全文获取类型
收费全文 | 658284篇 |
免费 | 5314篇 |
国内免费 | 1496篇 |
专业分类
化学 | 320430篇 |
晶体学 | 9250篇 |
力学 | 35763篇 |
综合类 | 24篇 |
数学 | 97156篇 |
物理学 | 202471篇 |
出版年
2021年 | 5634篇 |
2020年 | 6102篇 |
2019年 | 6969篇 |
2018年 | 13428篇 |
2017年 | 13728篇 |
2016年 | 15053篇 |
2015年 | 7276篇 |
2014年 | 11845篇 |
2013年 | 26656篇 |
2012年 | 22872篇 |
2011年 | 31031篇 |
2010年 | 22139篇 |
2009年 | 22319篇 |
2008年 | 28643篇 |
2007年 | 30437篇 |
2006年 | 21161篇 |
2005年 | 21504篇 |
2004年 | 18976篇 |
2003年 | 17765篇 |
2002年 | 16743篇 |
2001年 | 17194篇 |
2000年 | 13369篇 |
1999年 | 10177篇 |
1998年 | 8865篇 |
1997年 | 8675篇 |
1996年 | 8208篇 |
1995年 | 7381篇 |
1994年 | 7326篇 |
1993年 | 7125篇 |
1992年 | 7496篇 |
1991年 | 8093篇 |
1990年 | 7715篇 |
1989年 | 7698篇 |
1988年 | 7475篇 |
1987年 | 7276篇 |
1986年 | 6961篇 |
1985年 | 8880篇 |
1984年 | 9201篇 |
1983年 | 7794篇 |
1982年 | 8081篇 |
1981年 | 7586篇 |
1980年 | 7155篇 |
1979年 | 7831篇 |
1978年 | 8136篇 |
1977年 | 7994篇 |
1976年 | 8011篇 |
1975年 | 7685篇 |
1974年 | 7471篇 |
1973年 | 7866篇 |
1972年 | 5838篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
This paper deals with a singular perturbation of the stationary Stokes and Navier-Stokes systems. The term ε2Δp is added to the continuity equation, where ε is a small parameter. For a domain with cylindrical outlets to infinity and exponentially decaying data, existence and uniqueness of solutions under flux conditions at infinity are established for the linear problem and also for the nonlinear problem in the case of small data. Asymptotically exact estimates are proved for ε tending to zero. For sufficiently regular data, these estimates imply the convergence in H
loc
5/2−δ
for the velocity parts and in H
loc
3/2−δ
for the pressure parts, respectively. Bibliography: 17 titles.Dedicated to V. A. Solonnikov on the occasion of his 70th birthday__________Published in Zapiski Nauchnykh Seminarov POMI, Vol. 306, 2003, pp. 107–133. 相似文献
942.
943.
944.
B. P. Harlamov 《Journal of Mathematical Sciences》2005,128(1):2625-2639
Semi-Markov processes of diffusion type in the d-dimensional space (d > 1) are considered. We assume that the transition generating function of such a process satisfies a second-order differential equation of elliptic type. We apply methods of differential equations theory, especially of the theory of the Dirichlet problem, to study the transition generating function for a small neighborhood of the initial point of the process. Asymptotic expansions in the small scale parameter are obtained both for the first exit point distribution density and for the first exit time expectation for the case where the trajectory of the process leaves a small neighborhood of the initial point. We prove the existence of the Dynkin characteristic operator determined by a decreasing sequence of neighborhoods. Bibliography: 9 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 293, 2003, pp. 226–251. 相似文献
945.
946.
The finite-difference method is a numerical technique for obtaining approximate solutions to differential equations. The main
objective of the present study is to give a new aspect to the finite-difference method by using a variational derivative.
By applying this formulation, accurate values of the buckling loads of beams and frames with various end supports are obtained.
The performance of this formulation is verified by comparison with numerical examples in the literature
__________
Published in Prikladnaya Mekhanika, Vol. 41, No. 7, pp. 139–144, July 2005. 相似文献
947.
L. B. Beinenson 《Journal of Mathematical Sciences》2005,129(2):3730-3756
For an arbitrary poset H and measure ρ on H × R (where R is the real axis), we construct a monotone decreasing stochastic field ηρ and compute its finite-dimensional distributions. In the case where H is a Λ-semilattice and the measure ρ satisfies additional conditions, we compute various characteristics of the field ηρ such as the expectation of the field value at a point, variance of the field value at a point, and correlation function of the field. The described construction of random fields gives a new method for constructing positive definite functions on posets. Bibliography: 6 titles.__________Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 301, 2003, pp. 92–143. 相似文献
948.
Studies of thickness and temperature dependencies of the dielectric susceptibility of nitrobenzene interlayers formed on conductive substrates were carried out. The obtained data were processed under the assumption of the existence of dimers (with opposite directions of molecular dipole moments) in orientationally ordered wall-adjacent layers. The results were treated on the basis of Lifshits theory. 相似文献
949.
A. Peláiz-Barranco O. García-Zaldívar F. Calderón-Piñar 《Solid State Communications》2005,133(8):515-519
The Ac behaviour of PLZT 6/80/20 ferroelectric ceramics was analyzed around and above the phase transition. Two relaxation processes are identified, showing that the so-called ‘universal relaxation law’ holds for the ceramics. A critical point in the values of the Ac conductivity, around the temperature corresponding to the maximum of the dielectric losses, is observed below the transition temperature due to the relaxor behaviour. The frequency dependence of the Ac conductivity at various temperatures and the hysteresis loops show classical relaxor behaviour with a diffuse phase transition. 相似文献
950.
In this paper we introduce symplectic invariants for convex Hamiltonian energy surfaces and their periodic trajectories and show that these quentities satisfy several nontrivial relations. In particular we show that they can be used to prove multiplicity results for the number of periodic trajectories.This paper represents results obtained while holding a visiting position at the Courant Institute for Mathematical Sciences, New YorkResearch partially supported by NSF Grant No. DMS-8603149 and a Rutgers University Research Council Grant 相似文献