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   47篇
  免费   0篇
化学工业   1篇
机械仪表   2篇
建筑科学   5篇
轻工业   2篇
无线电   1篇
一般工业技术   5篇
冶金工业   27篇
原子能技术   1篇
自动化技术   3篇
  2019年   1篇
  2012年   1篇
  2011年   1篇
  2010年   3篇
  2009年   1篇
  2008年   2篇
  2007年   1篇
  2004年   1篇
  1999年   2篇
  1998年   6篇
  1997年   5篇
  1996年   3篇
  1995年   2篇
  1993年   2篇
  1988年   1篇
  1987年   1篇
  1985年   1篇
  1984年   1篇
  1983年   3篇
  1981年   1篇
  1978年   2篇
  1977年   1篇
  1975年   2篇
  1972年   1篇
  1969年   1篇
  1934年   1篇
排序方式: 共有47条查询结果,搜索用时 31 毫秒
31.
Whitt.  M 《电信科学》1999,15(10):51-51
1前言目前中国正准备大力发展无线电话业务,网络规划人员正在紧锣密鼓地分析各种网络技术的特点。由于中国幅员辽阔,因此无线通信系统必须在覆盖方面能提供卓越的灵活性、容量和可扩展性。中国兴旺发达的城市对无线电话网络容量的需求极其巨大。在大城市的业务需求不断增长的同时,乡村和偏远地区对经济、可靠的无线业务的需求也在不断增长。现在新一代更强大的基站技术,可让运营商更好地满足这个充满活力的电信市场的复杂的、不断变化的需求。这些基站利用创新的软件和无线技术,可以为中国的用户提供更加可靠而且经济高效的通信。为了…  相似文献   
32.
Redirected Free Exploration with Distractors (RFEDs) is a large-scale real-walking locomotion interface developed to enable people to walk freely in Virtual Environments (VEs) that are larger than the tracked space in their facility. This paper describes the RFED system in detail and reports on a user study that evaluated RFED by comparing it to Walking-in-Place (WIP) and Joystick (JS) interfaces. The RFED system is composed of two major components, redirection and distractors. This paper discusses design challenges, implementation details, and lessons learned during the development of two working RFED systems. The evaluation study examined the effect of the locomotion interface on users' cognitive performance on navigation and wayfinding measures. The results suggest that participants using RFED were significantly better at navigating and wayfinding through virtual mazes than participants using walking-in-place and joystick interfaces. Participants traveled shorter distances, made fewer wrong turns, pointed to hidden targets more accurately and more quickly, and were able to place and label targets on maps more accurately, and more accurately estimate the virtual environment size.  相似文献   
33.
34.
OBJECTIVE: To describe in detail the structure of the medial palmar intercarpal ligament (MPICL), the lateral palmar intercarpal ligament (LPICL), and a dorsomedial intercarpal ligament (DMICL) of the equine midcarpal joint. STUDY DESIGN: Dissections of equine midcarpal joints. ANIMALS AND SAMPLE POPULATION: Ten carpal joints from eight thoroughbred horses. METHODS: Detailed dissections of the midcarpal joint were performed, with particular attention paid to the MPICL, the LPICL, and the DMICL. The attachments and dimensions of these structures were recorded, as well as their behavior during joint movement. RESULTS: The DMICL arose from the dorsomedial surface of the radial carpal bone (CR) and coursed palmarodistally to insert on the dorsomedial aspect of the second carpal bone (C2). The LPICL attached proximally predominantly on the distal part of the palmaromedial surface of the ulnar carpal bone (CU). From here the ligament coursed distomedially and slightly palmarly to the proximal palmarolateral surface of the third carpal bone (C3). The structure of the MPICL was complex. It attached proximally to the distolateral surface of the CR and distally to the proximal palmaromedial surface of C3, and the proximal palmarolateral aspect of the C2. It could be divided into four fiber bundles in all carpi. The predominant direction of fibers was dorsoproximal to palmarodistal, whereas the palmaromedial bundle coursed palmaroproximal to dorsodistal. CONCLUSIONS: The orientation of their fibers indicate that the MPICL and DMICL primarily resist dorsomedial displacement of CR, whereas the LPICL resists dorsolateral displacement of the CU and intermediate carpal bone. CLINICAL RELEVANCE: An understanding of the structure of the intercarpal ligaments of the midcarpal joint is important in interpreting their function and the reasons for damage to their structure.  相似文献   
35.
36.
An evaluation is reported of methods used to prepare mosses for analysis when required for monitoring metal pollution. Fontinalis antipyretica and Rhynchostegium riparioides taken from the River Hoëgne, Belgium, were used for the study. The stages in preparation studied critically were the storage of the moss after it had been collected from the river, washing, choice of which particular fraction to use and the conditions for final drying prior to digestion. For any one particular treatment, the concentrations of metals analysed (Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb) were usually lower in Fontinalis than Rhynchostegium. Metal concentrations found as a result of the various treatments differed markedly for some metals, including Zn, Cd and Pb. However no one sequence of methods is ideal for all purposes. Criteria that need to be considered when selecting methods include the time and facilities available and whether the moss is to be used for monitoring long-term or short-term pollution.  相似文献   
37.
38.
39.
To test the social learning-based hypothesis that marital conflict resolution patterns are learned in the family of origin, longitudinal, observational data were used to assess prospective associations between family conflict interaction patterns during adolescence and offspring's later marital conflict interaction patterns. At age 14 years, 47 participants completed an observed family conflict resolution task with their parents. In a subsequent assessment 17 years later, the participants completed measures of marital adjustment and an observed marital conflict interaction task with their spouse. As predicted, levels of hostility and positive engagement expressed by parents and adolescents during family interactions were prospectively linked with levels of hostility and positive engagement expressed by offspring and their spouses during marital interactions. Family-of-origin hostility was a particularly robust predictor of marital interaction behaviors; it predicted later marital hostility and negatively predicted positive engagement, controlling for psychopathology and family-of-origin positive engagement. For men, family-of-origin hostility also predicted poorer marital adjustment, an effect that was mediated through hostility in marital interactions. These findings suggest a long-lasting influence of family communication patterns, particularly hostility, on offspring's intimate communication and relationship functioning. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
40.
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