全文获取类型
收费全文 | 1360篇 |
免费 | 80篇 |
国内免费 | 6篇 |
专业分类
化学 | 1181篇 |
晶体学 | 15篇 |
力学 | 13篇 |
数学 | 57篇 |
物理学 | 180篇 |
出版年
2023年 | 11篇 |
2022年 | 20篇 |
2021年 | 18篇 |
2020年 | 30篇 |
2019年 | 43篇 |
2018年 | 19篇 |
2017年 | 18篇 |
2016年 | 51篇 |
2015年 | 43篇 |
2014年 | 44篇 |
2013年 | 81篇 |
2012年 | 107篇 |
2011年 | 108篇 |
2010年 | 74篇 |
2009年 | 61篇 |
2008年 | 102篇 |
2007年 | 86篇 |
2006年 | 87篇 |
2005年 | 79篇 |
2004年 | 80篇 |
2003年 | 54篇 |
2002年 | 39篇 |
2001年 | 16篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 6篇 |
1997年 | 9篇 |
1996年 | 12篇 |
1995年 | 9篇 |
1994年 | 8篇 |
1993年 | 12篇 |
1992年 | 6篇 |
1991年 | 8篇 |
1990年 | 10篇 |
1989年 | 7篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 8篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 7篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 5篇 |
1976年 | 3篇 |
1975年 | 2篇 |
1937年 | 1篇 |
排序方式: 共有1446条查询结果,搜索用时 15 毫秒
111.
A rotaxane with a ferrocene moiety at the axle terminus was prepared. The redox potential of the ferrocene moiety decreased by ca. 80 mV when the rotaxane had a crown ether wheel capable of moving on the axle. Thus, the stabilization of the oxidized state of the ferrocene moiety is assumed to accompany the transposition of the wheel component on the axle toward the ferrocene moiety. [reaction--see text] 相似文献
112.
It is known that some partially coherent Gaussian Shell-model beams may generate, in free space, the same angular distribution of radiant intensity as a fully coherent laser beam. We show that this result also holds even if the beams propagate in atmospheric turbulence, irrespective of the particular model of turbulence used. The result is illustrated by an example. 相似文献
113.
[reaction: see text] The Pt-catalyzed carboselenation of terminal alkynes with selenoesters provided vinylselenides regio- and stereoselectively in moderate yields. 相似文献
114.
115.
116.
117.
Shin-ichi Nakakita Kayo Hasehira Tomohiro Hosokawa Masaaki Tokuda Ken Izumori Kaoru Takegawa Jun Hirabayashi 《Journal of chromatography. A》2009,1216(26):5112-5115
A rare sugar is considered to be a monosaccharide rarely found in nature. To investigate their natural distribution and biological roles, a robust analytical system must be used to isolate, identify, and quantify them. Herein, we report the development of such a system that can specifically quantify and chromatographically separate four aldopentoses and eight aldohexoses tagged with 2-aminopyridine. Purified monosaccharides derivatized with a pyridylamino moiety (PA–monosaccharides) are first chromatographed over a high-performance anion-exchange resin. But, because two of the PA–aldohexoses used in this study, PA–talose and PA–idose, co-elute with the common saccharides, PA–glucose and PA–mannose, respectively, a second chromatographic step, reversed-phase high-performance liquid chromatography, is used to completely separate them. Thus, as shown by the results of this study, chromatographic separation of PA–monosaccharides is achievable and provides a quantitative measurement of common and rare isomeric aldopentoses and aldohexoses. 相似文献
118.
Atula S.D. Sandanayaka Hisahiro Sasabe Toshikazu Takata Osamu Ito 《Journal of Photochemistry and Photobiology, C: Photochemistry Reviews》2010,11(2-3):73-92
The photosensitized electron-transfer processes in the rotaxane hybrids composed with electron-accepting fullerenes and various electron-donors placed in the rotaxanes are revealed with time-resolved fluorescence and absorption spectral methods. Porphyrins are most useful as light-harvesting donors and photosensitizing donors. In addition, aromatic amines and ferrocene act as electron-donor and also hole-shifting reagents in multi-component rotaxanes. In the rotaxanes with spatially placed donor-acceptor molecules, the role of triplet states becomes important compared with the covalently connected donor–acceptor molecular systems, which may be related to the “through-space” and “through-bond” electron transfer, respectively. In the designed multi-component rotaxanes which maintain mechanically or topologically the electron-acceptor, electron-donor, and hole-shifter, the photoinduced electron transfer, hole-shift, electron–hole recombination are established. As a whole, contribution of the triplet excited states is prominent compared with the covalently bonded molecules and supramolecular systems constructed with coordination bonds. 相似文献
119.
Shigenori Kashimura Yoshiyuki Tane Yoshihiro Murai Tomohiro Nakai Ryuich Hirose 《Tetrahedron letters》2008,49(2):269-271
Reduction of dichlorosilanes with Mg metal in the presence of Lewis acid and LiCl was found to be the highly practical method for the synthesis of polysilanes. 相似文献