全文获取类型
收费全文 | 13069篇 |
免费 | 1284篇 |
国内免费 | 993篇 |
专业分类
化学 | 893篇 |
晶体学 | 54篇 |
力学 | 3085篇 |
综合类 | 190篇 |
数学 | 8801篇 |
物理学 | 2323篇 |
出版年
2024年 | 19篇 |
2023年 | 138篇 |
2022年 | 143篇 |
2021年 | 174篇 |
2020年 | 320篇 |
2019年 | 324篇 |
2018年 | 338篇 |
2017年 | 364篇 |
2016年 | 422篇 |
2015年 | 366篇 |
2014年 | 569篇 |
2013年 | 1118篇 |
2012年 | 576篇 |
2011年 | 733篇 |
2010年 | 595篇 |
2009年 | 773篇 |
2008年 | 844篇 |
2007年 | 824篇 |
2006年 | 756篇 |
2005年 | 682篇 |
2004年 | 625篇 |
2003年 | 589篇 |
2002年 | 541篇 |
2001年 | 431篇 |
2000年 | 454篇 |
1999年 | 379篇 |
1998年 | 367篇 |
1997年 | 295篇 |
1996年 | 251篇 |
1995年 | 167篇 |
1994年 | 174篇 |
1993年 | 132篇 |
1992年 | 142篇 |
1991年 | 120篇 |
1990年 | 97篇 |
1989年 | 62篇 |
1988年 | 43篇 |
1987年 | 39篇 |
1986年 | 36篇 |
1985年 | 48篇 |
1984年 | 65篇 |
1983年 | 36篇 |
1982年 | 48篇 |
1981年 | 32篇 |
1980年 | 24篇 |
1979年 | 18篇 |
1978年 | 16篇 |
1977年 | 8篇 |
1973年 | 8篇 |
1957年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 203 毫秒
91.
Piotr Rybka 《Journal of Differential Equations》2002,181(2):340-366
We study the behavior of solutions of the modified Stefan problem in the plane for polygonal interfaces. We are particularly interested in a solution near a singularity of either the loss of a facet or the breaking of a facet. We establish precise regularity results if a facet disappears. We use them to establish the existence of a weak solution with singular data, i.e., when some of the zero-crystalline-curvature facets have zero length. 相似文献
92.
In this paper, we establish the existence of upper and lower solutions for a periodic boundary value problems (PBVP for short) of impulsive differential equations. which guarantees the existence of at least one solution for the problem. As an application, these results are applied to PBVP of ODE and some examples are given to illustrate our results. 相似文献
93.
对拟线性椭圆变分不等式的障碍最优控制问题(即以障碍为控制变量)进行了研究.指标泛函为Lagrange型,其中含有控制变量二阶导数的p次幂,这使得最优性条件的推导颇为不易.对所考虑的问题给出了最优控制的存在性定理以及必要条件. 相似文献
94.
本文给出了拟共形映照边界伸缩商与无限小边界伸缩商的一个等式h([μ])=inf_(μ1∈[μ])b([μ1]B);并给出了一个关于T_0空间的推论. 相似文献
95.
We report on the simultaneous generation of phase-conjugate signals by degenerate four-wave mixing (DFWM) and holographic processes using a nanosecond pulse and a CW lasers in polyvinyl alcohol (PVA) films doped with four kinds of saturable absorbing dyes. For the pulse laser, of the four kinds of dye-doped PVA films, the erythrosine B-doped PVA and uranine doped-PVA films generate PC signals only by the DFWM process, while the other dye-doped PVA films generate PC signals simultaneously by not only the DFWM process but also the holographic process. Especially, the safranin T-doped PVA film generates strong PC signals by the holographic process. In contrast, all of the dye-doped PVA films generate the two types of PC signals for the CW laser. The fading of dye molecules is found to result in the generation of the holographic component of PC signals which governs the temporal behavior of the total PC signals. 相似文献
96.
Based on the theory of calculus of variation, some suffcient conditions are given for some Euler-Lagrangcequations to be equivalently represented by finite or even infinite many Hamiltonian canonical equations. Meanwhile,some further applications for equations such as the KdV equation, MKdV equation, the general linear Euler Lagrangeequation and the cylindric shell equations are given. 相似文献
97.
This paper proposes the Rice condition numbers for invariant subspace, singular sub-spaces of a matrix and deflating subspaces of a regular matrix pair. The first-order perturbation estimations for these subspaces are derived by applying perturbation expansions of orthogonal projection operators. 相似文献
98.
This paper formulates a two-dimensional strip packing problem as a non-linear programming(NLP)problem and establishes the first-order optimality con-ditions for the NLP problem.A numerical algorithm for solving this NLP problemis given to find exact solutions to strip-packing problems involving up to 10 items.Approximate solutions can be found for big-sized problems by decomposing the setof items into small-sized blocks of which each block adopts the proposed numericalalgorithm.Numerical results show that the approximate solutions to big-sized prob-lems obtained by this method are superior to those by NFDH,FFDH and BFDHapproaches. 相似文献
99.
The phase boundary theory and the contact rule of phase regions are compared, and some weaknesses of the latter are manifested.
The comparison between the Gupta’s method and the boundary theory method for constructing multicomponent isobaric sections
is also presented. 相似文献
100.
全生寅 《数学的实践与认识》2006,36(1):253-256
证明了线性规划的K uhn-Tucker条件蕴含着它的对偶问题,解释了L agrange乘子的意义.进而显示了K-T条件中的互补松驰性与对偶线性规划的互补松紧定理之间的联系. 相似文献