首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6978篇
  免费   582篇
  国内免费   34篇
化学   5071篇
晶体学   28篇
力学   165篇
综合类   1篇
数学   1061篇
物理学   760篇
无线电   508篇
  2022年   40篇
  2021年   55篇
  2020年   75篇
  2019年   118篇
  2018年   90篇
  2017年   77篇
  2016年   232篇
  2015年   248篇
  2014年   265篇
  2013年   414篇
  2012年   331篇
  2011年   359篇
  2010年   314篇
  2009年   322篇
  2008年   351篇
  2007年   303篇
  2006年   284篇
  2005年   259篇
  2004年   289篇
  2003年   243篇
  2002年   295篇
  2001年   158篇
  2000年   151篇
  1999年   79篇
  1998年   70篇
  1997年   88篇
  1996年   102篇
  1995年   74篇
  1994年   86篇
  1993年   79篇
  1992年   73篇
  1991年   51篇
  1990年   55篇
  1989年   56篇
  1988年   54篇
  1987年   47篇
  1986年   47篇
  1985年   62篇
  1984年   76篇
  1983年   67篇
  1982年   83篇
  1981年   88篇
  1980年   77篇
  1979年   94篇
  1978年   82篇
  1977年   88篇
  1976年   87篇
  1975年   78篇
  1974年   80篇
  1973年   60篇
排序方式: 共有7594条查询结果,搜索用时 15 毫秒
991.
992.
This paper presents an in-depth study of the pros and cons of voltage-mode multiplexers for Gbps serial links and exploits the advantages of multiplexing in current domain. In addition, it proposes a new fully differential CMOS current-mode multiplexer where a high multiplexing speed is achieved by multiplexing at a low-impedance node. Multiplexing speed is further improved by inductive shunt peaking with active inductors. The differential configuration of the multiplexer minimizes the effect of common-mode disturbances, particularly those coupled from the power and ground rails. The flow of the output currents in the opposite directions minimizes the effect of electro-magnetic interference from channels, making the multiplexer particularly attractive for high-speed data transmission over long interconnects and printed-circuit-board (PCB) traces. The proposed multiplexer draws a constant current from the supply voltage, thereby minimizing both switching noise and noise injected to the substrate. A fully differential CMOS current-mode 8-to-l multiplexer has been implemented in TSMC’s 1.8 V 0.18 μm CMOS technology and analyzed using Spectre from Cadence Design Systems with BSIM3.3v device models. Simulation results demonstrate that the multiplexer offers sufficiently large eye-opening when multiplexed at 10 Gbps.Jean Jiang received the B.Eng. degree in Electrical Engineering from Wuhan University of Technology, Wuhan, China in 1995. From 1999 to 2001, she worked for Ericsson Global IT Services where she was a technical staff to maintain computer networks. Since 2002, she has been a research assistant with the System-on-Chip research lab of Ryerson University. She is currently a M.A.Sc candidate under the supervision of Dr. Fei Yuan in the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Canada. Her research interests are in analog CMOS circuit design for high-speed data communications. She was awarded the Ontario Graduate Scholarship (OGS) in 2003–2005 for academic excellence.Fei Yuan received the B.Eng. degree in electrical engineering from Shandong University, Jinan, China in 1985, the MASc. degree in chemical engineering and PhD. degree in electrical engineering from University of Waterloo, Waterloo, Ontario, Canada in 1995 and 1999, respectively.During 1985–1989, he was a Lecturer in the Department of Electrical Engineering, Changzhou Institute of Technology, Jiangsu, China. In 1989 he was a Visiting Professor at Humber College of Applied Arts and Technology, Toronto, Canada. During 1989–1994, he worked for Paton Controls Limited, Sarnia, Ontario, Canada as a Controls Engineer. Since July 1999 he has been with the Department of Electrical and Computer Engineering, Ryerson University, Toronto, Ontario, Canada, where he is currently an Associate Professor and the Associate Chair for Undergraduate Studies and Faculty Affairs. He is the co-author of the book “Computer Methods for Analysis of Mixed-Mode Switching Circuits” (Kluwer Academic Publishers, 2004, with Ajoy Opal). Dr. Yuan received an “Excellence of Teaching” award from Changzhou Institute of Technology in 1988, a post-graduate scholarship from Natural Science and Engineering Research Council (NSERC) of Canada during 1997–1998. He is a senior member of IEEE and a registered professional engineer in the province of Ontario, Canada.  相似文献   
993.
The synthesis, characteristics, and properties of amphipatic, water-soluble dendrigrafts, with a polystyrene core and polystyrene-b-poly(methyl vinyl ether) (PS-b-PMVE) diblock as external branches, are described. The dendrigrafts are observed by AFM and TEM as egglike or long cylindrical objects which can self-organize intramolecularly in segregated subdomains forming flowerlike or strings of flowerlike objects. In organic solvents the dendrigrafts behave as fully soluble isolated macromolecules and show in water a low critical solubility temperature (LCST) at t > 30 degrees C. The ability of the amphiphilic PS-b-PMVE dendrigrafts to complex and transport in water organic (pyrene) and metallo-organic (manganese tetraphenyl porphyrin) molecules is investigated. The possibility to stabilize the high oxidation state of metallo-porphyrin complexes through their encapsulation into the dendrigraft is shown.  相似文献   
994.
995.
996.
997.
Particular polarisation of surface waves is demonstrated using hyperfine dipolar magnetic transitions. We compare the relative intensities of F = 2, M = 2 ? F = 1, M = 1 andF = 2, M =-2 ? F = 1, M = -1 lines in the fundamental state of 87Rb  相似文献   
998.
Laboratory extraction test conditions do not accurately reflect the conditions within a land disposal facility. Current procedures lack the precision required for the results to be used as the basis for decision making.  相似文献   
999.
Fluorescence detected Lamb dips have been observed in D2CO. The D2CO was placed inside a CO2 waveguide laser cavity and fluorescence detection was performed with a InSb detector. Possible explanations for this observation are discussed.  相似文献   
1000.
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