全文获取类型
收费全文 | 107454篇 |
免费 | 9991篇 |
国内免费 | 10562篇 |
专业分类
化学 | 37165篇 |
晶体学 | 1227篇 |
力学 | 15171篇 |
综合类 | 1728篇 |
数学 | 38682篇 |
物理学 | 34034篇 |
出版年
2024年 | 186篇 |
2023年 | 1016篇 |
2022年 | 1980篇 |
2021年 | 2202篇 |
2020年 | 2474篇 |
2019年 | 2598篇 |
2018年 | 2294篇 |
2017年 | 2969篇 |
2016年 | 3377篇 |
2015年 | 2850篇 |
2014年 | 4389篇 |
2013年 | 7189篇 |
2012年 | 5095篇 |
2011年 | 5768篇 |
2010年 | 4954篇 |
2009年 | 6268篇 |
2008年 | 6567篇 |
2007年 | 6826篇 |
2006年 | 6289篇 |
2005年 | 5553篇 |
2004年 | 4963篇 |
2003年 | 4793篇 |
2002年 | 4422篇 |
2001年 | 3684篇 |
2000年 | 3549篇 |
1999年 | 3194篇 |
1998年 | 2981篇 |
1997年 | 2460篇 |
1996年 | 2148篇 |
1995年 | 1897篇 |
1994年 | 1759篇 |
1993年 | 1486篇 |
1992年 | 1461篇 |
1991年 | 1138篇 |
1990年 | 910篇 |
1989年 | 771篇 |
1988年 | 692篇 |
1987年 | 543篇 |
1986年 | 442篇 |
1985年 | 516篇 |
1984年 | 514篇 |
1983年 | 255篇 |
1982年 | 399篇 |
1981年 | 438篇 |
1980年 | 322篇 |
1979年 | 327篇 |
1978年 | 245篇 |
1977年 | 233篇 |
1976年 | 165篇 |
1974年 | 117篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
A. B. Vasil’eva A. A. Plotnikov 《Computational Mathematics and Mathematical Physics》2006,46(5):762-767
A singularly perturbed parabolic equation with a nonlinear right-hand side of a special form is examined. A numerical analytical study of such equations is performed. 相似文献
152.
O. Yu. Dashkova 《Algebra and Logic》2007,46(5):297-302
We are concerned with infinite-dimensional locally soluble linear groups of infinite central dimension that are not soluble
A3-groups and all of whose proper subgroups, which are not soluble A3-groups, have finite central dimension. The structure of groups in this class is described. The case of infinite-dimensional
locally nilpotent linear groups satisfying the specified conditions is treated separately. A similar problem is solved for
infinite-dimensional locally soluble linear groups of infinite fundamental dimension that are not soluble A3-groups and all of whose proper subgroups, which are not soluble A3-groups, have finite fundamental dimension.
__________
Translated from Algebra i Logika, Vol. 46, No. 5, pp. 548–559, September–October, 2007. 相似文献
153.
S. V. Tyshkevich 《Mathematical Notes》2007,81(5-6):851-853
154.
D.L. Skuratov Yu.L. Ratis I.A. Selezneva J. Pérez P. Fernández de Córdoba J.F. Urchueguía 《Applied Mathematical Modelling》2007
This paper deals with modelling the workpiece temperature field produced during the grinding process. The proposed model is given in terms of a two-dimensional boundary-value problem where the interdependence among the grinding wheel, the workpiece and the coolant is described by two variable functions in the boundary condition. An explicit integral form solution is constructed using the Laplace and Fourier transforms and the Green’s function method. 相似文献
155.
156.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
157.
In this paper we describe the design and manufacture of an axial-torsion test specimen, and provide relationships needed when
conducting stress-strain characterization experiments with the specimen. The specimen is a short hollow cylinder of rubber
bonded between two steel mounting rings, in which simultaneous axial and shear strains are produced via independently controlled
axial and twist displacements. We present calculations for the strain-displacement and stress-load relationships, and strain
energy density. These relationships have been established and validated via a combination of analytical and experimental techniques,
and finite element analysis. We have investigated the extent and effects of strain and stress field non-uniformity in the
test specimen. The specimen design is sufficiently simple that a closed-form expression for the strain-displacement relationship
has been successfully developed. 相似文献
158.
Jae-Yeon Lee Eugene Lubarsky Ben T. Zinn 《Proceedings of the Combustion Institute》2005,30(2):1757-1764
This paper describes an experimental investigation of the feasibility of using “slow” active control approaches, which “instantaneously” change liquid fuel spray properties, to suppress combustion instabilities. The objective of this control approach was to break up the feedback between the combustion process heat release and combustor pressure oscillations that drive the instability by changing the characteristics of the combustion process (e.g., the characteristic combustion time). To demonstrate the feasibility of such control, this study used a proprietary fuel injector (NanomiserTM), which can vary its fuel spray properties, to investigate the dependence of acoustics–combustion process coupling, i.e., the driving of combustion instabilities, upon the fuel spray properties. This study showed that by changing the spray characteristics it is possible to significantly damp combustion instabilities. Furthermore, using combustion zone chemiluminescence distributions, which were obtained by Abel’s deconvolution synchronized with measured acoustic data, it has been shown that the instabilities were mostly driven midway between the combustor centerline and wall, a short distance downstream from the flame holder, where the mean axial flow velocity is approximately zero in the vortex near the flame holder. The results of this study strongly suggest that a “slow” active control system that employs controllable fuel injectors could be effectively used to prevent the onset of detrimental combustion instabilities. 相似文献
159.
L. Bergamaschi G. Gambolati G. Pini 《Journal of Computational and Applied Mathematics》2007,210(1-2):64-70
Integration of the subsurface flow equation by finite elements (FE) in space and finite differences (FD) in time requires the repeated solution to sparse symmetric positive definite systems of linear equations. Iterative techniques based on preconditioned conjugate gradients (PCG) are one of the most attractive tool to solve the problem on sequential computers. A present challenge is to make PCG attractive in a parallel computing environment as well. To this aim a key factor is the development of an efficient parallel preconditioner. FSAI (factorized sparse approximate inverse) and enlarged FSAI relying on the approximate inverse of the coefficient matrix appears to be a most promising parallel preconditioner. In the present paper PCG using FSAI, diagonal and pARMS (parallel algebraic recursive multilevel solvers) preconditioners is implemented on the IBM SP4/512 and CLX/768 supercomputers with up to 32 processors to solve underground flow problems of a large size. The results show that FSAI may allow for a parallel relative efficiency larger than 50% on the largest problems with p=32 processors. Moreover, FSAI turns out to be significantly less expensive and more robust than pARMS. Finally, it is shown that for p in the upper range may be much improved if PCG–FSAI is implemented on CLX. 相似文献
160.
等腰三角形Mindlin板的自由振动分析 总被引:2,自引:0,他引:2
提出了一种新方法来对基于 Mindlin剪切变形理论的等腰三角形板进行自由振动分析 .此方法采用了一种新的基函数并利用 pb-2 Rayleigh-Ritz边界函数得到了一种新型的 Ritz方法 .这种方法的有效性通过收敛性和对比性分析得到了证实 .数值结果表明此方法相当精确有效 . 相似文献