全文获取类型
收费全文 | 1340464篇 |
免费 | 25797篇 |
国内免费 | 7780篇 |
专业分类
化学 | 662719篇 |
晶体学 | 20705篇 |
力学 | 75182篇 |
综合类 | 109篇 |
数学 | 242492篇 |
物理学 | 372834篇 |
出版年
2021年 | 13508篇 |
2020年 | 15913篇 |
2019年 | 16033篇 |
2018年 | 14476篇 |
2017年 | 12908篇 |
2016年 | 28480篇 |
2015年 | 20950篇 |
2014年 | 30369篇 |
2013年 | 74225篇 |
2012年 | 37586篇 |
2011年 | 35310篇 |
2010年 | 38196篇 |
2009年 | 40603篇 |
2008年 | 34680篇 |
2007年 | 30716篇 |
2006年 | 34334篇 |
2005年 | 28836篇 |
2004年 | 29411篇 |
2003年 | 27648篇 |
2002年 | 28370篇 |
2001年 | 27071篇 |
2000年 | 23824篇 |
1999年 | 22049篇 |
1998年 | 20830篇 |
1997年 | 20845篇 |
1996年 | 21011篇 |
1995年 | 19125篇 |
1994年 | 18554篇 |
1993年 | 18083篇 |
1992年 | 17912篇 |
1991年 | 18212篇 |
1990年 | 17427篇 |
1989年 | 17503篇 |
1988年 | 17086篇 |
1987年 | 17099篇 |
1986年 | 15983篇 |
1985年 | 22445篇 |
1984年 | 23724篇 |
1983年 | 19928篇 |
1982年 | 21613篇 |
1981年 | 20847篇 |
1980年 | 20189篇 |
1979年 | 20304篇 |
1978年 | 21652篇 |
1977年 | 21256篇 |
1976年 | 20919篇 |
1975年 | 19591篇 |
1974年 | 19240篇 |
1973年 | 19722篇 |
1972年 | 14202篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
841.
842.
Blokhina S. V. Bykova V. V. Sharapova A. V. Ol'khovich M. V. Trostin A. N. 《Russian Journal of General Chemistry》2003,73(2):257-259
The sorption properties of stationary phases based on nematic p-substituted azoxybenzenes were studied. Correlations were revealed between the structural selectivity of mesogens, chemical nature of terminal substituents, capability for dispersion interactions and polarity of the sorbents, temperature gradient of the retention indices, and thermodynamic parameters of solution of xylene isomers in the sorbents. 相似文献
843.
K.S. Govinder 《Journal of Mathematical Analysis and Applications》2003,287(2):399-404
Linear nth order (n?3) ordinary differential equations have been shown to possess n+1, n+2 or n+4 Lie point symmetries. Each class contains equations which are equivalent under point transformation. By taking the example of third order equations, we show that all linear equations are equivalent if the class of transformation is broadened to include nonlocal transformations and hence the representative of this class of equations is y(n)=0. 相似文献
844.
A group representation of radiation propagation in an anisotropic medium is developed. The system of wave equations for electromagnetic potentials, obtained from the Maxwell equations with account for the constitutive equations, has been factorized. It is shown that the linear differential operator of the factorized system is orthogonal in transparent crystals and unitary in gyrotropic ones and is represented through the momentum operator. On the basis of the commutation relations for the components of this operator, the eigenvalue problem has been solved and the expression for the change in the radiant energy in the crystal in the form of spherical waves has been obtained. The dependences of the ray and phase velocities and the polarization vectors of waves on the birefringence anisotropy and gyrotropy as well as on the angular momentum, displacement current, and bound charge determining them have been analyzed. It has been established that in the general case of gyrotropic crystals where the nonreciprocity phenomenon takes place and in magnetoelectrics Maxwell equations are represented in a form similar to the Dirac equations and the electromagnetic radiation is correctly described by means of bispinors and is quantized as fermions. 相似文献
845.
846.
847.
The influence of the well width fluctuations on the dependence of the binding energy of excitonic complexes in quantum wells is studied by using the path-integral Monte-Carlo technique. The results are compared with available experimental data and a good agreement is found.Postdoctoral researcher of FWO-Vlaanderen 相似文献
848.
The composite comprised of zinc oxide quantum dots and poly(amic acid) (PAAc) was prepared and studied by X-rays diffraction, X-ray photoelectron spectroscopy, light scattering, UV absorbance and UV fluorescence. The UV absorbance of the ZnO/PAAc composite was found to be much larger than that of its components taken separately. The fluorescence of the ZnO/PAAc composite was found to be shifted to longer wavelengthes in comparison with pure ZnO. The presence of the dopant dodecylbenzenesulfonic acid was found to affect the observed fluorescence. 相似文献
849.
A short and highly efficient approach was applied for the total synthesis of the gypsy moth sex pheromone (+)-disparlure and its enantiomer from isopropylidene D- and L-erythrose, using a common strategy. 相似文献
850.