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   6941篇
  免费   196篇
  国内免费   29篇
电工技术   103篇
综合类   2篇
化学工业   1423篇
金属工艺   287篇
机械仪表   184篇
建筑科学   104篇
矿业工程   8篇
能源动力   311篇
轻工业   271篇
水利工程   58篇
石油天然气   14篇
无线电   995篇
一般工业技术   1508篇
冶金工业   861篇
原子能技术   72篇
自动化技术   965篇
  2023年   69篇
  2022年   150篇
  2021年   178篇
  2020年   156篇
  2019年   145篇
  2018年   233篇
  2017年   189篇
  2016年   197篇
  2015年   108篇
  2014年   204篇
  2013年   403篇
  2012年   228篇
  2011年   304篇
  2010年   235篇
  2009年   277篇
  2008年   247篇
  2007年   202篇
  2006年   212篇
  2005年   154篇
  2004年   127篇
  2003年   130篇
  2002年   129篇
  2001年   126篇
  2000年   129篇
  1999年   112篇
  1998年   264篇
  1997年   182篇
  1996年   131篇
  1995年   130篇
  1994年   104篇
  1993年   133篇
  1992年   108篇
  1991年   97篇
  1990年   84篇
  1989年   75篇
  1988年   72篇
  1987年   75篇
  1986年   88篇
  1985年   106篇
  1984年   99篇
  1983年   95篇
  1982年   78篇
  1981年   63篇
  1980年   49篇
  1979年   46篇
  1978年   49篇
  1977年   62篇
  1976年   82篇
  1975年   43篇
  1973年   42篇
排序方式: 共有7166条查询结果,搜索用时 15 毫秒
31.
Various reaction variables in the hydrogen peroxide oxidation of starch in the presence of UV light have been investigated. Higher carboxyl and carbonyl contents of oxystarches were obtained under acidic than under alkaline conditions. Extent of oxidation was found to increase with time. Increasing the concentration of hydrogen peroxide results in an increase in the carboxyl and carbonyl contents. Apparently, air has no effect on the degree of oxidation whereas, oxygen seems to accelerate it.  相似文献   
32.
An amusing anecdote that is old (having appeared in Esquire and Reader's Digest over half a century ago) concerns a man who experienced severe motion sickness during train travel whenever he would ride backwards, i.e., sat facing the rear of the train; so he learned to exchange such a seat by requesting the passenger sitting opposite to him. When he got off the train very sick and nauseated one day, his friend receiving him at the train station asked what was wrong. He replied that he had been riding the train backwards. Why didn't you ask the person sitting across from you to change seats with you? asked his friend. How could I, said the traveler, There wasn't anybody in that seat.  相似文献   
33.
34.
35.
36.
In this paper TCAD-based simulation of a novel insulated shallow extension (ISE) cylindrical gate all around (CGAA) Schottky barrier (SB) MOSFET has been reported,to eliminate the suicidal ambipolar behavior (bias-dependent OFF state leakage current) of conventional SB-CGAA MOSFET by blocking the metal-induced gap states as well as unwanted charge sharing between source/channel and drain/channel regions.This novel structure offers low barrier height at the source and offers high ON-state current.The ION/IoFF of ISE-CGAA-SB-MOS-FET increases by 1177 times and offers steeper subthreshold slope (~60 mV/decade).However a little reduction in peak cut off frequency is observed and to further improve the cut-off frequency dual metal gate architecture has been employed and a comparative assessment of single metal gate,dual metal gate,single metal gate with ISE,and dual metal gate with ISE has been presented.The improved performance of Schottky barrier CGAA MOSFET by the incorporation of ISE makes it an attractive candidate for CMOS digital circuit design.The numerical simulation is performed using the ATLAS-3D device simulator.  相似文献   
37.
Wireless Personal Communications - The efficient management of resource sharing plays a crucial role in the cloud execution environment. The constraints such as heterogeneity and dynamic nature of...  相似文献   
38.
An analytical model of Al0.15Ga0.85N/GaN modulation doped field effect transistor (MODFET), which uses an accurate velocity field relationship and incorporates the dominant effect of piezoelectric polarization induced charge at the AlGaN/GaN interface is presented. The effect of traps has also been taken into account. The calculated DC characteristics are in excellent agreement with the measured data. The model is extended to predict the microwave performance of the device. High current levels (>500 mA/mm), large transconductance (160.83 mS/mm) and a high cutoff frequency (9.6 GHz) have been achieved analytically and are in close agreement with the experimental data.  相似文献   
39.
A grounded lamination gate (GLG) structure for high-/spl kappa/ gate-dielectric MOSFETs is proposed, with grounded metal plates in the spacer oxide region. Two-dimensional device simulations performed on the new structure demonstrate a significant improvement with respect to the threshold voltage roll-off with increasing gate-dielectric constant (due to parasitic internal fringe capacitance), keeping the equivalent oxide thickness same. A simple fabrication procedure for the GLG MOSFET is also presented.  相似文献   
40.
This paper analyzes the effect of temperature variation on various device architectures i.e. Insulated Shallow Extension Silicon On Nothing (ISESON), ISE and SON MOSFET using ATLAS 3D device simulator for 45 nm gate length. The simulation results obtained with the ATLAS has been validated by comparing it with reported experimental data of SON MOSFET. The simulation results demonstrate that out of three device designs, the ISESON MOSFET is the most suitable device for high speed, low voltage and high temperature applications. The integration of ISE and SON onto the conventional bulk MOSFET leads to the enhancement in analog device performance in terms of device efficiency (gm/Ids), device gain (gm/gd), output resistance (Rout) and early voltage (Vea).  相似文献   
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