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   20520篇
  免费   137篇
  国内免费   89篇
化学   10387篇
晶体学   417篇
力学   603篇
综合类   7篇
数学   1713篇
物理学   7619篇
  2017年   155篇
  2016年   243篇
  2015年   166篇
  2014年   267篇
  2013年   840篇
  2012年   576篇
  2011年   635篇
  2010年   462篇
  2009年   472篇
  2008年   624篇
  2007年   674篇
  2006年   637篇
  2005年   582篇
  2004年   502篇
  2003年   472篇
  2002年   467篇
  2001年   691篇
  2000年   512篇
  1999年   430篇
  1998年   351篇
  1997年   332篇
  1996年   303篇
  1995年   380篇
  1994年   349篇
  1993年   319篇
  1992年   346篇
  1991年   389篇
  1990年   362篇
  1989年   364篇
  1988年   335篇
  1987年   334篇
  1986年   328篇
  1985年   407篇
  1984年   424篇
  1983年   318篇
  1982年   327篇
  1981年   350篇
  1980年   324篇
  1979年   336篇
  1978年   335篇
  1977年   314篇
  1976年   332篇
  1975年   290篇
  1974年   283篇
  1973年   299篇
  1972年   182篇
  1969年   159篇
  1968年   189篇
  1967年   334篇
  1966年   284篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
121.
We present a density functional scheme for calculating the frequency-dependent linear response of superconductors. The central result is a set of integral equations determining the linear response of the normal and anomalous densities to external perturbations. Analytic solutions of these integral equations are obtained for homogeneous systems with separable effective interactions. For inhomogeneous superconductors, the formalism leads to a scheme for calculating the critical temperature without explicitly solving the gap equation. © 1995 John Wiley & Sons, Inc.  相似文献   
122.
[(C6H5)3P]2Ni(Me3Si? C?C? SiMe3). Preparation, Properties, and Structure of the First Stable Nickel(0) Complex with Bis(trimethylsilyl)acetylene The title compound is the first example of a nickel(0) complex with bis(trimethylsilyl)acetylene and obtained from (ph3P)2Ni(C2H4) and bis(trimethylsilyl)acetylene in tetrahydrofuran. The complex is characterized by some reactions, the i.r. spectrum and by a structural analysis with the aid of X-ray diffraction data. (ph3P)2Ni(Me3Si? C?C? SiMe3) crystallizes monoclinic in the space group C2/c with four formula units per unit cell (2468 observed, independent reflexions, R = 0.038). The cell dimensions are a = 20.927, b = 13.812, c = 14.238 Å, α = γ = 90°, β = 91.02°. The molecules are monomer in crystalls. The molecule is planar with ligands arranged trigonally about the central atome but distorted to the tetrahedral complex.  相似文献   
123.
124.
Structure changes occurring in hot-deformation of the austenite of steel, the - phase transformation of which takes place above room temperature, cannot directly be studied with quenched specimens. However, within certain limits a microstructure characterization is possible by means of investigation of carefully selected model alloys and/or by analysis of the microstructure inheritance associated with a martensitic - transition of the hot-worked austenite. Application of both procedures is demonstrated with results which were obtained in investigations of the hot-working behaviour of low-alloy spring steel and an Fe-Ni-C model alloy.  相似文献   
125.
Previous studies of the magnetic susceptibility of a Ag-3 at.% Mn spin-glass under high pressure are extended to include the systems Au-3at.% Mn, Cu-3at.% Mn and Au-3at.% Fe. In all four alloys the spin-glass freezing temperatureT 0 increases with pressure, yielding the volume dependences lnT 0/ lnV=–3.6±0.4, –4.1±0.6, –2.1±0.4 and –1.64±0.25, respectively. These results give information about the nature of the interaction mechanisms responsible for the spin-glass freezing phenomena. The pressure dependence of the Curie temperature of ferromagnetic Au-20at.% Fe was also studied.Dedicated to B. Mühlschlegel on the occasion of his 60th birthday  相似文献   
126.
Triphenylphosphane Nickel(0) Complexes with Isocyanide Ligands — [(RNC)nNi(PPh3)4–n] (n = 1–3) Synthesis and properties of the isocyanide triphenylphosphane nickel(0) complexes [(RNC)Ni(PPh3)3], [(RNC)2Ni(PPh3)2] and [(RNC)3Ni(PPh3)] (R = tBu, Cy, PhCH2, p-TosCH2) are described. I.r. and 31P n.m.r. spectra were recorded and the X-ray crystal structure of [(PhCH2NC)2Ni(PPh3)2] was determined.  相似文献   
127.
Summary The compositions of the neutral lipids of the mycelium and of the culture liquid from the pathogenic fungusVerticillium dahliae Kleb. have been investigated for the first time. The fatty-acid compositions of the main lipid fractions and the glyceride composition of the triglyceride fraction have been determined. The main acids of all the fractions are the 16:0 and 18:1 acids and in the triglyceride fraction, additionally, the 18:2 acid. Diisobutyl phthalate has been found in the combined neutral lipids of the fungal mycelium.V. I. Lenin Tashkent State University, Institute of the Chemistry of Plant Plant Substances, Academy of Sciences of the Uzbek SSR, Tashkent. Translated from Khimiya Prirodnykh Soedinenii, No. 4, pp. 431–435, July–August, 1976.  相似文献   
128.
129.
4-Methyl-5,6-dihydro-2H- and 4-methylenetetrahydropyrans undergo an ene- type reaction with phenylsulfinyl chloride in the presence of ZnCl2 to give the corresponding allylic sulfoxides.October Revolution Fortieth Anniversary, Bashkir State University, UfaTranslated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1446–1447, June, 1990.  相似文献   
130.
Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 9, pp. 2117–2120, September, 1989.  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