—cetyltrimethylammonium bromide (CTAB) as a catalytic system for free radical generation was studied by kinetic methods (from the oxygen consumption and hydroperoxide decomposition rates) and the inhibition method involving different acceptors of free radicals.  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