全文获取类型
收费全文 | 1388篇 |
免费 | 64篇 |
国内免费 | 59篇 |
专业分类
化学 | 134篇 |
晶体学 | 6篇 |
力学 | 43篇 |
综合类 | 6篇 |
数学 | 894篇 |
物理学 | 428篇 |
出版年
2023年 | 6篇 |
2022年 | 22篇 |
2021年 | 21篇 |
2020年 | 22篇 |
2019年 | 26篇 |
2018年 | 21篇 |
2017年 | 20篇 |
2016年 | 35篇 |
2015年 | 22篇 |
2014年 | 35篇 |
2013年 | 86篇 |
2012年 | 37篇 |
2011年 | 69篇 |
2010年 | 59篇 |
2009年 | 70篇 |
2008年 | 80篇 |
2007年 | 71篇 |
2006年 | 55篇 |
2005年 | 52篇 |
2004年 | 43篇 |
2003年 | 50篇 |
2002年 | 51篇 |
2001年 | 30篇 |
2000年 | 46篇 |
1999年 | 52篇 |
1998年 | 48篇 |
1997年 | 37篇 |
1996年 | 26篇 |
1995年 | 30篇 |
1994年 | 27篇 |
1993年 | 9篇 |
1992年 | 17篇 |
1991年 | 20篇 |
1990年 | 17篇 |
1989年 | 17篇 |
1988年 | 15篇 |
1987年 | 17篇 |
1986年 | 13篇 |
1985年 | 24篇 |
1984年 | 18篇 |
1983年 | 11篇 |
1982年 | 13篇 |
1981年 | 6篇 |
1979年 | 11篇 |
1978年 | 13篇 |
1977年 | 12篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1974年 | 6篇 |
1973年 | 4篇 |
排序方式: 共有1511条查询结果,搜索用时 0 毫秒
111.
Anders Rygh Swensen 《Stochastic Processes and their Applications》1983,15(2):181-191
In this note some problems of asymptotic inference in a class of non-stationary stochastic processes are considered. In particular, it is shown that no criterion based on the existence of uniformly most powerful tests over a local neighborhood can be used in this situation. 相似文献
112.
Two-Parametric Compound Binomial Approximations 总被引:1,自引:0,他引:1
We consider two-parametric compound binomial approximation of the generalized Poisson binomial distribution. We show that the accuracy of approximation essentially depends on the symmetry or shifting of distributions and construct asymptotic expansions. For the proofs, we combine the properties of norms with the results for convolutions of symmetric and shifted distributions. In the lattice case, we use the characteristic function method. In the case of almost binomial approximation, we apply Steins method.__________Published in Lietuvos Matematikos Rinkinys, Vol. 44, No. 4, pp. 443–466, October–December, 2004. 相似文献
113.
A 'chaos expansion' of the intersection local time functional of two independent Brownian motions in R
d
is given. The expansion is in terms of normal products of white noise (corresponding to multiple Wiener integrals). As a consequence of the local structure of the normal products, the kernel functions in the expansion are explicitly given and exhibit clearly the dimension dependent singularities of the local time functional. Their L
p
-properties are discussed. An important tool for deriving the chaos expansion is a computation of the 'S-transform' of the corresponding regularized intersection local times and a control about their singular limit. 相似文献
114.
115.
Sezgin Aygün Hüsnü Baysal İsmail Tarhan 《International Journal of Theoretical Physics》2007,46(10):2607-2616
In order to evaluate the energy distribution (due to matter and fields including gravitation) associated with a space-time model of cylindrically-symmetric Marder universe, we consider the Møller, Einstein, Bergmann–Thomson and Landau–Lifshitz energy and momentum definitions in the teleparallel gravity (TG). The energy-momentum distributions are found to be zero. These results are the same as a previous works of Aygün et al., they investigated the same problem in general relativity (GR) by using the Einstein, Møller, Bergmann–Thomson, Landau–Lifshitz (LL), Papapetrou, Qadir–Sharif and Weinberg’s definitions. These results support the viewpoints of Banerjee–Sen, Xulu, Radinschi and Aydo?du–Salt?. Another point is that our study agree with previous works of Cooperstock–Israelit, Rosen, Johri et al. This paper indicates an important point that these energy-momentum definitions agree with each other not only in general relativity but also in teleparallel gravity. It is also independent of the teleparallel dimensionless coupling constants, which means that it is valid not only in the teleparallel equivalent of general relativity, but also in any teleparallel model. 相似文献
116.
Using results for the distribution of perimeters of random polygons arising from random lines in a plane, we obtain new analytic
approximations to the distributions of areas and local line densities for random polygons and compute various limiting properties
of random polygons. Using simulation, we show that the lengths of adjacent sides of polygons generated by random line processes
in the plane are correlated with ρ=0.616±0.001. 相似文献
117.
Escort distributions are a well established but (for physicists) a relatively new concept that is rapidly gaining wide acceptance in world. In this work we wish to revisit the concept within the strictures of the celebrated semiclassical Husimi distributions (HDs) and thereby investigate the possibility of extracting new semiclassical information contained, not in the HD themselves, but in their associated escort Husimi distributions. We will also establish relations, for various information measures, between their deformed versions [J. Naudts, Physica A 316 (2002) 323] and those built up with escort HDs. Bounds on the concomitant power exponents will be determined. 相似文献
118.
G. Malescio 《Physica A》2007,383(2):643-650
We present a model describing a generic process in which a finite resource is partitioned and distributed among agents. Through numerical simulation we show that the model considered is able to originate, within a unifying approach, a variety of broad distributions and provides an interpretation of empirical properties of distributions observed in the real world. In particular it allows to relate the exponent of the power-law part of the distributions to resource abundance and accessibility, while the left-end exponential behavior, observed in many distributions, is related to the presence of dissipative effects. 相似文献
119.
Thereza Paiva 《Surface science》2007,601(2):419-424
We study height and roughness distributions of films grown with discrete Kardar-Parisi-Zhang (KPZ) models in a small time regime which is expected to parallel the typical experimental conditions. Those distributions are measured with square windows of sizes 8 ? r ? 128 gliding through a much larger surface. Results for models with weak finite-size corrections indicate that the absolute value of the skewness and the value of the kurtosis of height distributions converge to 0.2 ? ∣S∣ ? 0.3 and 0 ? Q ? 0.5, respectively. Despite the low accuracy of these results, they give additional support to a recent claim of KPZ scaling in oligomer films. However, there are significant finite-size effects in the scaled height distributions of models with large local slopes, such as ballistic deposition, which suggests that comparison of height distributions must not be used to rule out KPZ scaling. On the other hand, roughness distributions of the same models show good data collapse, with negligible dependence on time and window size. The estimates of skewness and kurtosis for roughness distributions are 1.7 ? S ? 2 and 3 ? Q ? 7. A stretched exponential tail was found, which seems to be a particular feature of KPZ systems in 2 + 1 dimensions. Moreover, the KPZ roughness distributions cannot be fitted by those of 1/fα noise. This study suggests that the roughness distribution is the best option to test KPZ scaling in the growth regime, and provides quantitative data for future comparison with other models or experiments. 相似文献
120.
For the multivariate ℓ1-norm symmetric distributions, which are generalizations of the n-dimensional exponential distribution with independent marginals, a geometric representation formula is given, together with some of its basic properties. This formula can especially be applied to a new developed and statistically well motivated system of sets. From that the distribution of a t-statistic adapted for the two-parameter exponential distribution and its generalizations is determined. Asymptotic normality of this adapted t-statistic is shown under certain conditions. 相似文献