全文获取类型
收费全文 | 67161篇 |
免费 | 6931篇 |
国内免费 | 4758篇 |
专业分类
化学 | 31411篇 |
晶体学 | 370篇 |
力学 | 7642篇 |
综合类 | 1129篇 |
数学 | 17897篇 |
物理学 | 20401篇 |
出版年
2024年 | 102篇 |
2023年 | 633篇 |
2022年 | 1340篇 |
2021年 | 1759篇 |
2020年 | 1806篇 |
2019年 | 1685篇 |
2018年 | 1580篇 |
2017年 | 2120篇 |
2016年 | 2619篇 |
2015年 | 2060篇 |
2014年 | 3070篇 |
2013年 | 4817篇 |
2012年 | 3908篇 |
2011年 | 3864篇 |
2010年 | 3294篇 |
2009年 | 4029篇 |
2008年 | 4113篇 |
2007年 | 4509篇 |
2006年 | 3723篇 |
2005年 | 3418篇 |
2004年 | 3265篇 |
2003年 | 2718篇 |
2002年 | 2298篇 |
2001年 | 1935篇 |
2000年 | 1758篇 |
1999年 | 1612篇 |
1998年 | 1464篇 |
1997年 | 1287篇 |
1996年 | 1151篇 |
1995年 | 1126篇 |
1994年 | 889篇 |
1993年 | 750篇 |
1992年 | 652篇 |
1991年 | 612篇 |
1990年 | 507篇 |
1989年 | 336篇 |
1988年 | 370篇 |
1987年 | 242篇 |
1986年 | 204篇 |
1985年 | 233篇 |
1984年 | 188篇 |
1983年 | 98篇 |
1982年 | 145篇 |
1981年 | 105篇 |
1980年 | 87篇 |
1979年 | 118篇 |
1978年 | 59篇 |
1977年 | 47篇 |
1976年 | 41篇 |
1973年 | 19篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
We consider the problem of maximizing a linear fractional function on the Pareto efficient frontier of two other linear fractional functions. We present a finite pivoting-type algorithm that solves the maximization problem while computing simultaneously the efficient frontier. Application to multistage efficiency analysis is discussed. An example demonstrating the computational procedure is included. 相似文献
82.
J Ashenfelter 《Pramana》2002,59(5):713-717
The ESTU began operation in 1988 and achieved the design voltage of 20 MV in 1990. Since that time, improvements to the gas
handling system, negative ion injector, accelerator terminal and control system have greatly increased its capability and
reliability. Today, the ESTU can efficiently produce an extensive assortment of stable ions at wide-ranging energies in support
of low-energy nuclear physics. 相似文献
83.
A. Mielke 《Journal of statistical physics》1991,62(3-4):509-528
The magnetic properties of the one-dimensional Hubbard model with a hardcore interaction on a ring (periodic boundary conditions) are investigated. At finite temperatures it is shown to behave up to exponentially small corrections as a pure paramagnet. An explicit expression for the ground-state degeneracies is derived. The eigenstates of this model are used to perform a perlurbational treatment for large but finite interactions. In first order inU
1 an effective Hamiltonian for the one-dimensional Hubbard model is derived. It is the Hamiltonian of the one-dimensional Hcisenberg model with antiferromagnetic couplings between nearest neighbor spins. An asymptotic expansion for the ground-state energy is given. The results are valid for arbitrary densities of electrons. 相似文献
84.
本文讨论中立型大系统,获得了这类问题稳定性的一些充分判据,作为特殊情况,还得到了与[1-11]中相应的一些不同的结果.这些结果并不象文献[1]和[2]那样,要求a_(ii)的上界q_(ii)小于零. 相似文献
85.
C M Srivastava 《Pramana》1989,32(3):251-267
A theory of high temperature superconductivity in YBa2Cu3O7_δ compound has been developed on the basis of the momentum pairing of electrons through the relativistic Darwin interaction.
The transport behaviour of electrons is explained in terms of a mechanism of correlated electron transfer arising from the
electron-phonon coupling. A model Hamiltonian has been developed to describe the superconducting properties of the system.
This gives an energy gap which is higher than the BCS value. Attempts have been made to explain the absence of isotope effect,
the linear dependence of specific heat, the presence of larger temperature-independent paramagnetism in the normal phase and
the softening of some of the optic phonon modes observed in this system. 相似文献
86.
空间遥感相机长条反射镜较圆反射镜的整体刚度相差很大,整个组件在随火箭发射过程中因力学环境引起的自身位置改变导致面形的微小畸变从而对成像质量造成严重影响。因此,反射镜组件的设计就成为整个相机系统研制的重点与难点之一。对其进行科学、严谨的力学环境仿真是设计中的有效辅助手段。对某相机的长条反射镜组件动力学响应进行了较为深入的研究,借助MSC-patran,用有限元法进行了求解。获得了组件的动力学特性。 相似文献
87.
88.
On Quantum Team Games 总被引:2,自引:0,他引:2
E. Ahmed M. F. Elettreby A. S. Hegazi 《International Journal of Theoretical Physics》2006,45(5):880-886
Recently Liu and Simaan (2004) convex static multi-team classical games have been introduced. Here they are generalized to both nonconvex, dynamic and quantum games. Puu's incomplete information dynamical systems are modified and applied to Cournot team game. The replicator dynamics of the quantum prisoner's dilemma game is also studied. 相似文献
89.
Blaise Faugeras Jé rô me Pousin Franck Fontvieille. 《Mathematics of Computation》2006,75(253):209-222
A numerical scheme based on an operator splitting method and a dense output event location algorithm is proposed to integrate a diffusion-dissolution/precipitation chemical initial-boundary value problem with jumping nonlinearities. The numerical analysis of the scheme is carried out and it is proved to be of order 2 in time. This global order estimate is illustrated numerically on a test case.
90.
Robert S. Strichartz 《Proceedings of the American Mathematical Society》2002,130(3):805-817
Harmonic mappings from the Sierpinski gasket to the circle are described explicitly in terms of boundary values and topological data. In particular, all such mappings minimize energy within a given homotopy class. Explicit formulas are also given for the energy of the mapping and its normal derivatives at boundary points.