全文获取类型
收费全文 | 2707篇 |
免费 | 264篇 |
国内免费 | 276篇 |
专业分类
化学 | 333篇 |
晶体学 | 20篇 |
力学 | 261篇 |
综合类 | 65篇 |
数学 | 1889篇 |
物理学 | 679篇 |
出版年
2024年 | 5篇 |
2023年 | 24篇 |
2022年 | 39篇 |
2021年 | 63篇 |
2020年 | 64篇 |
2019年 | 59篇 |
2018年 | 68篇 |
2017年 | 75篇 |
2016年 | 82篇 |
2015年 | 61篇 |
2014年 | 144篇 |
2013年 | 152篇 |
2012年 | 80篇 |
2011年 | 114篇 |
2010年 | 120篇 |
2009年 | 142篇 |
2008年 | 172篇 |
2007年 | 197篇 |
2006年 | 161篇 |
2005年 | 164篇 |
2004年 | 139篇 |
2003年 | 141篇 |
2002年 | 154篇 |
2001年 | 129篇 |
2000年 | 119篇 |
1999年 | 97篇 |
1998年 | 97篇 |
1997年 | 68篇 |
1996年 | 53篇 |
1995年 | 40篇 |
1994年 | 40篇 |
1993年 | 32篇 |
1992年 | 28篇 |
1991年 | 24篇 |
1990年 | 21篇 |
1989年 | 15篇 |
1988年 | 8篇 |
1987年 | 9篇 |
1986年 | 5篇 |
1985年 | 10篇 |
1984年 | 5篇 |
1982年 | 6篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1974年 | 3篇 |
1971年 | 1篇 |
排序方式: 共有3247条查询结果,搜索用时 0 毫秒
1.
对由一类非线性抛物型变分不等方程所描述的无穷维动力系统,给出了存在全局吸引子及弱近似惯性流形的充分条件. 相似文献
2.
Summary This paper is concerned with the problem of developing numerical integration algorithms for differential equations that, when
viewed as equations in some Euclidean space, naturally evolve on some embedded submanifold. It is desired to construct algorithms
whose iterates also evolve on the same manifold. These algorithms can therefore be viewed as integrating ordinary differential
equations on manifolds. The basic method “decouples” the computation of flows on the submanifold from the numerical integration
process. It is shown that two classes of single-step and multistep algorithms can be posed and analyzed theoretically, using
the concept of “freezing” the coefficients of differential operators obtained from the defining vector field. Explicit third-order
algorithms are derived, with additional equations augmenting those of their classical counterparts, obtained from “obstructions”
defined by nonvanishing Lie brackets. 相似文献
3.
Vladimir V. Vershinin 《Acta Appl Math》2003,75(1-3):281-292
Malcev–Poisson structure on a manifold is analogous to a Poisson structure with the Lie identity replaced by a slightly more general Malcev identity. Examples of such structures arise naturally. In the second part of the paper we study Malcev bialgebras. A theorem of characterization is proved. 相似文献
4.
The Iyengar Type Inequalities with Exact Estimations and the Chebyshev Central Algorithms of Integrals 总被引:3,自引:0,他引:3
Xing Hua WANG Shi Jun YANG 《数学学报(英文版)》2005,21(6):1361-1376
In this paper, both low order and high order extensions of the Iyengar type inequality are obtained. Such extensions are the best possible in the same sense as that of the Iyengar inequality. hzrthermore, the Chebyshev central algorithms of integrals for some function classes and some related problems are also considered and investigated. 相似文献
5.
6.
研究了γ-辐照前后纯Y2SiO5和Eu3+掺杂的Y2SiO5晶体吸收光谱的变化,辐照后,未退火和氢气退火的纯Y2SiO5晶体在260~270 nm和320 nm波段产生了附加吸收峰,分别是由F心和O-心的吸收引起的;经过空气退火的纯YSO晶体中,由于消除了氧空位,因此辐照后没有出现色心吸收峰。在Eu3+∶Y2SiO5晶体中,不但有相同的F心和O-心吸收峰,而且还有Eu2+离子在300 nm和390 nm的吸收峰。随着辐照剂量的增加,色心附加吸收峰增强。空气退火能减少Eu3+∶Y2SiO5晶体中的色心,而氢气退火能增加色心。 相似文献
7.
8.
Zhu Da xin 《数学年刊B辑(英文版)》1994,15(3):293-298
ACOMPLETEMETRICOFPOSITIVECURVATUREONR~nANDEXISTENCEOFCLOSEDGEODESICS¥ZHUDAXIN(DepartmentofMathematics,TianjinUniversitylTianj?.. 相似文献
9.
The surgery obstruction of a normal map to a simple Poincaré pair (X, Y) lies in the relative surgery obstruction group L *(π 1(Y) → π 1(X)). A well-known result of Wall, the so-called π-π-theorem, states that in higher dimensions a normal map of a manifold with boundary to a simple Poincaré pair with π 1(X) ? π 1(Y) is normally bordant to a simple homotopy equivalence of pairs. In order to study normal maps to a manifold with a submanifold, Wall introduced the surgery obstruction groups LP * for manifold pairs and splitting obstruction groups LS *. In the present paper, we formulate and prove for manifold pairs with boundary results similar to the π-π-theorem. We give direct geometric proofs, which are based on the original statements of Wall’s results and apply obtained results to investigate surgery on filtered manifolds. 相似文献
10.
A functional equation of nonlinear iterates is discussed on the circle S1 for its continuous solutions and differentiable solutions. By lifting to R, the existence, uniqueness and stability of those solutions are obtained. Techniques of continuation are used to guarantee the preservation of continuity and differentiability in lifting. 相似文献