全文获取类型
收费全文 | 25741篇 |
免费 | 3127篇 |
国内免费 | 2542篇 |
专业分类
化学 | 3926篇 |
晶体学 | 53篇 |
力学 | 2922篇 |
综合类 | 579篇 |
数学 | 14301篇 |
物理学 | 9629篇 |
出版年
2024年 | 35篇 |
2023年 | 212篇 |
2022年 | 451篇 |
2021年 | 466篇 |
2020年 | 547篇 |
2019年 | 567篇 |
2018年 | 575篇 |
2017年 | 780篇 |
2016年 | 854篇 |
2015年 | 735篇 |
2014年 | 1344篇 |
2013年 | 1706篇 |
2012年 | 1426篇 |
2011年 | 1673篇 |
2010年 | 1386篇 |
2009年 | 1719篇 |
2008年 | 1688篇 |
2007年 | 1801篇 |
2006年 | 1563篇 |
2005年 | 1523篇 |
2004年 | 1293篇 |
2003年 | 1169篇 |
2002年 | 992篇 |
2001年 | 888篇 |
2000年 | 818篇 |
1999年 | 733篇 |
1998年 | 662篇 |
1997年 | 604篇 |
1996年 | 451篇 |
1995年 | 381篇 |
1994年 | 316篇 |
1993年 | 247篇 |
1992年 | 203篇 |
1991年 | 186篇 |
1990年 | 181篇 |
1989年 | 138篇 |
1988年 | 124篇 |
1987年 | 118篇 |
1986年 | 96篇 |
1985年 | 114篇 |
1984年 | 89篇 |
1983年 | 54篇 |
1982年 | 93篇 |
1981年 | 86篇 |
1980年 | 50篇 |
1979年 | 51篇 |
1978年 | 43篇 |
1977年 | 35篇 |
1976年 | 41篇 |
1973年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
71.
风力发电机组变速恒频控制系统研究 总被引:2,自引:0,他引:2
全面介绍了一种最新应用于风力发电中的新型电机—无刷双馈电机,并分析了这种新型电机作变速恒频运行的原理并对这种电机进行了动态特性仿真研究,给出了形式简洁的控制方程和易于实现的控制方案。 相似文献
72.
袁文俊 《数学物理学报(A辑)》2003,23(2):224-230
该文考虑具有控制系数 A\-0 和系数仅有有限个极点的高阶线性齐次微分方程(1.1)。得到了一个复振荡结果,该结果是J. K. Langley[11]等作者在整系数下相应结果的推广。 相似文献
73.
A locally convex space is said to be a Gateaux differentiability space (GDS)provided every continuous convex function defined on a nonempty convex open subset D of the space is densely Gateaux differentiable in D.This paper shows that the product of a GDS and a family of separable Frechet spaces is a GDS,and that the product of a GDS and an arbitrary locally convex space endowed with the weak topology is a GDS. 相似文献
74.
75.
本文考虑广义C-R组^[1](H)的解f=u iv jw∈C^2的一些性质,提出与之相关的两个边值问题,用积分方程方法和调和函数性质证明了边值问题解的存在唯一性,并写出解的积分表达式. 相似文献
76.
B. Saha S. Bhattacharyya T. K. Mukherjee P. K. Mukherjee 《International journal of quantum chemistry》2003,92(5):413-418
In the framework of nonrelativistic variational formalism a new type of basis set is proposed, to estimate separately the effect of radial and angular correlations on the ground‐state energy for helium isoelectronic sequence H? to Ar16+. Effect of radial correlation is incorporated by using multiexponential functions arising from product basis sets suitably formed out of Slater‐type one‐particle orbitals. The angular correlation can be switched on by incorporating an expansion in terms of basis involving interparticle coordinates. With a set of six‐term Slater‐type one‐particle basis and five‐term interparticle expansion, the ground‐state energy of helium is estimated as ?2.9037236 (a.u.) compared with the multiterm variational estimates ?2.9037244 (a.u.) due to Pekeris and Thakkar and Smith and Drake. Matrix elements of different operators in the ground state have been calculated and found to be in good agreement with available accurate results. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 相似文献
77.
We present a practical polynomial-time algorithm for computing the
zeta function of a Kummer curve over a finite field of small
characteristic. Such algorithms have recently been obtained using a
method of Kedlaya based upon Monsky–Washnitzer cohomology, and are of
interest in cryptography. We take a different approach.
The problem is reduced to that of computing the L-function
of a multiplicative character sum. This latter task is achieved via a
cohomological formula based upon the work of Dwork and Reich. We show,
however, that our method and that of Kedlaya are very closely related.Dedicated to the memory of Gian-Carlo Rota 相似文献
78.
Lionel Thibault Nadia Zlateva 《Proceedings of the American Mathematical Society》2005,133(10):2939-2948
Using a quantitative version of the subdifferential characterization of directionally Lipschitz functions, we study the integrability of subdifferentials of such functions over arbitrary Banach space.
79.
The paper presents a new formulation of the integral boundary element method (BEM) using subdomain technique. A continuous approximation of the function and the function derivative in the direction normal to the boundary element (further ‘normal flux’) is introduced for solving the general form of a parabolic diffusion‐convective equation. Double nodes for normal flux approximation are used. The gradient continuity is required at the interior subdomain corners where compatibility and equilibrium interface conditions are prescribed. The obtained system matrix with more equations than unknowns is solved using the fast iterative linear least squares based solver. The robustness and stability of the developed formulation is shown on the cases of a backward‐facing step flow and a square‐driven cavity flow up to the Reynolds number value 50 000. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
80.