全文获取类型
收费全文 | 7370篇 |
免费 | 295篇 |
国内免费 | 36篇 |
专业分类
化学 | 5184篇 |
晶体学 | 138篇 |
力学 | 116篇 |
综合类 | 1篇 |
数学 | 849篇 |
物理学 | 1413篇 |
出版年
2023年 | 55篇 |
2022年 | 71篇 |
2021年 | 99篇 |
2020年 | 171篇 |
2019年 | 163篇 |
2018年 | 92篇 |
2017年 | 93篇 |
2016年 | 216篇 |
2015年 | 217篇 |
2014年 | 225篇 |
2013年 | 295篇 |
2012年 | 412篇 |
2011年 | 475篇 |
2010年 | 270篇 |
2009年 | 290篇 |
2008年 | 418篇 |
2007年 | 437篇 |
2006年 | 424篇 |
2005年 | 389篇 |
2004年 | 323篇 |
2003年 | 229篇 |
2002年 | 242篇 |
2001年 | 126篇 |
2000年 | 123篇 |
1999年 | 84篇 |
1998年 | 104篇 |
1997年 | 90篇 |
1996年 | 114篇 |
1995年 | 106篇 |
1994年 | 68篇 |
1993年 | 71篇 |
1992年 | 70篇 |
1991年 | 67篇 |
1990年 | 72篇 |
1989年 | 52篇 |
1988年 | 51篇 |
1987年 | 53篇 |
1986年 | 53篇 |
1985年 | 59篇 |
1984年 | 46篇 |
1983年 | 49篇 |
1982年 | 40篇 |
1981年 | 53篇 |
1980年 | 52篇 |
1978年 | 39篇 |
1977年 | 41篇 |
1976年 | 36篇 |
1973年 | 43篇 |
1972年 | 26篇 |
1971年 | 28篇 |
排序方式: 共有7701条查询结果,搜索用时 29 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.
3.
4.
5.
Martin Kellert Jan-Simon Jeshua Friedrichs Nadine Anke Ullrich Alexander Feinhals Jonas Tepper Peter Lnnecke Evamarie Hey-Hawkins 《Molecules (Basel, Switzerland)》2021,26(7)
The development of novel, tumor-selective and boron-rich compounds as potential agents for use in boron neutron capture therapy (BNCT) represents a very important field in cancer treatment by radiation therapy. Here, we report the design and synthesis of two promising compounds that combine meta-carborane, a water-soluble monosaccharide and a linking unit, namely glycine or ethylenediamine, for facile coupling with various tumor-selective biomolecules bearing a free amino or carboxylic acid group. In this work, coupling experiments with two selected biomolecules, a coumarin derivative and folic acid, were included. The task of every component in this approach was carefully chosen: the carborane moiety supplies ten boron atoms, which is a tenfold increase in boron content compared to the l-boronophenylalanine (l-BPA) presently used in BNCT; the sugar moiety compensates for the hydrophobic character of the carborane; the linking unit, depending on the chosen biomolecule, acts as the connection between the tumor-selective component and the boron-rich moiety; and the respective tumor-selective biomolecule provides the necessary selectivity. This approach makes it possible to develop a modular and feasible strategy for the synthesis of readily obtainable boron-rich agents with optimized properties for potential applications in BNCT. 相似文献
6.
7.
8.
Steven D. Bull Simon W. Epstein Nadeam Mujtaba Edward D. Savory Juan A. Tamayo 《Tetrahedron》2006,62(33):7911-7925
Enolates of (S)-N,N′-bis-(p-methoxybenzyl)-3-iso-propylpiperazine-2,5-dione exhibit high levels of enantiodiscrimination in alkylations with (RS)-1-aryl-1-bromoethanes and (RS)-2-bromoesters, affording substituted diketopiperazines containing two new stereogenic centres in high de. Deprotection and hydrolysis of the resultant substituted diketopiperazines provides a route to the asymmetric synthesis of homochiral methyl 2-amino-3-aryl-butanoates and 3-methyl-aspartates in high de and ee. 相似文献
9.
10.