全文获取类型
收费全文 | 2135篇 |
免费 | 513篇 |
国内免费 | 83篇 |
学科分类
数理化 | 2731篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 40篇 |
2021年 | 53篇 |
2020年 | 57篇 |
2019年 | 51篇 |
2018年 | 65篇 |
2017年 | 88篇 |
2016年 | 84篇 |
2015年 | 59篇 |
2014年 | 160篇 |
2013年 | 159篇 |
2012年 | 143篇 |
2011年 | 131篇 |
2010年 | 133篇 |
2009年 | 147篇 |
2008年 | 152篇 |
2007年 | 160篇 |
2006年 | 108篇 |
2005年 | 97篇 |
2004年 | 87篇 |
2003年 | 80篇 |
2002年 | 82篇 |
2001年 | 80篇 |
2000年 | 70篇 |
1999年 | 53篇 |
1998年 | 43篇 |
1997年 | 40篇 |
1996年 | 40篇 |
1995年 | 38篇 |
1994年 | 23篇 |
1993年 | 17篇 |
1992年 | 19篇 |
1991年 | 12篇 |
1990年 | 15篇 |
1989年 | 13篇 |
1988年 | 25篇 |
1987年 | 9篇 |
1986年 | 6篇 |
1985年 | 20篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 2篇 |
1977年 | 3篇 |
1975年 | 1篇 |
1970年 | 1篇 |
1959年 | 1篇 |
1957年 | 2篇 |
排序方式: 共有2731条查询结果,搜索用时 531 毫秒
1.
In recent years, spatial self-phase modulation (SSPM) with two-dimensional (2D) materials has attracted the attention of many researchers as an emerging and ubiquitous nonlinear optical effect. In this review, the state of the art of 2D material-based SSPM is summarized. SSPM measures or tunes the nonlinearity of 2D materials, and it is also an effective approach to study the band structure of 2D materials. Several modified forms of SSPM, such as high-order, white-light-excited, vector field excited, and optically nonlinearly enhanced SSPM are also presented. Subsequently, the physical origin of the SSPM formation mechanism is compared and analyzed. Furthermore, the applications of SSPM with 2D materials, including passive photonic devices, generation of Bessel beams, and identifying the mode of the orbital angular momentum, are listed. Finally, several urgent problems of the SSPM with 2D materials, potential applications, and prospects for future development are presented. 相似文献
2.
3.
Kasper K. Berthelsen Jesper Møller 《Bulletin of the Brazilian Mathematical Society》2002,33(3):351-367
This primer provides a self-contained exposition of the case where spatial birth-and-death processes are used for perfect
simulation of locally stable point processes. Particularly, a simple dominating coupling from the past (CFTP) algorithm and
the CFTP algorithms introduced in [13], [14], and [5] are studied. Some empirical results for the algorithms are discussed.
Received: 30 June 2002 相似文献
4.
This paper deals with mathematical human resource planning; more specifically, it suggests a new model for a manpower‐planning system. In general, we study a k‐classed hierarchical system where the workforce demand at each time period is satisfied through internal mobility and recruitment. The motivation for this work is based on various European Union incentives, which promote regional or local government assistance programs that could be exploited by firms not only for hiring and training newcomers, but also to improve the skills and knowledge of their existing personnel. In this respect, in our augmented mobility model we establish a new ‘training/standby’ class, which serves as a manpower inventory position for potential recruits. This class, which may very well be internal or external to the system, is incorporated into the framework of a non‐homogeneous Markov chain model. Furthermore, cost objectives are employed using the goal‐programming approach, under different operating assumptions, in order to minimize the operational cost in the presence of system's constraints and regulations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
5.
6.
LUO You-Hua GE Zi-Ming 《理论物理通讯》2006,46(12)
In noncommutative space, we examine the problem of a noninteracting and harmonically trapped BoseEinstein condensate, and derive a simple analytic expression for the effect of spatial noncommutativity on energy spectrum of the condensate. It indicates that the ground-state energy incorporating the spatial noncommutativity is reduced to a lower level, which depends upon the noncommutativity parameter θ. The gap between the noncommutative space and commutative one for the ground-state level of the condensate should be a signal of spatial noncommutativity. 相似文献
7.
在粗糙表面上用液晶空间光调制器进行振动测量 总被引:2,自引:2,他引:0
为实现在一段时间内连续实时观测振动物体的全息干涉图形,采用覆盖铝箔的喇叭作为振动物体,利用铝箔原有未经特殊处理表面反射的漫反射光成像,并用光寻址液晶空间光调制器(Liquid crystal-sparial lightmodulator,LC-SLM)作为全息记录载体,来实现振动测量。实验中采用时间平均干涉测量法,得到了不同振动频率下物体的干涉图形。同时在连续改变振动物体的振动频率时,可以清晰地观察到物体振动全息干涉图形的变化过程,即近实时的全息干涉图形。 相似文献
8.
9.
Various problems associated with optimal path planning for mobile observers such as mobile robots equipped with cameras to obtain maximum visual coverage of a surface in the three-dimensional Euclidean space are considered. The existence of solutions to these problems is discussed first. Then, optimality conditions are derived by considering local path perturbations. Numerical algorithms for solving the corresponding approximate problems are proposed. Detailed solutions to the optimal path planning problems for a few examples are given. 相似文献
10.
Asymptotic methods for contact problems are expounded. Some typical integral equations are considered 相似文献