全文获取类型
收费全文 | 3760篇 |
免费 | 140篇 |
国内免费 | 26篇 |
专业分类
化学 | 2511篇 |
晶体学 | 21篇 |
力学 | 89篇 |
数学 | 623篇 |
物理学 | 682篇 |
出版年
2023年 | 19篇 |
2022年 | 43篇 |
2021年 | 99篇 |
2020年 | 90篇 |
2019年 | 111篇 |
2018年 | 126篇 |
2017年 | 92篇 |
2016年 | 149篇 |
2015年 | 130篇 |
2014年 | 156篇 |
2013年 | 216篇 |
2012年 | 251篇 |
2011年 | 271篇 |
2010年 | 185篇 |
2009年 | 125篇 |
2008年 | 254篇 |
2007年 | 252篇 |
2006年 | 220篇 |
2005年 | 203篇 |
2004年 | 157篇 |
2003年 | 121篇 |
2002年 | 104篇 |
2001年 | 49篇 |
2000年 | 37篇 |
1999年 | 40篇 |
1998年 | 38篇 |
1997年 | 27篇 |
1996年 | 38篇 |
1995年 | 26篇 |
1994年 | 32篇 |
1993年 | 17篇 |
1992年 | 13篇 |
1991年 | 12篇 |
1990年 | 7篇 |
1989年 | 12篇 |
1988年 | 11篇 |
1986年 | 7篇 |
1985年 | 7篇 |
1984年 | 10篇 |
1983年 | 12篇 |
1982年 | 12篇 |
1981年 | 8篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1977年 | 8篇 |
1976年 | 14篇 |
1975年 | 15篇 |
1973年 | 8篇 |
1972年 | 6篇 |
1954年 | 5篇 |
排序方式: 共有3926条查询结果,搜索用时 15 毫秒
151.
The one-pot, three-step, four-component Ugi-IMDAF reaction with 5-hydroxymethylfurfural provides simple access to hydroxymethyl-substituted epoxyisoindolones in a diastereoselective and stereospecific manner. The protocol avoids the transfer or isolation of isocyanides, and the broad scope was illustrated by the synthesis of 22 different compounds bearing various substituents on the heterocyclic core. 相似文献
152.
Herein, we report a practical synthesis of 2-D-l-tryptophan via sequential Ir-catalyzed CH borylation, and Ir-catalyzed C-2-deborylative deuteration steps. In this synthetic sequence, deprotection of the Boc and methyl ester groups proved challenging, due to replacement of deuterium with hydrogen. However, mild deprotection conditions were developed to avoid this D/H scrambling. Further, 2-D-L-Tryptophan is stable in many buffers used for biological studies. 相似文献
153.
154.
Mokrushina A. N. Plotnikov V. A. Dem’yanov B. F. Makarov S. V. 《Technical Physics》2019,64(6):853-857
Technical Physics - The crystalline structure of intermetallic Cu3Sn synthesized by successively condensing thin layers of copper and tin on a substrate at 150°C has been studied. Cu3Sn... 相似文献
155.
156.
Dr. Jana Hudecová Dr. Josef Kapitán Prof. Martin Dračínský Pavel Michal Dr. Václav Profant Prof. Petr Bouř 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(59):e202202045
The histidine residue has an exceptional affinity for metals, but solution structure of its complexes are difficult to study. For zinc and nickel complexes, Raman and Raman optical activity (ROA) spectroscopy methods to investigate the link between spectral shapes and the geometry were used. The spectra were recorded and interpreted on the basis of ionic equilibria, molecular dynamics, ab initio molecular dynamics, and density functional theory. For zwitterionic histidine the dominant tautomer was determined by the decomposition of experimental spectra into calculated subspectra. An octahedral structure was found to prevail for the ZnHis2 complex in solution, in contrast to a tetrahedral arrangement in the crystal phase. The solution geometry of NiHis2 is more similar to the octahedral structure found by X-ray. The Raman and ROA structural determinations of metal complexes are dependent on extensive computations, but reveal unique information about the studied systems. 相似文献
157.
Annals of Global Analysis and Geometry - We study a natural class of LCK manifolds that we call integrable LCK manifolds: those where the anti-Lee form $$\eta $$ corresponds to an integrable... 相似文献
158.
Alfimov M. V. Chibisov A. K. Zakharova G. V. Fedotova T. V. Plotnikov V. G. 《Russian Physics Journal》2020,63(8):1363-1369
Russian Physics Journal - The results of investigations of the properties of cyanine dye dimers in the triplet state are presented. The formation of dimers is demonstrated as two absorption bands... 相似文献
159.
Ondřej Zvěřina Pavel Coufalík Josef Komárek Petr Gadas Jiřina Sysalová 《Chemical Papers》2014,68(2):197-202
An analysis of suspended particulate matter, with an emphasis on the Hg chemical forms, is presented. Dust samples originating from an area highly affected by traffic pollution in the city of Prague (Czech Republic) were sampled over a period of three years from air-conditioner filters and fractioned by size. The samples were morphologically characterised by scanning electron microscopy. The main method used for the analysis of constituent mercury compounds was sequential extraction by leaching solutions in combination with thermal desorption. The total mercury content ranged from 0.37 mg kg?1 to 0.82 mg kg?1. It emerged that the mercury was distributed in a wide spectrum of forms, and various trends in the distribution of these forms among the different size classes were observed. The fraction leached by nitric acid (consisting of elemental and complex-bound mercury) was the main constituent of total mercury. The highest content of this fraction was observed in the finest particle size class. The heterogeneity of morphology of the material increased with the size fraction. 相似文献
160.