全文获取类型
收费全文 | 2240篇 |
免费 | 349篇 |
国内免费 | 263篇 |
专业分类
化学 | 1614篇 |
晶体学 | 22篇 |
力学 | 86篇 |
综合类 | 14篇 |
数学 | 168篇 |
物理学 | 948篇 |
出版年
2023年 | 36篇 |
2022年 | 51篇 |
2021年 | 67篇 |
2020年 | 72篇 |
2019年 | 65篇 |
2018年 | 87篇 |
2017年 | 72篇 |
2016年 | 121篇 |
2015年 | 117篇 |
2014年 | 131篇 |
2013年 | 200篇 |
2012年 | 184篇 |
2011年 | 172篇 |
2010年 | 177篇 |
2009年 | 173篇 |
2008年 | 178篇 |
2007年 | 157篇 |
2006年 | 137篇 |
2005年 | 102篇 |
2004年 | 72篇 |
2003年 | 82篇 |
2002年 | 66篇 |
2001年 | 42篇 |
2000年 | 41篇 |
1999年 | 29篇 |
1998年 | 26篇 |
1997年 | 22篇 |
1996年 | 24篇 |
1995年 | 11篇 |
1994年 | 7篇 |
1993年 | 13篇 |
1992年 | 10篇 |
1991年 | 10篇 |
1990年 | 8篇 |
1989年 | 11篇 |
1988年 | 5篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 6篇 |
1984年 | 4篇 |
1983年 | 5篇 |
1982年 | 3篇 |
1981年 | 6篇 |
1980年 | 3篇 |
1977年 | 6篇 |
1976年 | 3篇 |
1975年 | 3篇 |
1972年 | 4篇 |
1971年 | 3篇 |
1970年 | 2篇 |
排序方式: 共有2852条查询结果,搜索用时 31 毫秒
1.
2.
3.
Stanislav Man 《Tetrahedron letters》2006,47(39):6961-6963
Two different procedures for β-allenyloxime cyclization are described. One leads to substituted 1-hydroxypyrrolidines and the other represents a new route to pyrroline-N-oxides. 相似文献
4.
Homo-apioneplanocin A was efficiently synthesized via stereoselective hydroxymethylation, regio- and chemoselective hydroboration, and chemoselective oxidation as key steps from d-ribose. 相似文献
5.
Hydrodynamic Properties of Fe3O4 Kerosene-Based Ferrofluids with Narrow Particle Size Distribution 下载免费PDF全文
We investigate the hydrodynamic properties of Fe3O4 kerosene-based ferrofluids with narrow particle size distribution. The ferrofluids are synthesized by improving chemical coprecipitation technique. A narrow distribution of 8.6-10.8nm particle sizes is obtained from the magnetization curve with the free-form model based on the Bayesian inference theory. The fitting result is consistent with average particle size obtained from x-ray diffraction. With the increase of applied magnetic field and magnetic particle concentration, apparent viscosity of ferrofluids increases. At concentration 4.04%, the type of flow for the ferrofluid transforms from Newtonian to Bingham plastic fluid as the applied magnetic field increases. 相似文献
6.
Ching Sum Hui Lillian Sze Man Lam Chun Yin Wai Kin Chan Aleksandra B. Djurii 《Journal of polymer science. Part A, Polymer chemistry》2003,41(11):1708-1715
Polyurethanes incorporated with rhenium diimine complexes were synthesized. The polymers exhibited interesting morphologies and solution properties. Results from gel permeation chromatography suggested the formation of polymer aggregates in solutions. The polymers could act as probes for metal ions. The addition of metal ions to polymer solutions led to significant changes in the electronic absorption properties of the polymer solutions. This was attributed to the interactions between the polyether moieties and metal ions. The metal complexes could also act as efficient photosensitizers. After doping with charge‐transport viologens, the photoconductivity of the polymers was greatly enhanced. The experimental quantum efficiency was simulated with Onsager's theory. The thermalization distances and the primary yields were typically 12–14 Å and 10?3, respectively. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1708–1715, 2003 相似文献
7.
Olga V. Man’ko 《Acta Physica Hungarica A》2004,19(3-4):313-316
A short review of the general principles of constructing tomograms of spin and quark states is presented. 相似文献
8.
Dong Il Han Hoe Jin Hah Hong-Woo Park Sang Man Koo 《Journal of Sol-Gel Science and Technology》2004,32(1-3):47-51
Composite silica particles were synthesized by a two-step (acid-base) process in an aqueous solution with a mixture of organoalkoxysilane monomers. The two-step process separates the hydrolysis and condensation procedures to easily control condensation rate. In this study, the silane monomers used were phenyltrimethoxysilane (PTMS), vinyltrimethoxysilane (VTMS), methyltrimethoxysilane (MTMS), and tetraethyl-orthosilicate (TEOS). The physical properties of the resultant composite particles were investigated with the change in the molar ratio of monomers. The size of the particles increased with increasing the molar ratio of RaSi(OR)3/RbSi(OR)3 or RaSi(OR)3/TEOS (Ra: phenyl; Rb: vinyl, methyl). 相似文献
9.
10.