全文获取类型
收费全文 | 4884篇 |
免费 | 508篇 |
国内免费 | 349篇 |
专业分类
化学 | 634篇 |
晶体学 | 39篇 |
力学 | 537篇 |
综合类 | 47篇 |
数学 | 2641篇 |
物理学 | 1843篇 |
出版年
2024年 | 8篇 |
2023年 | 43篇 |
2022年 | 75篇 |
2021年 | 94篇 |
2020年 | 93篇 |
2019年 | 138篇 |
2018年 | 135篇 |
2017年 | 146篇 |
2016年 | 145篇 |
2015年 | 150篇 |
2014年 | 256篇 |
2013年 | 530篇 |
2012年 | 255篇 |
2011年 | 302篇 |
2010年 | 296篇 |
2009年 | 373篇 |
2008年 | 364篇 |
2007年 | 333篇 |
2006年 | 261篇 |
2005年 | 222篇 |
2004年 | 195篇 |
2003年 | 193篇 |
2002年 | 186篇 |
2001年 | 162篇 |
2000年 | 133篇 |
1999年 | 105篇 |
1998年 | 100篇 |
1997年 | 83篇 |
1996年 | 67篇 |
1995年 | 50篇 |
1994年 | 37篇 |
1993年 | 23篇 |
1992年 | 38篇 |
1991年 | 25篇 |
1990年 | 11篇 |
1989年 | 8篇 |
1988年 | 17篇 |
1987年 | 12篇 |
1986年 | 13篇 |
1985年 | 11篇 |
1984年 | 4篇 |
1983年 | 7篇 |
1982年 | 14篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1971年 | 1篇 |
1957年 | 2篇 |
1936年 | 1篇 |
排序方式: 共有5741条查询结果,搜索用时 8 毫秒
11.
Zhimin He 《Journal of Mathematical Analysis and Applications》2004,296(1):97-109
In this paper, by means of a new twin fixed-point theorem in a cone, the existence of at least two positive solutions of m-point boundary value problem for second order dynamic equations on time scales is considered. 相似文献
12.
L. K. Seah U. S. Dinish S. K. Ong Z. X. Chao V. M. Murukeshan 《Optics & Laser Technology》2004,36(5):371-376
Imaging of latent fingerprints using time-resolved (TR) method offers a broader platform to eliminate the unwanted background emission. In this paper, a novel TR imaging technique is demonstrated and implemented, which facilitates the detection of latent fingerprints with nanosecond resolution. Simulated experiments were carried out with two overlapping fingerprints treated with two fluorescent powders having different lifetimes in nanosecond range. The dependence of the fluorescence emission intensity in nanosecond resolution of TR imaging is also revealed. 相似文献
13.
A Variable Neighborhood Search for the Multi Depot Vehicle Routing Problem with Time Windows 总被引:6,自引:0,他引:6
Michael Polacek Richard F. Hartl Karl Doerner Marc Reimann 《Journal of Heuristics》2004,10(6):613-627
The aim of this paper is to propose an algorithm based on the philosophy of the Variable Neighborhood Search (VNS) to solve Multi Depot Vehicle Routing Problems with Time Windows. The paper has two main contributions. First, from a technical point of view, it presents the first application of a VNS for this problem and several design issues of VNS algorithms are discussed. Second, from a problem oriented point of view the computational results show that the approach is competitive with an existing Tabu Search algorithm with respect to both solution quality and computation times. 相似文献
14.
This note investigates two long-standing conjectures on the Krull dimension of integer-valued polynomial rings and of polynomial rings in the context of (locally) essential domains.
15.
Jiqin Deng 《Journal of Mathematical Analysis and Applications》2007,332(1):475-486
In this paper, by using the fixed point theory, under quite general conditions on the nonlinear term, we obtain an existence result of bounded positive solutions of Schrödinger equations in two-dimensional exterior domains. 相似文献
16.
教学质量的时齐马尔可夫链评估法 总被引:1,自引:0,他引:1
本文研究了教学质量评估中的一种定量分析方法──时齐马尔可夫链评估法.阐明了这种方法的理论依据及其实施程序、并指出它较之其他教学质量评估法更显合理. 相似文献
17.
Yuan-Ming Wang 《Journal of Mathematical Analysis and Applications》2007,328(1):137-150
The aim of this paper is to investigate the asymptotic behavior of solutions for a class of three-species predator-prey reaction-diffusion systems with time delays under homogeneous Neumann boundary condition. Some simple and easily verifiable conditions are given to the rate constants of the reaction functions to ensure the convergence of the time-dependent solution to a constant steady-state solution. The conditions for the convergence are independent of diffusion coefficients and time delays, and the conclusions are directly applicable to the corresponding parabolic-ordinary differential system and to the corresponding system without time delays. 相似文献
18.
19.
John M. Davis Ian A. Gravagne 《Journal of Mathematical Analysis and Applications》2007,332(2):1291-1307
In this work, we reexamine the time scale Laplace transform as defined by Bohner and Peterson [M. Bohner, A. Peterson, Dynamic Equations on Time Scales: An Introduction with Applications, Birkhäuser, Boston, 2001; M. Bohner, A. Peterson, Laplace transform and Z-transform: Unification and extension, Methods Appl. Anal. 9 (1) (2002) 155-162]. In particular, we give conditions on the class of functions which have a transform, develop an inversion formula for the transform, and further, we provide a convolution for the transform. The notion of convolution leads to considering its algebraic structure—in particular the existence of an identity element—motivating the development of the Dirac delta functional on time scales. Applications and examples of these concepts are given. 相似文献
20.