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   4598篇
  免费   52篇
  国内免费   11篇
电工技术   56篇
综合类   3篇
化学工业   412篇
金属工艺   83篇
机械仪表   167篇
建筑科学   56篇
矿业工程   3篇
能源动力   108篇
轻工业   83篇
水利工程   28篇
石油天然气   8篇
无线电   511篇
一般工业技术   491篇
冶金工业   2111篇
原子能技术   18篇
自动化技术   523篇
  2023年   26篇
  2022年   57篇
  2021年   59篇
  2020年   51篇
  2019年   53篇
  2018年   64篇
  2017年   58篇
  2016年   81篇
  2015年   56篇
  2014年   66篇
  2013年   172篇
  2012年   88篇
  2011年   131篇
  2010年   110篇
  2009年   99篇
  2008年   101篇
  2007年   96篇
  2006年   89篇
  2005年   80篇
  2004年   60篇
  2003年   64篇
  2002年   74篇
  2001年   59篇
  2000年   63篇
  1999年   103篇
  1998年   709篇
  1997年   395篇
  1996年   288篇
  1995年   176篇
  1994年   124篇
  1993年   145篇
  1992年   58篇
  1991年   52篇
  1990年   62篇
  1989年   58篇
  1988年   42篇
  1987年   45篇
  1986年   35篇
  1985年   55篇
  1984年   22篇
  1983年   33篇
  1982年   39篇
  1981年   36篇
  1980年   39篇
  1979年   34篇
  1978年   21篇
  1977年   64篇
  1976年   111篇
  1975年   11篇
  1973年   11篇
排序方式: 共有4661条查询结果,搜索用时 15 毫秒
91.
Agriculture-based precise and accurate information needs to be disseminated promptly to farmers so that better decisions such as managing farm fields, making continuous and scientific changes in their production systems and grabbing advantage of market opportunities can be made. In this paper, mobile technology is assessed for the agriculture information dissemination system. A survey has been conducted to find out potential technology, related to the use of the Internet and mobile among farmers in the state of Punjab in India, to deliver agriculture-related information to them. Results show that agricultural information system needs to be developed based on the mass communication technology such as mobile systems. It is also noted that localization and native language of farmers are the concerns to be incorporated into the systems. It has been focused that the use of soft-computing techniques in conjunction with communication networks, for inferring the decision regarding best practices for agricultural activities, is helpful in the development of these systems.  相似文献   
92.
93.
94.
95.
The supply chains today have become vulnerable to frequent disruptions, and with continuing emphasis on efficiency, lacks robustness to deal with them. A part of the solution lies in forecasting the disruption beforehand and the other part in knowing which policies will suit such disrupted conditions best. Accurate and immediate forecasts are a must in a supply chain and hence play a huge role in stabilizing. This study compares the performance of three established forecasting methods (moving average, weighted moving average and exponential smoothing) as well as grey prediction method, during disruptions and stable situations. The experiments are performed in the form of discrete event simulation, on a four stage beer game settings. The results show that moving average and weighted moving average methods become incompetent during disruptions, and are useful only during stable times, when the demand hovers around a predefined mean value. Exponential smoothing and grey method seems to give better results during disruptions and also during stable times in upstream tiers. Grey prediction method in particular is the best method when the disruption frequency is high and also when the disruption impact is gradual rather than sudden.  相似文献   
96.
This paper presents the implementation of a novel InGaAs field-effect transistor (FET), using a ZnSe-ZnS-ZnMgS-ZnS stacked gate insulator, in a spatial wavefunction-switched (SWS) structural configuration. Unlike conventional FETs, SWS devices comprise two or more asymmetric coupled quantum wells (QWs). This feature enables carrier transfer vertically from one quantum well to another or laterally to the wells of adjacent SWS-FET devices by manipulation of the gate voltages (V g). Observation of an extra peak (near both accumulation and inversion regions) in the capacitance–voltage data in an InGaAs-AlInAs two-quantum-well SWS structure is presented as evidence of spatial switching. The peaks are attributed to the appearance of carriers first in the lower well and subsequently their transfer to the upper well as the gate voltage is increased. The electrical characteristics of a fabricated SWS InGaAs FET are also presented along with simulations of capacitance–voltage (CV) behavior, showing the effect of wavefunction switching between wells. Finally, logic operations involving simultaneous processing of multiple bits in a device, using coded spatial location of carriers in quantum well channels, are also described.  相似文献   
97.
This paper presents the fabrication of a negative-channel metal–oxide–semiconductor (NMOS) inverter based on quantum dot gate field-effect transistors (QDG-FETs). A QDG-FET produces one intermediate state in its transfer characteristic. NMOS inverters based on a QDG-FET produce three states in their transfer characteristic. The generation of the third state in the inverter characteristic makes this a promising circuit element for multivalued logic implementation. A circuit simulation result based on the Berkley simulation (BSIM) circuit model of the QDG-FET is also presented in this paper, predicting the fabricated device characteristic.  相似文献   
98.
Wireless Personal Communications - A relatively new area of research and development is Swarm Robotics. It is a part of the swarm intelligence field. In the proposed paper, we shall use swarm...  相似文献   
99.
In this article, two consecutive augmenting transistor P-channel metal oxide semiconductor (ATPMOS) configurations are proposed. These two ATPMOS configurations (ST ATPMOS and DT ATPMOS) are implemented on a 4 × 1 (multiplexer) mux circuit. Leakage power dissipation, dynamic power dissipation and delay performance parameters are calculated for both (ST ATPMOS and DT ATPMOS) ATPMOS configurations-based 4 × 1 mux circuits at different values of transistor’s width. Due to simulation, it is realised that the leakage power dissipation and dynamic power dissipation are reduced and delay is improved (delay is reduced) in the DT ATPMOS configuration-based mux circuit compared to the ST ATPMOS configuration-based mux circuit. The whole simulation process was carried out in 45-nm technology. The circuits were operated at 1-V power supply.  相似文献   
100.
The authors present a solution to the following problems related to architectural synthesis. (1) Given an input specification and a performance constraint, determine a lower bound number of resources (active and interconnect) required to execute the data flow graph while satisfying the performance constraint. (2) Determine a lower bound performance for executing an input specification for a given number of resources (active and interconnect). These bounds are close to the actual designs synthesized by several existing systems  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