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   727943篇
  免费   7265篇
  国内免费   2359篇
化学   363141篇
晶体学   10560篇
力学   36618篇
综合类   20篇
数学   110531篇
物理学   216697篇
  2021年   5794篇
  2020年   6336篇
  2019年   6932篇
  2018年   18505篇
  2017年   18361篇
  2016年   18968篇
  2015年   9027篇
  2014年   13349篇
  2013年   31279篇
  2012年   26961篇
  2011年   38083篇
  2010年   25740篇
  2009年   25988篇
  2008年   32157篇
  2007年   33867篇
  2006年   24373篇
  2005年   22485篇
  2004年   21343篇
  2003年   19374篇
  2002年   18518篇
  2001年   20148篇
  2000年   15358篇
  1999年   12012篇
  1998年   10088篇
  1997年   9707篇
  1996年   9349篇
  1995年   8203篇
  1994年   8149篇
  1993年   7871篇
  1992年   8629篇
  1991年   8872篇
  1990年   8483篇
  1989年   8242篇
  1988年   8092篇
  1987年   8064篇
  1986年   7633篇
  1985年   9831篇
  1984年   10021篇
  1983年   8122篇
  1982年   8291篇
  1981年   8052篇
  1980年   7633篇
  1979年   8255篇
  1978年   8366篇
  1977年   8243篇
  1976年   8165篇
  1975年   7682篇
  1974年   7580篇
  1973年   7573篇
  1972年   5393篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
81.
Transport as a consequence of state-dependent diffusion   总被引:1,自引:0,他引:1  
Overdamped particles subject to a drift in a force field with sinusoidal space dependence and also a sinusoidally modulated space-dependent diffusion, with the same period as the drift, experience a net driving force. The resulting current depends on the amplitude of the modulation of the diffusion and is a periodic function of the phase difference between the sinusoidal drift and the sinusoidal modulation of the diffusion. For small modulation amplitudes a particle subject to state-dependent noise behaves the same way as a particle subject to thermal noise but with a drift which, in addition to the sinusoidal term, contains a net force term.Dedicated to Professor Harry Thomas on the occasion of his 60th birthday  相似文献   
82.
83.
84.
A masked lithium homoenolate, generated by tellurium/lithium exchange, was reacted with epoxides. The lithium compound was also converted into other organometallics such as Grignard, and cuprates and the reactivity of those organometallics with epoxides was evaluated. The same building block was employed in the synthesis of (+/−)-frontalin.  相似文献   
85.
The main result of the paper is a theorem, using which a new proof of Roth’s theorem is obtained, a new solvability criterion for the matrix equation AX-YB = C is proved, a formula for a particular solution of the latter is derived, and the least of the orders of square nonsingular matrices containing a given rectangular matrix as a submatrix is determined. Bibliography: 5 titles. __________ Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 323, 2005, pp. 15–23.  相似文献   
86.
Using the method of the tensor Green’s function of the wave equation, the differential and total cross sections for the scattering of surface optical electromagnetic waves (surface plasmon polaritons) by a spherical nanoparticle into surface plasmon polaritons and light have been obtained with the inclusion of the magnetic dipole contribution. Using the example of noble metal systems, it has been shown that the magnetic dipole contribution may significantly affect the angular dependence of the differential cross sections and increase their anisotropy as the plasmon wavelength increases.  相似文献   
87.
We report morphologic changes of metallic surfaces at the onset of ablation, starting from gentle ablation to the emergence of ablation craters. The evolution of both observed melting zones and of ablation craters therein are investigated in dependence of the ablation laser fluence for nanosecond ultraviolet laser pulses. Further, consequences of crater formation for cluster synthesis within the released atomic vapor are pointed out. PACS 52.38.Mf; 79.20.Ds; 65.40.De  相似文献   
88.
Space-time directional Lyapunov exponents are introduced. They describe the maximal velocity of propagation to the right or to the left of fronts of perturbations in a frame moving with a given velocity. The continuity of these exponents as function of the velocity and an inequality relating them to the directional entropy is proved.  相似文献   
89.
We give sufficient conditions for Sobolev and Lipschitz functions in terms of their lower scaled-oscillation. The sharpness of these conditions is shown by examples. Our examples also show that a Stepanov-type differentiability theorem does not hold under the boundedness assumption of the lower scaled-oscillation.

  相似文献   

90.
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