全文获取类型
收费全文 | 5917篇 |
免费 | 1938篇 |
国内免费 | 357篇 |
专业分类
化学 | 257篇 |
晶体学 | 5篇 |
力学 | 809篇 |
综合类 | 119篇 |
数学 | 4085篇 |
物理学 | 2937篇 |
出版年
2024年 | 13篇 |
2023年 | 54篇 |
2022年 | 88篇 |
2021年 | 143篇 |
2020年 | 170篇 |
2019年 | 138篇 |
2018年 | 165篇 |
2017年 | 231篇 |
2016年 | 256篇 |
2015年 | 179篇 |
2014年 | 298篇 |
2013年 | 497篇 |
2012年 | 418篇 |
2011年 | 414篇 |
2010年 | 408篇 |
2009年 | 368篇 |
2008年 | 455篇 |
2007年 | 468篇 |
2006年 | 444篇 |
2005年 | 383篇 |
2004年 | 265篇 |
2003年 | 317篇 |
2002年 | 291篇 |
2001年 | 291篇 |
2000年 | 218篇 |
1999年 | 191篇 |
1998年 | 164篇 |
1997年 | 169篇 |
1996年 | 104篇 |
1995年 | 104篇 |
1994年 | 80篇 |
1993年 | 68篇 |
1992年 | 72篇 |
1991年 | 54篇 |
1990年 | 36篇 |
1989年 | 22篇 |
1988年 | 21篇 |
1987年 | 24篇 |
1986年 | 17篇 |
1985年 | 19篇 |
1984年 | 16篇 |
1983年 | 9篇 |
1982年 | 9篇 |
1981年 | 13篇 |
1980年 | 18篇 |
1979年 | 9篇 |
1978年 | 4篇 |
1977年 | 7篇 |
1975年 | 2篇 |
1957年 | 3篇 |
排序方式: 共有8212条查询结果,搜索用时 15 毫秒
61.
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
62.
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
63.
§ 1 IntroductionInthispaperwediscusstheglobalclassicalsolutionofamultidimensionalquasistationaryproblem .Theproblemcomesfromthediscussionofagrowthmodelofselfmaintainingprotocell(see [1— 3])inmultidimensionalcase .Theprotocellcanbevisualizedashavingaporousst… 相似文献
64.
应用广义胞映射方法研究了参激和外激共同作用的Duffing-van der Pol振子的随机分岔.以 系统参数通过某一临界值时,如果系统的随机吸引子或随机鞍的形态发生突然变化,则认为 系统发生随机分岔为定义,分析了参激强度和外激强度的变化对于随机分岔的影响.揭示了 随机分岔的发生主要是由于系统的随机吸引子与系统的随机鞍碰撞产生的.分析表明,广义 胞映射方法是分析随机分岔的有力工具,这种全局分析方法可以清晰地给出随机分岔的发生 和发展.
关键词:
随机分岔
全局分析
广义胞映射方法
随机吸引子
随机鞍 相似文献
65.
66.
共轭下降法的全局收敛性 总被引:3,自引:0,他引:3
本文提出了一种Armijo型的线搜索,并在这种线搜索下讨论了共轭下降法的全局收敛性,且可得方法在每次迭代均产生一个下降搜索方向. 相似文献
67.
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
68.
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
69.
P. Schlagheck A. Buchleitner 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2003,22(3):401-415
We provide a detailed quantum treatment of the spectral characteristics and of the dynamics of nondispersive two-electron
wave packets along the periodically driven, collinear frozen planet configuration of helium. These highly correlated, long-lived
wave packets arise as a quantum manifestation of regular islands in a mixed classical phase space, which are induced by nonlinear
resonances between the external driving and the unperturbed dynamics of the frozen-planet configuration. Particular emphasis
is given to the dependence of the ionization rates of the wave packet states on the driving field parameters and on the quantum
mechanical phase space resolution, preceded by a comparison of 1D and 3D life times of the unperturbed frozen planet. Furthermore,
we study the effect of a superimposed static electric field component, which, on the grounds of classical considerations,
is expected to stabilize the real 3D dynamics against large (and possibly ionizing) deviations from collinearity.
Received 7 November 2002 / Received in final form 2 December 2002 Published online 28 January 2003 相似文献
70.
章志飞 《浙江大学学报(理学版)》2003,30(6):609-611
利用Besov空间的热核刻画及压缩映射原理,研究半线性热方程ut-△u=u|u|a的初值问题,得到了当初值u0∈Lp0(Rn)且||u0||(B·)p-n (1/p0-1/p),∞(Rn)(p0=na/2,p>p0)充分小时,整体解的存在性及在一定条件下解的惟一性. 相似文献