全文获取类型
收费全文 | 109篇 |
免费 | 18篇 |
国内免费 | 14篇 |
专业分类
化学 | 2篇 |
力学 | 8篇 |
综合类 | 3篇 |
数学 | 36篇 |
物理学 | 42篇 |
无线电 | 50篇 |
出版年
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 2篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 1篇 |
2016年 | 3篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 9篇 |
2012年 | 6篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 1篇 |
2008年 | 12篇 |
2007年 | 6篇 |
2006年 | 6篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 4篇 |
2002年 | 2篇 |
2001年 | 3篇 |
2000年 | 5篇 |
1999年 | 3篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1996年 | 6篇 |
1995年 | 1篇 |
1994年 | 3篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1959年 | 1篇 |
排序方式: 共有141条查询结果,搜索用时 31 毫秒
1.
Yu Jun ZHU Jin Lian ZHANG Lian Fa HE 《数学学报(英文版)》2006,22(5):1321-1328
In this paper, we consider the shadowing and the inverse shadowing properties for C^1 endomorphisms. We show that near a hyperbolic set a C^1 endomorphism has the shadowing property, and a hyperbolic endomorphism has the inverse shadowing property with respect to a class of continuous methods. Moreover, each of these shadowing properties is also "uniform" with respect to C^1 perturbation. 相似文献
2.
A Study of Shadowing on Indoor Visible-Light Wireless Communication Utilizing Plural White LED Lightings 总被引:3,自引:1,他引:2
Toshihiko Komine Shinichiro Haruyama Masao Nakagawa 《Wireless Personal Communications》2005,34(1-2):211-225
White LED is considered as a strong candidate for the future lighting technology. We have proposed an optical wireless communication
system that employs white LEDs for indoor wireless networks. In this system, LED is used not only as a lighting device, but
also as a communication device. The transmitter has large optical power and large emission characteristics to function as
lighting device. And the system has specific wireless channel impulse response differing from infrared wireless communication.
In this paper, we discuss about shadowing effect on the system utilizing plural LED lightings including the performance of
ISI based on the impulse response. We consider the downlink transmission based on TDMA and evaluate the shadowing effect caused
by pedestrians with computer simulation. When the shadowing often occurs at 800 Mb/s, the performance of outage call duration
rate and blocking rate are improved by using 3 LED lightings compared with 1 or 2 LED lightings. And, we show that the system
with the optimal number of the LED lighting is robust against shadowing and can accommodate more calls.
Toshihiko Komine was born in Shizuoka, Japan, on November 17, 1978. He received the B.E. and M.E. degrees in Information and Computer Science
from Keio University, Yokohama, Japan, in 2001 and 2003 respectively. He is currently studying for the Ph.D. degree at Department
of Information and Computer Science, Keio University. His current research interests are optical wireless communications and
LED communications.
Shinichiro Haruyama is a professor at Department of Information and Computer Science, Faculty of Science and Technology, Keio University, Yokohama,
Japan. He received an M.S. in engineering science from University of California at Berkeley in 1983 and a Ph.D. in computer
science from the University of Texas at Austin in 1990. He worked for Bell Laboratories of AT{&}T and Lucent Technologies,
U.S.A from 1991 to 1996, and for Sony Computer Science Laboratories, Inc. from 1998 to 2002. His research interests include
reconfigurable system, system design automation, wireless communication, and visible light communication.
Masao Nakagawa was born in Tokyo, Japan in 1946. He received the B.E., M.E. and Ph.D. degrees in electrical engineering from Keio University,
Yokohama, Japan, in 1969, 1971 and 1974 respectively. Since 1973, he has been with the Department of Electrical Engineering,
Keio University, where he is now a Professor. His research interests are in CDMA, consumer Communications, Mobile communications,
ITS (Intelligent Transport Systems), Wireless Home Networks, and Visible light Communication. He received 1989 IEEE Consumer
Electronics Society Paper Award, 1999-Fall Best Paper Award in IEEE VTC, IEICE Achievement Award in 2000, IEICE Fellow Award
in 2001. He was the executive committee chairman on International Symposium on Spread Spectrum Techniques and Applications
in 1992 and the technical program committee chairman of ISITA (International Symposium on Spread Spectrum Techniques and Applications)
in 1994. He is an editor of Wireless Personal Communications and was a guest editor of the special issues on “CDMA Networks
I, II, III and IV” published in IEEE JSAC in 1994 (I and II) and 1996 (III and IV). He chairs the Wireless Home Link sub-committee
in MMAC (Multimedia Mobile Access Communication Promotion Committee). 相似文献
3.
Let M be a closed smooth manifold M, and let f : M → M be a diffeomorphism. In this paper, we consider a nontrivial transitive set Λ of f . We show that if f has the C1-stably average shadowing property on Λ, then Λ admits a dominated splitting. 相似文献
4.
This paper gives a brief and systematic presentation of the computer simulation techniques of satellite communications, especially for a mobile satellite channel, based on a summarization of the author's exploration and experience in this area. It includes the equivalent complex baseband notation (ECBN) method, a very convenient mathematical form for software simulation; development of a multi-functional and expandable channel simulation system on a computer from L-band to Ka-band; channel impulse or frequency response estimation in real time by the technique burst-mode link analyser with least-squares algorithm (BMLA/LS), modelling and simulation of the channel fast fading due to multipath and shadowing; acquisition of the equivalent normalized binary signal-to-noise ratio (Eb/N0) data at the channel input; and bit-error rate (BER) evaluation by the directly error-counting approach and the computational approach at the channel output in simulation. 相似文献
5.
强链回归集与强跟踪性 总被引:1,自引:0,他引:1
为了研究强跟踪性,本文给出了强链回归集的定义.证明了:若度量空间上的一个连续自映射有强跟踪性,则其强链回归集与极限集相同. 相似文献
6.
The deployment of Small Cells in fourth generation (4G) communication systems is aimed at providing significant capacity improvements and higher availabilities. However, the design of Small Cell systems in indoor environments is especially challenging due to high shadowing attenuation induced by clutter and human blockage. This paper studies node cooperation and multiple relaying and proposes novel analytical formulas for the outage probability of cooperative Small Cells suffering from shadowing. The channel fading gains are modeled as correlated lognormal random variables, in order to reflect the properties of indoor propagation environments. Various cooperative strategies are considered, taking into account the use of one or two relays and different receiver combining techniques. In addition, the relative performance of each cooperative configuration and the benefit of cooperation over non-cooperation are investigated. Finally, interesting and useful insights are produced regarding the impact of the correlated lognormal environment parameters on the configuration of cooperative Small Cells. 相似文献
7.
Bazil Taha?AhmedEmail author Miguel Calvo?Ramón Leandro?De?Haro Ariet 《Wireless Personal Communications》2004,31(1-2):19-31
The uplink capacity and the interference statistics (mean and variance) of the sectors of the cigar-shaped W-CDMA microcell are studied. A model with eighteen sectors is used to analyze the uplink. The microcells are assumed to exist in a long tunnel with at least nine base stations. The hybrid model of propagation is used in the calculations. The capacity and the interference statistics of the sectors are studied in terms of the most important parameters: sector radius, specific attenuation factor, antenna sidelobe levels, bend losses and the power control standard deviation error. 相似文献
8.
9.
本文用胶子结构函数的遮蔽效应和末态作用分析了在p-A碰撞中粲偶素和b夸克偶素产额压低的实验数据,较好地描述了粲偶素和b夸克偶素产额的压低与A和X2的关系. 相似文献
10.
Biglieri Ezio Caire Giuseppe Taricco Giorgio Ventura-Traveset Javier 《Wireless Personal Communications》1998,6(1-2):39-68
In this paper, the performance of coding and diversity in narrowband wireless cellular systems affected by fading, shadowing and co-channel interference is analyzed. We consider low-order diversity, that can be practically realized for both coherent and differential phase shift keying. We assume that the shadowing random processes affecting all transmitted signals do not vary appreciably over the transmission duration. Fading, on the contrary, is assumed to vary more rapidly. Our main focus here is on outage probability. After choosing a performance indicator, its expectation is taken with respect to fading and co-channel interference, conditionally on shadowing. Hence, the resulting average performance indicator is a random variable. The probability that this random variable exceeds a specified threshold defines the outage probability. We consider as performance indicators (i) the channel cut-off rate R0 and (ii) the bit error rate Pb of an actual coded scheme. As we are interested in interference-limited, rather than power-limited systems, we evaluate both R0 and Pb for very high signal-to-noise ratios. Results are parameterized by the frequency reuse factor and the diversity order. 相似文献