全文获取类型
收费全文 | 726篇 |
免费 | 21篇 |
国内免费 | 2篇 |
专业分类
化学 | 331篇 |
晶体学 | 1篇 |
力学 | 77篇 |
数学 | 175篇 |
物理学 | 165篇 |
出版年
2023年 | 11篇 |
2022年 | 8篇 |
2021年 | 27篇 |
2020年 | 19篇 |
2019年 | 16篇 |
2018年 | 23篇 |
2017年 | 20篇 |
2016年 | 37篇 |
2015年 | 22篇 |
2014年 | 20篇 |
2013年 | 47篇 |
2012年 | 27篇 |
2011年 | 31篇 |
2010年 | 25篇 |
2009年 | 21篇 |
2008年 | 34篇 |
2007年 | 27篇 |
2006年 | 31篇 |
2005年 | 24篇 |
2004年 | 26篇 |
2003年 | 10篇 |
2002年 | 15篇 |
2001年 | 8篇 |
2000年 | 10篇 |
1999年 | 10篇 |
1997年 | 5篇 |
1996年 | 7篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1993年 | 9篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1985年 | 4篇 |
1984年 | 4篇 |
1981年 | 5篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 4篇 |
1974年 | 6篇 |
1973年 | 4篇 |
1970年 | 7篇 |
1969年 | 5篇 |
1968年 | 5篇 |
1931年 | 4篇 |
1927年 | 3篇 |
1890年 | 3篇 |
1889年 | 3篇 |
1870年 | 4篇 |
排序方式: 共有749条查询结果,搜索用时 437 毫秒
641.
642.
643.
644.
645.
K. Eble H. Pfeiffers K. Jeschki W. Reidemeister G. D. Edson J. R. Stubbs G. D. Elsdon A. Pawletta Dagmar von Wentzky Petersheyde W. Leithe W. G. Lichatschew Arnaldo Foschini Bruno Rossi E. Letzig G. A. Richardson N. P. Tarassuk Giulio Buogo Lagrangé-Francès O. Mezger J. Umbrecht F. Kopatscheck und A. Foschini 《Fresenius' Journal of Analytical Chemistry》1935,103(1-2):64-70
Ohne Zusammenfassung 相似文献
646.
647.
Benedetto Bozzini Giulio Cerullo Lucia D’Urzo Dario Polli 《Electrochemistry communications》2009,11(4):799-803
In this paper we report the first in situ femtosecond spectroelectrochemistry experiment employing a broadband probe, allowing the measurement of ultrafast transient visible spectra with a fixed pump wavelength. We investigated in situ femtosecond transient reflectivity of a Au(1 1 1) electrode in contact with an aqueous KCl solution. The pump wavelength was set at 780 nm and a supercontinuum probe was employed, yielding ultrafast spectral information on the electron thermalisation dynamics in the range 450–650 nm. Electrochemical control allowed to investigate the dynamic response to different Cl? adsorption conditions. 相似文献
648.
Giulio Ciraolo Rolando Magnanini 《Mathematical Methods in the Applied Sciences》2009,32(10):1183-1206
We study the uniqueness of solutions of Helmholtz equation for a problem that concerns wave propagation in waveguides. The classical radiation condition does not apply to our problem because the inhomogeneity of the index of refraction extends to infinity in one direction. Also, because of the presence of a waveguide, some waves propagate in one direction with different propagation constants and without decaying in amplitude. We provide an explicit condition for uniqueness for rectilinear waveguides, which takes into account the physically significant components, corresponding to guided and non‐guided waves; this condition reduces to the classical Sommerfeld–Rellich condition in the relevant cases. By a careful asymptotic analysis we prove that the solution derived by Magnanini and Santosa (SIAM J. Appl. Math. 2001; 61 :1237–1252) for stratified media satisfies our radiation condition. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
649.
650.
Maiuri M Polli D Brida D Lüer L LaFountain AM Fuciman M Cogdell RJ Frank HA Cerullo G 《Physical chemistry chemical physics : PCCP》2012,14(18):6312-6319
In carotenoids internal conversion between the allowed (S(2)) and forbidden (S(1)) excited states occurs on a sub-picosecond timescale; the involvement of an intermediate excited state(s) (S(x)) mediating the process is controversial. Here we use high time resolution (sub-20 fs) broadband (1.2-2.5 eV) pump-probe spectroscopy to study the solvent dependence of excited state dynamics of spheroidene, a naturally-occurring carotenoid with ten conjugated double bonds. In the high polarizability solvent, CS(2), we find no evidence of an intermediate state, and the traditional three-level (S(0), S(1), S(2)) model fully accounts for the S(2)→ S(1) process. On the other hand, in the low polarizability solvent, cyclohexane, we find that rapid (~30 fs) relaxation to an intermediate state, S(x), lying between S(1) and S(2) is required to account for the data. We interpret these results as due to a shift of the S(2) energy, which positions the state above or below the energy of S(x) in response to changes in solvent polarizability. 相似文献