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   364篇
  免费   22篇
电工技术   1篇
化学工业   74篇
金属工艺   1篇
机械仪表   4篇
建筑科学   10篇
能源动力   8篇
轻工业   67篇
水利工程   2篇
石油天然气   2篇
无线电   10篇
一般工业技术   54篇
冶金工业   104篇
原子能技术   1篇
自动化技术   48篇
  2022年   6篇
  2021年   5篇
  2020年   3篇
  2019年   5篇
  2018年   11篇
  2017年   15篇
  2016年   10篇
  2015年   6篇
  2014年   11篇
  2013年   23篇
  2012年   15篇
  2011年   21篇
  2010年   15篇
  2009年   15篇
  2008年   16篇
  2007年   13篇
  2006年   18篇
  2005年   12篇
  2004年   15篇
  2003年   3篇
  2002年   4篇
  2001年   7篇
  2000年   9篇
  1999年   9篇
  1998年   8篇
  1997年   8篇
  1996年   4篇
  1995年   7篇
  1994年   4篇
  1993年   3篇
  1992年   8篇
  1991年   4篇
  1990年   7篇
  1989年   4篇
  1988年   3篇
  1987年   6篇
  1986年   3篇
  1985年   4篇
  1984年   3篇
  1983年   5篇
  1982年   3篇
  1980年   3篇
  1979年   2篇
  1978年   4篇
  1977年   3篇
  1974年   2篇
  1970年   3篇
  1969年   3篇
  1968年   3篇
  1967年   3篇
排序方式: 共有386条查询结果,搜索用时 15 毫秒
1.
Computer-aided software engineering ( CASE) is changing the way IS professionals develop information systems. This article demonstrates how traditional systems development methods are changing with automation, describes a new six-phase software development methodology— the CASE life cycle— designed to maximize the effective use of CASE technologies, and discusses how, organizations can make the transition to this new methodology.  相似文献   
2.
Examined the theory that chronic migraine headaches can lead to permanent changes in brain function in 71 female college students. Ss were 20 classic migraineurs, 27 common migraineurs, and 24 controls. No significant group differences were found on the Halstead Reitan Neuropsychological Test Battery and additional memory tests. Classic migraineurs had significantly higher scores than common migraineurs on the Hysteria and Paranoia scales of the Minnesota Multiphasic Personality Inventory (MMPI) and significantly higher scores than the controls on Hypochondriasis and Hysteria scales. Explanations for the lack of cognitive deficits in this group are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
3.
The frequencies of multinational papers in various sciences   总被引:2,自引:1,他引:1  
Multinational papers are defined here as ones written by authors who reside in different countries during the course of research. For each of 16 fields of science, I scanned the first 200 papers in 2005 in four major journals publishing original research papers. Those journals produced 40% of all the citations among those journals with Impact Factors greater than 1.0. The frequencies of multinational papers ranged from 13% in surgery to 55% in astronomy. Although one can list a dozen factors which might contribute toward multinational papers, I lack the data to test most of those. There are only minor correlations with team sizes and Impact Factors, inadequate to explain the range. There is a larger, but not convincing, dependence upon the fractions of single-author papers and its cause, if real, is unclear. However, the most prominent factor seems to be the nature of the objects studied; if they are usually local (e.g. in one hospital or in one laboratory), the papers tend to be domestic but if most of the objects are available simultaneously to scientists in many countries (e.g. the sky in astronomy or the oceans and the Earth’s atmosphere in geosciences or widespread diseases in the area of infectious diseases or plants and animals widely distributed in biology), the papers are often international. Auxiliary results for 2005 are an average of 5.5 ± 0.3 authors per paper and 6.6 ± 1.0% one-author papers.  相似文献   
4.
5.
6.
This article examines changes to the morphology of rotationally molded metallocene catalyzed linear low density polyethylene brought about by varying the cooling rate during processing. These changes in morphology lead to variations in the impact performance, which is reflected in the dynamic mechanical characteristics of the materials. Various analytical techniques are used in an attempt to explain the differences in impact behavior. Slow cooling is shown to result in high crystallinity, and in the formation of large spherulites, which in turn is detrimental to the impact performance of the material, particularly at low temperatures. The high crystallinity corresponds with a shift in the β transition of the material to a higher temperature, and is shown to result in a higher brittle–ductile transition. A case study was also carried out on samples from a finished part provided by an industrial molder, one section of which failed in a brittle manner when impact tested while the other failed in a ductile manner. Microscopy results showed that the brittle material had large spherulites at the inside surface, while the ductile material showed incipient degradation at this surface, which has previously been shown to be of benefit to impact strength in rotationally molded parts. Dynamic mechanical studies again showed a β transition at a higher temperature in the brittle samples. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1963–1971, 2006  相似文献   
7.
8.
Given the prevalence of computers in education today, it is critical to understand teachers’ perspectives regarding computer integration in their classrooms. The current study surveyed a random sample of a heterogeneous group of 185 elementary and 204 secondary teachers in order to provide a comprehensive summary of teacher characteristics and variables that best discriminate between teachers who integrate computers and those who do not. Discriminant Function Analysis indicated seven variables for elementary teachers and six for secondary teachers (accounting for 74% and 68% of the variance, respectively) that discriminated between high and low integrators. Variables included positive teaching experiences with computers; teacher’s comfort with computers; beliefs supporting the use of computers as an instructional tool; training; motivation; support; and teaching efficacy. Implications for support of computer integration in the classroom are discussed.  相似文献   
9.
10.
The present research examined disclosure in online social networking profiles (i.e., FACEBOOK™). Three studies were conducted. First, a scoring tool was developed in order to comprehensively assess the content of the personal profiles. Second, grouping categories (default/standard information, sensitive personal information, and potentially stigmatizing information) were developed to examine information pertinent to identity threat, personal and group threat. Third, a grouping strategy was developed to include all information present in FACEBOOK™, but to organize it in a meaningful way as a function of the content that was presented. Overall, approximately 25% of all possible information that could potentially be disclosed by users was disclosed. Presenting personal information such as gender and age was related to disclosure of other sensitive and highly personal information. Age and relationship status were important factors in determining disclosure. As age increased, the amount of personal information in profiles decreased. Those seeking a relationship were at greatest risk of threat, and disclosed the greatest amount of highly sensitive and potentially stigmatizing information. These implications of these findings with respect to social and legal threats, and potential means for identifying users placing themselves at greatest risk, are discussed.  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