全文获取类型
收费全文 | 12269篇 |
免费 | 2063篇 |
国内免费 | 722篇 |
专业分类
化学 | 2132篇 |
晶体学 | 78篇 |
力学 | 1175篇 |
综合类 | 192篇 |
数学 | 7246篇 |
物理学 | 4231篇 |
出版年
2023年 | 121篇 |
2022年 | 159篇 |
2021年 | 301篇 |
2020年 | 372篇 |
2019年 | 397篇 |
2018年 | 376篇 |
2017年 | 486篇 |
2016年 | 551篇 |
2015年 | 416篇 |
2014年 | 589篇 |
2013年 | 1079篇 |
2012年 | 699篇 |
2011年 | 718篇 |
2010年 | 622篇 |
2009年 | 716篇 |
2008年 | 816篇 |
2007年 | 704篇 |
2006年 | 664篇 |
2005年 | 607篇 |
2004年 | 486篇 |
2003年 | 521篇 |
2002年 | 469篇 |
2001年 | 407篇 |
2000年 | 359篇 |
1999年 | 327篇 |
1998年 | 240篇 |
1997年 | 257篇 |
1996年 | 193篇 |
1995年 | 198篇 |
1994年 | 127篇 |
1993年 | 102篇 |
1992年 | 99篇 |
1991年 | 95篇 |
1990年 | 78篇 |
1989年 | 69篇 |
1988年 | 66篇 |
1987年 | 61篇 |
1986年 | 55篇 |
1985年 | 73篇 |
1984年 | 54篇 |
1983年 | 33篇 |
1982年 | 55篇 |
1981年 | 34篇 |
1980年 | 40篇 |
1979年 | 37篇 |
1978年 | 24篇 |
1977年 | 34篇 |
1976年 | 28篇 |
1975年 | 10篇 |
1974年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 187 毫秒
31.
We consider the chemotaxis‐Navier–Stokes system 1.1-1.4 (Keller–Segel system) in the whole space, which describes the motion of oxygen‐driven bacteria, eukaryotes, in a fluid. We proved the global existence and time decay estimate of solutions to the Cauchy problem 1.1-1.2 in with the small initial data. Moreover, when the fluid motion is described by the Stokes equations, we established the global weak solutions to 1.3-1.4 in with the potential function ? is small and the initial density n0(x) has finite mass. 相似文献
32.
Basak Karpuz 《Mathematical Methods in the Applied Sciences》2019,42(9):2993-3001
In this paper, we give new sufficient conditions for both oscillation and nonoscillation of the delay dynamic equation where and satisfy τ(t) ≤ σ(t) for all large t and . As an important corollary, we obtain the time scale invariant integral condition for nonoscillation: for all large t. Also, with some examples, we show that newly presented results are sharp. 相似文献
33.
Balázs Gerencsér 《Stochastic Processes and their Applications》2019,129(9):3570-3584
The paper concerns a particular example of the Gibbs sampler and its mixing efficiency. Coordinates of a point are rerandomized in the unit square to approach a stationary distribution with density proportional to for with some large parameter .Diaconis conjectured the mixing time of this process to be which we confirm in this paper. This improves on the currently known estimate. 相似文献
34.
35.
Bilender P. Allahverdiev 《Mathematical Methods in the Applied Sciences》2019,42(1):229-236
In this study, maximal dissipative second‐order dynamic operators on semi‐infinite time scale are studied in the Hilbert space , that the extensions of a minimal symmetric operator in limit‐point case. We construct a self‐adjoint dilation of the dissipative operator together with its incoming and outgoing spectral representations so that we can determine the scattering function of the dilation as stated in the scheme of Lax‐Phillips. Moreover, we construct a functional model of the dissipative operator and identify its characteristic function in terms of the Weyl‐Titchmarsh function of a self‐adjoint second‐order dynamic operator. Finally, we prove the theorems on completeness of the system of root functions of the dissipative and accumulative dynamic operators. 相似文献
36.
Awatif Alqahtani Mohamed Jleli Bessem Samet 《Mathematical Methods in the Applied Sciences》2019,42(3):861-870
In this paper, some nonlocal in time differential inequalities of Sobolev type are considered. Using the nonlinear capacity method, sufficient conditions for the nonexistence of nontrivial global classical solutions are provided. 相似文献
37.
ABSTRACTA class of semilinear parabolic reaction diffusion equations with multiple time delays is considered. These time delays and corresponding weights are to be optimized such that the associated solution of the delay equation is the best approximation of a desired state function. The differentiability of the mapping is proved that associates the solution of the delay equation to the vector of weights and delays. Based on an adjoint calculus, first-order necessary optimality conditions are derived. Numerical test examples show the applicability of the concept of optimizing time delays. 相似文献
38.
本文针对求矩阵方程AXB+CXD=F唯一解的参数迭代法,分析当矩阵A,B,C,D均是Hermite正(负)定矩阵时,迭代矩阵的特征值表达式,给出了最优参数的确定方法,并提出了相应的加速算法. 相似文献
39.
It is shown that for , there exists an optimal packing with triples on points that contains no Pasch configurations. Furthermore, for all (mod 6), there exists a pairwise balanced design of order , whose blocks are all triples apart from a single quintuple, and that has no Pasch configurations amongst its triples. 相似文献
40.