全文获取类型
收费全文 | 520篇 |
免费 | 15篇 |
国内免费 | 3篇 |
专业分类
化学 | 289篇 |
晶体学 | 4篇 |
力学 | 13篇 |
数学 | 35篇 |
物理学 | 197篇 |
出版年
2023年 | 13篇 |
2022年 | 18篇 |
2021年 | 16篇 |
2020年 | 16篇 |
2019年 | 21篇 |
2018年 | 13篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 12篇 |
2014年 | 28篇 |
2013年 | 48篇 |
2012年 | 25篇 |
2011年 | 34篇 |
2010年 | 22篇 |
2009年 | 18篇 |
2008年 | 25篇 |
2007年 | 13篇 |
2006年 | 10篇 |
2005年 | 9篇 |
2004年 | 17篇 |
2003年 | 2篇 |
2002年 | 11篇 |
2001年 | 3篇 |
1998年 | 7篇 |
1996年 | 6篇 |
1995年 | 7篇 |
1994年 | 9篇 |
1993年 | 8篇 |
1992年 | 14篇 |
1991年 | 5篇 |
1990年 | 8篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 6篇 |
1985年 | 4篇 |
1984年 | 3篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 3篇 |
1980年 | 5篇 |
1979年 | 2篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 4篇 |
1974年 | 1篇 |
1973年 | 3篇 |
1972年 | 2篇 |
1970年 | 1篇 |
排序方式: 共有538条查询结果,搜索用时 31 毫秒
51.
James P. C. Coverdale Dr. Carlos Sanchez‐Cano Dr. Guy J. Clarkson Dr. Rina Soni Prof. Dr. Martin Wills Prof. Dr. Peter J. Sadler 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(22):8043-8046
Asymmetric transfer hydrogenation (ATH) is an important process in organic synthesis for which the Noyori‐type RuII catalysts [(arene)Ru(Tsdiamine)] are now well established and widely used. We now demonstrate for the first time the catalytic activity of the osmium analogues. X‐ray crystal structures of the 16‐electron OsII catalysts are almost identical to those of RuII. Intriguingly the precursor complex was isolated as a dichlorido complex with a monodentate amine ligand. The OsII catalysts are readily synthesised (within 1 h) and exhibit excellent enantioselectivity in ATH reactions of ketones. 相似文献
52.
53.
54.
Soni R Cheung FK Clarkson GC Martins JE Graham MA Wills M 《Organic & biomolecular chemistry》2011,9(9):3290-3294
Ru(II) complexes of TsDPEN containing two alkyl groups on the non-tosylated nitrogen atom are poor catalysts for asymmetric transfer hydrogenation of ketones and imines; this observation provides direct evidence for the importance of the N-H interaction in the transition state for ketone reduction. 相似文献
55.
Paradise CL Sarkar PR Razzak M De Brabander JK 《Organic & biomolecular chemistry》2011,9(11):4017-4020
Amino acid-derived propargylic amides are cyclised in a one-pot, Au(III)-catalysed operation to yield 5-bromomethyl oxazoles. These compounds are further elaborated to bis-heterocycles, dipeptide mimics and more. 相似文献
56.
Kokatam S Pandey D Gupta R Krishna R Soni R 《Combinatorial chemistry & high throughput screening》2011,14(8):703-709
Angiogenesis is a promising area of research that targets key therapeutic areas like cancer; wound healing, inflammatory diseases, etc. There is an increasing demand for screening of potential angiogenic and anti-angiogenic agents using sensitive, robust cell-based assays. We have developed a reporter vector containing cis-acting elements that respond to growth factors/angiogenic ligands for use in a cell-based luciferase reporter assay. We performed transient transfection of our reporter gene vector in MCF-7 cells to establish its application for screening of potential pro/anti-angiogenic agents. Reporter gene transactivation studies with different concentrations of fetal bovine serum clearly indicated that the vector is functionally responsive to the angiogenic signals mediated by serum growth factors. We also used endostatin to inhibit transactivation and prove responsiveness to the anti-angiogenic agent. This vector is a promising tool for studying angiogenesis using cell-based reporter gene assays. 相似文献
57.
58.
Chiral discrimination and recognition is important in peptide biosynthesis, amino acid synthesis and drug designing. Detailed
structural information is available about the peptide synthesis in ribosome. However, no detailed study is available about
the discrimination in peptide synthesis. We study the conformational energy variation of neutral methoxy phenyl alanine molecule
as a function of its different dihedral angle to locate the minimum energy conformation using quantum chemical theory. We
compared the intermolecular energy surfaces of phenyl alanine molecule in its neutral and zwitterionic state using quantum
chemical theory as a function of distance and mutual orientation. The energy surfaces are studied with rigid geometry by varying
the distance and orientation. The potential energy surfaces of L-L and D-L pairs are found to be dissimilar and reflect the underlying chirality of the homochiral pair and racemic nature of the heterochiral
pair. The intermolecular energy surface of homochiral pair is more favourable than the corresponding energy surface of heterochiral
pair. 相似文献
59.
We employ the hybrid soliton model of the nucleon consisting of a topological meson field and deeply bound quarks to investigate the behavior of the quarks on soliton matter as a function of density. We investigate a particular possible ground state by placing the solitons on a spatial lattice. The model suggests the transition of matter from a color insulator to a color conductor above a critical density of a few times normal nuclear density. 相似文献
60.
The oxide system Bi2.2Ca2.8−x
Sr
x
Cu2O
y
has been investigated for superconductivity as a function of Ca/Sr ratio withx=0.7, 1.0, 1.4 and 1.8. All these compositions are found to be superconducting with onset temperature in the range of 80–90
K implying a large homogeneity range between Sr and Ca for the superconductivity to occur in this system. Effect of partial
replacement of Bi by rare earths has been studied and it is observed that 20% replacement of Bi by Nd and Eu does not significantly
affect the superconducting transition temperature. 相似文献