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   4374篇
  免费   429篇
  国内免费   306篇
电工技术   109篇
技术理论   1篇
综合类   411篇
化学工业   176篇
金属工艺   73篇
机械仪表   363篇
建筑科学   300篇
矿业工程   53篇
能源动力   75篇
轻工业   54篇
水利工程   40篇
石油天然气   25篇
武器工业   102篇
无线电   822篇
一般工业技术   485篇
冶金工业   95篇
原子能技术   12篇
自动化技术   1913篇
  2024年   17篇
  2023年   52篇
  2022年   69篇
  2021年   119篇
  2020年   146篇
  2019年   128篇
  2018年   113篇
  2017年   155篇
  2016年   169篇
  2015年   227篇
  2014年   326篇
  2013年   316篇
  2012年   318篇
  2011年   363篇
  2010年   256篇
  2009年   264篇
  2008年   288篇
  2007年   310篇
  2006年   252篇
  2005年   244篇
  2004年   178篇
  2003年   178篇
  2002年   138篇
  2001年   83篇
  2000年   89篇
  1999年   67篇
  1998年   43篇
  1997年   40篇
  1996年   34篇
  1995年   18篇
  1994年   24篇
  1993年   13篇
  1992年   7篇
  1991年   7篇
  1990年   7篇
  1989年   11篇
  1988年   7篇
  1987年   3篇
  1986年   5篇
  1985年   4篇
  1984年   3篇
  1983年   4篇
  1982年   3篇
  1975年   1篇
  1973年   1篇
  1970年   2篇
  1969年   2篇
  1964年   1篇
  1959年   1篇
  1955年   1篇
排序方式: 共有5109条查询结果,搜索用时 15 毫秒
1.
The purpose of this study is to provide a comprehensive outline of the Value Chain (VC)1 of bio-coal in Finland, define the proper business models of bio-coal business, and investigate the interrelationships between VC activities. The major findings are: 1) the study found significant interrelationships between support and primary activities in the bio-coal VC which suggest that we should not emphasis only the core value/primary activities of the bio-coal business, but pay more attentions to the “side values”/support activities; 2) The study identified political and environmental factors as the effective drivers, while technology and cost-profit uncertainty as major restrictions for the Finnish bio-coal business. The authors would like to suggest that instead of purely “environmental concerns”, the term “sustainability credentials” should be emphasized, which means value creating and adding items should not limit to monetary values, but consider social and environmental value propositions. 3) The study identified “low competition” in the current bio-coal business in Finland, which implies opportunities of market entrance for Finnish and international companies; 4) The study identified that the current Finnish bio-coal model is the decentralized model at the local level. However, the future Finnish bio-coal model will be a large scaled model, with a focus on export sales.  相似文献   
2.
3.
4.
本文提出了一种远距离、大范围二维直线度测量的新方法.该方法采用特殊设计的十字线准直激光器及线阵CCD,通过特殊的光学系统结构设计,能在0-20m距离内连续测量,直线度范围可达70mm,精度优于0.1mm,实际测量结果表明,该方法可适应野外作业环境。  相似文献   
5.
摩擦强度对薄膜表面形态的作用:原子力显微镜下的观察   总被引:2,自引:2,他引:0  
郑文军 《液晶与显示》2002,17(6):422-428
展示了摩擦强度对聚酰亚胺薄膜表面形态的影响,原子力显微图像显示,机械摩擦会使聚酰亚胺薄膜表面上形成微沟槽,这些沟槽的表面具有丰富的表面精细构造。原子显微图像还揭示了机械摩擦可以改变被磨擦聚酰亚胺膜的表面形态。  相似文献   
6.
The increasing demands concerning the modifiability and connectivity of business processes cannot be met adequately anymore by relying on best practices only. There is an urgent need for a reference conceptual framework for studying, modeling, analyzing and designing business processes. The Language–Action Perspective (LAP), in particular Habermas’ theory of Communicative Action offers a sound and rigid foundation for such a framework. In this paper, the DEMO (Demo Engineering Methodology for Organizations)-framework is presented. It builds on the LAP-based theoretical foundation of the DEMO methodology. Several other LAP-based frameworks have been proposed in the past years. They are evaluated in a comparative review with the DEMO-framework. Several shortcomings of these frameworks are revealed and discussed. The practical applicability of the DEMO-framework is demonstrated using a small example.  相似文献   
7.
有近20年历史的爱立信AXE10交换机在信息时代到来之际再放异彩,目前,它作为公共平台广泛应用于PSTN、ISDN、IN,PLMN、信令网和商务通信等。  相似文献   
8.
Based on the literature dealing with the diffusion of innovation and with information systems, and building on the emerging concepts in electronic commerce (e-commerce), this paper aims at assessing the influence of various factors on firms’ future level of use of electronic marketplaces (e-marketplaces). This theoretical model is tested on data collected from 1,200 senior managers in Canadian firms. Findings indicate that a firm’s past experience in e-commerce, as well as the factors relating to its business relationships ultimately affect its future use of e-marketplaces. Results of TOBIT regressions also show that the complexity of sophisticated e-commerce implementations is negatively correlated with the future level of use of e-marketplaces, and that consultants and other experts play an essential role in encouraging and facilitating the use of this new type of electronic platform. Finally, our survey data demonstrate that the relative influence of some determinants differs according to the firms’ size. Pierre Hadaya is an assistant professor of MIS at the Faculté d’administration of the Université de Sherbrooke (Canada). He holds a Ph.D. in Management of Technology from the école Polytechnique de Montréal. His research interests lie at the intersection of information technology management, business strategy and interorganizational design.  相似文献   
9.
Business, not technology leaders should manage the change of Information Technology (IT) from a self-contained business support unit of the sixties to a distributed strategic business function of the nineties. Top management should recognize that a good business plan can only be developed and executed through the partnership between the business unit managers and the managers of the financial, the personnel, and the IT resource units. The technical problems associated with the management of IT may again be the easier part of the total management challenge.  相似文献   
10.
电控平行排列液晶光栅的光衍射特性研究   总被引:1,自引:0,他引:1  
对电控平行液晶光栅的理论进行了分析,并配以结构原理图。通过对平行排列及90°扭曲排列液晶指向矢的计算,得出液晶盒中相应的折射率、相位差与电压之间的关系图,两者经比较证明平行排列更具适用性,并在实验中观测到了平行排列液晶光栅衍射特性与电压的关系。  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