全文获取类型
收费全文 | 1237篇 |
免费 | 61篇 |
国内免费 | 4篇 |
专业分类
化学 | 889篇 |
晶体学 | 8篇 |
力学 | 39篇 |
数学 | 147篇 |
物理学 | 219篇 |
出版年
2023年 | 8篇 |
2022年 | 59篇 |
2021年 | 53篇 |
2020年 | 42篇 |
2019年 | 38篇 |
2018年 | 25篇 |
2017年 | 24篇 |
2016年 | 58篇 |
2015年 | 52篇 |
2014年 | 46篇 |
2013年 | 94篇 |
2012年 | 92篇 |
2011年 | 109篇 |
2010年 | 44篇 |
2009年 | 57篇 |
2008年 | 80篇 |
2007年 | 66篇 |
2006年 | 58篇 |
2005年 | 54篇 |
2004年 | 43篇 |
2003年 | 21篇 |
2002年 | 39篇 |
2001年 | 12篇 |
2000年 | 14篇 |
1999年 | 8篇 |
1998年 | 10篇 |
1997年 | 5篇 |
1996年 | 10篇 |
1995年 | 10篇 |
1994年 | 7篇 |
1993年 | 2篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1989年 | 4篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1986年 | 4篇 |
1985年 | 7篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 3篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1932年 | 1篇 |
1914年 | 1篇 |
1913年 | 1篇 |
1905年 | 1篇 |
1904年 | 1篇 |
1890年 | 1篇 |
排序方式: 共有1302条查询结果,搜索用时 31 毫秒
101.
Kapetanaki SM Ramsey M Gindt YM Schelvis JP 《Journal of the American Chemical Society》2004,126(20):6214-6215
Transient absorption spectroscopy is used to demonstrate that the electric dipole moment of the substrate cyclobutane thymine dimer affects the charge recombination reaction between fully reduced flavin adenine dinucleotide (FADH-) and the neutral radical tryptophan 306 (Trp306*) in Escherichia coli DNA photolyase. At pH 7.4, the charge recombination is slowed by a factor of 1.75 in the presence of substrate, but not at pH 5.4. Photolyase does bind substrate at pH 5.4, and it seems that this pH effect originates from the conversion of FADH- to FADH2 at lower pH. The free-energy changes calculated from the electric field parameters and from the change in electron transfer rate are in good agreement and support the idea that the substrate electric dipole is responsible for the observed change in electron transfer rate. It is expected that the substrate electric field will also modify the physiologically important from excited 1FADH- to the substrate in the DNA repair reaction. 相似文献
102.
103.
Raphaël Grougnet Prokopios Magiatis Sofia Mitaku Alexios‐Leandros Skaltsounis Pierre Cabalion François Tillequin Sylvie Michel 《Helvetica chimica acta》2011,94(4):656-661
Three new dammarane triterpenoids, gardaubryones A–C ( 1 – 3 ), were isolated from the gum collected on the aerial parts of Gardenia aubryi Vieill ., together with the known compounds hydroxydammarenone II ( 4 ), ocotillone ( 5 ), cabraleone, and hollongdione. The structures of the novel compounds were established on the basis of mass spectrometry, NMR experiments, and chemical‐correlation reactions. 相似文献
104.
Vladimir F. Petrov Sofia I. Torgova Ludmila A. Karamysheva Shunsuke Takenaka 《Liquid crystals》1999,26(8):1141-1162
In this review the effect on physico-chemical and electro-optical properties of the introduction of the trans-1,4-cyclohexylene fragment into the molecular core of liquid crystals is discussed, rationalized in terms of existent theories, and compared with the effect of other well-known molecular fragments. 相似文献
105.
Rajamalleswaramma Jogireddy Pierre‐Yves Dakas Gaëlle Valot Sofia Barluenga Nicolas Winssinger 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(43):11498-11506
A library of resorcylic acid lactones (RAL) containing a cis‐enone moiety targeting kinases bearing a cysteine residue within the ATP‐binding pocket was prepared using a fluorous‐mixture synthesis and evaluated against a panel of 19 kinases thus providing important structure–activity trends. Two new analogues were then profiled for their selectivity against a panel of 402 kinases providing the broadest evaluation of this pharmacophores’ selectivity. 相似文献
106.
F. Gomes Teixeira 《Monatshefte für Mathematik》1913,24(1):347-354
Sans résumé 相似文献
107.
Rendiconti del Circolo Matematico di Palermo Series 1 - 相似文献
108.
109.
Abada A. Kriewald J. Teixeira A. M. 《The European Physical Journal C - Particles and Fields》2021,81(11):1-15
The European Physical Journal C - We argue that high-quality data on the reaction $$e^+e^-\rightarrow \pi ^+\pi ^-\eta $$ will allow one to determine the doubly-virtual form factor $$\eta... 相似文献
110.
Ftima C. Teixeira Carla Lucas M. Joo M. Curto Antnio P. S. Teixeira M. Teresa Duarte Vnia Andr 《Heteroatom Chemistry》2016,27(1):3-11
Novel tetraethyl ethylene‐1,1‐bisphosphonate esters derived from 1H‐indazole, 1H‐pyrazolo[3,4‐b]pyridine, and 1H‐pyrazolo[3,4‐b]quinoline were synthesized by a Michael addition reaction of tetraethyl ethylidene‐1,1‐bisphosphonate with the corresponding heterocycle, using conventional heating and microwave‐assisted methods. The microwave‐assisted method provides shorter reaction times and better yields. The hydrolysis of bisphosphonates afforded the corresponding bisphosphonic acids or salt, using concentrated hydrochloric acid or TMSBr/collidine, respectively. All new compounds were fully characterized, and their structures were assigned using 1H, 31P, and 13C NMR and IR spectroscopies and mass spectrometry. The molecular structure of compound 6 was confirmed by X‐ray diffraction studies. 相似文献