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   10382篇
  免费   222篇
  国内免费   71篇
电工技术   206篇
技术理论   1篇
综合类   70篇
化学工业   462篇
金属工艺   349篇
机械仪表   125篇
建筑科学   123篇
矿业工程   49篇
能源动力   64篇
轻工业   223篇
水利工程   48篇
石油天然气   79篇
武器工业   4篇
无线电   413篇
一般工业技术   254篇
冶金工业   78篇
原子能技术   106篇
自动化技术   8021篇
  2024年   10篇
  2023年   43篇
  2022年   102篇
  2021年   141篇
  2020年   103篇
  2019年   81篇
  2018年   75篇
  2017年   84篇
  2016年   73篇
  2015年   89篇
  2014年   313篇
  2013年   282篇
  2012年   885篇
  2011年   2386篇
  2010年   1174篇
  2009年   1008篇
  2008年   717篇
  2007年   635篇
  2006年   474篇
  2005年   591篇
  2004年   527篇
  2003年   582篇
  2002年   274篇
  2001年   4篇
  2000年   5篇
  1999年   2篇
  1998年   2篇
  1997年   4篇
  1996年   1篇
  1995年   2篇
  1994年   2篇
  1986年   1篇
  1980年   2篇
  1959年   1篇
排序方式: 共有10000条查询结果,搜索用时 62 毫秒
31.
32.
The selection of valuable features is crucial in pattern recognition. In this paper we deal with the issue that part of features originate from directional instead of common linear data. Both for directional and linear data a theory for a statistical modeling exists. However, none of these theories gives an integrated solution to problems, where linear and directional variables are to be combined in a single, multivariate probability density function. We describe a general approach for a unified statistical modeling, given the constraint that variances of the circular variables are small. The method is practically evaluated in the context of our online handwriting recognition system frog on hand and the so-called tangent slope angle feature. Recognition results are compared with two alternative modeling approaches. The proposed solution gives significant improvements in recognition accuracy, computational speed and memory requirements.  相似文献   
33.
The Apollonius Tenth Problem, as defined by Apollonius of Perga circa 200 B.C., has been useful for various applications in addition to its theoretical interest. Even though particular cases have been handled previously, a general framework for the problem has never been reported. Presented in this paper is a theory to handle the Apollonius Tenth Problem by characterizing the spatial relationship among given circles and the desired Apollonius circles. Hence, the given three circles in this paper do not make any assumption regarding on the sizes of circles and the intersection/inclusion relationship among them. The observations made provide an easy-to-code algorithm to compute any desired Apollonius circle which is computationally efficient and robust.  相似文献   
34.
Years have lapsed since the inauguration of the first Wireless Application Protocol (WAP) application. One of the main reasons for the lukewarm response so far may be attributed to the lack of a “Killer” application. Many companies and developers have attempted to replicate email services (an Internet Killer appplication) within the WAP realm, but till now, no significant success has been reported. This paper will first discuss on the key functions which are lacking in the present WAP-email service, and which are arguably necessary if a much larger user base is to be attracted to these services. A new system will be proposed which can enable the user to send files residing in a remote personal computer (PC) as attachments to his emails using WAP-enabled mobile devices. The implementation of the system will be presented in details. Issue relating to the connection to various types of email servers and the security of the system will also be addressed in the paper.  相似文献   
35.
36.
The certainty equivalence approach to adaptive control is commonly used with two types of identifiers: passivity-based identifiers and swapping identifiers. The “passive” (also known as “observer-based”) approach is the prevalent identification technique in existing results on adaptive control for PDEs but has so far not been used in boundary control problems. The swapping approach, prevalent in finite-dimensional adaptive control is employed here for the first time in adaptive control of PDEs. For a class of unstable parabolic PDEs we prove a separation principle result for both the passive and swapping identifiers combined with the backstepping boundary controllers. The result is applicable in any dimension. For physical reasons we restrict our attention to dimensions no higher than three. The results of the paper are illustrated by simulations.  相似文献   
37.
38.
Time-domain limitations due to right half-plane zeros and poles in linear multivariable control systems are studied. Lower bounds on the interaction are derived. They show not only how the location of zeros and poles are critical in multivariable systems, but also how the zero and pole directions influence the performance. The results are illustrated on the quadruple-tank process, which is a new multivariable laboratory process.  相似文献   
39.
介绍了ICP等离子体光谱仪的原理及测定高纯氧化铁中铝、钙、硫、钾、镁、锰、钠和钛等8种杂质元素的分析方法,考察了样品的溶解方案及工作曲线的选择,确定了仪器最佳工作条件和方法检出限。  相似文献   
40.
This paper presents a novel concept for power quality hardware and software architecture. Software tools related to detection, classification and characterization of power quality events can be integrated into a Distribution Control Center in which the interconnection between different subsystems is being carried out through the Internet allowing flexibility to the system. This system is implemented using wavelet analysis applied in all proposed algorithms. Different power quality events are taken as examples to illustrate the capabilities of the proposed method. The obtained results reveal that the proposed architecture is feasible to be implemented as an integral part of a control center system.The proposed system has the property of fast and accurate detection and classification of any power quality disturbance event and introduces a new PQ index determination that allows characterizing any type of disturbance including the non-periodic signals.  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