全文获取类型
收费全文 | 4311篇 |
免费 | 527篇 |
国内免费 | 337篇 |
专业分类
化学 | 321篇 |
晶体学 | 2篇 |
力学 | 358篇 |
综合类 | 87篇 |
数学 | 3082篇 |
物理学 | 1325篇 |
出版年
2024年 | 7篇 |
2023年 | 42篇 |
2022年 | 52篇 |
2021年 | 84篇 |
2020年 | 113篇 |
2019年 | 94篇 |
2018年 | 94篇 |
2017年 | 123篇 |
2016年 | 138篇 |
2015年 | 98篇 |
2014年 | 153篇 |
2013年 | 300篇 |
2012年 | 220篇 |
2011年 | 220篇 |
2010年 | 201篇 |
2009年 | 270篇 |
2008年 | 318篇 |
2007年 | 293篇 |
2006年 | 317篇 |
2005年 | 290篇 |
2004年 | 217篇 |
2003年 | 207篇 |
2002年 | 170篇 |
2001年 | 148篇 |
2000年 | 152篇 |
1999年 | 126篇 |
1998年 | 98篇 |
1997年 | 78篇 |
1996年 | 81篇 |
1995年 | 54篇 |
1994年 | 59篇 |
1993年 | 36篇 |
1992年 | 43篇 |
1991年 | 35篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 23篇 |
1987年 | 28篇 |
1986年 | 22篇 |
1985年 | 20篇 |
1984年 | 19篇 |
1983年 | 8篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 11篇 |
1979年 | 11篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1971年 | 2篇 |
1957年 | 2篇 |
排序方式: 共有5175条查询结果,搜索用时 437 毫秒
11.
LIN Chang ZHANG Xiu-Lian 《理论物理通讯》2005,44(2):247-251
The nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation is analytically investigated by using the formally variable separation approach. New analytical solutions for the governing equation of this system have been obtained for dust acoustic waves in a dust plasma for the first time. We derive exact analytical expressions for the general case of the nonlinear dust acoustic waves in two-dimensional dust plasma with dust charge variation. 相似文献
12.
李永祥 《数学物理学报(A辑)》2003,23(2):245-252
该文讨论四阶常微分方程边值问题u^(4)(t)=f(t,u,u″), t∈[0,1],u(0)=u(1)=u″(0)=u″(1)=0解的存在性, 其中f(t,u,v):[0,1]×R×R→R为Carathéodory函数. 在不限制f关于u,v的增长阶, 不假定f关于u,v的单调性的一般情形下, 用上下解方法获得了解的存在性结果,并讨论了单调迭代求解的有效性. 相似文献
13.
该文讨论了一类非线性抛物型方程组解的性质,利用微分方程上、下解方法证明了初值适当小时,方程存在整体解;初值适当大时,解在有限时间上爆破,推广了文献[1]的结果. 相似文献
14.
We obtain exponential upper bounds for tails of distributions of generalized L-statistics based on a sample from an exponential distribution. We prove the asymptotic normality of generalized L-statistics based on a sample from the uniform distribution on [0,1] and of L-statistics with decomposed kernels (without any restrictions on the sample distribution type). 相似文献
15.
G. Z. Ruan S. Y. Wang Y. Yamamoto S. S. Zhu 《Journal of Optimization Theory and Applications》2004,123(2):409-429
In this paper, a model of a linear multilevel programming problem with dominated objective functions (LMPPD(l)) is proposed, where multiple reactions of the lower levels do not lead to any uncertainty in the upper-level decision making. Under the assumption that the constrained set is nonempty and bounded, a necessary optimality condition is obtained. Two types of geometric properties of the solution sets are studied. It is demonstrated that the feasible set of LMPPD(l) is neither necessarily composed of faces of the constrained set nor necessarily connected. These properties are different from the existing theoretical results for linear multilevel programming problems. 相似文献
16.
For vector quasivariational inequalities involving multifunctions in topological vector spaces, an existence result is obtained without a monotonicity assumption and with a convergence assumption weaker than semicontinuity. A new type of quasivariational inequality is proposed. Applications to quasicomplementarity problems and traffic network equilibria are considered. In particular, definitions of weak and strong Wardrop equilibria are introduced for the case of multivalued cost functions. 相似文献
17.
Many real problems can be modelled as robust shortest path problems on interval digraphs, where intervals represent uncertainty about real costs and a robust path is not too far from the shortest path for each possible configuration of the arc costs.A branch and bound algorithm for this problem is presented. 相似文献
18.
M. A. Efendiev J. Fuhrmann S. V. Zelik 《Mathematical Methods in the Applied Sciences》2004,27(8):907-930
For the Boussinesq approximation of the equations of coupled heat and fluid flow in a porous medium we show that the corresponding system of partial differential equations possesses a global attractor. We give lower and upper bounds of the Hausdorff dimension of the attractor depending on a physical parameter of the system, namely the Rayleigh number of the flow. Numerical experiments confirm the theoretical findings and raise new questions on the structure of the solutions of the system. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
19.
In this paper, a generalized anti–maximum principle for the second order differential operator with potentials is proved. As an application, we will give a monotone iterative scheme for periodic solutions of nonlinear second order equations. Such a scheme involves the Lp norms of the growth, 1 ≤ p ≤ ∞, while the usual one is just the case p = ∞. 相似文献
20.
本文得到了广义区间空间中几个参数型非空交定理,并用此结果证明了一些新型极大极小定理,截口定理,重合定理,以及变分不等式解的存在性定理。本文中的结果包含(1,3,5-12,14-16)中相应结果。 相似文献