全文获取类型
收费全文 | 8393篇 |
免费 | 1163篇 |
国内免费 | 637篇 |
专业分类
化学 | 923篇 |
晶体学 | 55篇 |
力学 | 1252篇 |
综合类 | 178篇 |
数学 | 5574篇 |
物理学 | 2211篇 |
出版年
2024年 | 16篇 |
2023年 | 89篇 |
2022年 | 153篇 |
2021年 | 160篇 |
2020年 | 213篇 |
2019年 | 196篇 |
2018年 | 240篇 |
2017年 | 284篇 |
2016年 | 341篇 |
2015年 | 239篇 |
2014年 | 370篇 |
2013年 | 639篇 |
2012年 | 429篇 |
2011年 | 482篇 |
2010年 | 460篇 |
2009年 | 522篇 |
2008年 | 532篇 |
2007年 | 537篇 |
2006年 | 493篇 |
2005年 | 457篇 |
2004年 | 418篇 |
2003年 | 359篇 |
2002年 | 361篇 |
2001年 | 272篇 |
2000年 | 287篇 |
1999年 | 211篇 |
1998年 | 193篇 |
1997年 | 187篇 |
1996年 | 146篇 |
1995年 | 143篇 |
1994年 | 101篇 |
1993年 | 97篇 |
1992年 | 91篇 |
1991年 | 60篇 |
1990年 | 72篇 |
1989年 | 37篇 |
1988年 | 34篇 |
1987年 | 39篇 |
1986年 | 28篇 |
1985年 | 26篇 |
1984年 | 30篇 |
1983年 | 12篇 |
1982年 | 18篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 13篇 |
1978年 | 21篇 |
1977年 | 18篇 |
1976年 | 9篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 16 毫秒
11.
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
12.
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
13.
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
14.
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
15.
线性分式规划最优解集的求法 总被引:5,自引:0,他引:5
薛声家 《应用数学与计算数学学报》2002,16(1):90-96
本文使用多面集的表示定理,导出了线性分式规划最优解集的结构,并给出确定全部最优解的计算步骤。 相似文献
16.
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
17.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
18.
19.
本文考察了包括平面上的各种广义 Cantor集 ,Sierpinski集和包括某些连续不可微曲线在内的广义 Sierpinski集 .由相似变换 ,导出了它们的级数表达式 ,并利用它和字符串空间的对应关系 ,计算出它们的Hausdorff维数 相似文献
20.
讨论了求解无约束线性最小二乘问题的一种并行单纯形法以及对它的改进算法并行共轭梯度—单纯形法 .算法本身具有很强的并行机制 ,能够充分地发挥并行机快速省时的特点 .本文也对算法做了理论分析 ,对算法的收敛性给予了证明 (在二维情形下 ) .最后做了数值实验 (由于软硬件条件的限制 ,并行算法未能在并行计算机上实现 ,鉴于这种情况 ,我们所做的数值实验均是在串行机上完成的 ) 相似文献