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   806篇
  免费   6篇
  国内免费   1篇
电工技术   10篇
化学工业   86篇
金属工艺   20篇
机械仪表   51篇
建筑科学   29篇
能源动力   13篇
轻工业   58篇
水利工程   4篇
石油天然气   1篇
无线电   41篇
一般工业技术   153篇
冶金工业   210篇
原子能技术   4篇
自动化技术   133篇
  2023年   8篇
  2022年   6篇
  2021年   10篇
  2020年   10篇
  2019年   19篇
  2018年   17篇
  2017年   16篇
  2016年   10篇
  2015年   6篇
  2014年   19篇
  2013年   60篇
  2012年   18篇
  2011年   30篇
  2010年   18篇
  2009年   27篇
  2008年   26篇
  2007年   34篇
  2006年   27篇
  2005年   20篇
  2004年   9篇
  2003年   21篇
  2002年   14篇
  2001年   15篇
  2000年   13篇
  1999年   15篇
  1998年   54篇
  1997年   29篇
  1996年   20篇
  1995年   13篇
  1994年   14篇
  1993年   11篇
  1992年   9篇
  1991年   10篇
  1990年   10篇
  1989年   6篇
  1988年   8篇
  1987年   12篇
  1986年   7篇
  1985年   10篇
  1984年   9篇
  1983年   16篇
  1982年   15篇
  1981年   5篇
  1980年   11篇
  1979年   7篇
  1978年   9篇
  1977年   10篇
  1976年   11篇
  1975年   7篇
  1969年   4篇
排序方式: 共有813条查询结果,搜索用时 15 毫秒
1.
Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies.  相似文献   
2.
The electronic encyclopedia exploratorium (E3) is a vision of a future computer system-an electronic book describing how thing work. Typical articles in E3 will describe such mechanisms as compression refrigerators, engines, telescopes, and mechanical linkages. Each article will provide simulations, three-dimensional animated graphics that the user can manipulate, laboratory areas that allow a user to modify the device or experiment with related artifacts, and a facility for asking questions and receiving customized, computer-generated English-language explanations. Some of the foundational technology is discussed, focusing on topics in artificial intelligence, graphics, and user interfaces. The initial prototype system and the technical lessons learned from it, as well as the second prototype currently under construction, are described  相似文献   
3.
GSM is a series of standards defining various aspects of mobile voice and data communications. These standards provide a framework that looks set to underlie modern mobile business communications well into the 21st century.  相似文献   
4.
5.
Transient fields of pulsed transducers in solids   总被引:1,自引:0,他引:1  
The radiation and propagation of elastic waves in solid media are of fundamental importance in ultrasonic NDE. Due to the limitation of analytical approaches, numerical procedures are most appropriate for solving the governing equations. In this paper, the finite element method is used to predict the transient fields of pulsed transducers in a solid medium with axisymmetric geometry. Comparisons with other models are performed. The transducer field interactions with spherical voids are also presented.  相似文献   
6.
Active transport of nitrofurantoin across the mammary epithelium in vivo   总被引:1,自引:0,他引:1  
Nitrofurantoin is a commonly used urinary tract antibiotic that has been found at high concentrations in human milk. In vivo studies in rats were carried out to determine the mechanism by which this drug crosses the mammary epithelium. Lactating rats were gavage-fed with nitrofurantoin, and their milk and plasma levels of the antibiotic were measured at intervals up to 8 hr. The average milk-to-plasma (M/P) ratio, calculated from the areas under the milk and plasma curves, respectively, was 23 compared with a ratio predicted to be about 0.3 on the basis of lipid partitioning and protein binding determinations. M/P ratios for two nitrofurantoin congeners were also calculated. The neutral compound furazolidone had a M/P ratio of about 1, as predicted, whereas the basic compound furaltadone had a M/P ratio of 3.49 compared with a predicted ratio of 1.4. These data suggest that nitrofurantoin and, to a lesser extent, furaltadone are actively transported across the mammary epithelium into milk.  相似文献   
7.
Social typicality effects occur when people apply their attitudes more consistently toward typical than toward atypical category members presumably because attitudes are directed toward the prototypic category member. Four studies tested whether individuals also apply social policy attitudes more consistently toward typical than toward atypical persons affected by the policy. Study 1 used attitude concept maps to assess how extensively individuals spontaneously reference the typical person affected by a social policy. Death penalty proponents did so more than did opponents; welfare proponents and opponents did so equally. In 3 other studies, death penalty proponents displayed greater typicality effects in sentencing "convicted murderers" than did opponents, welfare proponents and opponents displayed equal typicality effects in evaluating cases of suspected welfare fraud, and individuals whose attitude concept maps about welfare referred more to persons displayed greater typicality effects than did individuals whose maps referred more to principles. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
8.
9.
STUDY DESIGN: The effect of sitting versus standing posture on lumbar lordosis was studied retrospectively by radiographic analysis of 109 patients with low back pain. OBJECTIVE: To document changes in segmental and total lumbar lordosis between sitting and standing radiographs. SUMMARY OF BACKGROUND DATA: Preservation of physiologic lumbar lordosis is an important consideration when performing fusion of the lumbar spine. The appropriate degree of lumbar lordosis has not been defined. METHODS: Total and segmental lumbar lordosis from L1 to S1 was assessed by an independent observer using the Cobb angle measurements of the lateral radiographs of the lumbar spine obtained with the patient in the sitting and standing positions. RESULTS: Lumbar lordosis averaged 49 degrees standing and 34 degrees sitting from L1 to S1, 47 degrees standing and 33 degrees sitting from L2 to S1, 31 degrees standing and 22 degrees sitting from L4 to S1, and 18 degrees standing and 15 degrees sitting from L5 to S1. CONCLUSION: Lumbar lordosis while standing was nearly 50% greater on average than sitting lumbar lordosis. The clinical significance of this data may pertain to: 1) the known correlation of increased intradiscal pressure with sitting, which may be caused by this decrease in lordosis; 2) the benefit of a sitting lumbar support that increases lordosis; and 3) the consideration of an appropriate degree of lordosis in fusion of the lumbar spine.  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