全文获取类型
收费全文 | 655篇 |
免费 | 49篇 |
国内免费 | 4篇 |
专业分类
化学 | 448篇 |
晶体学 | 5篇 |
力学 | 13篇 |
综合类 | 1篇 |
数学 | 103篇 |
物理学 | 138篇 |
出版年
2023年 | 4篇 |
2022年 | 4篇 |
2021年 | 16篇 |
2020年 | 11篇 |
2019年 | 16篇 |
2018年 | 12篇 |
2017年 | 21篇 |
2016年 | 24篇 |
2015年 | 20篇 |
2014年 | 23篇 |
2013年 | 42篇 |
2012年 | 28篇 |
2011年 | 52篇 |
2010年 | 35篇 |
2009年 | 26篇 |
2008年 | 40篇 |
2007年 | 34篇 |
2006年 | 26篇 |
2005年 | 40篇 |
2004年 | 31篇 |
2003年 | 25篇 |
2002年 | 12篇 |
2001年 | 13篇 |
2000年 | 13篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 5篇 |
1996年 | 11篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 11篇 |
1991年 | 5篇 |
1989年 | 3篇 |
1988年 | 3篇 |
1987年 | 3篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 9篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 7篇 |
1974年 | 2篇 |
1972年 | 2篇 |
1968年 | 4篇 |
1967年 | 2篇 |
1928年 | 2篇 |
1927年 | 3篇 |
1920年 | 3篇 |
1893年 | 2篇 |
1883年 | 2篇 |
排序方式: 共有708条查询结果,搜索用时 31 毫秒
91.
P. A. Büger und A. Reis 《Fresenius' Journal of Analytical Chemistry》1968,235(2):181-182
Ohne Zusammenfassung 相似文献
92.
本文利用中心流面法的概念,指出叶轮机械的设计白变数在内、外环壁面上应有附加的限制条件,并导得其具体简明方程。同时,还定性地分析了S1流面的翘曲情况。 相似文献
93.
本文求出了Eliashberg方程在T=Tc时的解,得到了下面的临界温度级数表示式: 其中α0(μ*),α1(μ*)等系数是μ*的函数.此式表明,Tc不仅依赖于λ,〈ω2〉和μ*,而且依赖于有效声子谱α2F(ω)的各级矩〈ω2n〉.这是区别于前人的Tc公式最重要的一点。这说明像McMillan以及Allen和Dynes的Tc公式不仅是近似的,而主要是他们没有能正确地概括出α2F(ω)对Tc的影响. 相似文献
94.
Andresa JS Reis RM Gonzalez EP Santos LS Eberlin MN de Paula Nascente PA Tanimoto ST Machado SA Rodrigues-Filho UP 《Journal of colloid and interface science》2005,286(1):303-309
The present paper describes the one-pot procedure for the formation of self-assembled thin films of two silanes on the model oxidized silicon wafer, SiO2/Si. SiO2/Si is a model system for other surfaces, such as glass, quartz, aerosol, and silica gel. MALDI-TOF MS with and without a matrix, XPS, and AFM have confirmed the formation of self-assembled thin films of both 3-imidazolylpropyltrimethoxysilane (3-IPTS) and 4-(N-propyltriethoxysilane-imino)pyridine (4-PTSIP) on the SiO2/Si surface after 30 min. Longer adsorption times lead to the deposition of nonreacted 3-IPTS precursors and the formation of agglomerates on the 3-IPTS monolayer. The formation of 4-PTSIP self-assembled layers on SiO2/Si is also demonstrated. The present results for the flat SiO2/Si surface can lead to a better understanding of the formation of a stationary phase for affinity chromatography as well as transition-metal-supported catalysts on silica and their relationship with surface roughness and ordering. The 3-IPTS and 4-PTSIP modified SiO2/Si wafers can also be envisaged as possible built-on-silicon thin-layer chromatography (TLC) extraction devices for metal determination or N-heterocycle analytes, such as histidine and histamine, with "on-spot" MALDI-TOF MS detection. 相似文献
95.
We consider one typical two-parameter family of quadratic systems of 2 × 2 conservation laws, and study the geometry of the
behaviour of the possible solutions of the Riemann problem near an umbilic point, following the geometric approach presented
by Isaacson, Marchesin, Palmeira, Plohr, in A global formalism for nonlinear waves in conservation laws, Commun. Math. Phys. (1992). The corresponding phase portraits for the rarefaction curves, shock curves and composite curves
are discussed.
Financial support from FCT and Calouste Gulbenkian Foundation. 相似文献
96.
We discuss the analysis of linear constant coefficient differential algebraic equations
on infinite dimensional Hilbert spaces. We give solution concepts and discuss solvability criteria which are mainly based
on Laplace transform. Furthermore, we investigate the decoupling of these systems motivated by the Kronecker normal form for
the finite dimensional case. Applications are given by the analysis of mixed systems of ordinary differential, partial differential
and differential algebraic equations. 相似文献
97.
98.
Relatively f-disjunctive languages 总被引:2,自引:0,他引:2
Communicated by Boris M. Schein 相似文献
99.
In flow injection analysis, several plugs can be injected simultaneously into the same carrier system, in order to achieve overlapped zones. The potentialities of such sequential injections are studied in model systems with spectrophotometric detection; the procedure is shown to give better precision than the use of concentration gradients. The method is used with atomic absorption spectrometry to allow the determination of a wide range of manganese contents in rocks, and to facilitate the use of standard additions for the determination of copper in ethanol. 相似文献
100.
Trigo M Chen J Vishwanath VH Sheu YM Graber T Henning R Reis DA 《物理学评论B辑:凝聚态物质与材料物理学》2010,82(23):235205-235209
We use picosecond x-ray diffuse scattering to image the nonequilibrium vibrations in the lattice following ultrafast laser excitation. We present images of nonequilibrium phonons in InP and InSb throughout the Brillouin zone which remain out of equilibrium up to nanoseconds. The results are analyzed using a Born model that helps identify the phonon branches contributing to the observed features in the time-resolved diffuse scattering. In InP this analysis shows a delayed increase in the transverse-acoustic (TA) phonon population along high-symmetry directions accompanied by a decrease in the longitudinal-acoustic phonons. In InSb the increase in TA phonon population is less directional. 相似文献