全文获取类型
收费全文 | 2886篇 |
免费 | 71篇 |
国内免费 | 8篇 |
专业分类
化学 | 2289篇 |
晶体学 | 6篇 |
力学 | 31篇 |
数学 | 206篇 |
物理学 | 433篇 |
出版年
2023年 | 21篇 |
2021年 | 44篇 |
2020年 | 35篇 |
2019年 | 44篇 |
2018年 | 15篇 |
2017年 | 13篇 |
2016年 | 53篇 |
2015年 | 45篇 |
2014年 | 63篇 |
2013年 | 84篇 |
2012年 | 88篇 |
2011年 | 103篇 |
2010年 | 55篇 |
2009年 | 55篇 |
2008年 | 72篇 |
2007年 | 82篇 |
2006年 | 51篇 |
2005年 | 63篇 |
2004年 | 56篇 |
2003年 | 41篇 |
2002年 | 42篇 |
2001年 | 28篇 |
2000年 | 27篇 |
1999年 | 34篇 |
1998年 | 27篇 |
1997年 | 28篇 |
1996年 | 51篇 |
1995年 | 51篇 |
1994年 | 36篇 |
1993年 | 45篇 |
1992年 | 37篇 |
1991年 | 13篇 |
1988年 | 16篇 |
1987年 | 19篇 |
1986年 | 19篇 |
1985年 | 17篇 |
1984年 | 13篇 |
1982年 | 14篇 |
1980年 | 17篇 |
1976年 | 16篇 |
1974年 | 19篇 |
1967年 | 77篇 |
1966年 | 166篇 |
1965年 | 131篇 |
1964年 | 149篇 |
1963年 | 122篇 |
1962年 | 122篇 |
1961年 | 146篇 |
1960年 | 127篇 |
1959年 | 61篇 |
排序方式: 共有2965条查询结果,搜索用时 15 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.
Cavitation erosion is caused in solids exposed to strong pressure waves developing in an adjacent fluid field. The knowledge of the transient distribution of stresses in the solid is important to understand the cause of damaging by comparisons with breaking points of the material. The modeling of this problem requires the coupling of the models for the fluid and the solid. For this purpose, we use a strategy based on the solution of coupled Riemann problems that has been originally developed for the coupling of 2 fluids. This concept is exemplified for the coupling of a linear elastic structure with an ideal gas. The coupling procedure relies on the solution of a nonlinear equation. Existence and uniqueness of the solution is proven. The coupling conditions are validated by means of quasi‐1D problems for which an explicit solution can be determined. For a more realistic scenario, a 2D application is considered where in a compressible single fluid, a hot gas bubble at low pressure collapses in a cold gas at high pressure near an adjacent structure. 相似文献
3.
E. Baumann 《Fresenius' Journal of Analytical Chemistry》1877,16(1):133-134
Ohne Zusammenfassung 相似文献
4.
Astrid Baumann 《Mathematische Semesterberichte》1998,45(2):167-188
Zusammenfassung. Mit Hilfe der projektiven Geometrie werden neuartige Summationsformeln hergeleitet, die die Tschebyscheff-Polynome und modifizierte Polynome enthalten; z. B. gilt für alle :
Daraus ergeben sich wiederum interessante Summationsformeln für die Hyperbelfunktionen; es gilt z. B. für positive reelle
Zahlen t:
Eingegangen am 28.02.96, revidierte Fassung am 25.08.97 / Angenommen am 09.10.97 相似文献
5.
The classical rules for Cope rearrangements predict a transition state with chair form to be favored over the boat form. On the other hand, bridged homotropylidenes, which allow only a boat-form transition state by steric reasons, have extremely low barriers. A controversy about the correct pathway and the different possible intermediates and transition states of the reaction has gone on for years. In this work, the hypersurfaces of barbaralane, in comparison with the boat- and chair-form of hexa-1,5-diene, are computed by the ab inito CASSCF (6,6)/6-31G** method starting with UMP2/6-31G** natural orbitals (NO's). All three hypersurfaces show characteristic features, and, moreover differ from each other. A hitherto undiscussed intermediate, bicyclo[2.2.0]hexane, was localized on the boat-hexa-1,5-diene pathway. So it is noteworthy that our transition state for the boat-hexa-1,5-diene does not correspond to the transition states found by other authors for this conformation. The computed enthalpies of activation of boat- and chair-hexa-1,5-diene, and barbaralane are in good agreement with the experimental data. 相似文献
6.
7.
High-precision sub-pixel interpolation in particle image velocimetry image processing 总被引:4,自引:0,他引:4
The task of image interpolation and re-sampling for particle image velocimetry (PIV) is investigated, which is used for window shifting with sub-pixel accuracy and image or window deformation. A new interpolation scheme based on a Gaussian filter is introduced and compared with commonly used and widely accepted interpolation techniques in terms of the achievable root mean square deviation of the displacement estimates. 相似文献
8.
9.
10.