全文获取类型
收费全文 | 24448篇 |
免费 | 1691篇 |
国内免费 | 1118篇 |
专业分类
化学 | 1748篇 |
晶体学 | 31篇 |
力学 | 2561篇 |
综合类 | 301篇 |
数学 | 19911篇 |
物理学 | 2705篇 |
出版年
2024年 | 44篇 |
2023年 | 248篇 |
2022年 | 385篇 |
2021年 | 535篇 |
2020年 | 513篇 |
2019年 | 548篇 |
2018年 | 615篇 |
2017年 | 713篇 |
2016年 | 685篇 |
2015年 | 517篇 |
2014年 | 1082篇 |
2013年 | 1767篇 |
2012年 | 1247篇 |
2011年 | 1272篇 |
2010年 | 1153篇 |
2009年 | 1541篇 |
2008年 | 1550篇 |
2007年 | 1661篇 |
2006年 | 1381篇 |
2005年 | 1144篇 |
2004年 | 945篇 |
2003年 | 987篇 |
2002年 | 865篇 |
2001年 | 694篇 |
2000年 | 700篇 |
1999年 | 591篇 |
1998年 | 569篇 |
1997年 | 521篇 |
1996年 | 390篇 |
1995年 | 380篇 |
1994年 | 275篇 |
1993年 | 241篇 |
1992年 | 220篇 |
1991年 | 193篇 |
1990年 | 153篇 |
1989年 | 107篇 |
1988年 | 93篇 |
1987年 | 85篇 |
1986年 | 79篇 |
1985年 | 107篇 |
1984年 | 103篇 |
1983年 | 41篇 |
1982年 | 50篇 |
1981年 | 47篇 |
1980年 | 35篇 |
1979年 | 52篇 |
1978年 | 33篇 |
1977年 | 44篇 |
1976年 | 26篇 |
1974年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
Lin Surong 《Annals of Differential Equations》2006,22(4):517-523
The singularly perturbed boundary value problem for nonlinear higher order ordinary differential equation involving two small parameters has been considered. Under appropriate assumptions, for the three cases:ε/μ2→0(μ→0),μ2/ε→0 (ε→0) andε=μ2, the uniformly valid asymptotic solution is obtained by using the expansion method of two small parameters and the theory of differential inequality. 相似文献
22.
23.
Mark L. Agranovsky E. K. Narayanan 《Proceedings of the American Mathematical Society》2006,134(7):2117-2123
A test for a function to be a solution of an elliptic PDE is given in terms of extensions, as solutions, from the boundaries inside the domains belonging to an isotopic family. It generalizes a result of Ehrenpreis for spheres moved along a straight line.
24.
Albo Carlos Cavalheiro 《Applications of Mathematics》2006,51(6):619-628
In the paper we study the equation L
u
= f, where L is a degenerate elliptic operator, with Neumann boundary condition in a bounded open set μ. We prove existence and uniqueness
of solutions in the space H(μ) for the Neumann problem. 相似文献
25.
26.
Well-Posedness by Perturbations of Variational Problems 总被引:3,自引:0,他引:3
Lemaire B. Ould Ahmed Salem C. Revalski J. P. 《Journal of Optimization Theory and Applications》2002,115(2):345-368
In this paper, we consider the extension of the notion of well-posedness by perturbations, introduced by Zolezzi for optimization problems, to other related variational problems like inclusion problems and fixed-point problems. Then, we study the conditions under which there is equivalence of the well-posedness in the above sense between different problems. Relations with the so-called diagonal well-posedness are also given. Finally, an application to staircase iteration methods is presented. 相似文献
27.
本文定义了二阶微分方程的弱 Carathéodory解 ,在不涉及紧型条件的情形下 ,直接用迭代法证明了 Banach空间二阶非线性常微分方程两点边值问题存在唯一解 ,并给出逼近解迭代序列的误差估计 ,对周期边值问题得到类似的结果 相似文献
28.
This paper presents an adaptive memory-based method for solving the Capacitated Vehicle Routing Problem (CVRP), called BoneRoute. The CVRP deals with the problem of finding the optimal sequence of deliveries conducted by a fleet of homogeneous vehicles, based at one depot, to serve a set of customers. The computational performance of the BoneRoute was found to be very efficient, producing high quality solutions over two sets of well known case studies examined. 相似文献
29.
Volker Elling. 《Mathematics of Computation》2006,75(256):1721-1733
A particular case of initial data for the two-dimensional Euler equations is studied numerically. The results show that the Godunov method does not always converge to the physical solution, at least not on feasible grids. Moreover, they suggest that entropy solutions (in the weak entropy inequality sense) are not well posed.
30.
A new family of proximity graphs: Class cover catch digraphs 总被引:1,自引:0,他引:1
Jason DeVinney 《Discrete Applied Mathematics》2006,154(14):1975-1982
Motivated by issues in machine learning and statistical pattern classification, we investigate a class cover problem (CCP) with an associated family of directed graphs—class cover catch digraphs (CCCDs). CCCDs are a special case of catch digraphs. Solving the underlying CCP is equivalent to finding a smallest cardinality dominating set for the associated CCCD, which in turn provides regularization for statistical pattern classification. Some relevant properties of CCCDs are studied and a characterization of a family of CCCDs is given. 相似文献