全文获取类型
收费全文 | 846篇 |
免费 | 41篇 |
国内免费 | 6篇 |
专业分类
化学 | 542篇 |
晶体学 | 1篇 |
力学 | 10篇 |
数学 | 155篇 |
物理学 | 185篇 |
出版年
2024年 | 1篇 |
2023年 | 4篇 |
2022年 | 3篇 |
2021年 | 11篇 |
2020年 | 20篇 |
2019年 | 18篇 |
2018年 | 3篇 |
2017年 | 14篇 |
2016年 | 5篇 |
2015年 | 42篇 |
2014年 | 36篇 |
2013年 | 41篇 |
2012年 | 58篇 |
2011年 | 50篇 |
2010年 | 53篇 |
2009年 | 41篇 |
2008年 | 62篇 |
2007年 | 65篇 |
2006年 | 43篇 |
2005年 | 36篇 |
2004年 | 44篇 |
2003年 | 25篇 |
2002年 | 18篇 |
2001年 | 22篇 |
2000年 | 22篇 |
1999年 | 25篇 |
1998年 | 15篇 |
1997年 | 12篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1994年 | 10篇 |
1993年 | 4篇 |
1992年 | 5篇 |
1991年 | 7篇 |
1990年 | 3篇 |
1988年 | 4篇 |
1987年 | 2篇 |
1986年 | 7篇 |
1985年 | 6篇 |
1984年 | 19篇 |
1983年 | 4篇 |
1982年 | 9篇 |
1981年 | 4篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1938年 | 1篇 |
排序方式: 共有893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.
3.
《Solid State Ionics》2006,177(26-32):2543-2547
The impact of interfaces on variety of materials properties scales with the density of interfaces within a material. This statement holds true independent of the specific interfacial mechanism, as long as the density of interfaces is rather low. If the spacing between interfaces is being further reduced, interesting non-trivial effects are expected and have also been observed. In this paper, the ionic conductivity in ionic conductors and the storage capacity (non-stoichiometry) of mixed conductors as a function of size are considered. The discussion is based on the core–space charge model in which we assume that only the core of an interface exhibits its own defect energetics, while the energetics of the space charge layers remain unaltered (compared to the bulk). It is shown that in the case of Schottky profiles anomalous conductivity effects are predicted. As regards the non-stoichiometry effects, it is demonstrated that at sizes small compared to the Debye length the difference between a composite consisting of an ionic and an electronic conductor and a «true» mixed conductor becomes blurred. The latter effect has recently been detected in the field of Li-batteries and is here commented on. 相似文献
4.
We show that the refined analytic torsion is a holomorphic section of the determinant line bundle over the space of complex representations of the fundamental group of a closed oriented odd-dimensional manifold. Further, we calculate the ratio of the refined analytic torsion and the Farber-Turaev combinatorial torsion. As an application, we establish a formula relating the eta-invariant and the phase of the Farber-Turaev torsion, which extends a theorem of Farber and earlier results of ours. This formula allows to study the spectral flow using methods of combinatorial topology. 相似文献
5.
The three-loop form factors in massless QCD can be expressed as a linear combination of master integrals. Besides a number of master integrals which factorise into products of one-loop and two-loop integrals, one finds 16 genuine three-loop integrals. Of these, six have the form of a bubble insertion inside a one-loop or two-loop vertex integral. We compute all master integrals with these insertion topologies. 相似文献
6.
Muonium in liquid SiCl has been observed for the first time at low temperature (−65°C) The observed polarization of muonium
is as much as 25% of the total spin polarization and shows a fast relaxation rate. 相似文献
7.
P.R. Willmott R. Herger M.C. Falub L. Patthey M. Döbeli C.V. Falub M. Shi M. Schneider 《Applied Physics A: Materials Science & Processing》2004,79(4-6):1199-1201
A new ablation target geometry is presented that was used to produce thin films of La1-xSrxMnO3 grown heteroepitaxially on SrTiO3 by pulsed reactive crossed-beam laser ablation. The films were grown in order to perform angle-resolved photoelectron spectroscopy, which demands that the surface be atomically flat. In situ and ex situ analysis shows that this condition was met, even after depositing to a thickness of over 100 nm. PACS 61.10.-i; 61.18.Bn; 68.47.Gh; 71.27.+a; 81.15.Fg 相似文献
8.
We study the asymptotic behaviour of the solution of elliptic problems with periodic data when the size of the domain on which the problem is set becomes unbounded. To cite this article: M. Chipot, Y. Xie, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
9.
J Robert Huber 《Chemphyschem》2004,5(11):1663-1669
This Minireview gives an account of the photochemical decay of nitric acid HNO3 in the gas phase, which has been well investigated under bulk and molecular-beam conditions. Due to the importance of this molecule in atmospheric chemistry, attention was paid to the irradiation regions around 300 and 200 nm, where solar photolysis of HNO3 is expected to be particularly efficient. While the low-energy region is characterized by the products OH and NO2, the high-energy region gives rise to a variety of photochemical decay pathways, dominated by channels which lead to the products HONO + O in different electronic states. 相似文献
10.
《中国化学快报》2020,31(5):1317-1321
Dipyrrolyldiketone difluoroboron complexes (BONEPYs) were synthesized by condensation of the corresponding pyrroles and malonyl chloride followed by treatment with BF3·OEt2. The aryl-substituted pyrrole is introduced to form a cyclic system in order to investigate anion binding studies. In BONEPYs 1–3 the o-H of the aryl group forms hydrogen bonding with F− to give a more table complex. In contrast, the intramolecular hydrogen-bonded BONEPY endo-4 is more stable than its exo isomer. While adding F−, the hydrogen bonds must be broken first to give 4·(3)F−. Owing to the electron-rich group (-OMe), the o-H of the phenyl group can hardly interact with F− via hydrogen bonding to give the less stable complex 4·(5)F−. The energy differences between the different conformations were calculated using DFT methods, which is consistent to the experimental observations. 相似文献