全文获取类型
收费全文 | 11407篇 |
免费 | 753篇 |
国内免费 | 885篇 |
专业分类
化学 | 611篇 |
晶体学 | 7篇 |
力学 | 536篇 |
综合类 | 131篇 |
数学 | 6299篇 |
物理学 | 2025篇 |
综合类 | 3436篇 |
出版年
2024年 | 12篇 |
2023年 | 84篇 |
2022年 | 111篇 |
2021年 | 120篇 |
2020年 | 169篇 |
2019年 | 171篇 |
2018年 | 152篇 |
2017年 | 175篇 |
2016年 | 232篇 |
2015年 | 210篇 |
2014年 | 385篇 |
2013年 | 682篇 |
2012年 | 505篇 |
2011年 | 573篇 |
2010年 | 513篇 |
2009年 | 718篇 |
2008年 | 741篇 |
2007年 | 848篇 |
2006年 | 771篇 |
2005年 | 616篇 |
2004年 | 553篇 |
2003年 | 511篇 |
2002年 | 509篇 |
2001年 | 433篇 |
2000年 | 389篇 |
1999年 | 366篇 |
1998年 | 357篇 |
1997年 | 280篇 |
1996年 | 277篇 |
1995年 | 202篇 |
1994年 | 194篇 |
1993年 | 180篇 |
1992年 | 146篇 |
1991年 | 115篇 |
1990年 | 113篇 |
1989年 | 87篇 |
1988年 | 108篇 |
1987年 | 68篇 |
1986年 | 50篇 |
1985年 | 51篇 |
1984年 | 54篇 |
1983年 | 20篇 |
1982年 | 37篇 |
1981年 | 25篇 |
1980年 | 26篇 |
1979年 | 27篇 |
1978年 | 18篇 |
1977年 | 21篇 |
1976年 | 14篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 929 毫秒
1.
2.
杨茂财 《太原理工大学学报》2003,34(3):381-382
就相关熵的性质进行了讨论,证明了在pp密度逼近中使用的作为“距离”的相关熵不满足距离定义中的第三个条件,并给出了三角不等式成立的条件。 相似文献
3.
算法的相关性变换与划分带个数的关系 总被引:1,自引:0,他引:1
王树义 《大连理工大学学报》1995,35(3):422-424
使用相关性变换法,划分并映射循环算法到具有固定尺寸的Systolic阵列。下标集合被划分成若干条带,划分带的条数与变换后的Systolic阵列算法的执行时间成正比。指出了Moldovan给出的计算划分带条数的公式有很大局限性,给出了由空间变换计算划分带条数的方法。 相似文献
4.
We employ a first-principles plane wave method with the
relativistic analytic pseudopotential of Hartwigsen, Goedecker and Hutter
(HGH) scheme in the frame of DFT to calculate
the equilibrium lattice parameters and the thermodynamic properties of
AlB2 compound with hcp structure. The obtained lattice parameters are in
good agreement with the available experimental data and those calculated by
others. Through the quasi-harmonic Debye model, obtained successfully are
the dependences of the
normalized lattice parameters a/a0 and c/c0 on pressure P, the normalized
primitive cell volume V/V0 on pressure P, the variation of the thermal
expansion α with pressure P and temperature T, as well as the Debye
temperature \ThetaD and the heat capacity CV on pressure P and
temperature T. 相似文献
5.
Zhong-Qing Wang 《Journal of Mathematical Analysis and Applications》2002,274(1):374-403
An orthogonal system of rational functions is discussed. Some inverse inequalities, imbedding inequalities and approximation results are obtained. Two model problems are considered. The stabilities and convergences of proposed rational spectral schemes and rational pseudospectral schemes are proved. The techniques used in this paper are also applicable to other problems on the whole line. Numerical results show the efficiency of this approach. 相似文献
6.
Formalization for problems of multicriteria decision making under uncertainty is constructed in terms of guaranteed and weak
estimates. A relevant definition of the vector maximinimax value is given. Parameterization and approximation of maximum,
minimax, and maximinimax values based on the inverse logical convolution are suggested. An application for multicommodity
networks is considered.
Received: December 13, 2000 / Accepted: August 21, 2001?Published online May 8, 2002 相似文献
7.
Fabio Schoen 《Journal of Global Optimization》1991,1(3):207-228
In this paper stochastic algorithms for global optimization are reviewed. After a brief introduction on random-search techniques, a more detailed analysis is carried out on the application of simulated annealing to continuous global optimization. The aim of such an analysis is mainly that of presenting recent papers on the subject, which have received only scarce attention in the most recent published surveys. Finally a very brief presentation of clustering techniques is given. 相似文献
8.
9.
Vivek F. Farias 《Operations Research Letters》2006,34(2):180-190
We consider a problem of allocating limited quantities of M types of resources among N independent activities that evolve over T epochs. In each epoch, we assign to each activity a task which consumes resources, generates utility, and determines the subsequent state of the activity. We study the complexity of, and approximation algorithms for, maximizing average utility. 相似文献
10.
Dual fractional cutting plane algorithms, in which cutting planes are used to iteratively tighten a linear relaxation of an integer program,
are well-known and form the basis of the highly successful branch-and-cut method. It is rather less well-known that various primal cutting plane algorithms were developed in the 1960s, for example by Young. In a primal algorithm, the main role of the cutting
planes is to enable a feasible solution to the original problem to be improved. Research on these algorithms has been almost
non-existent.
In this paper we argue for a re-examination of these primal methods. We describe a new primal algorithm for pure 0-1 problems based on strong valid inequalities and give some encouraging computational results. Possible extensions to the case of general
mixed-integer programs are also discussed. 相似文献