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   357445篇
  免费   26019篇
  国内免费   13809篇
电工技术   19498篇
技术理论   57篇
综合类   21787篇
化学工业   60507篇
金属工艺   20052篇
机械仪表   22776篇
建筑科学   27822篇
矿业工程   11668篇
能源动力   10427篇
轻工业   20327篇
水利工程   5790篇
石油天然气   24132篇
武器工业   2841篇
无线电   39113篇
一般工业技术   42239篇
冶金工业   19483篇
原子能技术   3430篇
自动化技术   45324篇
  2024年   1371篇
  2023年   5461篇
  2022年   9380篇
  2021年   13300篇
  2020年   10353篇
  2019年   8493篇
  2018年   9744篇
  2017年   10962篇
  2016年   9800篇
  2015年   13045篇
  2014年   16858篇
  2013年   20410篇
  2012年   21586篇
  2011年   23994篇
  2010年   20678篇
  2009年   19871篇
  2008年   19429篇
  2007年   18793篇
  2006年   19823篇
  2005年   17437篇
  2004年   11355篇
  2003年   10237篇
  2002年   9479篇
  2001年   8629篇
  2000年   8739篇
  1999年   10360篇
  1998年   8650篇
  1997年   7164篇
  1996年   6737篇
  1995年   5673篇
  1994年   4613篇
  1993年   3293篇
  1992年   2647篇
  1991年   2058篇
  1990年   1589篇
  1989年   1305篇
  1988年   1078篇
  1987年   715篇
  1986年   548篇
  1985年   359篇
  1984年   256篇
  1983年   216篇
  1982年   209篇
  1981年   135篇
  1980年   140篇
  1979年   70篇
  1978年   34篇
  1977年   38篇
  1976年   55篇
  1975年   20篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
81.
Laguerre Functional Model has many advantages such as good approximation capability for the variances of system time‐delay, order and other structural parameters, low computational complexity, and the facility of online parameter identification, etc., so this model is suitable for complex industrial process control. A series of successful applications have been gained in linear and non‐linear predictive control fields by the control algorithm based on Laguerre Functional Model, however, former researchers have not systemically brought forward the theoretical analyses of the stability, robustness, and steady‐state performance of this algorithm, which are the keys to guarantee the feasibility of the control algorithm fundamentally. Aimed at this problem, we introduce the principles of the Incremental Mode Linear Laguerre Predictive Control (IMLLPC) algorithm, and then systemically propose the theoretical analyses and proofs of the stability and robustness of the algorithm, in addition, we also put forward the steady‐state performance analysis. At last, the control performances of this algorithm on two different physical industrial plants are presented in detail, and a number of experimental results validate the feasibility and superiority of IMLLPC algorithm. Copyright © 2005 John Wiley & Sons, Ltd.  相似文献   
82.
STUDYONRESIDUESOF~(14)C-FENITROTHIONINMODELRICE-FISHECOSYSTEMANDFIELDRICE-FISHECOSYSTEMZhangZhongliang(张仲良);WangHuaxin(王化新);G?..  相似文献   
83.
用于重离子核反应实验测量的纵向电场气体电离室   总被引:1,自引:0,他引:1  
本文报道了一种新型的大动态范围,多叠层探测器系统组件之一的纵向电场气体电离室的构造,性能和在中能得离子核反应实验中的应用。  相似文献   
84.
The manufacturing message specification (MMS) is the ISO standard communication protocol specific to manufacturing. To analyze MMS design and performance, service unit automats are introduced to represent individual MMS services, while service connection Petri Nets (PNs) are constructed from these automats to describe MMS service connections and processes. This approach makes MMS protocol specification and analysis possible in terms of well-developed concepts and methods in PN theory. It leads to a distributed and hierarchical model of MMS software system by integrating service connection PNs. A generalized stochastic PN for MMS performance evaluation is obtained by incorporating service parameters and time factors into the model. A technique based on T-invariants is used to simplify the performance analysis  相似文献   
85.
水利作为基础产业,一个基本要求就是要自我维持,自我发展,这就要求人们树立强烈的紧迫感、危机感和赶超意识,按照社会主义市场经济要求,建立水利良性发展机制,调整水利产业结构,大力兴办经济实体,发展壮大水利经济实力,形成水利为社会,社会办水利的新格局。  相似文献   
86.
We consider the problem of turbo multiuser detection for synchronous and asynchronous code-division multiple-access (CDMA) in the presence of unknown users. Turbo multiuser detectors, as previously developed, typically require knowledge of the signature waveforms of all of the users in the system and ignore users whose signature sequences are unknown, e.g., users outside the cell. We develop turbo multiuser detection for CDMA uplink systems and other environments in which the receiver has knowledge of the signature waveforms of only K˘⩽ K users. Subspace techniques are used to estimate the interference from the unknown-users and the interference estimate is subtracted from the received signal. We see that the new receiver significantly outperforms the conventional turbo multiuser receiver for moderate and high signal-to-noise ratios. It is also seen that the traditional turbo receiver provides little gain through iteration when unknown users are present  相似文献   
87.
88.
89.
Two new methods are proposed to implement the exclusive-OR and exclusive-NOR functions on the transistor level. The first method uses non-complementary signal inputs and the least number of transistors. The other one improves the performance of the prior method but two more transistors are utilized. Both of them have been fully simulated by HSPICE on a SUN SPARC 2 workstation  相似文献   
90.
A two-dimensional numerical simulation including a new interface state generation model has been developed to study the performance variation of a LDD MOSFET after a dc voltage stress. The spatial distribution of hot carrier induced interface states is calculated with a breaking silicon-hydrogen bond model. Mobility degradation and reduction of conduction charge due to interface traps are considered. A 0.6 μm LDD MOSFET was fabricated. The drain current degradation and the substrate current variation after a stress were characterized to compare the simulation. A reduction of the substrate current at Vg ≃0.5 Vd in a stressed device was observed from both the measurement and the simulation. Our study reveals that the reduction is attributed to a distance between a maximum channel electric field and generated interface states  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