全文获取类型
收费全文 | 34608篇 |
免费 | 5923篇 |
国内免费 | 4472篇 |
专业分类
化学 | 24682篇 |
晶体学 | 373篇 |
力学 | 2330篇 |
综合类 | 339篇 |
数学 | 4205篇 |
物理学 | 13074篇 |
出版年
2024年 | 73篇 |
2023年 | 666篇 |
2022年 | 898篇 |
2021年 | 1209篇 |
2020年 | 1404篇 |
2019年 | 1449篇 |
2018年 | 1139篇 |
2017年 | 1048篇 |
2016年 | 1619篇 |
2015年 | 1695篇 |
2014年 | 1981篇 |
2013年 | 2556篇 |
2012年 | 3049篇 |
2011年 | 3286篇 |
2010年 | 2197篇 |
2009年 | 2156篇 |
2008年 | 2219篇 |
2007年 | 1982篇 |
2006年 | 1889篇 |
2005年 | 1566篇 |
2004年 | 1366篇 |
2003年 | 1039篇 |
2002年 | 1071篇 |
2001年 | 883篇 |
2000年 | 771篇 |
1999年 | 753篇 |
1998年 | 630篇 |
1997年 | 540篇 |
1996年 | 536篇 |
1995年 | 497篇 |
1994年 | 446篇 |
1993年 | 381篇 |
1992年 | 347篇 |
1991年 | 302篇 |
1990年 | 261篇 |
1989年 | 231篇 |
1988年 | 160篇 |
1987年 | 130篇 |
1986年 | 114篇 |
1985年 | 122篇 |
1984年 | 70篇 |
1983年 | 61篇 |
1982年 | 61篇 |
1981年 | 33篇 |
1980年 | 18篇 |
1979年 | 15篇 |
1978年 | 8篇 |
1977年 | 10篇 |
1975年 | 8篇 |
1957年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
21.
S. Q. Hou W. Wang Z. Y. Wang Z. W. Hu K. Liu 《Journal of Applied Mechanics and Technical Physics》2018,59(1):153-162
In order to investigate the characteristics of force chains in a granular flow system, a parallel plate shear cell is constructed to simulate the shear movement of an infinite parallel plate and observe variations in relevant parameters. The shear dilatancy process is divided into three stages, namely, plastic strain, macroscopic failure, and granular recombination. The stickslip phenomenon is highly connected with the evolution of force chains during the shear dilatancy process. The load–distribution rate curves and patterns of the force chains are utilized to describe the load-carrying behaviors and morphologic changes of force chains separately. Force chains, namely, “diagonal gridding,” “tadpole-shaped,” and “pinnate” are defined according to the form of the force chains in the corresponding three stages. 相似文献
22.
This study is concerned with a new,explicit approach by means of which forms of the large strain elastic potential for multiaxial rubberlike elasticity may be obtained based on data for a single deformation mode.As a departure from usual studies,here for the first time errors may be estimated and rendered minimal for all possible deformation modes and,furthermore,failure behavior may be incorporated.Numerical examples presented are in accurate agreement with Treloar's well-known data. 相似文献
23.
Recently,the nested Mach–Zehnder interferometer[Phys.Rev.Lett.111,240402(2013)]was modified by adding Dove prisms in a paper[Quantum Stud.:Math.Found.2,255(2015)],and an interesting result is that,after the Dove prisms were inserted,a signal at the first mirror of the nested interferometer was obtained.But,according to the former original paper,the photons have never been present near that mirror.In this work,we interpret this result naturally by resorting to the three-path interference method.Moreover,we find that even though the photons have been somewhere,they can hide the trace of being there. 相似文献
24.
25.
Peng-Yan Gui Xiao-Hui Yan Wen-Juan Yuan Yuan-Liang Ma Xiao Ding Shuai Liu 《Natural product research》2019,33(19):2830-2836
A new A, D-seco limonoid, named 12-acetyloxyperforatin (1), along with three known ones, were isolated from the leaves of Harrisonia perforata. Their structures were elucidated on the basis of spectroscopic analysis, including extensive NMR techniques and computational modelling. These compounds showed no inhibitory activity against the 11β-HSD1 enzyme. 相似文献
26.
Sun Yuan Luo Shunlong Lei Xiangyun 《International Journal of Theoretical Physics》2021,60(9):3211-3224
International Journal of Theoretical Physics - Gram matrices arise naturally in the consideration of pair-wise overlap of a family of vectors or quantum pure states, and play an important role in... 相似文献
27.
28.
29.
30.