全文获取类型
收费全文 | 4857篇 |
免费 | 131篇 |
国内免费 | 108篇 |
专业分类
化学 | 115篇 |
晶体学 | 2篇 |
力学 | 1360篇 |
综合类 | 4篇 |
数学 | 2654篇 |
物理学 | 961篇 |
出版年
2023年 | 17篇 |
2022年 | 37篇 |
2021年 | 60篇 |
2020年 | 221篇 |
2019年 | 75篇 |
2018年 | 115篇 |
2017年 | 192篇 |
2016年 | 207篇 |
2015年 | 201篇 |
2014年 | 240篇 |
2013年 | 312篇 |
2012年 | 211篇 |
2011年 | 282篇 |
2010年 | 301篇 |
2009年 | 282篇 |
2008年 | 232篇 |
2007年 | 290篇 |
2006年 | 262篇 |
2005年 | 202篇 |
2004年 | 180篇 |
2003年 | 147篇 |
2002年 | 148篇 |
2001年 | 159篇 |
2000年 | 95篇 |
1999年 | 136篇 |
1998年 | 91篇 |
1997年 | 62篇 |
1996年 | 63篇 |
1995年 | 33篇 |
1994年 | 23篇 |
1993年 | 25篇 |
1992年 | 18篇 |
1991年 | 10篇 |
1990年 | 9篇 |
1989年 | 14篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 12篇 |
1985年 | 14篇 |
1984年 | 21篇 |
1983年 | 5篇 |
1982年 | 10篇 |
1981年 | 9篇 |
1980年 | 13篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1976年 | 8篇 |
1974年 | 4篇 |
1968年 | 2篇 |
1967年 | 2篇 |
排序方式: 共有5096条查询结果,搜索用时 31 毫秒
11.
Igor Chueshov 《Journal of Differential Equations》2007,233(1):42-86
We study von Karman evolution equations with non-linear dissipation and with partially clamped and partially free boundary conditions. Two distinctive mechanisms of dissipation are considered: (i) internal dissipation generated by non-linear operator, and (ii) boundary dissipation generated by shear forces friction acting on a free part of the boundary. The main emphasis is given to the effects of boundary dissipation. Under suitable hypotheses we prove existence of a compact global attractor and finiteness of its fractal dimension. We also show that any solution is stabilized to an equilibrium and estimate the rate of the convergence which, in turn, depends on the behaviour at the origin of the functions describing the dissipation. 相似文献
12.
O. A. Pshenitsyna 《Journal of Mathematical Sciences》2006,135(5):3384-3399
We consider the arithmetic properties of the factor-rank and term-rank functions for matrices over semirings. In particular,
we investigate the sets of matrices that satisfy the extremes of inequalities for these rank functions of matrix union. The
classification of the linear transformations that keep these sets invariant is obtained.
__________
Translated from Fundamentalnaya i Prikladnaya Matematika, Vol. 9, No. 3, pp. 175–197, 2003. 相似文献
13.
S.A. Grigorian 《Topology and its Applications》2006,153(18):3598-3614
Finite-sheeted covering mappings onto compact connected groups are studied. We show that for a covering mapping from a connected Hausdorff topological space onto a compact (in general, non-abelian) group there exists a topological group structure on the covering space such that the mapping becomes a homomorphism of groups. To prove this fact we construct an inverse system of covering mappings onto Lie groups which approximates the given covering mapping. As an application, it is shown that a covering mapping onto a compact connected abelian group G must be a homeomorphism provided that the character group of G admits division by degree of the mapping. We also get a criterion for triviality of coverings in terms of means and prove that each finite covering of G is equivalent to a polynomial covering. 相似文献
14.
In this paper, by means of the method of upper and lower solutions and monotone iterative technique, the existence of maximal and minimal solutions of the boundary value problems for first order impulsive delay differential equations is established. 相似文献
15.
A hierarchical structure (HS) analysis (β-test and γ-test) is applied to a fully developed turbulent pipe flow. Velocity signals are measured at two cross sections in the pipe and at a series of radial locations from the pipe wall. Particular attention is paid to the variation of turbulent statistics at wall units 10<y+<3000. It is shown that at all locations the velocity fluctuations satisfy the She–Leveque hierarchical symmetry (Phys. Rev. Lett. 72 (1994) 336). The measured HS parameters, β and γ, are interpreted in terms of the variation of fluid structures. Intense anisotropic fluid structures generated near the wall appear to be more singular than the most intermittent structures in isotropic turbulence and appear to be more outstanding compared to the background fluctuations; this yields a more intermittent velocity signal with smaller γ and β. As turbulence migrates into the logarithmic region, small-scale motions are generated by an energy cascade and large-scale organized structures emerge which are also less singular than the most intermittent structures of isotropic turbulence. At the center, turbulence is nearly isotropic, and β and γ are close to the 1994 She–Leveque predictions. A transition is observed from the logarithmic region to the center in which γ drops and the large-scale organized structures break down. We speculate that it is due to the growing eddy viscosity effects of widely spread turbulent fluctuations in a similar way as in the breakdown of the Taylor vortices in a turbulent Couette–Taylor flow at high Reynolds numbers. 相似文献
16.
Testing exponentiality against a class of alternatives which includes the RNBUE distributions based on the empirical laplace transform 总被引:1,自引:0,他引:1
S. G. Meintanis Ya. Yu. Nikitin A. V. Tchirina 《Journal of Mathematical Sciences》2007,145(2):4871-4879
A scale-free test for exponentiality is proposed which is consistent within an extended set of models, including, but not
limited to, the “renewal new better than used in expectation” (RNBUE) class of life distributions. The limiting null distribution of the test statistics is derived, and the approximate local
Bahadur efficiency is calculated for several families of alternatives. Finite-sample properties of the proposed procedures
are investigated via simulation. Bibliography: 24 titles.
__________
Translated from Zapiski Nauchnykh Seminarov POMI, Vol. 339, 2006, pp. 63–77. 相似文献
17.
We prove that a locally compact ANR-space X is a Q-manifold if and only if it has the Disjoint Disk Property (DDP), all points of X are homological Z
∞-points and X has the countable-dimensional approximation property (cd-AP), which means that each map f: K → X of a compact polyhedron can be approximated by a map with the countable-dimensional image. As an application we prove that
a space X with DDP and cd-AP is a Q-manifold if some finite power of X is a Q-manifold. If some finite power of a space X with cd-AP is a Q-manifold, then X
2 and X × [0, 1] are Q-manifolds as well. We construct a countable family χ of spaces with DDP and cd-AP such that no space X ∈ χ is homeomorphic to the Hilbert cube Q whereas the product X × Y of any different spaces X, Y ∈ χ is homeomorphic to Q. We also show that no uncountable family χ with such properties exists.
This work was supported by the Slovenian-Ukrainian (Grant No. SLO-UKR 04-06/07) 相似文献
18.
19.
20.
《European Journal of Mechanics - A/Solids》2007,26(5):901-908
By virtue of the Stroh formalism, we derive the exact closed-form solutions for the time-dependent two-dimensional Green's functions due to a line force and line dislocation in an anisotropic bimaterial with a viscous interface. We first reduce the boundary value problem to two coupled homogeneous first-order partial differential equations, which can be solved using a decoupling technique. The full-field expressions of the time-dependent displacements and stresses due to the line force and line dislocation interacting with the viscous interface are obtained. 相似文献