全文获取类型
收费全文 | 12082篇 |
免费 | 1449篇 |
国内免费 | 823篇 |
专业分类
化学 | 2401篇 |
晶体学 | 58篇 |
力学 | 1349篇 |
综合类 | 181篇 |
数学 | 6838篇 |
物理学 | 3527篇 |
出版年
2024年 | 21篇 |
2023年 | 116篇 |
2022年 | 193篇 |
2021年 | 229篇 |
2020年 | 334篇 |
2019年 | 329篇 |
2018年 | 327篇 |
2017年 | 359篇 |
2016年 | 423篇 |
2015年 | 303篇 |
2014年 | 473篇 |
2013年 | 1072篇 |
2012年 | 538篇 |
2011年 | 650篇 |
2010年 | 553篇 |
2009年 | 665篇 |
2008年 | 741篇 |
2007年 | 756篇 |
2006年 | 697篇 |
2005年 | 634篇 |
2004年 | 614篇 |
2003年 | 521篇 |
2002年 | 470篇 |
2001年 | 412篇 |
2000年 | 424篇 |
1999年 | 350篇 |
1998年 | 286篇 |
1997年 | 300篇 |
1996年 | 201篇 |
1995年 | 214篇 |
1994年 | 162篇 |
1993年 | 142篇 |
1992年 | 123篇 |
1991年 | 107篇 |
1990年 | 80篇 |
1989年 | 49篇 |
1988年 | 49篇 |
1987年 | 50篇 |
1986年 | 49篇 |
1985年 | 54篇 |
1984年 | 45篇 |
1983年 | 27篇 |
1982年 | 41篇 |
1981年 | 23篇 |
1980年 | 25篇 |
1979年 | 22篇 |
1978年 | 20篇 |
1977年 | 23篇 |
1974年 | 10篇 |
1973年 | 17篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
M. Büttiker 《Journal of statistical physics》1989,54(5-6):1425-1425
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 [M. Büttiker,Z. Phys. B
68:161 (1987)]. A specific example of this behavior [N. G. van Kampen,IBM J. Res. Dev.
32:107 (1988); R. Landauer,J. Stat. Phys.
53:233 (1988).] is the motion of overdamped particles in a ring subject to a nonuniform temperature field. When the drift and the temperature, which are periodic with a period equal to the ring circumference, are not in phase a noise-induced circulating current results.This paper will appear in a forthcoming issue of theJournal of Statistical Physics. 相似文献
12.
ZHAO Ren ZHANG Li-Chun HU Shuang-Qi 《理论物理通讯》2006,46(10)
We generalize the method that is used to study corrections to Cardy-Verlinde formula due to generalized uncertainty principle and discuss corrections to Cardy-Verlinde formula due to generalized uncertainty principle in (anti)-de Sitter space. Because in de Sitter black hole spacetime the radiation temperature of the black hole horizon is different from the one of the cosmological horizon, this spacetime is a thermodynamical non-equilibrium spacetime. 相似文献
13.
带干扰的多险种风险模型 总被引:2,自引:0,他引:2
由于保险公司风险经营规模不断扩大,用单一险种的模型来描述风险过程存在局限性,本文讨论了带干扰多险种风险模型,应用鞅论方法,得出伦德伯格不等式和最终破产概率公式。 相似文献
14.
A. D. Rogers 《Acta Mathematica Hungarica》2006,110(1-2):13-21
Summary A lower bound is established for the strip discrepancy of a broad class of point distributions. The bound implies unbounded
strip discrepancy for equally weighted point distributions under favorable conditions. The methods of proof use notions from
integral geometry. 相似文献
15.
The multilevel generalized assignment problem is a problem of assigning agents to tasks where the agents can perform tasks at more than one efficiency level. A profit is associated with each assignment and the objective of the problem is profit maximization. Two heuristic solution methods are presented for the problem. The heuristics are developed from solution methods for the generalized assignment problem. One method uses a regret minimization approach whilst the other method uses a repair approach on a relaxation of the problem. The heuristics are able to solve moderately large instances of the problem rapidly and effectively. Procedures for deriving an upper bound on the solution of the problem are also described. On larger and harder instances of the problem one heuristic is particularly effective. 相似文献
16.
We show that the difference between the Schrödinger uncertainty relations (UR) and the Heisenberg UR is fundamental. We propose a modified version of stochastic mechanics that allows clearly demonstrating that the contributions from the anticommutator and the commutator to the Schrödinger UR are equally important. A classification of quantum states minimizing the Schrödinger UR at an arbitrary instant is proposed. We show that the correlation of the coordinate and momentum fluctuations in such correlated-coherent states (CCS) is largely determined by the contributions from not only the commutator but also the anticommutator of the corresponding operators. We demonstrate that the character of this correlation changes qualitatively in time from the antiphase correlation typical for the Heisenberg UR to the inphase correlation for which the contribution from the anticommutator is decisive. We comparatively analyze properties of a free microparticle and a quantum oscillator in CCS and show that the CCS correspond to traveling-standing de Broglie waves in both models. 相似文献
17.
1.引 言 本文的目的是用求解偏微分方程(PDE)的方法来消除离散三角形曲面的噪声,所使用的方程是热传导方程到曲面的推广.热传导方程应用于图像处理已有二十余年的历史,有关参考文献相当丰富(见[1,11,12,19]).众所周知,对于给定的初始图像ρ0,热传导方程 在τ时刻的解与用Gauss滤波器Gσ(x)= (当标准差σ=2τ,时)和ρ0作卷积的结果相同.容易看出Gρ和ρ0的卷积运算相当于对ρ0做加权平均,当标准离差σ变大时,该加权平均在一个较大的范围实现,这解释了热传导方程的滤波作用.近来热传导方程已推广到空间曲面[4,5]以及高维空间中的二维流形(见[3]),对 相似文献
18.
In this paper we introduce a generalization of stable sets: stable multi-sets. A stable multi-set is an assignment of integers
to the vertices of a graph, such that specified bounds on vertices and edges are not exceeded. In case all vertex and edge
bounds equal one, stable multi-sets are equivalent to stable sets.
For the stable multi-set problem, we derive reduction rules and study the associated polytope. We state necessary and sufficient
conditions for the extreme points of the linear relaxation to be integer. These conditions generalize the conditions for the
stable set polytope. Moreover, the classes of odd cycle and clique inequalities for stable sets are generalized to stable
multi-sets and conditions for them to be facet defining are determined.
The study of stable multi-sets is initiated by optimization problems in the field of telecommunication networks. Stable multi-sets
emerge as an important substructure in the design of optical networks.
Received: February 14, 2001/Revised version: September 7, 2001 相似文献
19.
20.
陈泽乾 《数学物理学报(B辑英文版)》2002,22(3)
A new framework of Gaussian white noise calculus is established, in line with generalized expansion in [3, 4, 7]. A suitable frame of Fock expansion is presented on Gaussian generalized expansion functionals being introduced here, which provides the integral kernel operator decomposition of the second quantization of Koopman operators for chaotic dynamical systems, in terms of annihilation operators dt and its dual, creation operators t*. 相似文献