全文获取类型
收费全文 | 13030篇 |
免费 | 1953篇 |
国内免费 | 1306篇 |
专业分类
化学 | 3928篇 |
晶体学 | 49篇 |
力学 | 1783篇 |
综合类 | 174篇 |
数学 | 5420篇 |
物理学 | 4935篇 |
出版年
2024年 | 31篇 |
2023年 | 141篇 |
2022年 | 287篇 |
2021年 | 348篇 |
2020年 | 370篇 |
2019年 | 359篇 |
2018年 | 383篇 |
2017年 | 446篇 |
2016年 | 540篇 |
2015年 | 430篇 |
2014年 | 702篇 |
2013年 | 1003篇 |
2012年 | 717篇 |
2011年 | 763篇 |
2010年 | 619篇 |
2009年 | 774篇 |
2008年 | 816篇 |
2007年 | 837篇 |
2006年 | 753篇 |
2005年 | 679篇 |
2004年 | 597篇 |
2003年 | 566篇 |
2002年 | 541篇 |
2001年 | 460篇 |
2000年 | 483篇 |
1999年 | 380篇 |
1998年 | 313篇 |
1997年 | 287篇 |
1996年 | 267篇 |
1995年 | 230篇 |
1994年 | 176篇 |
1993年 | 165篇 |
1992年 | 146篇 |
1991年 | 122篇 |
1990年 | 75篇 |
1989年 | 54篇 |
1988年 | 54篇 |
1987年 | 57篇 |
1986年 | 50篇 |
1985年 | 49篇 |
1984年 | 49篇 |
1983年 | 23篇 |
1982年 | 37篇 |
1981年 | 23篇 |
1980年 | 24篇 |
1979年 | 23篇 |
1978年 | 12篇 |
1977年 | 6篇 |
1976年 | 11篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
基于校园网的实验管理系统的设计 总被引:2,自引:1,他引:1
主要讨论了应用实验室管理系统的必要性,并从用户需求分析、系统总体设计、功能模块的设计等方面对B/S实验室管理系统的开发进行了详细的阐述。 相似文献
3.
本文首先将文[1]中的BLD映射推广为弱(L1,L2)-BLD映射,并证明了如下正则性结果:存在两个可积指数 P1=P1(n,L1,L2)<n<q1=q1(n,L1,L2),使得对任意弱(L1,L2)-BLD映射f∈(Ω,Rn),都有f∈(Ω,Rn),即f为(L1,L2)-BLD映射. 相似文献
4.
We derive an explicit autocorrelation function (ACF) formula of state of polarization for a fiber transmission system with polarization mode dispersion (PMD) and polarization dependent loss (PDL), which is found to agree well with Monte Carlo simulation. Then we use the new ACF to investigate the combined effect of PMD and PDL on the polarization multiplexed scheme. We find the performance of the polarization multiplexed scheme can be deteriorated more severely than the case without PDL. 相似文献
5.
Equilibrium Problems with Applications to Eigenvalue Problems 总被引:5,自引:0,他引:5
In this paper, we consider equilibrium problems and introduce the concept of (S)+ condition for bifunctions. Existence results for equilibrium problems with the (S)+ condition are derived. As special cases, we obtain several existence results for the generalized nonlinear variational inequality studied by Ding and Tarafdar (Ref. 1) and the generalized variational inequality studied by Cubiotti and Yao (Ref. 2). Finally, applications to a class of eigenvalue problems are given. 相似文献
6.
M. Castagnino R. Id Betan R. Laura 《International Journal of Theoretical Physics》2003,42(10):2423-2439
By extending the notion of mixed states to functionals acting on the space of observables with diagonal singularity we obtain a well-defined complex spectral decomposition of the time evolution for a quantum decaying system. In this formalism, generalized Gamow states are obtained with well-defined physical properties. 相似文献
7.
The finite-difference method is a numerical technique for obtaining approximate solutions to differential equations. The main
objective of the present study is to give a new aspect to the finite-difference method by using a variational derivative.
By applying this formulation, accurate values of the buckling loads of beams and frames with various end supports are obtained.
The performance of this formulation is verified by comparison with numerical examples in the literature
__________
Published in Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 139–144, July 2005. 相似文献
8.
Hubert Grudziński 《Reports on Mathematical Physics》2004,53(2):317-328
The eigenvalues and eigenfunctions of an elementary 3-fermion 2-body operator 3P2g∧I1A3∑1≤i≤j≤3P2g(i, j)A3 acting on a 3-particle antisymmetric finite-dimensional Hilbert space have been found. Here Pg2 denotes the projection operator onto a 2-particle antisymmetric function g2, while A3 denotes the 3-particle antisymmetrizing operator. 相似文献
9.
Mats Gyllenberg 《Journal of Differential Equations》2004,205(1):50-76
For time-periodic dissipative and irreducible type-K competitive Kolmogorov systems, it is proved that there is a canonically defined countable family F of unordered, disjoint invariant sets with the property that, for every persistent trajectory whose ω-limit set is not a cycle, there exists a unique trajectory in some element of F such that these two trajectories are asymptotic and the corresponding points in these two trajectories are K-related. 相似文献
10.
S. Carl 《Journal of Differential Equations》2004,199(1):77-95
In this paper we consider systems of quasilinear elliptic variational inequalities, and prove the existence of minimal and maximal (in the set theoretical sense) solutions within some ordered interval of an appropriately defined pair of sub- and supersolutions. We show that the notion of sub- and supersolutions of variational inequalities introduced here is consistent with the usual notion of sub-supersolutions for (variational) equations. For weakly coupled quasimonotone systems of variational inequalities the existence of smallest and greatest solutions is proved. 相似文献