全文获取类型
收费全文 | 20213篇 |
免费 | 1338篇 |
国内免费 | 971篇 |
专业分类
化学 | 1319篇 |
晶体学 | 31篇 |
力学 | 1099篇 |
综合类 | 149篇 |
数学 | 7186篇 |
物理学 | 1534篇 |
综合类 | 11204篇 |
出版年
2024年 | 111篇 |
2023年 | 304篇 |
2022年 | 570篇 |
2021年 | 629篇 |
2020年 | 502篇 |
2019年 | 496篇 |
2018年 | 495篇 |
2017年 | 625篇 |
2016年 | 601篇 |
2015年 | 594篇 |
2014年 | 1058篇 |
2013年 | 1099篇 |
2012年 | 1307篇 |
2011年 | 1204篇 |
2010年 | 975篇 |
2009年 | 1107篇 |
2008年 | 1084篇 |
2007年 | 1314篇 |
2006年 | 1095篇 |
2005年 | 899篇 |
2004年 | 754篇 |
2003年 | 654篇 |
2002年 | 585篇 |
2001年 | 543篇 |
2000年 | 498篇 |
1999年 | 405篇 |
1998年 | 408篇 |
1997年 | 354篇 |
1996年 | 279篇 |
1995年 | 276篇 |
1994年 | 231篇 |
1993年 | 222篇 |
1992年 | 195篇 |
1991年 | 175篇 |
1990年 | 144篇 |
1989年 | 137篇 |
1988年 | 112篇 |
1987年 | 81篇 |
1986年 | 57篇 |
1985年 | 63篇 |
1984年 | 57篇 |
1983年 | 17篇 |
1982年 | 35篇 |
1981年 | 21篇 |
1980年 | 21篇 |
1979年 | 34篇 |
1978年 | 20篇 |
1977年 | 29篇 |
1976年 | 18篇 |
1955年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
91.
L.G. Casado I. García T. Csendes V.G. Ruíz 《Journal of Optimization Theory and Applications》2003,118(1):27-43
Based on the investigation carried out in Ref. 1, this paper incorporates new studies about the properties of inclusion functions on subintervals while a branch-and-bound algorithm is solving global optimization problems. It is found that the relative place of the global minimum value within the inclusion function value of the objective function at the current interval indicates mostly whether the given interval is close to a minimizer point. This information is used in a heuristic interval rejection rule that can save a considerable amount of computation. Illustrative examples are discussed and an extended numerical study shows the advantages of the new approach. 相似文献
92.
93.
Arnold Neumaier 《Journal of Global Optimization》2003,25(2):175-181
A family of multivariate rational functions is constructed. It has strong local minimizers with prescribed function values at prescribed positions. While there might be additional local minima, such minima cannot be global. A second family of multivariate rational functions is given, having prescribed global minimizers and prescribed interpolating data. 相似文献
94.
Java程序的优化 总被引:2,自引:0,他引:2
张青 《青海师范大学学报(自然科学版)》2004,(4):42-44
本文通过使用Jayap对Java语言的字节代码进行分析,找到程序中产生瓶颈的原因,给出程序的优化方法。 相似文献
95.
The system design must be started from the concept with low cost and high performance. In this point, the topological shape of the structure is very important in the view of the structural rigidities and light-weight design.In this paper, the optimization methodology is presented in the design stage of the large optical mirror. We obtain the optimal layout through the topology optimization and then design the details through the size or shape optimization for structural rigidity. 相似文献
96.
Andrea Grosso Marco Locatelli Fabio Schoen 《Computational Optimization and Applications》2007,38(3):351-370
In this paper we perform a computational analysis of a population based approach for global optimization, Population Basin
Hopping (PBH), which was proven to be very efficient on very challenging global optimization problems by the authors (see
). The experimental analysis aims at understanding more deeply how the approach works and why it is successful on challenging
problems. 相似文献
97.
Discrete global descent method for discrete global optimization and nonlinear integer programming 总被引:2,自引:0,他引:2
A novel method, entitled the discrete global descent method, is developed in this paper to solve discrete global optimization
problems and nonlinear integer programming problems. This method moves from one discrete minimizer of the objective function
f to another better one at each iteration with the help of an auxiliary function, entitled the discrete global descent function.
The discrete global descent function guarantees that its discrete minimizers coincide with the better discrete minimizers
of f under some standard assumptions. This property also ensures that a better discrete minimizer of f can be found by some classical local search methods. Numerical experiments on several test problems with up to 100 integer
variables and up to 1.38 × 10104 feasible points have demonstrated the applicability and efficiency of the proposed method. 相似文献
98.
文章建立一个随机内生增长模型来阐明主要政策参数对经济增长与社会福利的影响.若对生产函数、效用函数、偏好及随机干扰作一些特殊的假设,我们证明了主要政策参数的均衡值能被模型参数唯一决定.进一步我们还得到了期望增长率与储蓄的清晰解.文章的最后,我们证明了政府支出直接影响个体决策者的决策:即提高经济增长率将减少福利;反之,增加福利将减少增长率. 相似文献
99.
In this note we show that many classes of global optimization problems can be treated most satisfactorily by classical optimization theory and conventional algorithms. We focus on the class of problems involving the minimization of the product of several convex functions on a convex set which was studied recently by Kunoet al. [3]. It is shown that these problems are typical composite concave programming problems and thus can be handled elegantly by c-programming [4]–[8] and its techniques. 相似文献
100.
侯祥朝 《华侨大学学报(自然科学版)》2002,23(3):263-266
工程项目结构分解及其编码是项目管理的基础工作。目前该方法的应用缺乏统一的标准和规范,影响其应用效果。针对这种情况,提出该方法的优化途径--分解对象标准化,分解步骤统一化,分解规则规范化。进而指出该方法新的应用领域,特别是在项目管理信息集成方面,及对提高工程项目管理水平所起的作用。 相似文献