全文获取类型
收费全文 | 21157篇 |
免费 | 735篇 |
国内免费 | 94篇 |
专业分类
化学 | 13348篇 |
晶体学 | 141篇 |
力学 | 614篇 |
数学 | 2787篇 |
物理学 | 5096篇 |
出版年
2023年 | 124篇 |
2022年 | 179篇 |
2021年 | 217篇 |
2020年 | 364篇 |
2019年 | 304篇 |
2018年 | 204篇 |
2017年 | 195篇 |
2016年 | 474篇 |
2015年 | 471篇 |
2014年 | 558篇 |
2013年 | 872篇 |
2012年 | 1064篇 |
2011年 | 1248篇 |
2010年 | 710篇 |
2009年 | 619篇 |
2008年 | 1018篇 |
2007年 | 1057篇 |
2006年 | 1005篇 |
2005年 | 980篇 |
2004年 | 840篇 |
2003年 | 667篇 |
2002年 | 628篇 |
2001年 | 538篇 |
2000年 | 475篇 |
1999年 | 317篇 |
1998年 | 270篇 |
1997年 | 275篇 |
1996年 | 328篇 |
1995年 | 316篇 |
1994年 | 306篇 |
1993年 | 317篇 |
1992年 | 292篇 |
1991年 | 274篇 |
1990年 | 211篇 |
1989年 | 233篇 |
1988年 | 247篇 |
1987年 | 223篇 |
1986年 | 174篇 |
1985年 | 222篇 |
1984年 | 209篇 |
1983年 | 156篇 |
1982年 | 198篇 |
1981年 | 176篇 |
1980年 | 178篇 |
1979年 | 175篇 |
1978年 | 182篇 |
1977年 | 138篇 |
1976年 | 150篇 |
1974年 | 127篇 |
1973年 | 110篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
Laurens Kooijman Dr. Matthias Schuster Christian Baumann Simon Jurt Dr. Frank Löhr Dr. Boris Fürtig Prof. Dr. Peter Güntert Prof. Dr. Oliver Zerbe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(47):21151-21158
To achieve efficient proton pumping in the light-driven proton pump bacteriorhodopsin (bR), the protein must be tightly coupled to the retinal to rapidly convert retinal isomerization into protein structural rearrangements. Methyl group dynamics of bR embedded in lipid nanodiscs were determined in the dark-adapted state, and were found to be mostly well ordered at the cytosolic side. Methyl groups in the M145A mutant of bR, which displays only 10 % residual proton pumping activity, are less well ordered, suggesting a link between side-chain dynamics on the cytosolic side of the bR cavity and proton pumping activity. In addition, slow conformational exchange, attributed to low frequency motions of aromatic rings, was indirectly observed for residues on the extracellular side of the bR cavity. This may be related to reorganization of the water network. These observations provide a detailed picture of previously undescribed equilibrium dynamics on different time scales for ground-state bR. 相似文献
2.
Dr. Kathiravan Murugesan Vishwas G. Chandrashekhar Dr. Carsten Kreyenschulte Prof. Dr. Matthias Beller Dr. Rajenahally V. Jagadeesh 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(40):17561-17565
Herein, we report the synthesis of specific silica-supported Co/Co3O4 core–shell based nanoparticles prepared by template synthesis of cobalt-pyromellitic acid on silica and subsequent pyrolysis. The optimal catalyst material allows for general and selective hydrogenation of pyridines, quinolines, and other heteroarenes including acridine, phenanthroline, naphthyridine, quinoxaline, imidazo[1,2-a]pyridine, and indole under comparably mild reaction conditions. In addition, recycling of these Co nanoparticles and their ability for dehydrogenation catalysis are showcased. 相似文献
3.
Synthesis of Highly Substituted γ‐Butyrolactones by a Gold‐Catalyzed Cascade Reaction of Benzyl Esters
下载免费PDF全文
![点击此处可从《Chemistry (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maria Camila Blanco Jaimes Alexander Ahrens Daniel Pflästerer Dr. Matthias Rudolph Prof. Dr. A. Stephen K. Hashmi 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(1):427-433
Easily accessible benzylic esters of 3‐butynoic acids in a gold‐catalyzed cyclization/rearrangement cascade reaction provided 3‐propargyl γ‐butyrolactones with the alkene and the carbonyl group not being conjugated. Crossover experiments showed that the formation of the new C?C bond is an intermolecular process. Initially propargylic–benzylic esters were used, but alkyl‐substituted benzylic esters worked equally well. In the case of the propargylic–benzylic products, a simple treatment of the products with aluminum oxide initiated a twofold tautomerization to the allenyl‐substituted γ‐butyrolactones with conjugation of the carbonyl group, the olefin, and the allene. The synthetic sequence can be conducted stepwise or as a one‐pot cascade reaction with similar yields. Even in the presence of the gold catalyst the new allene remains intact. 相似文献
4.
5.
Vsevolod Khikhlovskyi Albert J. J. M. van Breemen Jasper J. Michels René A. J. Janssen Gerwin H. Gelinck Martijn Kemerink 《Journal of Polymer Science.Polymer Physics》2015,53(17):1231-1237
In many organic electronic devices functionality is achieved by blending two or more materials, typically polymers or molecules, with distinctly different optical or electrical properties in a single film. The local scale morphology of such blends is vital for the device performance. Here, a simple approach to study the full 3D morphology of phase‐separated blends, taking advantage of the possibility to selectively dissolve the different components is introduced. This method is applied in combination with AFM to investigate a blend of a semiconducting and ferroelectric polymer typically used as active layer in organic ferroelectric resistive switches. It is found that the blend consists of a ferroelectric matrix with three types of embedded semiconductor domains and a thin wetting layer at the bottom electrode. Statistical analysis of the obtained images excludes the presence of a fourth type of domains. The criteria for the applicability of the presented technique are discussed. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 1231–1237 相似文献
6.
7.
8.
9.