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   891篇
  免费   2篇
化学工业   19篇
矿业工程   4篇
能源动力   3篇
轻工业   5篇
无线电   12篇
一般工业技术   5篇
冶金工业   830篇
自动化技术   15篇
  2023年   2篇
  2022年   2篇
  2021年   2篇
  2020年   2篇
  2016年   1篇
  2015年   2篇
  2014年   2篇
  2013年   12篇
  2012年   1篇
  2011年   2篇
  2010年   1篇
  2008年   1篇
  2007年   2篇
  2006年   3篇
  2005年   4篇
  2003年   2篇
  2001年   1篇
  2000年   2篇
  1999年   21篇
  1998年   239篇
  1997年   169篇
  1996年   97篇
  1995年   50篇
  1994年   53篇
  1993年   56篇
  1992年   4篇
  1991年   8篇
  1990年   5篇
  1989年   6篇
  1988年   5篇
  1987年   5篇
  1986年   4篇
  1985年   2篇
  1983年   2篇
  1982年   4篇
  1981年   5篇
  1980年   9篇
  1979年   1篇
  1977年   29篇
  1976年   63篇
  1975年   1篇
  1974年   2篇
  1973年   2篇
  1968年   3篇
  1966年   2篇
  1964年   1篇
  1961年   1篇
排序方式: 共有893条查询结果,搜索用时 15 毫秒
11.
12.
13.
14.
We report an unusual case in which an apparently normal upper lobe of the right lung was supplied by major systemic arterial and pulmonary arterial vessels. The anomalous artery arose from the descending aorta. Following interruption of this vessel, the machinery-like murmur previously present disappeared.  相似文献   
15.
This paper presents a simple model of an AI (artificial intelligence) arms race, where several development teams race to build the first AI. Under the assumption that the first AI will be very powerful and transformative, each team is incentivised to finish first—by skimping on safety precautions if need be. This paper presents the Nash equilibrium of this process, where each team takes the correct amount of safety precautions in the arms race. Having extra development teams and extra enmity between teams can increase the danger of an AI disaster, especially if risk-taking is more important than skill in developing the AI. Surprisingly, information also increases the risks: the more teams know about each others’ capabilities (and about their own), the more the danger increases. Should these results persist in more realistic models and analysis, it points the way to methods of increasing the chance of the safe development of AI.  相似文献   
16.
Using Web services, the authors have been able to increase the amount of data accessible through the Naval Research Laboratory’s Geospatial Information Database (GIDB) portal. They created a Web crawler for Web Mapping Services (WMS) that harvests and adds data to the portal index and a translator that provides access to non-WMS data through the WMS interface. The Integrated Web Services Broker, using traditional Web services standards, provides automated access to meteorological and oceanographic data.  相似文献   
17.
18.
19.
Esophageal transit scintigraphy seems to be a valid methodology to assess impaired esophageal motility in early stages of disease. The purpose of this study was to discriminate patients with primary Raynaud's phenomenon (RP) and patients with systemic sclerosis (SSc) from healthy subjects by esophageal scintigraphy with a semisolid meal. METHODS: We studied 32 patients with primary RP, 18 with SSc and 13 healthy subjects. Dysphagia, acid regurgitation and heartburn were scored. After an overnight fast, all subjects underwent esophageal scintigraphy, using a semisolid orally ingested bolus (10 mL apple puree) labeled with 99mTc-sulfur colloid. Esophageal transit and emptying time and integral value were evaluated with the subjects in the upright (sitting) and supine positions. Transit time was defined as the time from the entry of 50% of radioactivity into the upper esophagus until the clearance of 50% of the bolus from the whole esophagus. Emptying time was defined as the time from the entry of 50% of radioactivity into the upper esophagus, until the clearance of 100% of the bolus from the whole esophagus. Integral value was defined as the total counts under the time-activity curve normalized to the maximum. RESULTS: Esophageal transit and emptying time and integral value, evaluated in both positions, were significantly higher in patients with SSc than in healthy subjects and than in patients with RP. Moreover, patients with RP had all three parameters, assessed in supine position, significantly longer compared to healthy subjects. Clinical scores regarding dysphagia, acid regurgitation and heartburn were not significantly different between patients with RP and SSc. CONCLUSION: Esophageal transit and emptying time and integral value appear to be able to discriminate patients with primary RP from patients with SSc and patients with RP from healthy subjects, suggesting an early mild esophageal dysfunction in RP.  相似文献   
20.
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