全文获取类型
收费全文 | 128篇 |
免费 | 2篇 |
专业分类
化学 | 17篇 |
力学 | 1篇 |
数学 | 9篇 |
物理学 | 103篇 |
出版年
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 1篇 |
2014年 | 1篇 |
2013年 | 1篇 |
2012年 | 1篇 |
2011年 | 4篇 |
2010年 | 1篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2007年 | 2篇 |
2006年 | 2篇 |
2005年 | 5篇 |
2004年 | 4篇 |
2002年 | 7篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 6篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1993年 | 5篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 5篇 |
1989年 | 3篇 |
1988年 | 8篇 |
1987年 | 4篇 |
1986年 | 2篇 |
1985年 | 4篇 |
1984年 | 8篇 |
1983年 | 3篇 |
1982年 | 4篇 |
1981年 | 5篇 |
1980年 | 2篇 |
1979年 | 2篇 |
1978年 | 5篇 |
1977年 | 2篇 |
1976年 | 1篇 |
1975年 | 2篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1970年 | 1篇 |
排序方式: 共有130条查询结果,搜索用时 62 毫秒
101.
102.
Asad Haris Daniela Witten Noah Simon 《Journal of computational and graphical statistics》2016,25(4):981-1004
We consider the task of fitting a regression model involving interactions among a potentially large set of covariates, in which we wish to enforce strong heredity. We propose FAMILY, a very general framework for this task. Our proposal is a generalization of several existing methods, such as VANISH, hierNet, the all-pairs lasso, and the lasso using only main effects. It can be formulated as the solution to a convex optimization problem, which we solve using an efficient alternating directions method of multipliers (ADMM) algorithm. This algorithm has guaranteed convergence to the global optimum, can be easily specialized to any convex penalty function of interest, and allows for a straightforward extension to the setting of generalized linear models. We derive an unbiased estimator of the degrees of freedom of FAMILY, and explore its performance in a simulation study and on an HIV sequence dataset. Supplementary materials for this article are available online. 相似文献
103.
Heterotic and Type I string dynamics from eleven dimensions 总被引:1,自引:0,他引:1
We propose that the ten-dimensional E8 × E8 heterotic string is related to an eleven-dimensional theory on the orbifold
in the same way that the Type IIA string in ten dimensions is related to
. This in particular determines the strong coupling behavior of the ten-dimensional E8 × E8 theory. It also leads to a plausible scenario whereby duality between SO(32) heterotic and Type I superstrings follows from the classical symmetries of the eleven-dimensional world, just as the
duality of the ten-dimensional Type IIB theory follows from eleven-dimensional diffeomorphism invariance. 相似文献
104.
Robert Friedman John Morgan Edward Witten 《Communications in Mathematical Physics》1997,187(3):679-743
To understand in detail duality between heterotic string and F theory compactifications, it is important to understand the construction of holomorphic G bundles over elliptic Calabi-Yau manifolds, for various groups G. In this paper, we develop techniques to describe these bundles, and make several detailed comparisons between the heterotic
string and F theory.
Received: 6 February 1997 / Accepted: 29 May 1997 相似文献
105.
106.
Adaptive text mining: inferring structure from sequences 总被引:1,自引:0,他引:1
I. H. Witten 《Journal of Discrete Algorithms》2004,2(2):137
Text mining is about inferring structure from sequences representing natural language text, and may be defined as the process of analyzing text to extract information that is useful for particular purposes. Although hand-crafted heuristics are a common practical approach for extracting information from text, a general, and generalizable, approach requires adaptive techniques. This paper studies the way in which the adaptive techniques used in text compression can be applied to text mining. It develops several examples: extraction of hierarchical phrase structures from text, identification of keyphrases in documents, locating proper names and quantities of interest in a piece of text, text categorization, word segmentation, acronym extraction, and structure recognition. We conclude that compression forms a sound unifying principle that allows many text mining problems to be tacked adaptively. 相似文献
107.
A study is made of the implications of heterotic string T-duality and extended gauge symmetry for the conjectured equivalence of heterotic and Type I superstrings. While at first sight heterotic string world-sheet dynamics appears to conflict with Type I perturbation theory, a closer look shows that Type I perturbation theory “miraculously” breaks down, in some cases via novel mechanisms, whenever the heterotic string has massless particles not present in Type I perturbation theory. This strongly suggests that the two theories actually are equivalent. As further evidence in the same direction, we show that the Dirichlet one-brane of Type I string theory has the same world-sheet structure as the heterotic string. 相似文献
108.
Edward Witten 《Nuclear Physics B》1983,223(2):433-444
It is shown that ordinary baryons can be understood as solitons in current algebra effective lagrangians. The formation of color flux tubes can also be seen in current algebra, under certain conditions. 相似文献
109.
Edward Witten 《Communications in Mathematical Physics》1984,92(4):455-472
A non-abelian generalization of the usual formulas for bosonization of fermions in 1+1 dimensions is presented. Any fermi theory in 1+1 dimensions is equivalent to a local bose theory which manifestly possesses all the symmetries of the fermi theory.Supported in part by NSF Grant PHY-80-19754 相似文献
110.
This paper analyzes harvesting in simple one species iterative density-dependent population models. Several harvest management policies are considered, including a constant effort policy, an on-off constant harvest policy, and several policies that include protective strategies. Results for quadratic, Ricker, and Beverton-Holt growth functions are contrasted. It is found that even for the Beverton-Holt case, there are parameter regions where periodic or chaotic behavior can occur under certain harvest policies. In fact, regions of stability and irregularity can alternate. 相似文献