Bibliometric analysis of nicotine research in China during the period of 1991 to 2007

With the widespread exposure of people to nicotine through recreational use of tobacco products, research into nicotine has attracted increasing attention. Tobacco smoking is by far the most important cause of lung cancer. As the world's largest producer and consumer of tobacco products, China bears a large proportion of the global burden of smoking-related disease; therefore, information on nicotine publications should be collected to formulate future research policy. In the present study, we investigated nicotine-related research articles published by Chinese authors that were indexed in the Science Citation Index (SCI) from 1991 to 2007. An indicator "citations per publication" (CPP) was used in the study to evaluate the impact of journals, articles, and institutes. The quantity of publications has increased at a quicker pace than the worldwide trend. Article visibility, measured as the frequency of being cited, also increased during the period. However, the overall quality of articles, based on the impact factor of journals publishing those articles, dropped behind the worldwide average level. There has been an increase in international collaboration, mainly with researchers in the USA. The average CPP of international co-authorship articles was higher than that of single country publications. Besides the USA, nicotine research in China will benefit from more collaboration with Taiwan, England, and Germany. Some 110 of 264 articles were published by a single institute, and the top six institutes were compared from various angles. Seventy-two subject categories were covered, and trends (in terms of both quantity and quality) of nicotine research in China were compared with worldwide trends. In addition, analysis of keywords in both nicotine and lung cancer research fields was applied to indicate research interests. Mutual cooperation among multiple disciplines needs further strengthening.

Abundance and conservation status of the Yangtze finless porpoise in the Yangtze River, China

middle and lower reaches of the Yangtze River, China. It is the only freshwater population of porpoises in the world and is currently listed as Endangered by IUCN. In November and December 2006 we used two boats and line transect methods to survey the entire current range of the population, except for two lakes (Poyang and Dongting). Sighting results were similar for both boats, so we pooled all data and analyzed them using two line transect models and a strip transect model. All models produced similar estimates of abundance (1111, 1225 and 1000). We then added independent estimates of the number of porpoises from the two lakes for a total estimate of approximately 1800 porpoises. Our findings indicate that the population continues to decline and that its distribution is becoming more fragmented. Our current estimate in the main river is slightly less than half the estimate from surveys between 1984 and 1991 (which was probably an underestimate). We also found an apparent gap in the distribution of porpoises between Yueyang and Shishou (similar to 150 km), where sightings had previously been common. Continued threats to Yangtze finless porpoises include bycatch in unregulated and unselective fishing, habitat degradation through dredging, pollution and noise, vessel strikes and water development. Immediate protective measures are urgently needed to ensure the persistence of finless porpoises in the Yangtze River. The survey design and analytical methods developed in this study might be appropriate for surveys of cetaceans in other river systems. (c) 2008 Elsevier Ltd. All rights reserved.

一种开关电源的调控电路

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高光电转换效率的P-N结硅光电二极管

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一种半导体的掺杂技术

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一种斩波调压直流电源

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2008年全球粮食危机和中国粮食问题观察

粮食问题是人类面临的全球性问题之一,世界各国都认识到粮食问题是关系本世纪全球的安全性问题。为此,1996年11月在罗马召开联合国粮食高峰会议。我国人口占世界的22%,我国的粮食问题不仅是自身的安全性问题,更影响全世界的粮食