全文获取类型
收费全文 | 392805篇 |
免费 | 5095篇 |
国内免费 | 1205篇 |
专业分类
化学 | 212989篇 |
晶体学 | 5490篇 |
力学 | 16154篇 |
综合类 | 9篇 |
数学 | 45689篇 |
物理学 | 118774篇 |
出版年
2020年 | 3077篇 |
2019年 | 3279篇 |
2018年 | 4014篇 |
2017年 | 3946篇 |
2016年 | 6590篇 |
2015年 | 4541篇 |
2014年 | 6629篇 |
2013年 | 17953篇 |
2012年 | 13244篇 |
2011年 | 16434篇 |
2010年 | 10845篇 |
2009年 | 10605篇 |
2008年 | 14906篇 |
2007年 | 15082篇 |
2006年 | 13814篇 |
2005年 | 12798篇 |
2004年 | 11345篇 |
2003年 | 9962篇 |
2002年 | 9889篇 |
2001年 | 10945篇 |
2000年 | 8400篇 |
1999年 | 6562篇 |
1998年 | 5583篇 |
1997年 | 5549篇 |
1996年 | 5196篇 |
1995年 | 4942篇 |
1994年 | 4813篇 |
1993年 | 4818篇 |
1992年 | 5201篇 |
1991年 | 5223篇 |
1990年 | 4897篇 |
1989年 | 4829篇 |
1988年 | 4850篇 |
1987年 | 4660篇 |
1986年 | 4465篇 |
1985年 | 6083篇 |
1984年 | 6276篇 |
1983年 | 5207篇 |
1982年 | 5707篇 |
1981年 | 5511篇 |
1980年 | 5328篇 |
1979年 | 5460篇 |
1978年 | 5819篇 |
1977年 | 5583篇 |
1976年 | 5721篇 |
1975年 | 5252篇 |
1974年 | 5423篇 |
1973年 | 5727篇 |
1972年 | 3571篇 |
1971年 | 2933篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
22.
Ibotov Sh. Kh. Yuldasheva N. K. Mukarramov N. I. Zakirova R. P. Gusakova S. D. 《Chemistry of Natural Compounds》2022,58(4):728-731
Chemistry of Natural Compounds - 相似文献
23.
Russian Chemical Bulletin - The N-methylation of primary carboxamides is based on two consecutive reactions. The silylation of the corresponding carboxamides with chloro(chloromethyl)dimethylsilane... 相似文献
24.
Theoretical and Mathematical Physics - We present a one-line closed-form expression for the three-parameter breather of the nonlinear Schrödinger equation. This provides an analytic proof of... 相似文献
25.
Ukrainian Mathematical Journal - We establish new criteria of compatibility for a linear system of equations (equivalent to the Kronecker–Capelli theorem) or inequalities (equivalent to the... 相似文献
26.
Restricted testing conditions were considered recently. For the maximal operator, Hytönen, Li and Sawyer [8] first obtained parental testing condition. Later, they [9] showed that it suffices to restrict testing to doubling cubes. Chen and Lacey [3] gave a similar restricted testing condition. In our paper, we discuss a version of the latter in the multilinear setting.
相似文献27.
Physics of Particles and Nuclei Letters - When creating accelerators and storage-ring installations in a compact space, there is not always enough space for all the necessary magnet elements. In... 相似文献
28.
29.
In a 2:2 reaction with silver(I) chloride or bromide, 1,5-bis(1-phospholano)pentane ( 1a ) afforded frame-like macrocyclic structures, with intra- ( 2 , Cl) or intermolecular ( 3 , Br) halido bridges. In contrast, 1,7-bis(1-phospholano)heptane ( 1b ) formed coordination polymers 4a (Cl) and 4b (Br) with bridging bis-phospholane and halido ligands. A unique paddle wheel-type metallacryptand structure 5 was obtained from 1a and silver(I) bromide in a 2:3 reaction (M:L). All complexes were fully characterized by NMR, IR spectroscopy, mass spectrometry, and X-ray crystallography. 相似文献
30.
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