全文获取类型
收费全文 | 452篇 |
免费 | 8篇 |
国内免费 | 1篇 |
专业分类
化学 | 297篇 |
晶体学 | 4篇 |
力学 | 15篇 |
数学 | 23篇 |
物理学 | 122篇 |
出版年
2023年 | 3篇 |
2021年 | 5篇 |
2020年 | 5篇 |
2019年 | 4篇 |
2018年 | 4篇 |
2017年 | 2篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 23篇 |
2012年 | 23篇 |
2011年 | 35篇 |
2010年 | 22篇 |
2009年 | 17篇 |
2008年 | 24篇 |
2007年 | 24篇 |
2006年 | 26篇 |
2005年 | 24篇 |
2004年 | 16篇 |
2003年 | 20篇 |
2002年 | 17篇 |
2001年 | 4篇 |
2000年 | 9篇 |
1999年 | 12篇 |
1998年 | 9篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 6篇 |
1992年 | 4篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 6篇 |
1986年 | 2篇 |
1985年 | 3篇 |
1984年 | 5篇 |
1982年 | 3篇 |
1981年 | 4篇 |
1980年 | 5篇 |
1979年 | 6篇 |
1978年 | 3篇 |
1977年 | 9篇 |
1976年 | 3篇 |
1973年 | 6篇 |
1972年 | 3篇 |
1969年 | 3篇 |
1966年 | 2篇 |
1938年 | 2篇 |
1933年 | 2篇 |
1887年 | 2篇 |
排序方式: 共有461条查询结果,搜索用时 15 毫秒
51.
T. Auguste C. Fourcade Dutin A. Dubrouil O. Gobert O. Hort E. Mével S. Petit E. Constant D. Descamps 《Applied physics. B, Lasers and optics》2013,111(1):75-87
We report experimental and numerical results on the post-compression of 40 fs duration pulses down to 10 fs at high energy level (multi-mJ). The spectral broadening is achieved through the self-phase modulation resulting from optical-field-ionization of different noble gases (He, Ne, Ar) by the 40-fs laser pulse propagating in a low-pressure gas-filled hollow capillary. We discuss the influence of the multi-ionization dynamics, through the gas dependence, on the laser energy carried by the capillary, as well as on the duration and temporal shape of the post-compressed pulses. In all the different experimental conditions investigated in this article (pressures and gases used), the experimental data is in good agreement with the numerical results from a three-dimension propagation code. Through this study, we demonstrate the robustness of the proposed post-compression technique with regard to multi-ionization, indicating that it can be used on a large intensity range by judiciously choosing the gas. 相似文献
52.
Grandeury A. Renou L. Dufour F. Petit S. Gouhier G. Coquerel G. 《Journal of Thermal Analysis and Calorimetry》2004,77(2):377-390
The crystallization behaviour and the physical characterization of supramolecular complexes formed between permethylated-α-cyclodextrin
(TMα-CD) and the enantiomers of phenylethanol (PE) are investigated. According to crystal structure analyses, complexes containing
the pure guest enantiomers are almost isomorphous, indicating that the host presents a poor ability to distinguish PE enantiomers
at a molecular level. Nevertheless, crystallizations from racemic PE in water induce an efficient chiral discrimination and
allow the enantio-separation of the guests despite the existence of a solid solution revealed by XRPD and coupled TG-DSC analyses.
The enantiodifferentiation is explained by solubility differences between the two diastereomeric complexes in the studied
temperature range. Moreover, it is shown that the diastereomeric complex TMα-CD/(S)-PE crystallizes in two distinct phases: a monohydrate and an anhydrous form, with a transition temperature close to 37°C.
The insertion of a water molecule in the crystals grown below 37°C does not involve any other change of the crystal packing
nor of the molecular conformation, but leads to different crystal growth mechanisms inducing different morphologies and distinct
thermal behaviours.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
53.
It is well known that photoresist gratings can be used for coupling light into and out of optical waveguides. To understand the coupling phenomena, and as a first step of a theoretical study, we deal here with the diffraction of a plane electromagnetic wave by a photoresist grating lying on a dielectric optical guide. Using a rigorous electromagnetic formalism, we find the sharp resonances already described by Hope and relate them with the existence of modes in the optical guide. 相似文献
54.
The Soret effect (thermal diffusion) of dilute aqueous solutions of NH4Cl, Me4NCl, Et4NCl, n-Pr4NCl, and n-Bu4NCl has been investigated potentiometrically using the silver, silver chloride thermocell. The molar entropies (heats) of transport have been derived from the initial and final thermoelectric powers. The concentration dependence of the entropy of transport has been examined and the effect of the ionic size on the heat of transport is discussed. The molar entropy of tetrabutylammonium chloride exhibits a sharp minimum in the neighborhood of 0.002M, the reason of which is as yet unclear. 相似文献
55.
56.
In two previous papers, we proposed a rigorous electromagnetic formalism to study the coupling resonances which occur when a plane wave illuminates a grating coupler waveguide system under a convenient angle of incidence. We deal here with the case when a limited incident beam impinges on the system, and we try to optimize the parameters of the beam in order to get the best coupling coefficient. Numerical results are given for both lossless and lossy photo-resists. 相似文献
57.
58.
59.
Hydroxylation of some bi- or tricyclic amides or lactams, the determination of the absolute configuration of the alcohols obtained and the topology of the hydroxylating site of Beauveria sulfurescens based on these absolute configurations, are discussed. 相似文献
60.
We present a rigorous solution for the problem of diffraction at a locally deformed plane wave-guide. This method can be applied to the study of mode coupling and mode conversion. 相似文献