全文获取类型
收费全文 | 16973篇 |
免费 | 2560篇 |
国内免费 | 2476篇 |
专业分类
化学 | 12257篇 |
晶体学 | 206篇 |
力学 | 1194篇 |
综合类 | 176篇 |
数学 | 1953篇 |
物理学 | 6223篇 |
出版年
2024年 | 52篇 |
2023年 | 261篇 |
2022年 | 457篇 |
2021年 | 518篇 |
2020年 | 580篇 |
2019年 | 572篇 |
2018年 | 471篇 |
2017年 | 481篇 |
2016年 | 700篇 |
2015年 | 707篇 |
2014年 | 858篇 |
2013年 | 1196篇 |
2012年 | 1319篇 |
2011年 | 1428篇 |
2010年 | 1001篇 |
2009年 | 1032篇 |
2008年 | 1119篇 |
2007年 | 1033篇 |
2006年 | 960篇 |
2005年 | 882篇 |
2004年 | 670篇 |
2003年 | 555篇 |
2002年 | 577篇 |
2001年 | 531篇 |
2000年 | 437篇 |
1999年 | 447篇 |
1998年 | 429篇 |
1997年 | 342篇 |
1996年 | 310篇 |
1995年 | 280篇 |
1994年 | 301篇 |
1993年 | 207篇 |
1992年 | 201篇 |
1991年 | 180篇 |
1990年 | 165篇 |
1989年 | 104篇 |
1988年 | 97篇 |
1987年 | 96篇 |
1986年 | 90篇 |
1985年 | 83篇 |
1984年 | 52篇 |
1983年 | 42篇 |
1982年 | 40篇 |
1981年 | 31篇 |
1980年 | 22篇 |
1979年 | 16篇 |
1978年 | 14篇 |
1977年 | 8篇 |
1976年 | 8篇 |
1973年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
一类非线性单调型方程的区域分裂法 总被引:1,自引:0,他引:1
本文考虑了一类非线性单调问题的加性Schwgrz交替法和异步平行算法,并得到了在能量模意义下的收敛性结果,最后还讨论了格式的有限元离散。 相似文献
32.
33.
34.
For vertical-cavity surface-emitting lasers (VCSELs) with polarization-rotated feedback, there exist several synchronization
types such as synchronizations between total powers and synchronizations between separate polarization modes. Based on the
two-mode rate equations, we study and compare numerically the performances of different synchronization types. Our results
show that three synchronization types exhibit good performances when their synchronization conditions are satisfied. They
are the complete synchronization between total powers, complete synchronization between x-polarized modes, and generalized synchronization between x-polarized and y-polarized modes. The former two types are sensitive to the injection rate and spontaneous emission, while the third type
is contrary. Synchronization type with the best performance may switch from one to another, with changing of injection rate
and spontaneous emission factor. 相似文献
35.
Tao Jin Feng-Xian Jiang Xiao-Li Li Fang Wang Xiao-Hua Shen Rui-Qiang Zhang Hai-Shun Wu 《Applied Surface Science》2006,253(5):2708-2712
CoPt/Ag and [C/CoPt]n/Ag thin films have been prepared onto the glass substrates by magnetron sputtering. We investigated the evolution of texture and magnetic properties of CoPt/Ag and [C/CoPt]n/Ag films. The results show that C-doping plays an important role in improving (0 0 1) texture, improving the order parameter S, reducing the intergrain interactions, and making the magnetization reversal mechanism more close to Stoner-Wolfarth rotational mechanism. The growth mechanism of (0 0 1) texture also seems to be related strongly to the films thickness. Our results show that the highly (0 0 1)-oriented films with ordered fct phase have a significant potential for the perpendicular media of extremely high-density recording. 相似文献
36.
Han-xing Wang Xi Hu Qin Zhang 《应用数学学报(英文版)》2007,23(2):235-244
In this paper,we present a random graph model with spatial reuse for a mobile ad hoc network(MANET) based on the dynamic source routing protocol.Many important performance parameters of theMANET are obtained,such as the average flooding distance (AFD),the probability generating function of theflooding distance,and the probability of a flooding route to be symmetric.Compared with the random graphmodel without spatial reuse,this model is much more effective because it has a smaller value of AFD and alarger probability for finding a symmetric valid route. 相似文献
37.
The sound field both in the loudspeaker box and in the room is calculated by an analytical solution of three-dimensional wave equation. It is shown in theory that the amplitude response in small rooms is affected by the following positions: driver position on the front panel of the box, box position in the room, absorption material position in the box and absorption material position on the interior walls of the room. Both our computer prediction and experiments prove that the optimum positions are beneficial to the amplitude response. 相似文献
38.
5‐Methylene‐2‐oxazolidinone (1) and 5‐methylene‐1,3‐thiazolidine‐2‐thione (4) react with various isocyanates to give the corresponding urethanes 3 and 5 in high yields in the presence of palladium(0) or palladium(II) catalyst under mild reaction conditions. A mechanism is proposed. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
39.
40.
Yu Zanping Zhou Zheyan School of Math.and Computer Science Fujian Normal University Fuzhou ) Shen Jianhe 《Annals of Differential Equations》2007,23(3):365-372
The paper aims to obtain existence and uniqueness of the solution as well as asymptotic estimate of the solution for singularly perturbed nonlinear third- order Robin boundary value problem with a turning point.In order to achieve this aim,existence and uniqueness of the solution for third-order nonlinear Robin boundary value problem is derived first based on the upper and lower solutions method under relatively weaker conditions.In this manner,the goal of this paper is gained by applying the existence and uniqueness results mentioned above. 相似文献