全文获取类型
收费全文 | 54篇 |
免费 | 9篇 |
国内免费 | 6篇 |
专业分类
化学 | 3篇 |
力学 | 6篇 |
数学 | 52篇 |
物理学 | 8篇 |
出版年
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 2篇 |
2019年 | 2篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 6篇 |
2013年 | 1篇 |
2012年 | 2篇 |
2011年 | 2篇 |
2010年 | 3篇 |
2009年 | 4篇 |
2008年 | 5篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 4篇 |
2004年 | 2篇 |
2003年 | 3篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 2篇 |
1989年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有69条查询结果,搜索用时 15 毫秒
61.
Debora Impera 《Journal of Geometry and Physics》2012,62(2):412-426
In this paper we prove Hessian and Laplacian comparison theorems for the Lorentzian distance function in a spacetime with sectional (or Ricci) curvature bounded by a certain function by means of a comparison criterion for Riccati equations. Using these results, under suitable conditions, we are able to obtain some estimates on the higher order mean curvatures of spacelike hypersurfaces satisfying a Omori-Yau maximum principle for certain elliptic operators. 相似文献
62.
We investigate proper biharmonic hypersurfaces with at most three distinct principal curvatures in space forms. We obtain the full classification of proper biharmonic hypersurfaces in 4‐dimensional space forms (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
63.
64.
We derive, for the square operator of Yau, an analogue of the Omori–Yau maximum principle for the Laplacian. We then apply
it to obtain nonexistence results concerning complete noncompact spacelike hypersurfaces immersed with constant higher order
mean curvature in a conformally stationary Lorentz manifold. 相似文献
65.
We propose a new truncated Newton method for large scale unconstrained optimization, where a Conjugate Gradient (CG)-based
technique is adopted to solve Newton’s equation. In the current iteration, the Krylov method computes a pair of search directions:
the first approximates the Newton step of the quadratic convex model, while the second is a suitable negative curvature direction.
A test based on the quadratic model of the objective function is used to select the most promising between the two search
directions. Both the latter selection rule and the CG stopping criterion for approximately solving Newton’s equation, strongly
rely on conjugacy conditions. An appropriate linesearch technique is adopted for each search direction: a nonmonotone stabilization
is used with the approximate Newton step, while an Armijo type linesearch is used for the negative curvature direction. The
proposed algorithm is both globally and superlinearly convergent to stationary points satisfying second order necessary conditions.
We carry out a significant numerical experience in order to test our proposal. 相似文献
66.
We establish some estimates for the higher-order mean curvatures, the scalar curvature and the Ricci curvature of a complete spacelike hypersurface in de Sitter space which is contained in certain unbounded regions of the ambient space. Our results will be an application of a generalized maximum principle due to Omori. 相似文献
67.
ON CONFIDENCE REGIONS OF SEMIPARAMETRIC NONLINEAR REGRESSION MODELS(A GEOMETRIC APPROACH) 总被引:1,自引:0,他引:1
1IntroductionSelltipaxanetricmodelsaxemodelscolltaillingbothparametricalldnonparametriccom-pOnents,wl1erethenol1parametriccomponentplaystheroleofanusianceparameter.Moreprecisely,asellliparametriclllodelisparameterizedbyaparameterofillteresttakingvaI1lesinfinite-din1el1sionajEuclidenspaceal1danusianceparantetertakingvaluesininfinite-dimellsionalspace.Tl1ismodelembodiesacolllpro11tisebetweenemployingagelleralnonparametricspeci-ficatioll.wl1ich,iftheconditiol1il1gvariablesarehighdimensional,woul… 相似文献
68.
We show that if two Riemannian metrics
and g are pointwiseprojectively equivalent and the Ricci curvatures satisfy
Ric, then the projective equivalence is trivialprovided that g is complete. In this case,
is parallel with respect to g and the Riemann curvatures of g and
are equal.The Ricci curvature condition can be weakened when the manifold iscompact. This rigidity theorem actually holds for more general geometricstructures, such as Finsler metrics and sprays. In this paper, we willalso discuss several examples and show that the completeness of g cannot be dropped. 相似文献
69.
Yu Ping SONG 《数学学报(英文版)》2014,(1)
An umbilical free oriented hypersurfacex:M→Rnwith non-zero principal curvatures is called a Laguerre isoparametric hypersurface if its Laguerre form C=i Ciωi=iρ1(Ei(logρ)(r ri)Ei(r))ωi vanishes and Laguerre shape operator S=ρ1(S 1 rid)has constant eigenvalues.Hereρ=i(r ri)2,r=r1+r2+···+rn 1n 1is the mean curvature radius andSis the shape operator ofx.{Ei}is a local basis for Laguerre metric g=ρ2III with dual basis{ωi}and III is the third fundamental form ofx.In this paper,we classify all Laguerre isoparametric hypersurfaces in Rn(n3)with two distinct non-zero principal curvatures up to Laguerre transformations. 相似文献