全文获取类型
收费全文 | 766篇 |
免费 | 10篇 |
国内免费 | 3篇 |
专业分类
化学 | 425篇 |
晶体学 | 2篇 |
力学 | 15篇 |
数学 | 152篇 |
物理学 | 185篇 |
出版年
2022年 | 8篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 6篇 |
2018年 | 7篇 |
2016年 | 9篇 |
2015年 | 10篇 |
2014年 | 17篇 |
2013年 | 49篇 |
2012年 | 28篇 |
2011年 | 52篇 |
2010年 | 19篇 |
2009年 | 9篇 |
2008年 | 51篇 |
2007年 | 44篇 |
2006年 | 50篇 |
2005年 | 40篇 |
2004年 | 28篇 |
2003年 | 36篇 |
2002年 | 27篇 |
2001年 | 27篇 |
2000年 | 8篇 |
1999年 | 9篇 |
1998年 | 9篇 |
1997年 | 8篇 |
1996年 | 14篇 |
1995年 | 9篇 |
1994年 | 4篇 |
1992年 | 10篇 |
1990年 | 13篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1985年 | 11篇 |
1984年 | 6篇 |
1983年 | 5篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 6篇 |
1979年 | 6篇 |
1978年 | 11篇 |
1977年 | 11篇 |
1976年 | 9篇 |
1975年 | 6篇 |
1974年 | 5篇 |
1973年 | 7篇 |
1972年 | 5篇 |
1971年 | 7篇 |
1970年 | 8篇 |
排序方式: 共有779条查询结果,搜索用时 15 毫秒
71.
Consider a system of two queues in parallel, one of which is a ⋅|M|1 single-server infinite capacity queue, and the other a ⋅|G
(N)|∞ batch service queue. A stream of general arrivals choose which queue to join, after observing the current state of the
system, and so as to minimize their own expected delay. We show that a unique user equilibrium (user optimal policy) exists
and that it possesses various monotonicity properties, using sample path and coupling arguments. This is a very simplified
model of a transportation network with a choice of private and public modes of transport. Under probabilistic routing (which
is equivalent to the assumption that users have knowledge only of the mean delays on routes), the network may exhibit the
Downs–Thomson paradox observed in transportation networks with expected delay increasing as the capacity of the ⋅|M|1 queue (private transport) is increased. We give examples where state-dependent routing mitigates the Downs–Thomson effect
observed under probabilistic routing, and providing additional information on the state of the system to users reduces delay
considerably. 相似文献
72.
73.
74.
75.
O. S. Klass O. Biham M. Levy O. Malcai S. Solomon 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,55(2):143-147
Statistical regularities at
the top end of the wealth distribution in the United States are
examined using the Forbes 400 lists of richest Americans,
published between 1988 and 2003.
It is found that the wealths are distributed according to a power-law
(Pareto) distribution.
This result is explained using a
simple stochastic model
of multiple investors that incorporates the
efficient market hypothesis
as well as the multiplicative nature of financial market fluctuations. 相似文献
76.
77.
Inventiones mathematicae - 相似文献
78.
P. J. Solomon 《商业与工业应用随机模型》1989,5(2):153-164
The present paper describes an example of practical analysis of data from an application of visual analogue scales. Potentially useful and simple methods for analysing visual analogue scales are described for effective handling of complex data when the desire is to compare two or more groups of patients. Visual analogue scales were used to assess subjective tolerability in the International Prospective Primary Prevention Study in Hypertension, a large scale clinical trial. The methods are illustrated on the IPPPSH data. 相似文献
79.
M. Pelton C. Santori G.S. Solomon O. Benson Y. Yamamoto 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2002,18(2):179-190
Current quantum cryptography systems are limited by the attenuated coherent pulses they use as light sources: a security loophole
is opened up by the possibility of multiple-photon pulses. By replacing the source with a single-photon emitter, transmission
rates of secure information can be improved. We have investigated the use of single self-assembled InAs/GaAs quantum dots
as such single-photon sources, and have seen a tenfold reduction in the multi-photon probability as compared to Poissonian
pulses. An extension of our experiment should also allow for the generation of triggered, polarization-entangled photon pairs.
The utility of these light sources is currently limited by the low efficiency with which photons are collected. However, by
fabricating an optical microcavity containing a single quantum dot, the spontaneous emission rate into a single mode can be
enhanced. Using this method, we have seen 78% coupling of single-dot radiation into a single cavity resonance. The enhanced
spontaneous decay should also allow for higher photon pulse rates, up to about 3 GHz.
Received 8 July 2001 and Received in final form 25 August 2001 相似文献
80.