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   480篇
  免费   10篇
电工技术   4篇
综合类   1篇
化学工业   42篇
金属工艺   17篇
机械仪表   17篇
建筑科学   27篇
矿业工程   2篇
能源动力   7篇
轻工业   56篇
水利工程   1篇
无线电   42篇
一般工业技术   50篇
冶金工业   164篇
原子能技术   6篇
自动化技术   54篇
  2023年   3篇
  2022年   2篇
  2021年   3篇
  2020年   9篇
  2019年   7篇
  2018年   4篇
  2017年   5篇
  2016年   9篇
  2015年   5篇
  2014年   5篇
  2013年   20篇
  2012年   24篇
  2011年   19篇
  2010年   24篇
  2009年   23篇
  2008年   14篇
  2007年   24篇
  2006年   17篇
  2005年   9篇
  2004年   15篇
  2003年   15篇
  2002年   11篇
  2001年   10篇
  2000年   7篇
  1999年   16篇
  1998年   25篇
  1997年   25篇
  1996年   8篇
  1995年   9篇
  1994年   7篇
  1993年   17篇
  1992年   6篇
  1991年   6篇
  1990年   5篇
  1989年   9篇
  1988年   8篇
  1987年   3篇
  1986年   5篇
  1985年   2篇
  1984年   7篇
  1983年   5篇
  1982年   3篇
  1981年   7篇
  1980年   5篇
  1979年   3篇
  1976年   8篇
  1971年   2篇
  1967年   2篇
  1908年   4篇
  1906年   2篇
排序方式: 共有490条查询结果,搜索用时 343 毫秒
1.
2.
Recent research suggests that implementing information systems presents considerable difficulties and that many implementations are total or partial failures. This paper argues that what both practitioners and students require are richer and more acceptable models of information systems implementation. Accordingly, case study data concerning the introduction of manufacturing resource planning (MRP II) are used to illustrate five patterns of behaviour (rites) which capture important social actions; and four components of changing psychological orientation. It is argued that appreciation of the rites and psychological developments identified here will support effective change programmes. Guidelines based on our model are provided for practitioners.  相似文献   
3.
Senior nursing students described their interactions with faculty in a journal writing assignment. These interactions were categorized by the ethical perspectives of justice, autonomy, beneficence, and caring. An ethical analysis of faculty-student interactions is a strategy that may help nursing faculty and students understand differing perceptions about their relationships.  相似文献   
4.
The fabrication of novel tilted fibre Bragg gratings coupling light out of the fibre core into two different directions is demonstrated. These gratings in combination with a fibre based quarter waveplate are used to form a high-speed fibre polarimeter for real-time polarisation monitoring.  相似文献   
5.
No longer satisfied with compromising and controlling individual computers, a new breed of hackers have set their sights on virtual networks of zombie systems, which they use in concert to accomplish various nefarious deeds. Beware the botnet.  相似文献   
6.
Human apolipoprotein (apo) E, a polymorphic protein with three common alleles, epsilon 2, epsilon 3, and epsilon 4, plays an important role in lipoprotein metabolism. This article describes the association of this polymorphism with lipids, apolipoproteins, and lipoproteins with a particular regard to lipoprotein particles, as defined by their apolipoprotein content, as well as the risk of myocardial infarction in a multicenter population-based case-control study (ECTIM study). In the ECTIM study, 574 male patients aged 25 to 64 were examined 3 to 9 months after myocardial infarction in four regions participating in the World Health Organization MONICA project: Belfast (Northern Ireland) and Lille, Strasbourg, and Toulouse (France). Control subjects (n = 722) were randomly selected from the regional populations. The distribution of apoE phenotypes was significantly different across the four control samples (P = .04), with a higher frequency of the epsilon 4 allele in Belfast (14.3%) than in Toulouse (8.2%). The association of apoE polymorphism with biological measurements was studied in the control groups (n = 640) after men with coronary heart disease or those taking hypolipidemic drugs were omitted, with the apoE3/3 phenotype as a reference after adjustment for concomitant factors. Individuals carrying the epsilon 2 allele had lower levels of plasma cholesterol, low-density lipoprotein cholesterol (LDL-C), and apoB and higher levels of triglycerides, very-low-density lipoprotein cholesterol (VLDL-C), apoC-III, apoE, lipoprotein (Lp) C-III:B, and Lp E:B. However, the effect of the epsilon 2 allele on triglyceride, VLDL-C, apoE, and Lp E:B parameters was heterogeneous across the populations.(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   
7.
Technical Note: Selecting a Classification Method by Cross-Validation   总被引:3,自引:0,他引:3  
Schaffer  Cullen 《Machine Learning》1993,13(1):135-143
If we lack relevant problem-specific knowledge, cross-validation methods may be used to select a classification method empirically. We examine this idea here to show in what senses cross-validation does and does not solve the selection problem. As illustrated empirically, cross-validation may lead to higher average performance than application of any single classification strategy, and it also cuts the risk of poor performance. On the other hand, cross-validation is no more or less a form of bias than simpler strategies, and applying it appropriately ultimately depends in the same way on prior knowledge. In fact, cross-validation may be seen as a way of applying partial information about the applicability of alternative classification strategies.  相似文献   
8.
Schaffer  Cullen 《Machine Learning》1993,12(1-3):167-183
This article reports the results of a study of domain-independent function finding based on a collection of several hundred real scientific data sets. Prior studies have introduced the controversial idea of discovering functional relationships of interest to scientists directly from the data they collect. The evidence presented here supports the view that this is sometimes possible, but it also suggests how often purely data-driven discovery is not possible and how much more difficult it may be than has often been assumed. Experience with sampled examples of real scientific data suggests as well that emphasis on search in prior studies may have been misplaced. For the function-finding problems studied here, scientists typically propose only a handful of different functional relationships. The difficulty is not in searching through a large space of relationships but in evaluating a few common ones to determine if they are likely to be of scientific interest.  相似文献   
9.
The paper talks about the spreading "X as a service" phenomenon in the IT arena, cloud computing, and SLA. In the article, the author mentioned that "X as a Service" has entered the vocabulary in many forms, mostly in computing aspect. Also, cloud computing can lead to significant savings as well as significant service improvements. Cloud computing vendors would like to reap most of those benefits.It can change this by bringing past experiences and good judgment into play and adapt them to new situation. That is the mark of being a "professional" in IT field. Experience, understanding, and thoughtfulness can help the contract people write an effective service level agreement (SLA) that puts its needs in good legal form. Ideally the SLA will include all needed services and none that aren't needed.  相似文献   
10.
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