全文获取类型
收费全文 | 14060篇 |
免费 | 2681篇 |
国内免费 | 3759篇 |
专业分类
化学 | 3382篇 |
晶体学 | 137篇 |
力学 | 742篇 |
综合类 | 700篇 |
数学 | 11575篇 |
物理学 | 3964篇 |
出版年
2024年 | 60篇 |
2023年 | 271篇 |
2022年 | 278篇 |
2021年 | 291篇 |
2020年 | 261篇 |
2019年 | 290篇 |
2018年 | 160篇 |
2017年 | 349篇 |
2016年 | 341篇 |
2015年 | 449篇 |
2014年 | 846篇 |
2013年 | 698篇 |
2012年 | 910篇 |
2011年 | 850篇 |
2010年 | 1032篇 |
2009年 | 925篇 |
2008年 | 1324篇 |
2007年 | 1097篇 |
2006年 | 982篇 |
2005年 | 974篇 |
2004年 | 810篇 |
2003年 | 871篇 |
2002年 | 703篇 |
2001年 | 789篇 |
2000年 | 757篇 |
1999年 | 560篇 |
1998年 | 475篇 |
1997年 | 453篇 |
1996年 | 467篇 |
1995年 | 465篇 |
1994年 | 365篇 |
1993年 | 275篇 |
1992年 | 279篇 |
1991年 | 249篇 |
1990年 | 231篇 |
1989年 | 174篇 |
1988年 | 49篇 |
1987年 | 38篇 |
1986年 | 22篇 |
1985年 | 20篇 |
1984年 | 13篇 |
1983年 | 16篇 |
1982年 | 9篇 |
1981年 | 2篇 |
1980年 | 4篇 |
1979年 | 3篇 |
1963年 | 1篇 |
1959年 | 8篇 |
1951年 | 1篇 |
1936年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
On the Existence of Positive
Periodic Solutions for Neutral Functional Differential Equation
with Multiple Deviating Arguments 总被引:3,自引:0,他引:3
Shi-pingLu Wei-gaoGe 《应用数学学报(英文版)》2003,19(4):631-640
By means of an abstract continuation theory for κ-set contraction and continuation theorem of coincidence degree principle, some criteria are established for the existence of positive periodic solutions of following neutral functional differential equation dN/dt=N(t)[α(t)-β(t)N(t)-∑j=1^n bj(t)N(t-σj(t))-∑i=1^mci(t)N‘(t-γi(t)0]. 相似文献
992.
Li-xingZhu Wei-xingSong Heng-jianCui 《应用数学学报(英文版)》2003,19(3):353-362
When a regression model is applied as an approximation of underlying model of data, the model checking is important and relevant. In this paper, we investigate the lack-of-fit test for a polynomial error-in-variables model. As the ordinary residuals are biased when there exist measurement errors in covariables,we correct them and then construct a residual-based test of score type. The constructed test is asymptotically chi-squared under null hypotheses. Simulation study shows that the test can maintain the significance level well.The choice of weight functions involved in the test statistic and the related power study are also investigated.The application to two examples is illustrated. The approach can be readily extended to handle more general models. 相似文献
993.
THE SPACE—FRACTIONAL TELEGRAPH EQUATION AND THE RELATED FRACTIONAL TELEGRAPH PROCESS 总被引:1,自引:0,他引:1
The space-fractional telegraph equation is analyzed and the Fourier transform of its fundamental solution is obtained and discussed.A symmetric process with discontinuous trajectories, whose transition function satisfies the space-fractional telegraph equation, is presented. Its limiting behaviour and the connection with symmetric stable processes is also examined. 相似文献
994.
Wen-junSun 《应用数学学报(英文版)》2003,19(1):143-156
This paper deals with the existence and nonexistence of global positive solution to a semilinear reaction-diffusion system with nonlinear boundary conditions.For the heat diffusion case,the necessary and sufficient conditions on the global existence of all positive solutions are obtained.For the general fast diffusion case,we get some conditions on the global existence and nonexistence of positive solutions.The results of this paper fill the some gaps which were left in this field. 相似文献
995.
Tai-PingLiu TommasoRuggeri 《应用数学学报(英文版)》2003,19(1):1-12
In shock wave theory there are two considerations in selecting the physically relevant shock waves.There is the admissibility criterion for the well-posedness of hyperbolic conservation laws.Another consideraztion concerns the entropy production across the shochs.The latter is natural from the physical point of view,but is not sufficient in its straightforward formulation,if the system is not genuinely nonlinear.In this paper we propose the principles of increasing entropy production and that of the superposition of shocks.These principles arc shown to be equivalent to the admissibility criterion. 相似文献
996.
A family of subspaces of a complex separable Hilbert space is transitive if every bounded operator which leaves each of its
members invariant is scalar. This article surveys some results concerning transitive families of small cardinality, and adds
some new ones. The minimum cardinality of a transitive family in finite dimensions (greater than 2) is 4. In infinite dimensions
a transitive pair of linear manifolds exists but the minimum cardinality of a transitive family of dense operator ranges or
norm-closed subspaces is not known. However, a transitive family of dense operator ranges with 5 elements can be found, and
so can a transitive family of norm-closed subspaces with 4 elements. In finite dimensions (> 1) three nest algebras (corresponding
to maximal nests) can intersect in the scalar operators, but two cannot. It is not known if this is the case in infinite dimensions
for maximal nests of type ω + 1. Four such nest algebras can intersect in the scalar operators.
Received June 15, 2002, Accepted November 27, 2002 相似文献
997.
CongWenLIU JiHuaiSHI 《数学学报(英文版)》2003,19(1):187-200
In 1993,Ahern,Flores and Rudin showed that,if f is integrable over the unit ball BC^n of C^n and satisfies∫BC^nfoφdv=f(φ(0)) for every φ∈Aut(BC^n),then f is M-harmonic if and only if n≤11.The present paper is about an analogous question in the context of the unit ball Bn of R^n as well as in the weighted setting. 相似文献
998.
具强迫力的奇数阶中立型微分方程的振动性 总被引:3,自引:0,他引:3
Abstract. In this paper, the forced odd order neutral differential equations of the form are con-sidered 相似文献
999.
宋儒瑛 《浙江大学学报(理学版)》2000,27(2):128-133
本文研究一类混合指数型积分算子与 Besov型空间的关系 ,重点探讨了该算子关于 Besov型空 间的饱和性 . 相似文献
1000.
矩阵损失下多维几何分布均值 的线性估计可容许性 总被引:4,自引:0,他引:4
郑海 《浙江大学学报(理学版)》2000,27(2):171-174
本文在矩阵损失函数 (d - λ ) (d - λ )′下讨论多维几何分布均值参数 λ的线性估计在齐次线性 估计类中的可容许性 . 相似文献