全文获取类型
收费全文 | 10358篇 |
免费 | 524篇 |
国内免费 | 601篇 |
专业分类
化学 | 1473篇 |
晶体学 | 24篇 |
力学 | 342篇 |
综合类 | 62篇 |
数学 | 2717篇 |
物理学 | 1182篇 |
综合类 | 5683篇 |
出版年
2024年 | 18篇 |
2023年 | 69篇 |
2022年 | 91篇 |
2021年 | 136篇 |
2020年 | 168篇 |
2019年 | 172篇 |
2018年 | 146篇 |
2017年 | 211篇 |
2016年 | 199篇 |
2015年 | 212篇 |
2014年 | 455篇 |
2013年 | 548篇 |
2012年 | 486篇 |
2011年 | 595篇 |
2010年 | 512篇 |
2009年 | 629篇 |
2008年 | 608篇 |
2007年 | 730篇 |
2006年 | 715篇 |
2005年 | 587篇 |
2004年 | 514篇 |
2003年 | 537篇 |
2002年 | 433篇 |
2001年 | 440篇 |
2000年 | 361篇 |
1999年 | 283篇 |
1998年 | 252篇 |
1997年 | 194篇 |
1996年 | 155篇 |
1995年 | 143篇 |
1994年 | 134篇 |
1993年 | 110篇 |
1992年 | 92篇 |
1991年 | 77篇 |
1990年 | 62篇 |
1989年 | 57篇 |
1988年 | 68篇 |
1987年 | 45篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 28篇 |
1983年 | 15篇 |
1982年 | 23篇 |
1981年 | 16篇 |
1980年 | 24篇 |
1979年 | 26篇 |
1978年 | 10篇 |
1977年 | 11篇 |
1973年 | 4篇 |
1955年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Ziemowit Rzeszotnik Darrin Speegle 《Proceedings of the American Mathematical Society》2002,130(10):2921-2930
We show that any wavelet, with the support of its Fourier transform small enough, can be interpolated from a pair of wavelet sets. In particular, the support of the Fourier transform of such wavelets must contain a wavelet set, answering a special case of an open problem of Larson. The interpolation procedure, which was introduced by X. Dai and D. Larson, allows us also to prove the extension property.
12.
不完全信息群体决策专家权重的集结 总被引:8,自引:5,他引:3
本文对于属性权重信息和属性效用信息都不完全的群体多属性决策问题,通过构造属性值区间和运用系统聚类分析法,对群体决策中的专家进行分类,并确定每位专家的权重. 相似文献
13.
It is long known that the Fokker-Planck equation with prescribed constant coefficients of diffusion and linear friction describes
the ensemble average of the stochastic evolutions in velocity space of a Brownian test particle immersed in a heat bath of
fixed temperature. Apparently, it is not so well known that the same partial differential equation, but now with constant
coefficients which are functionals of the solution itself rather than being prescribed, describes the kinetic evolution (in
the N→∞ limit) of an
isolated
N-particle system with certain stochastic interactions. Here we discuss in detail this recently discovered interpretation.
An erratum to this article can be found at 相似文献
14.
L. T. Ashchepkov 《Computational Mathematics and Mathematical Physics》2006,46(7):1168-1175
A general nonlinear programming problem with interval functions is considered. Two reductions of this problem to the deterministic nonlinear programming problem are proposed, and illustrative examples are discussed. 相似文献
15.
A Modified Quasi-Newton Method for Structured Optimization with Partial Information on the Hessian 总被引:2,自引:0,他引:2
This paper develops a modified quasi-Newton method for structured unconstrained optimization with partial information on the
Hessian, based on a better approximation to the Hessian in current search direction. The new approximation is decided by both
function values and gradients at the last two iterations unlike the original one which only uses the gradients at the last
two iterations. The modified method owns local and superlinear convergence. Numerical experiments show that the proposed method
is encouraging comparing with the methods proposed in [4] for structured unconstrained optimization
Presented at the 6th International Conference on Optimization: Techniques and Applications, Ballarat, Australia, December
9–11, 2004 相似文献
16.
17.
M. D. Srinivas 《Pramana》2003,60(6):1137-1152
We derive an optimal bound on the sum of entropic uncertainties of two or more observables when they are sequentially measured
on the same ensemble of systems. This optimal bound is shown to be greater than or equal to the bounds derived in the literature
on the sum of entropie uncertainties of two observables which are measured on distinct but identically prepared ensembles
of systems. In the case of a two-dimensional Hilbert space, the optimum bound for successive measurements of two-spin components,
is seen to be strictly greater than the optimal bound for the case when they are measured on distinct ensembles, except when
the spin components are mutually parallel or perpendicular 相似文献
18.
郎炜 《科技情报开发与经济》2007,17(13):259-260
介绍了热量计量的基本原理和热费确定的基本原则,阐述了供热总费用的构成与计算原理以及用户热费的构成与计算原理。 相似文献
19.
S. Mancini D. Vitali V. Giovannetti P. Tombesi 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):417-422
We show that the optomechanical coupling between an optical cavity mode and two movable cavity mirrors is able to entangle
two different macroscopic oscillation modes of the mirrors. This continuous variable entanglement is maintained by the light
bouncing between the mirrors and is robust against thermal noise. In fact, it could be experimentally demonstrated using present
technology.
Received 2 September 2002 / Received in final form 10 October 2002 Published online 7 January 2003 相似文献
20.
We investigate the effects of adding uniformity requirements to concepts in computable structure theory such as computable categoricity (of a structure) and intrinsic computability (of a relation on a computable structure). We consider and compare two different notions of uniformity, previously studied by Kudinov and by Ventsov. We discuss some of their results and establish new ones, while also exploring the connections with the relative computable structure theory of Ash, Knight, Manasse, and Slaman and Chisholm and with previous work of Ash, Knight, and Slaman on uniformity in a general computable structure-theoretical setting. 相似文献