首页 | 官方网站   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   326篇
  免费   20篇
工业技术   346篇
  2022年   6篇
  2021年   5篇
  2020年   2篇
  2019年   5篇
  2018年   11篇
  2017年   15篇
  2016年   9篇
  2015年   6篇
  2014年   11篇
  2013年   19篇
  2012年   14篇
  2011年   18篇
  2010年   14篇
  2009年   14篇
  2008年   14篇
  2007年   9篇
  2006年   17篇
  2005年   12篇
  2004年   14篇
  2003年   3篇
  2002年   3篇
  2001年   6篇
  2000年   6篇
  1999年   9篇
  1998年   7篇
  1997年   6篇
  1996年   4篇
  1995年   7篇
  1994年   3篇
  1993年   3篇
  1992年   6篇
  1991年   3篇
  1990年   7篇
  1989年   3篇
  1988年   3篇
  1987年   5篇
  1986年   2篇
  1985年   3篇
  1984年   2篇
  1983年   5篇
  1982年   3篇
  1980年   3篇
  1979年   2篇
  1978年   4篇
  1977年   2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346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.
4.
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   
5.
6.
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   
7.
8.
The purpose of this study is to explore the dynamics underlying disparities in Internet use among school age children in the US. The analysis found that a broad range of demographic, geographic and economic factors significantly influence Internet use among children. Significantly, the availability of household computing resources and adult Internet users in the household were most important in explaining disparities in use among children. To expand universal Internet access, future public policy should focus on providing support for in-home access; continued support for public access at out-of-home locations such as schools, and providing technical support, training and expertise to school age children.
Paul F. ClearyEmail:
  相似文献   
9.
As part of a study to characterise bioabsorbable scaffolds for tissue engineering an investigation has been conducted into the rate of degradation of polyglycolic acid (PGA). This is one of the most commonly used bioabsorbable materials and has been used in sutures since the 60s and more recently in cell scaffolds, drug delivery devices and bone fixation pins. This study looks at the influence that surface-to-volume ratio i.e. thickness of material, has on degradation. By degrading various thicknesses of PGA in a buffer saline solution over 24 days and testing their properties at regular intervals, a knowledge of how surface-to-volume ratio affects degradation was developed. Properties such as weight loss, crystallinity, molecular weight and structural integrity were measured. Results showed that rate of mass loss was dependent on sample thickness but crystallinity, melting point and molecular weight were independent of thickness.  相似文献   
10.
Abstract Empirical studies and theory suggest that educational dialogue can be used to support learners in the development of reasoning, critical thinking and argumentation. This paper presents an educational design for synchronous online peer discussion that guides student dialogue in ways that lead to improved argumentation and collaborative knowledge development. This design includes a mediating interface – or tool, linked to a broader set of online educational activities – a designed local context, where the latter aims to provide conditions that support argumentation. The approach is based on collaborative working and dialogue game approaches to discussion. Preliminary findings with UK Open University students showed the argumentation process was more coherent, varied, deeper and extended when using our interaction design compared with the use of a simple unstructured interface.  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-23

京公网安备 11010802026262号