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   3796篇
  免费   227篇
  国内免费   36篇
电工技术   60篇
综合类   67篇
化学工业   845篇
金属工艺   165篇
机械仪表   151篇
建筑科学   202篇
矿业工程   42篇
能源动力   249篇
轻工业   516篇
水利工程   22篇
石油天然气   38篇
武器工业   2篇
无线电   205篇
一般工业技术   575篇
冶金工业   350篇
原子能技术   48篇
自动化技术   522篇
  2024年   15篇
  2023年   41篇
  2022年   73篇
  2021年   108篇
  2020年   136篇
  2019年   119篇
  2018年   164篇
  2017年   148篇
  2016年   169篇
  2015年   101篇
  2014年   170篇
  2013年   390篇
  2012年   205篇
  2011年   206篇
  2010年   176篇
  2009年   221篇
  2008年   174篇
  2007年   160篇
  2006年   126篇
  2005年   80篇
  2004年   94篇
  2003年   115篇
  2002年   161篇
  2001年   126篇
  2000年   67篇
  1999年   55篇
  1998年   133篇
  1997年   69篇
  1996年   55篇
  1995年   28篇
  1994年   28篇
  1993年   18篇
  1992年   10篇
  1991年   15篇
  1990年   10篇
  1989年   11篇
  1988年   6篇
  1987年   7篇
  1986年   9篇
  1985年   11篇
  1984年   7篇
  1983年   11篇
  1982年   4篇
  1980年   3篇
  1979年   3篇
  1978年   4篇
  1976年   5篇
  1974年   2篇
  1973年   2篇
  1965年   3篇
排序方式: 共有4059条查询结果,搜索用时 15 毫秒
91.
The acidity constants, pK(a) values for protonation of some substituted thiazole derivatives were calculated by using AM1 and PM3 basis sets of semi-empirical methods and B3LYP/6-31G(d) basis sets of density functional theory (DFT) calculated physical and thermodynamic parameters. Correlation search among the experimental and calculated acidity constants, pK(a) values, revealed that the best correlation exist between the experimental and ab initio calculated pK(a) values with a regression of R(2)=0.98.  相似文献   
92.
In this paper we present storage structures for efficiently processing XML path queries on healthcare data stored in smart cards using XML format. In the design of the storage structures that we present, properties of healthcare data and fundamental types of queries on the healthcare data are taken into account as well as the constraints of the smart cards. We compare the space and time efficiency of the proposed storage structures for various types of queries.  相似文献   
93.
利用近红外光谱法测定了烷烃分子的分子连接指数 ,并探讨了混合烃分子连接指数与单烃分子连接指数之间的关系。结果表明 :单烷烃分子连接指数具有可测性 ,而混合烃分子连接指数与单烃的分子连接指数之间存在线性加和的关系  相似文献   
94.
分析了传统单一C/S结构的不足以及新型N层B/S结构的优越性,阐述了基于Web技术的网络管理是未来网络管理的发展趋势,结合现代软件开发中的软件复用理论,提出并设计实现了一种基于COM技术与N层B/S结构的SNMP网管系统模型,着重叙述了该系统中所使用的关键技术与设计要点。  相似文献   
95.
快速移植的微型呼叫中心设计   总被引:1,自引:0,他引:1  
介绍了如何构建微型呼叫中心的系统设计及组成,给出了相应的系统结构,并对微型呼叫中心核心部分的设计进行了描述。该设计方案的优点是投资少,软件开发和扩展均较容易,实施快速,特别适合接入线路不多的微型呼叫中心。  相似文献   
96.
A multimedia presentation is a synchronized, and possibly interactive, delivery of multimedia data to users. We expect that, in the future, multimedia presentations will be stored into and queried from multimedia databases. In an earlier work, we have designed a graphical query language, called GVISUAL, that allows users to query multimedia presentations based on content information. In this paper, we discuss GVISUAL query processing techniques for multimedia presentations. More specifically, we discuss the translation of GVISUAL queries into an operator-based language, called O-Algebra, with three new operators, and efficient implementations of the new O-Algebra operators using a coding system called nodecodes.  相似文献   
97.
High throughput biological data need to be processed, analyzed, and interpreted to address problems in life sciences. Bioinformatics, computational biology, and systems biology deal with biological problems using computational methods. Clustering is one of the methods used to gain insight into biological processes, particularly at the genomics level. Clearly, clustering can be used in many areas of biological data analysis. However, this paper presents a review of the current clustering algorithms designed especially for analyzing gene expression data. It is also intended to introduce one of the main problems in bioinformatics – clustering gene expression data – to the operations research community.  相似文献   
98.
The main purpose of this study was to investigate the views of primary students about interactive whiteboard [IWB] use in their classes from attitudinal and pedagogical perspectives. Research was designed as an empirical approach to phenomenology. Data was collected from fifty primary students (fourth to eighth) through focus group interviews. Nvivo 9 qualitative data analysis software was used to analyze data. Results showed that students like instruction with IWB especially for such reasons/capabilities as practical and economical use, better visual presentation, and test-based use. Students were predominantly uncomfortable with the technical problems. They believed that instruction with IWB positively impacted their learning especially because of visualization and contextualization, effective presentation, test-based use, and motivational factors. Finally it was inferred that IWBs were not used to their full potential, and both technical problems and common practices indicated that teachers were still at an initial stage of transmission to instruction with IWB and they needed both technical and pedagogical training.  相似文献   
99.
This paper considers the problem of multirobot coordination in pick-and-place tasks on a conveyor band. The robot team is composed of identical robots with mutually exclusive, but neighboring workspaces. The products are fed in at one end of the band, move through each workspace sequentially until being picked up and are collected at the other end—if not picked up interim. Each robot has the same task—that is picking up and packaging as many products as possible. We propose an approach based on noncooperative game theory where each robot uses local observations of the conveyor band and their neighbors' actions in order to decide on its actions. The developed algorithm has been implemented and tested in a simulated manufacturing environment using Webots. Results obtained from the simulations are analyzed using a variety of statistical performance measures.  相似文献   
100.
Multiscale modeling and integration of physiological models carry challenges due to the complex nature of physiological processes. High coupling within and among scales present a significant challenge in constructing and integrating multiscale physiological models. In order to deal with such challenges in a systematic way, there is a significant need for an information technology framework together with related analytical and computational tools that will facilitate integration of models and simulations of complex biological systems. Physiological Model Simulation, Integration and Modeling Framework (Phy-SIM) is an information technology framework providing the tools to facilitate development, integration and simulation of integrated models of human physiology. Phy-SIM brings software level solutions to the challenges raised by the complex nature of physiological systems. The aim of Phy-SIM, and this paper is to lay some foundation with the new approaches such as information flow and modular representation of the physiological models. The ultimate goal is to enhance the development of both the models and the integration approaches of multiscale physiological processes and thus this paper focuses on the design approaches that would achieve such a goal.  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