全文获取类型
收费全文 | 582987篇 |
免费 | 5918篇 |
国内免费 | 1753篇 |
专业分类
化学 | 313789篇 |
晶体学 | 8592篇 |
力学 | 25126篇 |
综合类 | 19篇 |
数学 | 69387篇 |
物理学 | 173745篇 |
出版年
2021年 | 4863篇 |
2020年 | 5434篇 |
2019年 | 5960篇 |
2018年 | 7849篇 |
2017年 | 7696篇 |
2016年 | 11437篇 |
2015年 | 7097篇 |
2014年 | 10967篇 |
2013年 | 26486篇 |
2012年 | 20090篇 |
2011年 | 24699篇 |
2010年 | 17528篇 |
2009年 | 17236篇 |
2008年 | 22886篇 |
2007年 | 22888篇 |
2006年 | 21250篇 |
2005年 | 19143篇 |
2004年 | 17530篇 |
2003年 | 15585篇 |
2002年 | 15414篇 |
2001年 | 16980篇 |
2000年 | 13067篇 |
1999年 | 10180篇 |
1998年 | 8558篇 |
1997年 | 8341篇 |
1996年 | 8015篇 |
1995年 | 7020篇 |
1994年 | 7010篇 |
1993年 | 6887篇 |
1992年 | 7580篇 |
1991年 | 7730篇 |
1990年 | 7357篇 |
1989年 | 7176篇 |
1988年 | 7198篇 |
1987年 | 7041篇 |
1986年 | 6698篇 |
1985年 | 8723篇 |
1984年 | 8993篇 |
1983年 | 7145篇 |
1982年 | 7431篇 |
1981年 | 7309篇 |
1980年 | 6816篇 |
1979年 | 7347篇 |
1978年 | 7632篇 |
1977年 | 7488篇 |
1976年 | 7439篇 |
1975年 | 6930篇 |
1974年 | 6908篇 |
1973年 | 7010篇 |
1972年 | 4872篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
811.
Epitaxial and c-axis oriented double perovskite Sr2CrWO6 thin films were prepared on SrTiO3 (100) and LaAlO3 (100) substrates by pulsed-laser deposition. Structural, magnetic and transport properties were found to be sensitive to the gas conditions employed during the deposition. A small amount of oxygen along with Ar during the deposition was found to be essential for B-site ordering; such films displayed lattice parameters close to the bulk value and display ferromagnetic metallic behavior. The Curie temperature observed above 500 K in these films is higher than bulk Sr2CrWO6 samples. Films grown without oxygen were observed to have long c-parameter and no B-site ordering; they were non-magnetic and semiconducting. 相似文献
812.
M. V. Davidovich 《Radiophysics and Quantum Electronics》2006,49(3):210-219
We propose a method which transforms homogeneous integral equations into inhomogeneous ones for problems of diffraction by
semi-infinite structures. New integral equations and the corresponding stationary functionals dependent on the desired scattering
parameters are obtained. The consideration is performed for the open-end diffraction problem of a parallel-plate waveguide
which has a rigorous solution, but the method has sufficient generality to use it for two-dimensional surface integral equations
describing planar and nonplanar structures as well as for an arbitrary structure of waveguide transformer type, the solution
for which can be sought in the finite domain. The method is based on field representation at the infinity as incident and
scattered waves.
__________
Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 3, pp. 235–245, March 2006. 相似文献
813.
814.
815.
A potential of interatomic interaction for simulating complex structural states of solids (grain boundaries and heterogeneous equilibrium states) is put forward. In simulating heterogeneous states of systems, the potential must simultaneously provide for stability conditions for several phases in equilibrium and correct values of a number of macroscopic parameters such as lattice constants, elastic moduli, internal energy, heat capacity, and stability parameters. The existing empirical potentials of interatomic interaction fail to provide agreement of the calculated and experimentally obtained parameters determining the structure of the system and structural transformations due to changes in the external parameters. The potential under discussion is a polynomial representing a solution to the problem of interpolation of functions and their derivatives to the nth order prescribed on a finite system of points (Hermit interpolation problem). The relation for a general solution to the foregoing problem is so complicated that it is virtually inapplicable. A new polynomial is constructed on the basis of the Lagrangian interpolation polynomial. The interpolation of the known interatomic potentials with allowance for the fourth-order derivatives by the polynomial is achieved with high accuracy where three to four interpolation nodes are specified. Local changes can easily be introduced to the polynomial. In doing so, the values of the potential and its derivatives in other regions of space are retained. This allows mechanical stability for stable and metastable phases to be ensured. 相似文献
816.
817.
We give estimates of quark masses from a comparison of two methods of regularizing the coefficient of the Schwinger term. The masses of the first radial excited states of ?, ω, and ? would have to be slightly higher than indicated by the new Orsay data for this method to yield real solutions for the masses of theu, d, ands quarks. 相似文献
818.
819.
For quantum deformations of finite-dimensional contragredient Lie (super)algebras we give an explicit formula for the universalR-matrix. This formula generalizes the analogous formulae for quantized semisimple Lie algebras obtained by M. Rosso, A. N. Kirillov, and N. Reshetikhin, Ya. S. Soibelman, and S. Z. Levendorskii. Our approach is based on careful analysis of quantized rank 1 and 2 (super)algebras, a combinatorial structure of the root systems and algebraic properties ofq-exponential functions. We don't use quantum Weyl group. 相似文献
820.