全文获取类型
收费全文 | 8958篇 |
免费 | 940篇 |
国内免费 | 732篇 |
专业分类
化学 | 1501篇 |
晶体学 | 18篇 |
力学 | 939篇 |
综合类 | 175篇 |
数学 | 4381篇 |
物理学 | 3616篇 |
出版年
2024年 | 12篇 |
2023年 | 60篇 |
2022年 | 160篇 |
2021年 | 135篇 |
2020年 | 211篇 |
2019年 | 221篇 |
2018年 | 230篇 |
2017年 | 303篇 |
2016年 | 332篇 |
2015年 | 229篇 |
2014年 | 497篇 |
2013年 | 640篇 |
2012年 | 430篇 |
2011年 | 522篇 |
2010年 | 417篇 |
2009年 | 616篇 |
2008年 | 684篇 |
2007年 | 656篇 |
2006年 | 598篇 |
2005年 | 526篇 |
2004年 | 458篇 |
2003年 | 381篇 |
2002年 | 329篇 |
2001年 | 288篇 |
2000年 | 292篇 |
1999年 | 245篇 |
1998年 | 216篇 |
1997年 | 205篇 |
1996年 | 127篇 |
1995年 | 107篇 |
1994年 | 81篇 |
1993年 | 44篇 |
1992年 | 38篇 |
1991年 | 41篇 |
1990年 | 24篇 |
1989年 | 34篇 |
1988年 | 52篇 |
1987年 | 29篇 |
1986年 | 14篇 |
1985年 | 21篇 |
1984年 | 25篇 |
1983年 | 9篇 |
1982年 | 17篇 |
1981年 | 25篇 |
1980年 | 10篇 |
1979年 | 5篇 |
1978年 | 7篇 |
1977年 | 10篇 |
1976年 | 5篇 |
1957年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 8 毫秒
51.
M. Z. Abd-Alla H. A. Hassan H. A. Ayad 《Journal of Difference Equations and Applications》2018,24(8):1318-1345
This paper introduces sampling representations for discrete signals arising from self adjoint difference operators with mixed boundary conditions. The theory of linear operators on finite-dimensional inner product spaces is employed to study the second-order difference operators. We give necessary and sufficient conditions that make the operators self adjoint. The equivalence between the difference operator and a Hermitian Green's matrix is established. Sampling theorems are derived for discrete transforms associated with the difference operator. The results are exhibited via illustrative examples, involving sampling representations for the discrete Hartley transform. Families of discrete fractional Fourier-type transforms are introduced with an application to image encryption. 相似文献
52.
分析了噪声对小波变换重建超短脉冲光谱相位的影响. 在理想情况和附加噪声、倍增噪声, 以及干涉条纹采样量化干扰的情况下,分析了小波变换对几种光谱相位的重建精度. 结果显 示,在理想情况和噪声干扰的情况下,小波变换的相位重建精度都在003rad范围以内. 这 说明小波变换是一种精确可信的光谱相位重建方法,具有很强的抗噪声干扰能力. 另外,将 小波变换的轨迹图类比SHG FROG的轨迹图,可以直接定性判断脉冲的啁啾特征.
关键词:
超短脉冲
相位重建
小波变换
噪声 相似文献
53.
Bernhard Krötz 《Functional Analysis and Its Applications》2009,43(1):30-43
In this paper, we define a horospherical transform for a semisimple symmetric space Y. A natural double fibration is used to assign a more geometrical space Ξ of horospheres to Y. The horospherical transform relates certain integrable analytic functions on Y to analytic functions on Ξ by fiber integration. We determine the kernel of the horospherical transform and establish that the transform is injective on functions belonging to the most continuous spectrum of Y. 相似文献
54.
A differential equation‐based framework is suitable for the modeling of nonequilibrium complex systems if its solution is able to reach, as time goes to infinity, the related nonequilibrium steady states. The thermostatted kinetic theory framework has been recently proposed for the modeling of complex systems subjected to an external force field. The present paper is devoted to the mathematical proof of the convergence of the solutions of the thermostatted kinetic framework towards the related nonequilibrium stationary states. The proof of the main result is gained by employing the Fourier transform and distribution theory arguments. 相似文献
55.
More new exact solutions for a class of nonlinear coupled
differential equations are obtained by using a direct and efficient
hyperbola function transform method based on the idea of the extended
homogeneous balance method. 相似文献
56.
??In this paper, we consider a perturbed compound Poisson risk model with dependence, where the dependence structure for the claim size and the inter-claim time is modeled by a generalized Farlie-Gumbel-Morgenstern copula. The integro equations, the Laplace transforms and the defective renewal equations for the Gerber-Shiu functions are obtained. For exponential claims, some explicit expressions are obtained, and some numerical examples for the ruin probabilities are also provided. 相似文献
57.
In this paper we provide a general method to prove that certain nonlinear families of continuous functions contain dense linear manifolds. An application is furnished.
58.
59.
60.
We construct an example of a nonseparable Banach space which does not admit a support set.2 It is a consistent (and necessarily independent from the axioms of ZFC) example of a space C(K) of continuous functions on a compact Hausdorff K with the supremum norm. The construction depends on a construction of a Boolean algebra with some combinatorial properties. The space is also hereditarily Lindelöf in the weak topology but it doesn't have any nonseparable subspace nor any nonseparable quotient which is a C(K) space for K dispersed. 相似文献