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   7062篇
  免费   402篇
  国内免费   419篇
化学   2206篇
晶体学   58篇
力学   162篇
综合类   145篇
数学   4360篇
物理学   952篇
  2023年   35篇
  2022年   157篇
  2021年   166篇
  2020年   145篇
  2019年   183篇
  2018年   205篇
  2017年   163篇
  2016年   163篇
  2015年   168篇
  2014年   222篇
  2013年   545篇
  2012年   279篇
  2011年   370篇
  2010年   352篇
  2009年   433篇
  2008年   462篇
  2007年   456篇
  2006年   411篇
  2005年   323篇
  2004年   317篇
  2003年   253篇
  2002年   218篇
  2001年   181篇
  2000年   210篇
  1999年   199篇
  1998年   151篇
  1997年   145篇
  1996年   99篇
  1995年   95篇
  1994年   92篇
  1993年   96篇
  1992年   76篇
  1991年   61篇
  1990年   55篇
  1989年   48篇
  1988年   43篇
  1987年   41篇
  1986年   36篇
  1985年   27篇
  1984年   33篇
  1983年   15篇
  1982年   27篇
  1981年   20篇
  1980年   23篇
  1979年   29篇
  1978年   25篇
  1977年   9篇
  1976年   8篇
  1975年   4篇
  1974年   3篇
排序方式: 共有7883条查询结果,搜索用时 46 毫秒
91.
An analogy between social and hydrodynamic processes is developed. The relation of the state system to the passionarity theory suggested by L. N. Gumilev is discussed.  相似文献   
92.
在误差序列为Lqmixingale情形下,给出了半参数回归模型中β和g(t)估计,研究了估计量的q阶平均相合性在较一般的条件下,得到了理想的结果  相似文献   
93.
The extension of Banach Lie-Poisson spaces is studied and linked to the extension of a special class of Banach Lie algebras. The case of W∗-algebras is given particular attention. Semidirect products and the extension of the restricted Banach Lie-Poisson space by the Banach Lie-Poisson space of compact operators are given as examples.  相似文献   
94.
The fracture mechanisms of Hg0.8Cd0.2Te induced by pulsed TEA-CO2 laser have been investigated theoretically and experimentally in this paper. The Hg0.8Cd0.2Te target was irradiated by a TEA-CO2 laser with wavelength of 10.6 μm and spike width of 240 ns in an ambient atmosphere. The evident cracks can be found on the surface of the target from the scanning electron microscopy (SEM) photos, indicating that the severe breaks happened during the experiment. Theoretical analysis has also been carried out and the results show that the fracture of Hg0.8Cd0.2Te is mainly induced by thermal stresses, although there are three forces (thermal stress, evaporation wave and laser-supported detonation (LSD) wave) exerted on the target surface during the process.  相似文献   
95.
A model for the dynamic, adhesive, frictionless contact between a viscoelastic body and a deformable foundation is described. The adhesion process is modeled by a bonding field on the contact surface. The contact is described by a modified normal compliance condition. The tangential shear due to the bonding field is included. The problem is formulated as a coupled system of a variational equality for the displacements and a differential equation for the bonding field. The existence of a unique weak solution for the problem is established, together with a partial regularity result. The existence proof proceeds by construction of an appropriate mapping which is shown to be a contraction on a Hilbert space.  相似文献   
96.
We provide a proof of Connes’ formula for a representative of the Hochschild class of the Chern character for (p,∞)-summable spectral triples. Our proof is valid for all semifinite von Neumann algebras, and all integral p?1. We employ the minimum possible hypotheses on the spectral triples.  相似文献   
97.
We prove that a large class of self-injective algebras of tilted type is invariant under stable equivalences of module categories.

  相似文献   

98.
When trains of impulse controls are present on the right-hand side of a system of ordinary differential equations, the solution is no longer smooth and contains jumps which can accumulate at several points in the time interval. In technological and physical systems the sum of the absolute value of all the impulses is finite and hence the total variation of the solution is finite. So the solution at best belongs to the space BV of vector functions with bounded variation. Unless variable node methods are used, the loss of smoothness of the solution would a priori make higher-order methods over a fixed mesh inactractive. Indeed in general the order of -convergence is and the nodal rate is . However in the linear case -convergence rate remains but the nodal rate can go up to by using one-step or multistep scheme with a nodal rate up to when the solution belongs to . Proofs are given of error estimates and several numerical experiments confirm the optimality of the estimates. Received March 15, 1996 / Revised version received January 3, 1997  相似文献   
99.
In this paper, we derive a one-parameter family of symplectic Runge-Kutta-Nyström methods of order 2s-1 and a two-parameter family of symplectic Runge-Kutta methods of order 2s-2.  相似文献   
100.
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