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   49053篇
  免费   3710篇
  国内免费   5521篇
电工技术   2209篇
技术理论   66篇
综合类   5840篇
化学工业   6332篇
金属工艺   989篇
机械仪表   2558篇
建筑科学   17409篇
矿业工程   3396篇
能源动力   1383篇
轻工业   959篇
水利工程   2695篇
石油天然气   1342篇
武器工业   738篇
无线电   1974篇
一般工业技术   4317篇
冶金工业   1195篇
原子能技术   143篇
自动化技术   4739篇
  2024年   200篇
  2023年   754篇
  2022年   1048篇
  2021年   1450篇
  2020年   1532篇
  2019年   1110篇
  2018年   1047篇
  2017年   1275篇
  2016年   1565篇
  2015年   1668篇
  2014年   4397篇
  2013年   3061篇
  2012年   3727篇
  2011年   3857篇
  2010年   3210篇
  2009年   3270篇
  2008年   3192篇
  2007年   3786篇
  2006年   3376篇
  2005年   3016篇
  2004年   2661篇
  2003年   2033篇
  2002年   1472篇
  2001年   1139篇
  2000年   966篇
  1999年   740篇
  1998年   523篇
  1997年   455篇
  1996年   368篇
  1995年   313篇
  1994年   237篇
  1993年   185篇
  1992年   151篇
  1991年   88篇
  1990年   71篇
  1989年   58篇
  1988年   46篇
  1987年   37篇
  1986年   19篇
  1985年   22篇
  1984年   33篇
  1983年   20篇
  1982年   15篇
  1981年   10篇
  1980年   15篇
  1979年   13篇
  1961年   4篇
  1958年   4篇
  1957年   6篇
  1951年   8篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
The portability of software has become a major commercial issue in recent times. Such portability does not come easily, as few if any computer languages are really portable in practice. An additional complicating factor, especially in the commercial environment, is that the resulting software must be efficient. This paper describes the design and successful implementation of a 500,000+ line portable FORTRAN 77 package for the processing of seismic data. The package exhibits demonstrably high efficiency on a wide variety of machines from minicomputers to the largest supercomputers. Experiences gained during this exercise throw much light on the integration of the various thought processes which occur during the software engineering cycle, especially the notion of locality.  相似文献   
32.
介绍了我院资源开发工程系的历史、现状和前景,指出了面临的问题及摆脱困境的途径。  相似文献   
33.
Recent advances in the realization of individual molecular‐scale devices [1,2] highlight the integration of individual devices into large‐scale functional circuits as the major challenge. DNA‐programmed assembly is a promising avenue in that direction due to the large amount of information that can be coded into the molecules and the ability to translate that information into physical constructs [3]. Large‐scale DNA‐templated electronics require, however, complex manipulation of double‐stranded DNA (dsDNA) molecules, as well as patterning of the electrical properties instilled to them by, e.g., metallization. To that end, sequence‐specific molecular lithography on single DNA molecules has been developed [4]. This was achieved by harnessing the exquisite homologous recombination process of the RecA protein. Sequence‐specific patterning of the metal coating of DNA molecules, localization of arbitrary labeled molecular objects at any desired dsDNA address without prior modifications, and generation of molecularly accurate stable dsDNA‐dsDNA junctions are demonstrated. The information encoded in the DNA molecules directs the lithographic process in analogy to the masks used in conventional microelectronics. The RecA protein provides the assembling capabilities, as well as the resist function.  相似文献   
34.
随着国家加入WTO,国际间的竞争日益激烈,工程造价管理将受到怎样的影响,通过对比分析,比较现行的工程监理咨询制度与境外先进技术和管理的差距,如何把握机遇,面对挑战,文章试做一个探讨。  相似文献   
35.
This paper presents the Navigation Maps Modeling approach (NMM), which provides platform independent models for characterizing navigation maps of web applications. The NMM approach is conceived to obtain a trade off between high and low-level design notations. As high-level design notations, NMM models permit architectural details that may hinder the overall understanding of the web application to be left out. As low-level design notations, NMM models can easily be transformed into detailed architectural designs, which are very valuable at coding and maintenance stages.  相似文献   
36.
In the history of operations research in industry there has been an abundance of analyses and recommendations produced in millions of man hours by dedicated OR specialists. And yet the net improvement is significantly lower than expected. There are numerous reasons for this shortfall: incomplete analysis, too much theory, incomplete implementation, unreliable recommendations, or a combination of some of these reasons.
By describing several examples, the major reasons for the fragility of the link between recommendation and implementation will be reviewed. What has to be done today to increase the likelihood of implementing an OR recommendation and thus improve the performance of an industrial entity by using the power of OR tools will then be described.  相似文献   
37.
专家系统的研究越来越受到人们的重视,它在综合机械化采煤中的应用刚刚起步,文章详细地论述了ZJXT系统的知识获取与知识库构造,推理机的特点及系统的功能。  相似文献   
38.
39.
A sensing strategy for the reverse engineering of machined parts   总被引:1,自引:0,他引:1  
The reverse engineering of machined parts requires sensing an existing part and producing a design (and perhaps a manufacturing process) for it. We have developed a reverse engineering system that has proven effective with a set of machined parts. This paper describes the system, presents some results, and discusses strategy for a new system.This work was supported by ARPA under ARO grant number DAAH04-93-G-0420, DARPA grant N00014-91-J-4123, NSF grant CDA 9024721, and a University of Utah Research Committee grant. All opinions, findings, conclusions or recommendations expressed in this document are those of the authors and do not necessarily reflect the views of the sponsoring agencies.  相似文献   
40.
专家系统在化工中的应用进展   总被引:2,自引:0,他引:2  
本文综述了近年来专家系统在化工领域的应用状况,并指出今后的发展趋势。  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