全文获取类型
收费全文 | 97250篇 |
免费 | 11465篇 |
国内免费 | 12049篇 |
专业分类
化学 | 70063篇 |
晶体学 | 1182篇 |
力学 | 5162篇 |
综合类 | 1179篇 |
数学 | 11956篇 |
物理学 | 31222篇 |
出版年
2024年 | 134篇 |
2023年 | 994篇 |
2022年 | 1927篇 |
2021年 | 3412篇 |
2020年 | 3326篇 |
2019年 | 2941篇 |
2018年 | 2575篇 |
2017年 | 3185篇 |
2016年 | 3752篇 |
2015年 | 3421篇 |
2014年 | 4495篇 |
2013年 | 7301篇 |
2012年 | 5305篇 |
2011年 | 5876篇 |
2010年 | 4973篇 |
2009年 | 6015篇 |
2008年 | 5964篇 |
2007年 | 6143篇 |
2006年 | 5369篇 |
2005年 | 4319篇 |
2004年 | 4142篇 |
2003年 | 3673篇 |
2002年 | 5659篇 |
2001年 | 3133篇 |
2000年 | 2505篇 |
1999年 | 2040篇 |
1998年 | 1974篇 |
1997年 | 1604篇 |
1996年 | 1657篇 |
1995年 | 1453篇 |
1994年 | 1375篇 |
1993年 | 1211篇 |
1992年 | 1171篇 |
1991年 | 754篇 |
1990年 | 600篇 |
1989年 | 537篇 |
1988年 | 570篇 |
1987年 | 430篇 |
1986年 | 385篇 |
1985年 | 454篇 |
1984年 | 364篇 |
1983年 | 179篇 |
1982年 | 404篇 |
1981年 | 554篇 |
1980年 | 500篇 |
1979年 | 514篇 |
1978年 | 415篇 |
1977年 | 304篇 |
1976年 | 266篇 |
1973年 | 189篇 |
排序方式: 共有10000条查询结果,搜索用时 390 毫秒
991.
Peter Köhler 《Aequationes Mathematicae》1990,39(1):6-18
LetC
m
be a compound quadrature formula, i.e.C
m
is obtained by dividing the interval of integration [a, b] intom subintervals of equal length, and applying the same quadrature formulaQ
n
to every subinterval. LetR
m
be the corresponding error functional. Iff
(r)
> 0 impliesR
m
[f] > 0 (orR
m
[f] < 0),=" then=" we=" say=">C
m
is positive definite (or negative definite, respectively) of orderr. This is the case for most of the well-known quadrature formulas. The assumption thatf
(r)
> 0 may be weakened to the requirement that all divided differences of orderr off are non-negative. Thenf is calledr-convex. Now letC
m
be positive definite or negative definite of orderr, and letf be continuous andr-convex. We prove the following direct and inverse theorems for the errorR
m
[f], where , denotes the modulus of continuity of orderr:
相似文献
992.
Yosihiko Ogata 《Annals of the Institute of Statistical Mathematics》1990,42(3):403-433
This paper describes a method for an objective selection of the optimal prior distribution, or for adjusting its hyper-parameter, among the competing priors for a variety of Bayesian models. In order to implement this method, the integration of very high dimensional functions is required to get the normalizing constants of the posterior and even of the prior distribution. The logarithm of the high dimensional integral is reduced to the one-dimensional integration of a cerain function with respect to the scalar parameter over the range of the unit interval. Having decided the prior, the Bayes estimate or the posterior mean is used mainly here in addition to the posterior mode. All of these are based on the simulation of Gibbs distributions such as Metropolis' Monte Carlo algorithm. The improvement of the integration's accuracy is substantial in comparison with the conventional crude Monte Carlo integration. In the present method, we have essentially no practical restrictions in modeling the prior and the likelihood. Illustrative artificial data of the lattice system are given to show the practicability of the present procedure. 相似文献
993.
Summary We prove that the error inn-point Gaussian quadrature, with respect to the standard weight functionw1, is of best possible orderO(n
–2) for every bounded convex function. This result solves an open problem proposed by H. Braß and published in the problem section of the proceedings of the 2. Conference on Numerical Integration held in 1981 at the Mathematisches Forschungsinstitut Oberwolfach (Hämmerlin 1982; Problem 2). Furthermore, we investigate this problem for positive quadrature rules and for general product quadrature. In particular, for the special class of Jacobian weight functionsw
, (x)=(1–x)(1+x), we show that the above result for Gaussian quadrature is not valid precisely ifw
, is unbounded.Dedicated to Prof. H. Braß on the occasion of his 55th birthday 相似文献
994.
E. Mieloszyk 《Periodica Mathematica Hungarica》1990,21(1):43-53
Applying Bittner's operational calculus we present a method to give approximate solutions of linear partial differential equations of first order
|
设为首页 | 免责声明 | 关于勤云 | 加入收藏 |
Copyright©北京勤云科技发展有限公司 京ICP备09084417号 |