全文获取类型
收费全文 | 8796篇 |
免费 | 1014篇 |
国内免费 | 1326篇 |
专业分类
化学 | 2487篇 |
晶体学 | 40篇 |
力学 | 878篇 |
综合类 | 192篇 |
数学 | 5893篇 |
物理学 | 1646篇 |
出版年
2024年 | 20篇 |
2023年 | 100篇 |
2022年 | 150篇 |
2021年 | 170篇 |
2020年 | 285篇 |
2019年 | 262篇 |
2018年 | 259篇 |
2017年 | 345篇 |
2016年 | 372篇 |
2015年 | 248篇 |
2014年 | 426篇 |
2013年 | 699篇 |
2012年 | 539篇 |
2011年 | 532篇 |
2010年 | 453篇 |
2009年 | 555篇 |
2008年 | 603篇 |
2007年 | 572篇 |
2006年 | 529篇 |
2005年 | 489篇 |
2004年 | 474篇 |
2003年 | 376篇 |
2002年 | 349篇 |
2001年 | 265篇 |
2000年 | 294篇 |
1999年 | 244篇 |
1998年 | 194篇 |
1997年 | 213篇 |
1996年 | 178篇 |
1995年 | 177篇 |
1994年 | 107篇 |
1993年 | 108篇 |
1992年 | 100篇 |
1991年 | 66篇 |
1990年 | 69篇 |
1989年 | 41篇 |
1988年 | 31篇 |
1987年 | 27篇 |
1986年 | 26篇 |
1985年 | 24篇 |
1984年 | 24篇 |
1983年 | 12篇 |
1982年 | 23篇 |
1981年 | 7篇 |
1980年 | 17篇 |
1979年 | 12篇 |
1978年 | 17篇 |
1977年 | 14篇 |
1974年 | 8篇 |
1973年 | 7篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
941.
In this paper, we investigate the mean squared derivative cost functions that arise in various applications such as in motor control, biometrics and optimal transport theory. We provide qualitative properties, explicit analytical formulas and computational algorithms for the cost functions. We also perform numerical simulations to illustrate the analytical results. In addition, as a by‐product of our analysis, we obtain an explicit formula for the inverse of a Wronskian matrix that is of independent interest in linear algebra and differential equations theory. Copyright © 2017 John Wiley & Sons, Ltd. 相似文献
942.
Peijun Li Gaofeng Zheng Weiying Zheng 《Mathematical Methods in the Applied Sciences》2017,40(3):573-588
This paper is concerned with the mathematical analysis of the electromagnetic wave scattering by an unbounded dielectric medium, which is mounted on a perfectly conducting infinite plane. By introducing a transparent boundary condition on a plane surface confining the medium, the scattering problem is modeled as a boundary value problem of Maxwell's equations. Based on a variational formulation, the problem is shown to have a unique weak solution for a wide class of dielectric permittivity and magnetic permeability by using the generalized Lax–Milgram theorem. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
943.
Composite generalized Laguerre spectral method for nonlinear Fokker–Planck equations on the whole line 下载免费PDF全文
Tian‐jun Wang 《Mathematical Methods in the Applied Sciences》2017,40(5):1462-1474
In this paper, we propose a composite Laguerre spectral method for the nonlinear Fokker–Planck equations modelling the relaxation of fermion and boson gases. A composite Laguerre spectral scheme is constructed. Its convergence is proved. Numerical results show the efficiency of this approach and coincide well with theoretical analysis. Some results on the Laguerre approximation and techniques used in this paper are also applicable to other nonlinear problems on the whole line. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
944.
The transport dynamics in complex systems governing by anomalous diffusion modelled with Riesz fractional partial differential equations 下载免费PDF全文
Santanu Saha Ray 《Mathematical Methods in the Applied Sciences》2017,40(5):1637-1648
In this paper, numerical solutions of fractional Fokker–Planck equations with Riesz space fractional derivatives have been developed. Here, the fractional Fokker–Planck equations have been considered in a finite domain. In order to deal with the Riesz fractional derivative operator, shifted Grünwald approximation and fractional centred difference approaches have been used. The explicit finite difference method and Crank–Nicolson implicit method have been applied to obtain the numerical solutions of fractional diffusion equation and fractional Fokker–Planck equations, respectively. Numerical results are presented to demonstrate the accuracy and effectiveness of the proposed numerical solution techniques. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
945.
Modeling social‐ecological systems is difficult due to the complexity of ecosystems and of individual and collective human behavior. Key components of the social‐ecological system are often over‐simplified or omitted. Generalized modeling is a dynamical systems approach that can overcome some of these challenges. It can rigorously analyze qualitative system dynamics such as regime shifts despite incomplete knowledge of the model's constituent processes. Here, we review generalized modeling and use a recent study on the Baltic Sea cod fishery's boom and collapse to demonstrate its application to modeling the dynamics of empirical social‐ecological systems. These empirical applications demand new methods of analysis suited to larger, more complicated generalized models. Generalized modeling is a promising tool for rapidly developing mathematically rigorous, process‐based understanding of a social‐ecological system's dynamics despite limited knowledge of the system. 相似文献
946.
针对带有不确定参数的一类混沌金融系统,提出了实现驱动系统和响应系统广义投影同步的自适应控制策略,并基于Lyapunov稳定性理论给出和验证了广义投影同步稳定性判据.数值仿真验证了控制策略和理论分析的有效性. 相似文献
947.
借助于广义算子半群和广义积分算子半群的关系,讨论广义算子半群的Perron型指数稳定性,研究了广义积分算子半群的渐近行为. 相似文献
948.
对于聚集数据的线性模型,提出了广义聚集双参数估计的概念,给出了广义聚集双参数估计的两种相对效率,并得到了这两种相对效率的上界. 相似文献
949.
本文以非等距B_3样条函数为基函数分别建立了旋转壳子午向和环向形函数,其中环向形函数满足周期性条件。采取先子午向插值后环向插值的方式得到旋转壳广义样条子域位移模式。该模式可沿子午向与环向各结线任意设取结点,亦即不同环线可以有不同的结点数,从而大大提高了样条子域法的灵活性,拓宽了其应用范围。 相似文献
950.
Weakly R-KKM mappings——intersection theorems and minimax inequalities in topological spaces 总被引:1,自引:0,他引:1
In this paper, we introduce the concepts of weakly R-KKM mappings, R-convex and ,R-β-quasiconvex in general topological spaces without any convex structure. Relating to these, we obtain an extension to general topological spaces of Fan's matching theorem, namely that Lemma 1.2 in this paper. On this basis, two intersection theorems are proved in topological spaces. By using intersection theorems, some minimax inequalities of Ky Fan type are also proved in topological spaces. Our results generalize and improve the corresponding results in the literature. 相似文献