全文获取类型
收费全文 | 1671篇 |
免费 | 36篇 |
国内免费 | 8篇 |
专业分类
化学 | 1124篇 |
晶体学 | 7篇 |
力学 | 44篇 |
数学 | 242篇 |
物理学 | 298篇 |
出版年
2023年 | 8篇 |
2022年 | 34篇 |
2021年 | 40篇 |
2020年 | 23篇 |
2019年 | 25篇 |
2018年 | 27篇 |
2017年 | 18篇 |
2016年 | 47篇 |
2015年 | 50篇 |
2014年 | 42篇 |
2013年 | 79篇 |
2012年 | 92篇 |
2011年 | 117篇 |
2010年 | 80篇 |
2009年 | 62篇 |
2008年 | 116篇 |
2007年 | 102篇 |
2006年 | 115篇 |
2005年 | 97篇 |
2004年 | 86篇 |
2003年 | 71篇 |
2002年 | 63篇 |
2001年 | 24篇 |
2000年 | 20篇 |
1999年 | 14篇 |
1998年 | 15篇 |
1997年 | 13篇 |
1996年 | 22篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1993年 | 4篇 |
1992年 | 10篇 |
1991年 | 13篇 |
1990年 | 5篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 6篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 11篇 |
1983年 | 6篇 |
1982年 | 17篇 |
1981年 | 16篇 |
1980年 | 8篇 |
1979年 | 4篇 |
1978年 | 9篇 |
1977年 | 7篇 |
1976年 | 5篇 |
1975年 | 8篇 |
1970年 | 5篇 |
排序方式: 共有1715条查询结果,搜索用时 15 毫秒
1.
2.
3.
4.
5.
Massimo Camarda Antonino La Magna Francesco La Via 《Journal of computational physics》2007,227(2):1075-1093
A modified Kinetic Lattice Monte Carlo model has been developed to predict growth rate regimes and defect formation in the case of the homo-epitaxial growth of close packed crystalline structures. The model is an improvement over standard Monte Carlo algorithms, which usually retain fixed atom positions and bond partners indicative of perfect crystal lattices. Indeed, we extend the concepts of Monte Carlo growth simulations on super-lattices containing additional sites (defect sites) with respect to those of the reference material. This extension implies a reconsideration of the energetic mapping, which is extensively presented, and allows to describe a complex phenomenology that is out of accessibility of standard stochastic approaches. Results obtained using the Kawasaki and the Bond-Counting rules for the transition probability of the Monte Carlo event are discussed in details. These results demonstrate how the defect types (local or extended), the formation mechanisms and the defect generation regimes can be characterized using our approach. 相似文献
6.
We prove that Gibbs states for the Hamiltonian
, with thes
x varying on theN-dimensional unit sphere, obtained with nonrandom boundary conditions (in a suitable sense), are almost surely rotationally invariant if
withJ
xy i.i.d. bounded random variables with zero average, 1 in one dimension, and 2 in two dimensions. 相似文献
7.
Giuseppe Bartoli Sandra Giuli Enrico Marcantoni Massimo Massaccesi 《Tetrahedron letters》2006,47(37):6501-6504
The arylidene malonates with two different geminal carboxylate functions, a suitable class of substrates of several synthetic and pharmacological studies, are easily available through Knoevenagel condensation of ethyl tert-butyl malonate and different aromatic aldehydes. The results have increased the potentialities of CeCl3·7H2O-NaI system as a type of water-tolerant green Lewis acid promoter for carbon-carbon bond forming procedures. 相似文献
8.
A polyclonal, multispecific antiserum was raised against a whole 3[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate-extract of nonirradiated Blepharisma japonicum cells. It was used to reveal the composition of solutions that were hypothesized to contain the photoreceptor of the ciliate. A Bio-Gel A 1.5 m fine column chromatography of the extract allowed recovery of a single elution peak isolated by recording the 580 nm light absorbance. Fused-rocket immunoelectrophoresis of this material revealed a large number of > 300 kDa coeluted proteins. Blepharismin-rich material with a molecular mass of approximately 50 kDa, consisting of at least nine proteins was obtained when the same extract underwent preparative isoelectric focusing before column chromatography separation. Purification of the pigment obtained from light-exposed cells gave blepharismin-rich material with a molecular weight of approximately 200 kDa. Comparison of the materials obtained under the same conditions, either from the dark-kept or light-irradiated cells, by means of pore-gradient electrophoresis confirmed that proteins present in the two preparations were different. It revealed only a very small amount, if any, of proteins in the chromatography fractions with the highest absorbance at 600 nm. Results are discussed on the basis of the hypothesis that a specific blepharismin-binding protein does not exist in the protozoan. 相似文献
9.
Nicolas?Ferré Alessandro?Cembran Marco?Garavelli Massimo?OlivucciEmail author 《Theoretical chemistry accounts》2004,112(4):335-341
A special hybrid quantum mechanics/molecular mechanics forcefield is defined, parameterized and validated for studying the photoisomerization path of the retinal chromophore in the rhodopsin protein. It couples a multireference ab initio Hamiltonian (CASSCF and second-order multireference many-body perturbation theory using a CASSCF reference) to describe the chromophore while the rest of the protein is approximated with the Amber forcefield. The frontier has been carefully parameterized in order to reproduce full quantum mechanics torsional energy profiles, for both the ground state and the first excited state. It is also shown that replacing the chromophore counterion with point charges is a valid approximation. This result is interpreted in terms of a cancellation effect for which a possible explanation is given. 相似文献
10.
Massimo Lucarini Fabio Sciubba Donatella Capitani Maria Enrica Di Cocco Laura D’Evoli Alessandra Durazzo 《Natural product research》2020,34(1):53-62
AbstractThe study focuses on the understanding, at molecular level, the mechanism of interaction between protein and flavonoids. Collagen and catechin interactions were investigated by NMR in solution and solid state. The effect of catechin on the stability of collagen to oxidation was also explored. Collagen was treated with two concentrations of catechin solutions. Oxidation was carried out by incubation of collagen solution with three oxidation systems: Fe(II)/H2O2, Cu(II)/H2O2, and NaOCl/H2O2. The effects of oxidation systems were evaluated by high resolution 1?D and 2?D proton spectroscopy and solid state NMR (13C CP MAS) experiments. Interactions between collagen and catechin preferentially occur between catechin B ring and the amino acids Pro and Hyp of collagen. Results showed that both iron and copper oxidation systems were able to interact with collagen by site specific attack. Moreover, catechin protects collagen proline from oxidation by metal/H2O2 systems, preventing copper and iron approach to collagene molecule;this behaviour was more evident for the copper/H2O2 system. 相似文献