全文获取类型
收费全文 | 1008篇 |
免费 | 43篇 |
国内免费 | 3篇 |
专业分类
化学 | 611篇 |
晶体学 | 5篇 |
力学 | 42篇 |
数学 | 213篇 |
物理学 | 183篇 |
出版年
2023年 | 11篇 |
2022年 | 17篇 |
2021年 | 19篇 |
2020年 | 23篇 |
2019年 | 13篇 |
2018年 | 18篇 |
2017年 | 20篇 |
2016年 | 27篇 |
2015年 | 34篇 |
2014年 | 34篇 |
2013年 | 60篇 |
2012年 | 85篇 |
2011年 | 94篇 |
2010年 | 54篇 |
2009年 | 41篇 |
2008年 | 85篇 |
2007年 | 60篇 |
2006年 | 55篇 |
2005年 | 51篇 |
2004年 | 40篇 |
2003年 | 38篇 |
2002年 | 38篇 |
2001年 | 14篇 |
2000年 | 13篇 |
1999年 | 6篇 |
1998年 | 6篇 |
1997年 | 6篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1987年 | 2篇 |
1986年 | 5篇 |
1985年 | 3篇 |
1984年 | 9篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 4篇 |
1976年 | 6篇 |
1973年 | 2篇 |
1969年 | 1篇 |
1938年 | 1篇 |
1931年 | 2篇 |
1926年 | 1篇 |
1900年 | 1篇 |
1886年 | 2篇 |
1883年 | 1篇 |
排序方式: 共有1054条查询结果,搜索用时 0 毫秒
71.
We address the problem of degree of polarization (DOP) estimation in images limited by additive Gaussian detector noise. We derive and analyze the probability density function (PDF) of the pixelwise DOP estimate, which is shown to have significantly different statistical properties than when noise is Gamma distributed (speckle). We then determine the Cramer-Rao Lower Bound and the maximum likelihood estimator of the DOP. We deduce from this study practical solutions for characterizing and reducing the noise in these images. 相似文献
72.
Sébastien DegorceFrédéric H. Jung Craig S. Harris Patrice KozaJonathan Lecoq Arnaud Stevenin 《Tetrahedron letters》2011,52(50):6719-6722
The synthesis of differentially-substituted 3,5-bis(arylamino)pyrazoles has not yet been documented. During our investigation, we managed to develop a novel, entirely combinatorial synthesis of 3,5-bis(arylamino)pyrazoles relying on a simple one-pot two-step operation. 相似文献
73.
Julien Amalric Claude Poleunis Arnaud Delcorte Jacqueline Marchand-Brynaert 《Surface science》2012,606(13-14):1071-1077
Chalcogenide glasses are useful optic materials that find applications in infrared spectroscopy, sensors and thermal imaging. A route for direct surface modification of such glasses with organic layers has been investigated by static Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The GAS (germanium–arsenic–selenium) glasses are modified by deposition followed by UV-irradiation of disulfide- or/and silane-functionalized organic molecules. SIMS analysis shows the characteristic fragments of the grafted molecules and organic–inorganic fragments which prove unambiguously the binding mode to the surface: disulfides, after S–S cleavage, are linked to arsenic and selenium; triethoxysilanes bind exclusively to oxidized germanium. The successive grafting of disulfide and silane compounds on the same substrate (IG2 glass with 33% of Ge) affords a “mixed” organic layer on the glass surface. From water contact angle measurements and X-ray Photo-electron Spectroscopy (XPS), the coverage density is not significantly improved comparatively to the “non-mixed” layers. However, the grafting of both types of molecules allows to reach a more homogeneous coverage. 相似文献
74.
Lionel Santinacci Anne-Marie Gonçalves Muriel Bouttemy Arnaud Etcheberry 《Journal of Solid State Electrochemistry》2010,14(7):1177-1184
In this paper, we investigate the properties of porous structures anodically grown onto n-InP (100) in HCl. In situ electrochemical
characterizations show the pore morphology strongly influences the properties of the InP surfaces. Both dc- and ac-electrochemical
measurements reveal an enhancement of the capacitive current and a modification of the electronic distribution at the interface.
Photocurrent spectra performed during the pore growth are also strongly modified. For low anodic charges, an increase of the
photocurrent with a redshift of the absorption edge is measured. These evolutions can be respectively ascribed (i) to a reflection decrease due to a surface roughening and (ii) to the creation of surface states within the band gap. For higher anodic charges, the photocurrent drops with a narrowing
of the spectrum. Using a model based on the “dead” layer, the porous layer is considered as an absorbent film that progressively
attenuates the photocurrent of the bulk semiconductor. 相似文献
75.
76.
77.
78.
Véronique Dupuis Nils Blanc Luis E. Diaz-Sanchez Arnaud Hillion Alexandre Tamion Florent Tournus Gustavo M. Pastor Andrei Rogalev Fabrice Wilhelm 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2013,67(2):1-4
In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device. 相似文献
79.
We study the relationship between two classical approaches for quantitative ergodic properties: the first one based on Lyapunov type controls and popularized by Meyn and Tweedie, the second one based on functional inequalities (of Poincaré type). We show that they can be linked through new inequalities (Lyapunov-Poincaré inequalities). Explicit examples for diffusion processes are studied, improving some results in the literature. The example of the kinetic Fokker-Planck equation recently studied by Hérau and Nier, Helffer and Nier, and Villani is in particular discussed in the final section. 相似文献
80.