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   57篇
  免费   0篇
化学工业   18篇
机械仪表   1篇
能源动力   1篇
轻工业   7篇
无线电   11篇
一般工业技术   6篇
冶金工业   10篇
自动化技术   3篇
  2020年   1篇
  2019年   1篇
  2018年   1篇
  2013年   5篇
  2012年   1篇
  2010年   2篇
  2008年   2篇
  2007年   3篇
  2005年   2篇
  2004年   1篇
  2003年   3篇
  2002年   3篇
  2001年   3篇
  1999年   3篇
  1998年   3篇
  1997年   3篇
  1996年   2篇
  1994年   2篇
  1993年   1篇
  1992年   1篇
  1990年   1篇
  1981年   1篇
  1977年   3篇
  1975年   1篇
  1974年   1篇
  1973年   2篇
  1972年   2篇
  1971年   1篇
  1969年   1篇
  1956年   1篇
排序方式: 共有57条查询结果,搜索用时 171 毫秒
51.
IgG non anti-RH1(D) monoclonal Rh antibodies were evaluated by flow cytometry. The values obtained with these antibodies were less strong than those obtained with anti-RH1(D) antibodies. For a significant number of antibodies, the signal was not high enough to give reliable results for the antibody specificity. Despite these drawbacks, flow cytometry was an efficient tool to appreciate the variation of reactivity by different antibodies with normal or variant cells. These variations were not always obvious by serological means.  相似文献   
52.
Social networks are said to facilitate learning and adaptation by providing the connections through which network nodes (or agents) share information and experience. Yet, our understanding of how this process unfolds in real-world networks remains underdeveloped. This paper explores this gap through a case study of al-Muhajiroun, an activist network that continues to call for the establishment of an Islamic state in Britain despite being formally outlawed by British authorities. Drawing on organisation theory and social network analysis, we formulate three hypotheses regarding the learning capacity and social network properties of al-Muhajiroun (AM) and its successor groups. We then test these hypotheses using mixed methods. Our methods combine quantitative analysis of three agent-based networks in AM measured for structural properties that facilitate learning, including connectedness, betweenness centrality and eigenvector centrality, with qualitative analysis of interviews with AM activists focusing organisational adaptation and learning. The results of these analyses confirm that al-Muhajiroun activists respond to government pressure by changing their operations, including creating new platforms under different names and adjusting leadership roles among movement veterans to accommodate their spiritual leader's unwelcome exodus to Lebanon. Simple as they are effective, these adaptations have allowed al-Muhajiroun and its successor groups to continue their activism in an increasingly hostile environment.  相似文献   
53.
This work examines the wetting of a range of low packing density (high porosity), porous, fibrous media by mineral oils. The fibrous media were suspended above a vessel of oil, and the rate of imbibation of oil was measured by means of a balance under the oil and a load cell above the media. It was found that the height of the oil column within the media over time generally resembled the classical capillary rise curve. Capillary rise models were fitted to the data to predict an equivalent capillary diameter, dynamic contact angle, and height of the liquid column as time approaches infinity, using the known filter and oil properties. Different capillary models were examined, and it was found that the modified Washburn equation was the simplest model to use and produced an acceptable agreement between theory and experiment. It was found that the adjustment phase of the curve from the fibrous media was generally more rapid than for a typical capillary, presumably since the fibrous media can be wetted not only from directly below (as with a capillary), but also through the meniscus at the sides of the media. It was found that a linear correlation existed between the effective capillary diameter of the media, and the packing density of the media divided by the fibre diameter. The results appear to be relatively independent of the material type. These results allow capillary diameters to be determined for fibrous media from easily measured parameters, without the requirement of conducting wetting experiments or ‘bubble-point’ tests.  相似文献   
54.
ABSTRACT: Commercial cold-pressed citrus oils containing terpene chlorohydrins may have quality and safety implications for end-users of these oils. Concentrations of (1S, 2S, 4R)-2-chloro-8- p -menthen-1-ol (1), (1 R , 2 R , 4 R )-2-chloro-8- p -menthen-1-ol (2), and (1 R , 2 R , 4 R )-2,9-dichloro-8- p -menthen-1-ol (3) in some citrus essential oils ranged from less than 1 ppm to 30 ppm measured by gas chromatography with a halogen detector. Reduction reactions of these compounds were accomplished by continuous mixing (reaction) of the oil with dilute solutions of KOH. Greater than 95% reduction of 1 and 3 were accomplished after reaction for 15 h with 0.5 N KOH or after 24 h with 0.25 N KOH in oils with either 25 or 30 ppm (1). Similar treatment of an oil containing 5 ppm (1) resulted in reduction to below the threshold limit of quantification (0.4 ppm). Sensory analyses of tasting solutions did not detect any flavor difference between untreated or KOH-treated oils.  相似文献   
55.
The development of deep-sea detectors has significantly enhanced the potential for tsunami detection, particularly in the Pacific region. The detectors work in combination with satellite communication technology and surface communication buoys to provide an efficient and effective warning technology. The objective of this study is to identify the optimal distribution of a limited number of detectors, given that a maximum of six potential buoy sites has already been determined. Two objective functions are developed, one for a Pacific-wide warning potential, and the second a more specific USA warning potential. The resulting non-linear 0-1 integer-programming problems are readily solved using enumeration techniques.
The results conclude that three detectors in the Tsunami Warning System can achieve the maximum warning potential for both the Pacific region and the USA.  相似文献   
56.
Sensitivity analysis screening methods aim to isolate the most important factors in experiments involving a large number of significant factors and interactions.This paper extends the one-factor-at-a-time screening method proposed by Morris. The new method, in addition to the ‘overall' sensitivity measures already provided by the traditional Morris method, offers estimates of the two-factor interaction effects. The number of model evaluations required is O(k2), where k is the number of model input factors.The efficient sampling strategy in the parameter space is based on concepts of graph theory and on the solution of the ‘handcuffed prisoner problem'.  相似文献   
57.
We report both infrared absorption and 11B nuclear magnetic resonance measurements that provide evidence for the presence of boron carbide icosahedra in amorphous hydrogenated boron carbide (a‐B:C:H) thin films. The infrared absorption spectra are dominated by a broad line at 1280 cm-1 with a FWHM of 320 cm-1, and the 11B nuclear magnetic resonance spectra are dominated by a line with a chemical shift of 4 ppm and FWHM of 35 ppm; similar features have been previously reported in polycrystalline boron carbide, where boron carbide icosahedra make up the unit cell. We also suggest that it is these icosahedra that increase the hardness of these films over those films without boron, by playing the role of nanocrystals in a nanocrystal/amorphous matrix composite system. This revised version was published online in July 2006 with corrections to the Cover Date.  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