全文获取类型
收费全文 | 277603篇 |
免费 | 3954篇 |
国内免费 | 830篇 |
专业分类
化学 | 137789篇 |
晶体学 | 3020篇 |
力学 | 14705篇 |
综合类 | 7篇 |
数学 | 54399篇 |
物理学 | 72467篇 |
出版年
2021年 | 1608篇 |
2020年 | 1911篇 |
2019年 | 1972篇 |
2018年 | 12402篇 |
2017年 | 12040篇 |
2016年 | 9874篇 |
2015年 | 3872篇 |
2014年 | 4281篇 |
2013年 | 9848篇 |
2012年 | 12132篇 |
2011年 | 19696篇 |
2010年 | 11763篇 |
2009年 | 11780篇 |
2008年 | 14983篇 |
2007年 | 17036篇 |
2006年 | 8432篇 |
2005年 | 8870篇 |
2004年 | 8149篇 |
2003年 | 7597篇 |
2002年 | 6451篇 |
2001年 | 5441篇 |
2000年 | 4342篇 |
1999年 | 3250篇 |
1998年 | 2847篇 |
1997年 | 2708篇 |
1996年 | 2665篇 |
1995年 | 2314篇 |
1994年 | 2327篇 |
1993年 | 2192篇 |
1992年 | 2438篇 |
1991年 | 2515篇 |
1990年 | 2288篇 |
1989年 | 2295篇 |
1988年 | 2179篇 |
1987年 | 2064篇 |
1986年 | 1964篇 |
1985年 | 2614篇 |
1984年 | 2735篇 |
1983年 | 2179篇 |
1982年 | 2455篇 |
1981年 | 2310篇 |
1980年 | 2214篇 |
1979年 | 2358篇 |
1978年 | 2488篇 |
1977年 | 2321篇 |
1976年 | 2403篇 |
1975年 | 2274篇 |
1974年 | 2332篇 |
1973年 | 2322篇 |
1972年 | 1492篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
3.
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
4.
ABSTRACTThe Coupled-Cluster (CC) theory is one of the most successful high precision methods used to solve the stationary Schrödinger equation. In this article, we address the mathematical foundation of this theory with focus on the advances made in the past decade. Rather than solely relying on spectral gap assumptions (non-degeneracy of the ground state), we highlight the importance of coercivity assumptions – Gårding type inequalities – for the local uniqueness of the CC solution. Based on local strong monotonicity, different sufficient conditions for a local unique solution are suggested. One of the criteria assumes the relative smallness of the total cluster amplitudes (after possibly removing the single amplitudes) compared to the Gårding constants. In the extended CC theory the Lagrange multipliers are wave function parameters and, by means of the bivariational principle, we here derive a connection between the exact cluster amplitudes and the Lagrange multipliers. This relation might prove useful when determining the quality of a CC solution. Furthermore, the use of an Aubin–Nitsche duality type method in different CC approaches is discussed and contrasted with the bivariational principle. 相似文献
5.
Kazakova E. F. Dmitrieva N. E. Zvereva N. L. 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2020,94(2):341-344
Russian Journal of Physical Chemistry A - Rapidly quenched alloys of aluminum with cobalt and zirconium are investigated using a combination of means of physicochemical analysis to study the... 相似文献
6.
7.
Dr. Sabin Llona‐Minguez Dr. Matthieu Desroses Artin Ghassemian Dr. Sylvain A. Jacques Dr. Lars Eriksson Rebecka Isacksson Tobias Koolmeister Dr. Pål Stenmark Dr. Martin Scobie Prof. Thomas Helleday 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(20):7394-7398
A two‐step synthesis of structurally diverse pyrrole‐containing bicyclic systems is reported. ortho‐Nitro‐haloarenes coupled with vinylic N‐methyliminodiacetic acid (MIDA) boronates generate ortho‐vinyl‐nitroarenes, which undergo a “metal‐free” nitrene insertion, resulting in a new pyrrole ring. This novel synthetic approach has a wide substrate tolerance and it is applicable in the preparation of more complex “drug‐like” molecules. Interestingly, an ortho‐nitro‐allylarene derivative furnished a cyclic β‐aminophosphonate motif. 相似文献
8.
The European Physical Journal Special Topics - The removal of suspended particles from the interior of a thermocapillary liquid bridge via a finite-particle-size effect restricting the particle... 相似文献
9.
10.
Mesoscopic modeling at the pore scale offers great promise in exploring the underlying structure transport performance of flow through porous media. The present work studies the fluid flow subjected to capillarity-induced resonance in porous media characterized by different porous structure and wettability. The effects of porosity and wettability on the displacement behavior of the fluid flow through porous media are discussed. The results are presented in the form of temporal evolution of percentage saturation and displacement of the fluid front through porous media. The present study reveals that the vibration in the form of acoustic excitation could be significant in the mobilization of fluid through the porous media. The dependence of displacement of the fluid on physicochemical parameters like wettability of the surface, frequency along with the porosity is analyzed. It was observed that the mean displacement of the fluid is more in the case of invading fluid with wetting phase where the driving force strength is not so dominant. 相似文献