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   20649篇
  免费   153篇
  国内免费   89篇
化学   10484篇
晶体学   417篇
力学   604篇
综合类   7篇
数学   1722篇
物理学   7657篇
  2016年   246篇
  2015年   171篇
  2014年   267篇
  2013年   844篇
  2012年   578篇
  2011年   640篇
  2010年   464篇
  2009年   476篇
  2008年   626篇
  2007年   676篇
  2006年   643篇
  2005年   587篇
  2004年   502篇
  2003年   475篇
  2002年   469篇
  2001年   698篇
  2000年   515篇
  1999年   433篇
  1998年   354篇
  1997年   334篇
  1996年   306篇
  1995年   383篇
  1994年   351篇
  1993年   320篇
  1992年   349篇
  1991年   393篇
  1990年   365篇
  1989年   364篇
  1988年   337篇
  1987年   334篇
  1986年   328篇
  1985年   407篇
  1984年   425篇
  1983年   320篇
  1982年   329篇
  1981年   352篇
  1980年   328篇
  1979年   342篇
  1978年   342篇
  1977年   318篇
  1976年   333篇
  1975年   294篇
  1974年   288篇
  1973年   299篇
  1972年   185篇
  1971年   156篇
  1969年   159篇
  1968年   191篇
  1967年   334篇
  1966年   285篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
In this paper we prove that iff ∈ C([-π,π]2) and the function f is bounded partial p-variation for some p ∈ [1, ∞), then the double trigonometric Fourier series of a function f is uniformly (C;-α,-β) summable (α β< 1/p,α,β> 0) in the sense of Pringsheim. If α β≥ 1/p, then there exists a continuous function f0 of bounded partial double trigonometric Fourier series of fo diverge over cubes.  相似文献   
93.
This paper studies the problem of uniformly dissipative solutions of somefifth order non-linear differential equations by the use of frequency domaintechnique. We use the generalized theorem of Yacubovich on dissipativity toobtain some new sufficient conditions of the existence of solutions that aredissipative for (1.1) and (1.2).  相似文献   
94.
The effect of entrance channel on decrease of the complete fusion cross sections and on the yield of reaction products are associated with the quasifission which depends on the mass asymmetry and shell structure of colliding nuclei. In reactions of massive projectile and target nuclei, the competition between complete fusion and quasifission appears at the stage of compound nucleus formation, in addition to the increase of the fission probability. It is shown that the yield of quasifission products may be symmetric or asymmetric in dependence on peculiarities of shell structure of reaction fragments. Marima of mass or charge distributions are connected with the peculiarities of shell structure of reaction fragments.  相似文献   
95.
The perovskite-like compounds ACu3Ru4O12 (A=Na, Ca, Sr, La, Nd) are studied by means of density functional theory based electronic structure calculations using the augmented spherical wave (ASW) method. The electronic properties are strongly influenced by covalent-type bonding between transition metal d and oxygen p states. The characteristic tilting of the RuO6 octahedra arises mainly from the Cu–O bonding, allowing for optimal bond lengths between these two atoms. Our results provide a deeper understanding of octahedral tilting as a universal mechanism, applicable to a large variety of multinary compounds.  相似文献   
96.
A novel liquid scintillator system using metal β-diketonate chemistry based on loadings of indium, a target of current interest in low energy solar neutrino detection, is developed. The optical absorption, fluorescence and scintillation properties for this new system are described. The scintillation light output as found from the irradiation by low energy gamma-rays is presented. Notable light yields are found.  相似文献   
97.
98.
99.
Amorphous ribbons of Mg-Y-TM-[Ag] (TM: Cu, Ni), prepared by melt spinning, were subjected to electrochemical investigations. Oxide layers formed anodically under potentiostatic control in different electrolytes were investigated by AES and sputter depth profiling. Problems and specific features of characterization of the composition of oxide layers and amorphous ternary or quaternary Mg-based alloys have been investigated. In the alloys the Mg(KL(23)L(23)) peak exhibits a different shape compared to that in the pure element. Analysis of the peak of elastically scattered electrons proved the absence of plasmon loss features, characteristic of pure Mg, in the alloy. A different loss feature emerges in Mg(KL(23)L(23)) and Cu(L(23)VV). The system Mg-Y-TM-[Ag] suffers preferential sputtering. Depletion of Mg and enrichment of TM and Y are found. This is attributed mainly to the preferential sputtering of Mg. Thickness and composition of the formed oxide layer depend on the electrochemical treatment. After removing the oxide by sputtering the concentration of the underlying alloy was found to be affected by the treatment.  相似文献   
100.
A novel preference for planar tetracoordination was observed over the conventional tetrahedral arrangement in a new series of C5H2, C5H4, C5H41+/2+ and related compounds. The stability of these molecules is assessed with the ring-opening barriers, HOMO-LUMO gap, singlet-triplet energy differences and nucleus independent chemical shift values.  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