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   352110篇
  免费   4318篇
  国内免费   1203篇
化学   192611篇
晶体学   5186篇
力学   13780篇
综合类   16篇
数学   40579篇
物理学   105459篇
  2020年   2966篇
  2019年   3134篇
  2018年   4225篇
  2017年   4065篇
  2016年   6320篇
  2015年   3945篇
  2014年   5824篇
  2013年   15142篇
  2012年   11351篇
  2011年   13858篇
  2010年   9579篇
  2009年   9013篇
  2008年   12936篇
  2007年   13002篇
  2006年   12300篇
  2005年   11393篇
  2004年   10102篇
  2003年   9146篇
  2002年   8789篇
  2001年   9465篇
  2000年   7455篇
  1999年   5685篇
  1998年   4955篇
  1997年   4946篇
  1996年   4787篇
  1995年   4202篇
  1994年   4143篇
  1993年   4172篇
  1992年   4524篇
  1991年   4437篇
  1990年   4247篇
  1989年   4238篇
  1988年   4121篇
  1987年   4131篇
  1986年   3901篇
  1985年   5259篇
  1984年   5453篇
  1983年   4464篇
  1982年   5042篇
  1981年   4723篇
  1980年   4557篇
  1979年   4775篇
  1978年   4985篇
  1977年   4911篇
  1976年   4871篇
  1975年   4639篇
  1974年   4530篇
  1973年   4797篇
  1972年   3110篇
  1967年   2967篇
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
1.
Numerical Algorithms - In this work, we propose a fractional extension of the one-dimensional nonlinear vibration problem on an elastic string. The fractional problem is governed by a hyperbolic...  相似文献   
2.
Theoretical and Mathematical Physics - Dynamic systems acting on the plane and possessing the Wada property have been observed. There exist only two topological types, symmetric and antisymmetric,...  相似文献   
3.
Shavgulidze  N. E. 《Mathematical Notes》2021,110(1-2):297-300
Mathematical Notes -  相似文献   
4.
Crystallography Reports - The recombinant С-terminal fragment of myomesin-2 was purified to a homogeneous state. The crystallization conditions for the С-terminal fragment of myomesin-2...  相似文献   
5.
Differential Equations - Galathea traps for confining plasma in a magnetic field created by current-carrying conductors immersed in the plasma volume constitute a promising class of objects for...  相似文献   
6.
Crystallography Reports - Methods of coherent X-ray diffraction imaging of the spatial structure of noncrystalline objects and nanocrystals (nanostructures) are considered. Particular attention is...  相似文献   
7.
8.
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR.  相似文献   
9.
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the...  相似文献   
10.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure.  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