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   496488篇
  免费   4384篇
  国内免费   1511篇
化学   258122篇
晶体学   7711篇
力学   22360篇
综合类   11篇
数学   59638篇
物理学   154541篇
  2021年   4318篇
  2020年   4674篇
  2019年   5269篇
  2018年   7233篇
  2017年   7378篇
  2016年   10192篇
  2015年   5891篇
  2014年   9748篇
  2013年   22980篇
  2012年   17459篇
  2011年   20973篇
  2010年   15389篇
  2009年   15245篇
  2008年   19277篇
  2007年   19327篇
  2006年   17872篇
  2005年   15803篇
  2004年   14471篇
  2003年   12939篇
  2002年   12854篇
  2001年   14629篇
  2000年   11116篇
  1999年   8606篇
  1998年   7266篇
  1997年   7159篇
  1996年   6708篇
  1995年   5736篇
  1994年   5752篇
  1993年   5684篇
  1992年   6138篇
  1991年   6425篇
  1990年   6087篇
  1989年   5994篇
  1988年   5762篇
  1987年   5816篇
  1986年   5571篇
  1985年   7125篇
  1984年   7289篇
  1983年   6008篇
  1982年   6301篇
  1981年   5970篇
  1980年   5757篇
  1979年   6196篇
  1978年   6301篇
  1977年   6289篇
  1976年   6256篇
  1975年   5902篇
  1974年   5823篇
  1973年   6019篇
  1972年   4188篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
791.
The diffraction of normal shock with yawed wedges of small angles have been considered in this paper. Vorticity distribution of the fluid particle over the diffracted shock has been determined for several Mach numbers of the shock wave. The Mach reflection effects have also been investigated when the bend is concave to the flow.  相似文献   
792.
We consider almost upper-semicontinuous processes defined on a finite Markov chain. The distributions of functionals associated with the exit of these processes from a finite interval are studied. We also consider some modifications of these processes. __________ Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 59, No. 4, pp. 555–565, April, 2007.  相似文献   
793.
In the present work we consider the problem of interpolating scattered data using radial basis functions (RBF). In general, it is well known that this leads to a discrete linear inverse problem that needs to be regularized in order to provide a meaningful solution. The work focuses on a metric-regularization approach, based on a new class of RBF, called anisotropic RBF. The work provides theoretical justifications for the regularization approach and it considers a suitable proposal for the metric, supporting it by numerical examples.  相似文献   
794.
A theorem on the existence of a G-representation and a differential-geometric criterion of the kinematic integrability for nonlinear differential equations from the Λ2-G-classes is proved. Examples of zero-curvature representations and metrics for some equations of mathematical physics are presented. __________ Translated from Fundamental’naya i Prikladnaya Matematika (Fundamental and Applied Mathematics), Vol. 11, No. 1, Geometry, 2005.  相似文献   
795.
We consider a mathematical model of sorption that allows for external diffusion kinetics and a redox reaction. Two inverse problems are considered for this model, uniqueness is proved, and numerical solution methods are proposed. The efficiency of the numerical methods is investigated by computer experiments. __________ Translated from Prikladnaya Matematika i Informatika, No. 23, pp. 15–23, 2006.  相似文献   
796.
The photogyrotropic properties of several mordant yellow azo dyes in gelatin and polymer matrices that are in the normal state or exposed to circularly polarized light are investigated. A model explanation for the experimental data is given.  相似文献   
797.
It is suggested to produce metal-carbon composite coatings by magnetron sputtering of mosaic cathodes, which are Group IV, V, and VI metals. The mosaic structure of the cathode elements are computer-optimized for each of the metals. Reflection electron diffraction studies show that the coatings have the amorphous or nanocrystalline structures, which are thermally stable. The coatings offer specific physical properties, in particular, low friction factor and high hardness.  相似文献   
798.
799.
(Na, K)NbO3 crystals with a perovskite structure and a KNbO3 content up to 40 mol % were grown from flux with the use of the solvent NaBO2. The dielectric measurements of the crystals grown revealed phase transitions that had never been observed before in ceramic samples.  相似文献   
800.
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