全文获取类型
收费全文 | 2384篇 |
免费 | 31篇 |
国内免费 | 15篇 |
专业分类
化学 | 1413篇 |
晶体学 | 28篇 |
力学 | 83篇 |
数学 | 420篇 |
物理学 | 486篇 |
出版年
2020年 | 18篇 |
2019年 | 17篇 |
2018年 | 19篇 |
2017年 | 21篇 |
2016年 | 32篇 |
2015年 | 28篇 |
2014年 | 25篇 |
2013年 | 111篇 |
2012年 | 85篇 |
2011年 | 93篇 |
2010年 | 56篇 |
2009年 | 64篇 |
2008年 | 100篇 |
2007年 | 109篇 |
2006年 | 100篇 |
2005年 | 103篇 |
2004年 | 109篇 |
2003年 | 78篇 |
2002年 | 74篇 |
2001年 | 49篇 |
2000年 | 46篇 |
1999年 | 59篇 |
1998年 | 28篇 |
1997年 | 33篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 31篇 |
1993年 | 23篇 |
1992年 | 39篇 |
1991年 | 23篇 |
1990年 | 35篇 |
1989年 | 41篇 |
1988年 | 16篇 |
1987年 | 25篇 |
1986年 | 29篇 |
1985年 | 44篇 |
1984年 | 50篇 |
1983年 | 36篇 |
1982年 | 38篇 |
1981年 | 58篇 |
1980年 | 37篇 |
1979年 | 43篇 |
1978年 | 38篇 |
1977年 | 44篇 |
1976年 | 25篇 |
1975年 | 33篇 |
1974年 | 36篇 |
1973年 | 37篇 |
1972年 | 26篇 |
1970年 | 18篇 |
排序方式: 共有2430条查询结果,搜索用时 15 毫秒
991.
Howard See 《Rheologica Acta》2003,42(1-2):86-92
A comparison was made of the behaviour of a magnetorheological suspension under steady shear flow and constant velocity squeezing
flow. The strain rates and sample dimensions were chosen to be comparable in the two deformation modes, and the dependence
of the mechanical properties on the magnetic flux density B was investigated. The measurements found that the mechanical response
under squeezing flow scaled as B0.91, whereas the response under shearing scaled as B1.4, close to theoretical predictions. This difference of the field dependence between the shearing and squeezing flows was possibly
due to the different microstructural rearrangement processes which occur in the two deformation modes. 相似文献
992.
Howard Jacobowitz 《Proceedings of the American Mathematical Society》2006,134(3):893-895
If the dimension of is denoted by or , then a generic map satisfies , while in certain cases there is no map that satisfies .
993.
S. J. Dilworth Ralph Howard James W. Roberts 《Transactions of the American Mathematical Society》2006,358(8):3413-3445
Let be the standard -dimensional simplex and let . Then a function with domain a convex set in a real vector space is -almost convex iff for all and the inequality holds. A detailed study of the properties of -almost convex functions is made. If contains at least one point that is not a vertex, then an extremal -almost convex function is constructed with the properties that it vanishes on the vertices of and if is any bounded -almost convex function with on the vertices of , then for all . In the special case , the barycenter of , very explicit formulas are given for and . These are of interest, as and are extremal in various geometric and analytic inequalities and theorems.
994.
Peter Howard 《偏微分方程通讯》2013,38(1):73-121
ABSTRACT We consider degenerate viscous shock waves arising in systems of two conservation laws, where degeneracy describes viscous shock waves for which the asymptotic endstates are sonic to the hyperbolic system (the shock speed is equal to one of the characteristic speeds). In particular, we develop detailed pointwise estimates on the Green's function associated with the linearized perturbation equation, sufficient for establishing that spectral stability implies nonlinear stability. The analysis of degenerate viscous shock waves involves several new features, such as algebraic (nonintegrable) convection coefficients, loss of analyticity of the Evans function at the leading eigenvalue, and asymptotic time decay of perturbations intermediate between that of the Lax case and that of the undercompressive case. 相似文献
995.
David M. Howard 《Discrete Mathematics》2010,310(21):2890-2894
Fix integers n and k with n≥k≥3. Duffus and Sands proved that if P is a finite poset and n≤|C|≤n+(n−k)/(k−2) for every maximal chain in P, then P must contain k pairwise disjoint maximal antichains. They also constructed a family of examples to show that these inequalities are tight. These examples are two-dimensional which suggests that the dual statement may also hold. In this paper, we show that this is correct. Specifically, we show that if P is a finite poset and n≤|A|≤n+(n−k)/(k−2) for every maximal antichain in P, then P has k pairwise disjoint maximal chains. Our argument actually proves a somewhat stronger result, and we are able to show that an analogous result holds for antichains. 相似文献
996.
We define an ending lamination for a Weil–Petersson geodesic ray. Despite the lack of a natural visual boundary for the Weil–Petersson
metric [Bro2], these ending laminations provide an effective boundary theory that encodes much of its asymptotic CAT(0) geometry.
In particular, we prove an ending lamination theorem (Theorem 1.1) for the full-measure set of rays that recur to the thick part, and we show that the association of an ending
lamination embeds asymptote classes of recurrent rays into the Gromov-boundary of the curve complex C(S){\mathcal{C}(S)}. As an application, we establish fundamentals of the topological dynamics of the Weil–Petersson geodesic flow, showing density
of closed orbits and topological transitivity. 相似文献
997.
A rainbow matching for (not necessarily distinct) sets of hypergraph edges is a matching consisting of k edges, one from each . The aim of the article is twofold—to put order in the multitude of conjectures that relate to this concept (some first presented here), and to prove partial results on one of the central conjectures. 相似文献
998.
999.
Using a simplified pointwise iteration scheme, we establish nonlinear phase-asymptotic orbital stability of large-amplitude Lax, undercompressive, overcompressive, and mixed under-overcompressive type shock profiles of strictly parabolic systems of conservation laws with respect to initial perturbations |u0(x)|?E0(1+|x|)−3/2 in C0+α, E0 sufficiently small, under the necessary conditions of spectral and hyperbolic stability together with transversality of the connecting profile. This completes the program initiated by Zumbrun and Howard in [K. Zumbrun, P. Howard, Pointwise semigroup methods and stability of viscous shock waves, Indiana Univ. Math. J. 47 (4) (1998) 741-871], extending to the general undercompressive case results obtained for Lax and overcompressive shock profiles in [A. Szepessy, Z. Xin, Nonlinear stability of viscous shock waves, Arch. Ration. Mech. Anal. 122 (1993) 53-103; T.-P. Liu, Pointwise convergence to shock waves for viscous conservation laws, Comm. Pure Appl. Math. 50 (11) (1997) 1113-1182; K. Zumbrun, P. Howard, Pointwise semigroup methods and stability of viscous shock waves, Indiana Univ. Math. J. 47 (4) (1998) 741-871; K. Zumbrun, Refined wave-tracking and nonlinear stability of viscous Lax shocks, Methods Appl. Anal. 7 (2000) 747-768; M.-R. Raoofi, L1-asymptotic behavior of perturbed viscous shock profiles, thesis, Indiana Univ., 2004; C. Mascia, K. Zumbrun, Pointwise Green's function bounds and stability of relaxation shocks, Indiana Univ. Math. J. 51 (4) (2002) 773-904; C. Mascia, K. Zumbrun, Stability of small-amplitude shock profiles of symmetric hyperbolic-parabolic systems, Comm. Pure Appl. Math. 57 (7) (2004) 841-876; C. Mascia, K. Zumbrun, Pointwise Green's function bounds for shock profiles with degenerate viscosity, Arch. Ration. Mech. Anal. 169 (3) (2003) 177-263; C. Mascia, K. Zumbrun, Stability of large-amplitude shock profiles of hyperbolic-parabolic systems, Arch. Ration. Mech. Anal. 172 (1) (2004) 93-131; C. Mascia, K. Zumbrun, Stability of large-amplitude shock profiles of general relaxation systems, SIAM J. Math. Anal., in press], and for special “weakly coupled” (respectively scalar diffusive-dispersive) undercompressive profiles in [T.P. Liu, K. Zumbrun, Nonlinear stability of an undercompressive shock for complex Burgers equation, Comm. Math. Phys. 168 (1) (1995) 163-186; T.P. Liu, K. Zumbrun, On nonlinear stability of general undercompressive viscous shock waves, Comm. Math. Phys. 174 (2) (1995) 319-345] (respectively [P. Howard, K. Zumbrun, Pointwise estimates for dispersive-diffusive shock waves, Arch. Ration. Mech. Anal. 155 (2000) 85-169]). In particular, together with spectral results of [K. Zumbrun, Dynamical stability of phase transitions in the p-system with viscosity-capillarity, SIAM J. Appl. Math. 60 (2000) 1913-1924], our results yield nonlinear stability of large-amplitude undercompressive phase-transitional profiles near equilibrium of Slemrod's model [M. Slemrod, Admissibility criteria for propagating phase boundaries in a van der Waals fluid, Arch. Ration. Mech. Anal. 81 (4) (1983) 301-315] for van der Waal gas dynamics or elasticity with viscosity-capillarity. 相似文献
1000.