全文获取类型
收费全文 | 3311篇 |
免费 | 197篇 |
国内免费 | 10篇 |
专业分类
化学 | 2237篇 |
晶体学 | 6篇 |
力学 | 116篇 |
数学 | 603篇 |
物理学 | 556篇 |
出版年
2023年 | 44篇 |
2022年 | 36篇 |
2021年 | 82篇 |
2020年 | 72篇 |
2019年 | 99篇 |
2018年 | 70篇 |
2017年 | 46篇 |
2016年 | 145篇 |
2015年 | 120篇 |
2014年 | 125篇 |
2013年 | 194篇 |
2012年 | 302篇 |
2011年 | 329篇 |
2010年 | 181篇 |
2009年 | 158篇 |
2008年 | 250篇 |
2007年 | 229篇 |
2006年 | 216篇 |
2005年 | 182篇 |
2004年 | 154篇 |
2003年 | 112篇 |
2002年 | 96篇 |
2001年 | 40篇 |
2000年 | 39篇 |
1999年 | 26篇 |
1998年 | 16篇 |
1997年 | 12篇 |
1996年 | 9篇 |
1995年 | 4篇 |
1994年 | 8篇 |
1993年 | 8篇 |
1992年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1987年 | 7篇 |
1986年 | 4篇 |
1985年 | 5篇 |
1984年 | 4篇 |
1983年 | 6篇 |
1982年 | 6篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1979年 | 4篇 |
1977年 | 4篇 |
1976年 | 5篇 |
1975年 | 4篇 |
1974年 | 6篇 |
1929年 | 4篇 |
1907年 | 2篇 |
排序方式: 共有3518条查询结果,搜索用时 218 毫秒
991.
We provide an effective characterization of the planar octagonal tilings which admit weak local rules. As a corollary, we show that they are all based on quadratic irrationalities, as conjectured by Thang Le in the 1990s. 相似文献
992.
Dorian Sonet Mattéo Cayla Dr. Raphaël Méreau Estelle Morvan Aline Lacoudre Dr. Nicolas Vanthuyne Muriel Albalat Dr. Dario M. Bassani Dr. Antoine Scalabre Dr. Emilie Pouget Prof. Dr. Brigitte Bibal 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(72):e202202695
Chiral trifluoromethyl alcohol groups were introduced at the hindered ortho positions of 9,10-diphenylanthracenes to investigate their effects on the physical properties and reactivity towards oxidative dearomatization. In such compact structures, the position in different quadrants and the preferred orientation of the −CH(OH)CF3 groups were determined by the relative and absolute configurations of each stereoisomer, respectively. As a consequence, the stereochemistry governs the organization of the H-bonded molecules in single crystals (homochiral dimers vs ribbon), whereas in chlorinated solvents, they all behave as discrete compounds. Concerning their reactivity, the stereospecific dearomative oxidation of these molecules leads to 9,10-bis-spiro-isobenzofuran-anthracenes, when using organic single-electron transfer oxidants. The chiroptical properties of the alcohols and the corresponding dearomatized products were compared and showed an important modulation of the intensity. 相似文献
993.
994.
995.
996.
997.
998.
In this work, crack initiation in adhesive lap joints of arbitrary joint configuration is studied by means of a finite fracture mechanics approach. The analysis is based on a general stress solution for adhesive joints combined with a coupled stress and energy criterion. The instantaneous formation of a crack of finite size is predicted if a stress and energy criterion are satisfied simultaneously. The closed-form analytical solution of the stress field allows for an efficient evaluation of the crack initiation load and corresponding finite crack length. A comparison to experimental results from literature and to numerical results obtained with a cohesive zone model approach shows a good agreement. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
999.
Nicolas Triantafyllidis 《Journal of the mechanics and physics of solids》2004,52(9):2127-2148
The electromagnetic forming (EMF) process is an attractive manufacturing technique, which uses electromagnetic (Lorentz) body forces to fabricate metallic parts. One of the many advantages of EMF is the considerable ductility increase observed in several metals, with aluminum featuring prominently among them. The quantitative explanation of this phenomenon is the primary motivation of this work.To study the ductility increase due to EMF, an aluminum ring is placed outside a fixed coil, which is connected to a capacitor. Upon the capacitor's discharge, the time varying current in the coil induces a larger current in the ring specimen and the resulting Lorentz forces make it expand. The coupled coil-ring electromagnetic and thermomechanical problem is solved, using an experimentally obtained constitutive model for a particular aluminum alloy. Our results show that for realistic imperfections, the EMF ring starts necking at strains about six times larger than its static counterpart, as observed experimentally. This study establishes the importance of solving the fully coupled electromagnetic and thermomechanical problem and provides insight on how different constitutive parameters influence ductility in an EMF process. 相似文献
1000.