全文获取类型
收费全文 | 14423篇 |
免费 | 971篇 |
国内免费 | 807篇 |
专业分类
化学 | 206篇 |
晶体学 | 2篇 |
力学 | 1442篇 |
综合类 | 166篇 |
数学 | 13299篇 |
物理学 | 1086篇 |
出版年
2024年 | 30篇 |
2023年 | 139篇 |
2022年 | 168篇 |
2021年 | 201篇 |
2020年 | 314篇 |
2019年 | 324篇 |
2018年 | 378篇 |
2017年 | 385篇 |
2016年 | 372篇 |
2015年 | 274篇 |
2014年 | 607篇 |
2013年 | 1148篇 |
2012年 | 650篇 |
2011年 | 764篇 |
2010年 | 679篇 |
2009年 | 939篇 |
2008年 | 987篇 |
2007年 | 1017篇 |
2006年 | 896篇 |
2005年 | 696篇 |
2004年 | 598篇 |
2003年 | 666篇 |
2002年 | 573篇 |
2001年 | 431篇 |
2000年 | 442篇 |
1999年 | 393篇 |
1998年 | 362篇 |
1997年 | 323篇 |
1996年 | 248篇 |
1995年 | 204篇 |
1994年 | 138篇 |
1993年 | 119篇 |
1992年 | 119篇 |
1991年 | 104篇 |
1990年 | 79篇 |
1989年 | 38篇 |
1988年 | 41篇 |
1987年 | 38篇 |
1986年 | 41篇 |
1985年 | 54篇 |
1984年 | 53篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 25篇 |
1980年 | 18篇 |
1979年 | 21篇 |
1978年 | 14篇 |
1977年 | 15篇 |
1976年 | 9篇 |
1936年 | 3篇 |
排序方式: 共有10000条查询结果,搜索用时 703 毫秒
171.
B. Ivorra A. M. Ramos B. Mohammadi 《Journal of Optimization Theory and Applications》2007,135(3):549-561
This paper has two objectives. We introduce a new global optimization algorithm reformulating optimization problems in terms
of boundary-value problems. Then, we apply this algorithm to a pointwise control problem of the viscous Burgers equation,
where the control weight coefficient is progressively decreased. The results are compared with those obtained with a genetic
algorithm and an LM-BFGS algorithm in order to check the efficiency of our method and the necessity of using global optimization
techniques. 相似文献
172.
Lai-Jiu Lin 《Journal of Global Optimization》2007,38(1):21-39
In this paper, we study an existence theorem of systems of generalized quasivariational inclusions problem. By this result,
we establish the existence theorems of solutions of systems of generalized equations, systems of generalized vector quasiequilibrium
problem, collective variational fixed point, systems of generalized quasiloose saddle point, systems of minimax theorem, mathematical
program with systems of variational inclusions constraints, mathematical program with systems of equilibrium constraints and
systems of bilevel problem and semi-infinite problem with systems of equilibrium problem constraints.
This research was supported by the National Science Council of the Republic of China. 相似文献
173.
174.
In this article, we show how to construct pairs of orthogonal pandiagonal Latin squares and panmagic squares from certain types of modular n‐queens solutions. We prove that when these modular n‐queens solutions are symmetric, the panmagic squares thus constructed will be associative, where for an n × n associative magic square A = (aij), for all i and j it holds that aij + an?i?1,n?j?1 = c for a fixed c. We further show how to construct orthogonal Latin squares whose modular difference diagonals are Latin from any modular n‐queens solution. As well, we analyze constructing orthogonal pandiagonal Latin squares from particular classes of non‐linear modular n‐queens solutions. These pandiagonal Latin squares are not row cyclic, giving a partial solution to a problem of Hedayat. © 2007 Wiley Periodicals, Inc. J Combin Designs 15: 221–234, 2007 相似文献
175.
An energy-dependent partitioning scheme is explored for extracting a small number of eigenvalues of a real symmetric matrix with the help of genetic algorithm. The proposed method is tested with matrices of different sizes (30 × 30 to 1000 × 1000). Comparison is made with Löwdin’s strategy for solving the problem. The relative advantages and disadvantages of the GA-based method are analyzed 相似文献
176.
We give a competitive algorithm to identify all d defective edges in a hypergraph with d unknown. Damaschke did the d=1 case for 2-graphs, Triesch extended the d=1 case to r-graphs, and Johann did the general d case for 2-graphs. So ours is the first attempt to solve the searching for defective edges problem in its full generality. Further, all the above three papers assumed d known. We give a competitive algorithm where d is unknown. 相似文献
177.
For linear statistical ill-posed problems in Hilbert spaces we introduce an adaptive procedure to recover the unknown solution from indirect discrete and noisy data. This procedure is shown to be order optimal for a large class of problems. Smoothness of the solution is measured in terms of general source conditions. The concept of operator monotone functions turns out to be an important tool for the analysis.
178.
Blow Up of Solutions to Semilinear Wave Equations with Critical Exponent in High Dimensions 总被引:5,自引:2,他引:3
下载免费PDF全文
![点击此处可从《数学年刊B辑(英文版)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Yi ZHOU 《数学年刊B辑(英文版)》2007,28(2):205-212
In this paper, the author considers the Cauchy problem for semilinear wave equations with critical exponent in n≥4 space dimensions. Under some positivity conditions on the initial data, it is proved that there can be no global solutions no matter how small the initial data are. 相似文献
179.
V. S. Klimov 《Mathematical Notes》2007,81(1-2):61-71
We study homology characteristics of critical values and extremals of Lipschitz functionals defined on bounded closed convex subsets of a reflexive space that are invariant under deformations. Sufficient conditions for the existence of a bifurcation point of a multivalued potential operator (the switch principle for the typical number of an extremal) are established. 相似文献
180.
Gui-xiang Xu Institute of Applied Physics Computational Mathematics P.O.Box Beijing China 《应用数学学报(英文版)》2007,(4)
In this paper,we consider the local and global solution for the nonlinear Schrdinger equationwith data in the homogeneous and nonhomogeneous Besov space and the scattering result for small data.Thetechniques to be used are adapted from the Strichartz type estimate,Kato's smoothing effect and the maximalfunction(in time)estimate for the free Schrdinger operator. 相似文献