全文获取类型
收费全文 | 9572篇 |
免费 | 306篇 |
国内免费 | 396篇 |
专业分类
化学 | 1309篇 |
晶体学 | 9篇 |
力学 | 363篇 |
综合类 | 81篇 |
数学 | 7940篇 |
物理学 | 572篇 |
出版年
2023年 | 47篇 |
2022年 | 103篇 |
2021年 | 108篇 |
2020年 | 111篇 |
2019年 | 127篇 |
2018年 | 128篇 |
2017年 | 162篇 |
2016年 | 171篇 |
2015年 | 162篇 |
2014年 | 391篇 |
2013年 | 487篇 |
2012年 | 537篇 |
2011年 | 463篇 |
2010年 | 435篇 |
2009年 | 647篇 |
2008年 | 652篇 |
2007年 | 638篇 |
2006年 | 447篇 |
2005年 | 400篇 |
2004年 | 324篇 |
2003年 | 296篇 |
2002年 | 295篇 |
2001年 | 270篇 |
2000年 | 288篇 |
1999年 | 243篇 |
1998年 | 200篇 |
1997年 | 183篇 |
1996年 | 202篇 |
1995年 | 197篇 |
1994年 | 154篇 |
1993年 | 149篇 |
1992年 | 150篇 |
1991年 | 136篇 |
1990年 | 111篇 |
1989年 | 72篇 |
1988年 | 92篇 |
1987年 | 64篇 |
1986年 | 89篇 |
1985年 | 113篇 |
1984年 | 84篇 |
1983年 | 25篇 |
1982年 | 50篇 |
1981年 | 43篇 |
1980年 | 33篇 |
1979年 | 27篇 |
1978年 | 51篇 |
1977年 | 47篇 |
1976年 | 26篇 |
1975年 | 12篇 |
1974年 | 12篇 |
排序方式: 共有10000条查询结果,搜索用时 11 毫秒
1.
Chien-Hsin Cheng 《中国化学会会志》1994,41(1):33-38
Dynamic and static scattering of light was employed to investigate mixed micelles of two homologous anionic surfactants-sodium octyl sulfate and sodium hexadecyl sulfate, above the phase boundary temperature and critical micelle concentrations (cmc). The results indicate that the mixed micelles change from prolate to sphcrical as the molar ratio SOS/SHS increases from 1 to 8. Below 1 or above 8, the formation of micelles is due to one surfactant dissolving the other. 相似文献
2.
M. M. Kostreva 《Journal of Optimization Theory and Applications》1989,62(1):63-76
Murty's algorithm for the linear complementarity problem is generalized to solve the optimality conditions for linear and convex quadratic programming problems with both equality and inequality constraints. An implementation is suggested which provides both efficiency and tight error control. Numerical experiments as well as field tests in various applications show favorable results.The author thanks K. G. Murty for his encouragement and helpful comments. 相似文献
3.
Dean A. Carlson 《Journal of Mathematical Analysis and Applications》2002,276(2):561-588
The method of equivalent variational methods, originally due to Carathéodory for free problems in the calculus of variations is extended to investigate feedback Nash equilibria for a class of n-person differential games. Both the finite-horizon and infinite-horizon cases are considered. Examples are given to illustrate the presented results. 相似文献
4.
Mikhail Andramonov 《Journal of Global Optimization》2002,24(2):115-132
We consider applications of disjunctive programming to global optimization and problems with equilibrium constraints. We propose a modification of the algorithm of F. Beaumont for disjunctive programming problems and show its numerical efficiency. 相似文献
5.
We consider the problem of maximizing a linear fractional function on the Pareto efficient frontier of two other linear fractional functions. We present a finite pivoting-type algorithm that solves the maximization problem while computing simultaneously the efficient frontier. Application to multistage efficiency analysis is discussed. An example demonstrating the computational procedure is included. 相似文献
6.
Constraint Programming and Operations Research: Comments from an Operations Researcher 总被引:4,自引:0,他引:4
Michel Gendreau 《Journal of Heuristics》2002,8(1):19-24
This paper relates the author's personal experience with constraint programming and gives a personal assessment of the relationships between constraint programming and operations research. 相似文献
7.
最速下降规则不失为一可用规则 总被引:5,自引:4,他引:1
本从统计意义上平均迭代次数的观点出发,指出求解线性规划的最速下降规则是可取的,好用的。 相似文献
8.
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
9.
This paper deals with mathematical human resource planning; more specifically, it suggests a new model for a manpower‐planning system. In general, we study a k‐classed hierarchical system where the workforce demand at each time period is satisfied through internal mobility and recruitment. The motivation for this work is based on various European Union incentives, which promote regional or local government assistance programs that could be exploited by firms not only for hiring and training newcomers, but also to improve the skills and knowledge of their existing personnel. In this respect, in our augmented mobility model we establish a new ‘training/standby’ class, which serves as a manpower inventory position for potential recruits. This class, which may very well be internal or external to the system, is incorporated into the framework of a non‐homogeneous Markov chain model. Furthermore, cost objectives are employed using the goal‐programming approach, under different operating assumptions, in order to minimize the operational cost in the presence of system's constraints and regulations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
10.
Toward Fuzzy Optimization without Mathematical Ambiguity 总被引:15,自引:0,他引:15
Baoding Liu 《Fuzzy Optimization and Decision Making》2002,1(1):43-63
Fuzzy programming has been discussed widely in literature and applied in such various disciplines as operations research, economic management, business administration, and engineering. The main purpose of this paper is to present a brief review on fuzzy programming models, and classify them into three broad classes: expected value model, chance-constrained programming and dependent-chance programming. In order to solve general fuzzy programming models, a hybrid intelligent algorithm is also documented. Finally, some related topics are discussed. 相似文献