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   4361篇
  免费   304篇
  国内免费   224篇
电工技术   100篇
技术理论   1篇
综合类   623篇
化学工业   80篇
金属工艺   48篇
机械仪表   217篇
建筑科学   419篇
矿业工程   87篇
能源动力   12篇
轻工业   152篇
水利工程   65篇
石油天然气   21篇
武器工业   15篇
无线电   342篇
一般工业技术   142篇
冶金工业   60篇
原子能技术   4篇
自动化技术   2501篇
  2024年   1篇
  2023年   20篇
  2022年   46篇
  2021年   62篇
  2020年   79篇
  2019年   58篇
  2018年   64篇
  2017年   97篇
  2016年   103篇
  2015年   111篇
  2014年   265篇
  2013年   236篇
  2012年   360篇
  2011年   330篇
  2010年   365篇
  2009年   372篇
  2008年   426篇
  2007年   402篇
  2006年   347篇
  2005年   307篇
  2004年   216篇
  2003年   195篇
  2002年   138篇
  2001年   96篇
  2000年   68篇
  1999年   52篇
  1998年   24篇
  1997年   10篇
  1996年   13篇
  1995年   6篇
  1994年   9篇
  1993年   1篇
  1992年   1篇
  1991年   1篇
  1990年   2篇
  1989年   4篇
  1983年   1篇
  1980年   1篇
排序方式: 共有4889条查询结果,搜索用时 15 毫秒
1.
The supply of electrical energy is critical to convenient and comfortable living. However, people consume a large amount of energy, contributing to an energy crisis and global warming, and damaging some ecological cycles. Residential electricity consumption has greater elasticity than industrial and business consumption; it therefore has high energy-saving potential. This work establishes an automated platform, which provides information about residential electricity consumption in each city in Taiwan. Machine learning was used to forecast future residential electricity demand. A nature-inspired optimization method was applied to enhance the accuracy of the best machine learner, yielding an even better hybrid ensemble model. Performance measures indicate that the resulting model is accurate and provides effective information for reference. An automatic web-based system based on the model was combined with a web crawler and scheduled to run automatically to provide information on monthly residential electricity consumption in each county and city. By providing energy consumption information across the country, power providers and government can discuss policy and set different goals for energy use. The results of this study can facilitate the early implementation of energy-saving and carbon emission-reducing in cities and aid utility companies in establishing energy conservation guidelines.  相似文献   
2.
李鹏  王先科 《中州煤炭》2022,(9):276-278
为了方便煤炭的运输,某矿使用了矿用履带式搬运车。履带运输车解决了轮式运输车在恶劣道路条件下不能行走的问题,这种履带车是一种新型的运输工具,其特点是体积小、转弯灵活、动力强大,可在不受场地限制的情况下轻松通过狭窄的地方,能有效解决山区、土壤、陡坡等恶劣条件下物料的运输问题,适合普通运输车辆无法通行的地方。介绍了矿用履带式搬运车的主要结构以及工作原理,并给出了实际应用中应注意的事项。  相似文献   
3.
Beginning in 2013, sites at the 128-m bottom depth contour were added to the sampling design of the annual Lake Michigan bottom trawl survey for prey fish, which has been conducted by the U.S. Geological Survey Great Lakes Science Center (GLSC) each fall since 1973, to better assess fish depth distributions in a changing ecosystem. The standard sampling design included bottom depths from 9 to 110 m, although the GLSC also sporadically conducted bottom trawl tows at the 128-m bottom depth contour during 1973–1988. Enactment of this new sampling design in 2013 revealed that mean biomass density of deepwater sculpins (Myoxocephalus thompsonii) at the 128-m depth exceeded the sum of mean biomass densities at shallower depths, indicating that the bulk of the deepwater sculpin population is residing in waters deeper than 110 m. Thus, our findings supported the hypothesis that the depth distribution of the deepwater sculpin population had shifted to deeper waters beginning in 2007, thereby explaining, at least in part, the marked decline in deepwater sculpin abundance since 2006 based on the standard sampling design. In contrast, our results did not support the hypothesis that the slimy sculpin (Cottus cognatus) population had shifted to deeper waters sometime after 2000. A portion of the burbot (Lota lota) population may have also shifted in depth distribution to waters deeper than 110 m after 2007, based on our results. Our findings have served as an impetus to further expand the range of depths sampled in our bottom trawl survey.  相似文献   
4.
Studies on customer’s needs, desires and preferences have become highly important in the product design and development process. One consideration in usability is the cognitive aspect, which is related to the accommodation and evaluation of human cognitive capabilities, limitations and tendencies. In addition to the cognitive aspect, a recent study has shown that the affective aspect has been considered in the evaluation of product usability. Thus, both cognitive and affective aspects are deemed to be important for product design and the development process. Inherently, both aspects deliver complete human and product interaction and experience. However, studies that consider the affective process as a complement to the cognitive process for usability are relatively rare. To address this gap, this study discusses how an integrative framework of the cognitive and affective aspects can be applied to a product for usability assessment via empirical studies on e-commerce and e-learning platforms. The sample involved 230 respondents, using purposive sampling. The result shows that both cognitive and affective aspects have a significant effect, although with different weights. The affective aspect has been shown to improve product usability and user’s acceptance.  相似文献   
5.
Responsiveness is a critical metric for web performance. Recent work in the Internet Engineering Task Force (IETF) and World Wide Web Consortium (W3C) has resulted in a new set of web protocols, including definition of the hypertext transfer protocol version 2 (HTTP/2) and a corresponding set of TCP updates. Together, these have been designed to reduce the web page download latency compared with HTTP/1.1. This paper describes the main features of the new protocols and discusses the impact of path delay on their expected performance. It then presents a set of tests to evaluate whether current implementations of the new protocols can offer benefit with an operational satellite access network and suggests how the specifications can evolve and be tuned to further enhance performance for long network paths. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
6.
Wang  Yi-Ting  Shen  Jie  Li  Zhi-Xu  Yang  Qiang  Liu  An  Zhao  Peng-Peng  Xu  Jia-Jie  Zhao  Lei  Yang  Xun-Jie 《计算机科学技术学报》2020,35(4):724-738
Journal of Computer Science and Technology - Entity linking (EL) is the task of determining the identity of textual entity mentions given a predefined knowledge base (KB). Plenty of existing...  相似文献   
7.
介绍了新型轻钢龙骨结构多层建筑的结构体系和使用性能,并通过对齐齐哈尔市备建的一幢六层新型轻钢龙骨结构教学楼的力学试验结果和ANSYS建模计算结果的比较,对其安全性能做出了分析,最后针对这种结构体系的应用提出了发展的前景和所存在的问题。  相似文献   
8.
陈杰 《煤矿机械》2004,(12):84-85
介绍了CAD CAM网站中动态页面的设计。为了实现用户与网站的交互功能 ,在词汇查询与问题讨论部分采用ASP技术 ,使本站能够根据用户的需求在数据库中调取相关数据 ,动态生成页面。  相似文献   
9.
矿井移动通信是矿井现代化的重要组成部分.可将各种井下流动作业人员进行有效组织;对事故可及时报警和组织抢救等。因此,矿山井下移动通信系统对于提高矿井自动化程度,加强安全防护等有着重要的意义。  相似文献   
10.
本文介绍采用B/S系统网络架构,选择开发模式以及网络数据库;并采用模块化的编程方法,开发煤矿通风机在线选型系统;最后,以某矿的主通风机选型实例对系统的主要计算模块进行了测试和检验。  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