全文获取类型
收费全文 | 1112篇 |
免费 | 33篇 |
国内免费 | 5篇 |
专业分类
化学 | 723篇 |
晶体学 | 4篇 |
力学 | 21篇 |
数学 | 229篇 |
物理学 | 173篇 |
出版年
2023年 | 11篇 |
2022年 | 7篇 |
2021年 | 30篇 |
2020年 | 13篇 |
2019年 | 37篇 |
2018年 | 24篇 |
2017年 | 24篇 |
2016年 | 38篇 |
2015年 | 44篇 |
2014年 | 42篇 |
2013年 | 86篇 |
2012年 | 61篇 |
2011年 | 68篇 |
2010年 | 50篇 |
2009年 | 53篇 |
2008年 | 62篇 |
2007年 | 74篇 |
2006年 | 42篇 |
2005年 | 32篇 |
2004年 | 36篇 |
2003年 | 30篇 |
2002年 | 36篇 |
2001年 | 15篇 |
2000年 | 24篇 |
1999年 | 18篇 |
1998年 | 13篇 |
1997年 | 8篇 |
1996年 | 21篇 |
1995年 | 10篇 |
1994年 | 13篇 |
1993年 | 9篇 |
1992年 | 8篇 |
1991年 | 5篇 |
1990年 | 9篇 |
1989年 | 7篇 |
1988年 | 8篇 |
1987年 | 3篇 |
1986年 | 10篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1978年 | 3篇 |
1975年 | 4篇 |
1974年 | 2篇 |
1973年 | 9篇 |
1955年 | 2篇 |
1931年 | 2篇 |
排序方式: 共有1150条查询结果,搜索用时 375 毫秒
81.
Dr. Nina Erini Vera Beermann Martin Gocyla Manuel Gliech Dr. Marc Heggen Dr. Rafal E. Dunin-Borkowski Prof. Peter Strasser 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2017,129(23):6633-6638
Direct ethanol fuel cells are attractive power sources based on a biorenewable, high energy-density fuel. Their efficiency is limited by the lack of active anode materials which catalyze the breaking of the C−C bond coupled to the 12-electron oxidation to CO2. We report shape-controlled PtNiRh octahedral ethanol oxidation electrocatalysts with excellent activity and previously unachieved low onset potentials as low as 0.1 V vs. RHE, while being highly selective to complete oxidation to CO2. Our comprehensive characterization and in situ electrochemical ATR studies suggest that the formation of a ternary surface site ensemble around the octahedral Pt3Ni1Rhx nanoparticles plays a crucial mechanistic role for this behavior. 相似文献
82.
Maria J. Alves Vera C.M. Duarte Hélio Faustino António Gil Fortes 《Tetrahedron: Asymmetry》2010,21(15):1817-1820
Erythrose benzylidene-acetal 1,3-butadienes are studied as partners in Diels–Alder cycloadditions. A high diastereofacial improvement is found in cases where both the alcohol function is protected and a π–π interaction between the diene and dienophile is possible. Several competing factors have been studied independently in order to explain its influence on the selectivity of the cycloadditions. 相似文献
83.
Alpha-galactosyl ceramide has been identified to be a potent stimulatory agent for a novel immunological process, mediated by CD1 molecules. This paper describes a short and efficient synthesis of alpha-galactosyl ceramide. Starting from commercially available 2-deoxy galactose, a suitable sphingosine derivative was obtained in nine steps and 36% overall yield, which was subsequently glycosylated to give the target molecule. This flexible route will provide various glycolipids for further exploration of this interesting biological process. 相似文献
84.
Experiments are presented elucidating how the evolution of foam microstructure by gas diffusion from high to low pressure bubbles can significantly speed up the rate of gravitational drainage, and vice versa. This includes detailed data on the liquid-fraction dependence of the coarsening rate, and on the liquid-fraction and the bubble-size profiles across a sample. These results can be described by a "coarsening equation" for the increase of bubble growth rate for drier foams. Spatial variation of the average bubble size and liquid fraction can also affect the growth and drainage rates. 相似文献
85.
86.
Schmidt KS Filippov DV Meeuwenoord NJ van Der Marel GA van Boom JH Lippert B Reedijk J 《Angewandte Chemie (International ed. in English)》2000,39(2):375-377
Cross-linking ability is possible with the oligonucleotide-tethered, monofunctional trans-Pt(II) complex shown. It was synthesized by a novel solid-phase approach comprising conjugation of immobilized tetrathymidylic acid with a trans-a(2)Pt(II) building unit, ammonolysis, and transformation of the resulting complex (R=1-N-cyclohexylmethylthyminate) into the chloro derivative (R=Cl). a=NH(2)CH(3), T=thymine. 相似文献
87.
88.
89.
90.
J. Stach U. Abram R. Kirmse W. Dietzsch Vera K. Belyaeva I.N. Marov 《Polyhedron》1983,2(11):1205-1207
During the reaction of [Cu(mnt)2]2? with CuX2 (X = Cl, Br) [Cu(mnt)X2]2? species are formed and characterized EPR spectroscopically supporting a dissociative mechanism for ligand exchange reactions between [Cu(mnt)2]2? and other Cu(II), Ni(II) and Pd(II) complexes which contain unsaturated dichalcogeno ligands. 相似文献