全文获取类型
收费全文 | 261167篇 |
免费 | 2556篇 |
国内免费 | 812篇 |
专业分类
化学 | 141921篇 |
晶体学 | 3879篇 |
力学 | 11099篇 |
综合类 | 12篇 |
数学 | 26705篇 |
物理学 | 80919篇 |
出版年
2018年 | 2033篇 |
2017年 | 1946篇 |
2016年 | 3596篇 |
2015年 | 2422篇 |
2014年 | 3583篇 |
2013年 | 10611篇 |
2012年 | 7848篇 |
2011年 | 10040篇 |
2010年 | 6670篇 |
2009年 | 6483篇 |
2008年 | 9092篇 |
2007年 | 9200篇 |
2006年 | 8895篇 |
2005年 | 8400篇 |
2004年 | 7403篇 |
2003年 | 6618篇 |
2002年 | 6553篇 |
2001年 | 7326篇 |
2000年 | 5615篇 |
1999年 | 4508篇 |
1998年 | 3927篇 |
1997年 | 3823篇 |
1996年 | 3586篇 |
1995年 | 3461篇 |
1994年 | 3257篇 |
1993年 | 3087篇 |
1992年 | 3552篇 |
1991年 | 3608篇 |
1990年 | 3364篇 |
1989年 | 3368篇 |
1988年 | 3319篇 |
1987年 | 3226篇 |
1986年 | 3075篇 |
1985年 | 4096篇 |
1984年 | 4305篇 |
1983年 | 3557篇 |
1982年 | 4005篇 |
1981年 | 3728篇 |
1980年 | 3730篇 |
1979年 | 3841篇 |
1978年 | 4095篇 |
1977年 | 3917篇 |
1976年 | 3981篇 |
1975年 | 3812篇 |
1974年 | 3738篇 |
1973年 | 3944篇 |
1972年 | 2491篇 |
1971年 | 2065篇 |
1968年 | 2030篇 |
1967年 | 2087篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
2.
The European Physical Journal E - The isothermal gas adsorption of two hexane isomers (n-hexane and cyclohexane) in the mesopores of MCM-41 silica have been investigated by small angle neutron... 相似文献
3.
Investigated is the dependency of the crack tip opening displacement (CTOD) on the local microstructure of the heat affected zone in high-strength low-alloy (HSLA) microalloyed steel. Since the initiation of the crack tip location could not be controlled in fatigue, any possible correlation between heat iput in welding and fracture toughness could be smeared. Modified CTOD data are defined; they show that the fracture resistance of the weld joint decreased as the heat input increased. 相似文献
4.
The interaction of isotactic polypropylene with ethylene propylene diene terpolymer in their blends has been investigated by use of differential scanning calorimetry, dynamic mechanical analysis, wide- and small-angle x-ray scattering, and by investigating the nucleation and kinetics of crystallization of the iPP component under the polarization microscope. It is found, that the dispersion of the EPDM component in the iPP matrix is dependent on blend composition and is maximal at 10% EPDM content. An interface layer between the two components is formed by migration of iPP molecules into the EPDM phase. A model for this interface is proposed. 相似文献
5.
6.
NaY zeolite samples loaded with sodium metal by vapor phase deposition have been investigated using129Xe NMR spectroscopy. At low sodium concentration, the129Xe NMR spectrum showed three resonance lines which clearly indicate the existence of distinct domains in the zeolite sample. Such an observation suggests that the diffusion of the xenon atoms into each domain only occurs with respect to the NMR time scale (2.9 ms). As the sodium concentration increases, observation of a single broad line indicate a macroscopic homogenization of the system. The shift of this line is explained in part due to a paramagnetic interaction between the xenon atoms and the unpaired electrons of particles containing an odd number of sodium atoms. The linewidth is due to the distribution of the local magnetic fields partially averaged by the rapid motion of the xenon atoms and to the statistical distribution of the sodium particles in the supercage cavities. The paramagnetic interaction vanishes with the oxidation of the sample leading to a narrowing and a shift of the line to higher magnetic fields. 相似文献
7.
Alloys of the systems Fe–Al (mixable over the whole concentration range) and Fe–Mg (insoluble with each other) were produced by implantation of Fe ions into Al and Mg, respectively. The implantation energy was 200 keV and the ion doses ranged from 1 × 1014 to 9 × 1017cm-2The obtained implantation profiles were determined by Auger electron spectroscopy depth profiling. Maximum iron concentrations reached were up to 60 at.% for implantation into Al and 94 at.% for implantation into Mg. Phase analysis of the implanted layers was performed by conversion electron Mössbauer spectroscopy and X‐ray diffraction. For implantation into Mg, two different kinds of Mössbauer spectra were obtained: at low doses paramagnetic doublets indicating at least two different iron sites and at high doses a dominant ferromagnetic six‐line‐pattern with a small paramagnetic fraction. The X‐ray diffraction pattern concluded that in the latter case a dilated αiron lattice is formed. For implantation into Al, the Mössbauer spectra were doublet structures very similar to those obtained at amorphous Fe–Al alloys produced by rapid quenching methods. They also indicated at least two different main iron environments. For the highest implanted sample a ferromagnetic six‐line‐pattern with magnetic field values close to those of Fe3Al appeared. 相似文献
8.
9.
Ya. V. Fattakhov M. F. Galyautdinov T. N. L’vova I. B. Khaibullin 《Technical Physics》1997,42(12):1457-1459
The first results regarding the formation of a two-dimensional periodic structure of local melting regions on a silicon surface
upon pulsed light irradiation are presented. The conditions are established, and the mechanism of the formation of such structures
is discussed.
Zh. Tekh. Fiz. 67, 97–99 (December 1997) 相似文献
10.