全文获取类型
收费全文 | 1899960篇 |
免费 | 50756篇 |
国内免费 | 19410篇 |
专业分类
电工技术 | 52283篇 |
技术理论 | 37篇 |
综合类 | 26289篇 |
化学工业 | 329112篇 |
金属工艺 | 83251篇 |
机械仪表 | 65880篇 |
建筑科学 | 73175篇 |
矿业工程 | 22519篇 |
能源动力 | 59065篇 |
轻工业 | 140315篇 |
水利工程 | 21506篇 |
石油天然气 | 59256篇 |
武器工业 | 2797篇 |
无线电 | 232111篇 |
一般工业技术 | 332493篇 |
冶金工业 | 219868篇 |
原子能技术 | 37549篇 |
自动化技术 | 212620篇 |
出版年
2022年 | 19208篇 |
2021年 | 28433篇 |
2020年 | 21386篇 |
2019年 | 22579篇 |
2018年 | 26761篇 |
2017年 | 27486篇 |
2016年 | 31123篇 |
2015年 | 29974篇 |
2014年 | 44138篇 |
2013年 | 105943篇 |
2012年 | 57396篇 |
2011年 | 72824篇 |
2010年 | 62898篇 |
2009年 | 69889篇 |
2008年 | 64530篇 |
2007年 | 61770篇 |
2006年 | 63386篇 |
2005年 | 56692篇 |
2004年 | 52649篇 |
2003年 | 51168篇 |
2002年 | 49305篇 |
2001年 | 45824篇 |
2000年 | 44637篇 |
1999年 | 45811篇 |
1998年 | 64921篇 |
1997年 | 52754篇 |
1996年 | 46018篇 |
1995年 | 38349篇 |
1994年 | 35073篇 |
1993年 | 33681篇 |
1992年 | 29065篇 |
1991年 | 25760篇 |
1990年 | 25643篇 |
1989年 | 24493篇 |
1988年 | 22903篇 |
1987年 | 20779篇 |
1986年 | 20149篇 |
1985年 | 23356篇 |
1984年 | 23017篇 |
1983年 | 20921篇 |
1982年 | 19707篇 |
1981年 | 19842篇 |
1980年 | 18417篇 |
1979年 | 18853篇 |
1978年 | 18008篇 |
1977年 | 18434篇 |
1976年 | 20451篇 |
1975年 | 16221篇 |
1974年 | 15714篇 |
1973年 | 15832篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Meghelli M. Rylyakov A.V. Zier S.J. Sorna M. Friedman D. 《Solid-State Circuits, IEEE Journal of》2003,38(12):2147-2154
A 43-Gb/s receiver (Rx) and transmitter (Tx) chip set for SONET OC-768 transmission systems is reported. Both ICs are implemented in a 0.18-/spl mu/m SiGe BiCMOS technology featuring 120-GHz f/sub T/ and 100 GHz f/sub max/. The Rx includes a limiting amplifier, a half-rate clock and data recovery unit, a 1:4 demultiplexer, a frequency acquisition aid, and a frequency lock detector. Input sensitivity for a bit-error rate less than 10/sup -9/ is 40 mV and jitter generation better than 230 fs rms. The IC dissipates 2.4 W from a -3.6-V supply voltage. The Tx integrates a half-rate clock multiplier unit with a 4:1 multiplexer. Measured clock jitter generation is better than 170 fs rms. The IC consumes 2.3 W from a -3.6-V supply voltage. 相似文献
992.
993.
L. A. Dombrovskii 《High Temperature》2003,41(6):819-824
Theoretical models of heat transfer by radiation through a vapor gap under conditions of film boiling of liquid are treated, namely, a general wave model for a gap of arbitrary thickness and an approximate model of geometrical optics. Calculations are performed of heat transfer by radiation under conditions of film boiling of water on hot surfaces of refractory metal and molten oxide. Practical recommendations are given to calculate the distribution of the power of absorbed radiation in a water layer. 相似文献
994.
995.
M. Riad Manaa Laurence E. Fried Evan J. Reed 《Journal of Computer-Aided Materials Design》2003,10(2):75-97
In this article, we review recent atomistic computational techniques to study the electronic structure aspects and chemistry
of energetic materials at high-pressure and/or high temperature. While several mechanisms have been proposed for the initial
events of energetic materials at high-pressure, we explore the validity of a proposed shear-induced local metallization via
molecular bond bending in the insensitive explosive TATB. We study the effect of high-stress (both uniform and uniaxial) on
the electronic energy band-gap and the first chemical event of a prototypical energetic material, that of nitromethane. We
also determine chemical reactions rate laws and decomposition mechanisms from a quantum-based molecular dynamics simulation
of HMX, a widely used explosive material, at conditions of high density and temperature similar to that encounter under detonation.
Finally, we review a new multi-scale computational tool recently developed to model the shock-induced chemistry of energetic
materials at the atomistic level, and report its applicability to shocked solid nitromethane.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
996.
Th. Heins 《e & i Elektrotechnik und Informationstechnik》2003,120(11):400-401
An enterprise is not just a tall shiny building or a collection of facilities. Rather, it is the sum of individuals collectively engaged in a common pursuit. From an information and communications perspective, this realization changes everything. By looking at the enterprise as a boundary-less collection of individuals who sometimes work in an office, sometimes at home, and sometimes on the road, we need new communications concepts designed to work with and enhance our complex home and work lives. 相似文献
997.
998.
In this practical case study the method of self-organizing map (SOM) neural net is applied to analyze a CMOS process problem, where the device under study is a heartbeat rate monitor integrated circuit. The wafer yield is analyzed against the process control monitoring (PCM) parameter measurement values. The SOM efficiently reduces the parameter space dimensions and helps in visualizing the different parameter relations. This makes it possible to identify the most probable PCM parameters affecting the yield. Those were found out to be NMOS transistor drain current and aluminium sheet resistance. 相似文献
999.
1000.
I. I. Abramov I. A. Goncharenko S. A. Ignatenko A. V. Korolev E. G. Novik A. I. Rogachev 《Russian Microelectronics》2003,32(2):97-104
The concept and structure of the NANODEV simulation software are described. NANODEV deals with nanoelectronic devices that exploit single-electron tunneling, resonant tunneling, or quantum interference. It can use both simplified and sophisticated models and enables one to evaluate a wide variety of devices and configurations. The capabilities of NANODEV are illustrated by examples. 相似文献