全文获取类型
收费全文 | 1832篇 |
免费 | 206篇 |
国内免费 | 217篇 |
专业分类
化学 | 69篇 |
晶体学 | 2篇 |
力学 | 134篇 |
综合类 | 61篇 |
数学 | 1590篇 |
物理学 | 399篇 |
出版年
2024年 | 1篇 |
2023年 | 27篇 |
2022年 | 19篇 |
2021年 | 44篇 |
2020年 | 64篇 |
2019年 | 50篇 |
2018年 | 39篇 |
2017年 | 42篇 |
2016年 | 59篇 |
2015年 | 51篇 |
2014年 | 111篇 |
2013年 | 99篇 |
2012年 | 66篇 |
2011年 | 72篇 |
2010年 | 91篇 |
2009年 | 108篇 |
2008年 | 125篇 |
2007年 | 151篇 |
2006年 | 112篇 |
2005年 | 106篇 |
2004年 | 98篇 |
2003年 | 101篇 |
2002年 | 105篇 |
2001年 | 67篇 |
2000年 | 68篇 |
1999年 | 80篇 |
1998年 | 57篇 |
1997年 | 63篇 |
1996年 | 41篇 |
1995年 | 26篇 |
1994年 | 31篇 |
1993年 | 17篇 |
1992年 | 9篇 |
1991年 | 13篇 |
1990年 | 8篇 |
1989年 | 8篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
1957年 | 1篇 |
排序方式: 共有2255条查询结果,搜索用时 15 毫秒
81.
We study the injectivity radius bound for 3-d Ricci flow with bounded curvature. As applications, we show the long time existence of the Ricci flow with positive Ricci curvature and with curvature decay condition at infinity. We partially settle a question of Chow-Lu-Ni [Hamilton’s Ricci Flow, p. 302]. 相似文献
82.
83.
84.
Yawei CHU 《Frontiers of Mathematics in China》2012,7(1):19-27
Let (M
n
, g) be an n-dimensional complete noncompact Riemannian manifold with harmonic curvature and positive Sobolev constant. In this paper,
by employing an elliptic estimation method, we show that (M
n
, g) is a space form if it has sufficiently small L
n/2-norms of trace-free curvature tensor and nonnegative scalar curvature. Moreover, we get a gap theorem for (M
n
, g) with positive scalar curvature. 相似文献
85.
LIU Shi-Da SHI Shao-Ying LIU Shi-Kuo FU Zun-Tao LIANG Fu-Ming XIN Guo-Jun 《理论物理通讯》2005,43(4):604-606
The vortex is a common phenomenon in
fluid field. In this paper, vortex can be represented by curvature
c, which varies with arc length s. The variance of point
(x,y) with arc length in stream line satisfies a 2-order
variable-coefficient linear ordinary differential equation. The
type vortex can be analyzed qualitatively by this ordinary
differential equation. 相似文献
86.
We use a new method to construct a class of asymptotically locally flat, scalar flat metrics. These metrics were constructed via algebraic geometry method by LeBrun before and provide counterexamples to the generalized positive action conjecture of Hawking and Pope. 相似文献
87.
The solitary wave and wave front are two
important behaviors of nonlinear evolution equations.
Geometrically, solitary wave and wave front are all plane curve.
In this paper, they can be represented in terms of curvature
c(s), which varies with arc length s. For solitary wave when
s → ±∞, then its curvature c(s) approaches
zero, and when s=0, the curvature c(s) reaches its maximum.
For wave front, when s → ±∞, then its
curvature c(s) approaches zero, and when s=0, the curvature
c(s) is still zero, but c'(s) ≠ 0. That is, s=0 is a
turning point. When c(s) is given, the variance at some point
(x,y) in stream line with arc length s satisfies a 2-order
linear variable-coefficient ordinary differential equation. From
this equation, it can be determined qualitatively whether the
given curvature is a solitary wave or wave front. 相似文献
88.
Shape bifurcation of an elastic wafer due to surface stress 总被引:1,自引:0,他引:1
IntroductionSurfacestressisresponsibleformanymesoscopicalphenomenainmaterialsandthushasbeenstudiedextensively[1~ 5 ].Althoughtheabsolutevalueofsurfacestressofasolidcurrentlycannotbeobtainedbyexperiments,themethodformeasuringitschangehasbeenwellestablished .Theprincipleisratherclear.Whenthesurfacestressononesurfaceofawafer,eitherfreestandingorclampedatoneend ,changesduetocertainreasonssuchasadsorption ,thedifferencebetweenthesurfacestressonthissurfaceandthatontheoppositeoneresultsinabendingmom… 相似文献
89.
Guo-lian~Xu ChandrajitL.Bajaj 《计算数学(英文版)》2003,21(5):681-688
In this paper, we provide simple and explicit formulas for computing Riemannian curvatures, mean curvature vectors, principal curvatures and principal directions for a 2-dimensional Riemannian manifold embedded in IR^k with k ≥ 3. 相似文献
90.
IntroductionLetΓ0 beasmoothconnectedhypersurfaceanditistheboundaryofaboundedopensetU Rn.Supposethatt0 isatime ,M =M(x) ∈C3withM( 0 ) =0 ,M′(x) >0 ,andl1,l2 ,… ,lnarepositiverealnumbers.{Γt} 0 ≤t≤t0 isaclassicalsmoothsurface,anditistheboundaryofaboundedopensetUt,whichisdiff… 相似文献