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   144篇
  免费   3篇
  2022年   1篇
  2021年   1篇
  2020年   1篇
  2019年   2篇
  2018年   3篇
  2017年   1篇
  2016年   3篇
  2015年   4篇
  2014年   4篇
  2013年   15篇
  2012年   9篇
  2011年   19篇
  2010年   9篇
  2009年   8篇
  2008年   11篇
  2007年   10篇
  2006年   7篇
  2005年   4篇
  2004年   3篇
  2003年   6篇
  2002年   1篇
  2000年   1篇
  1998年   2篇
  1997年   2篇
  1995年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
  1984年   3篇
  1981年   1篇
  1980年   1篇
  1979年   1篇
  1978年   1篇
  1975年   1篇
  1972年   1篇
  1967年   1篇
  1966年   1篇
  1964年   1篇
  1963年   1篇
  1957年   1篇
排序方式: 共有147条查询结果,搜索用时 15 毫秒
1.
2.
City dwellers occasionally must seek jobs, dwellings, or particular services or goods. Two very different ways exist by which the individual may conduct such a search. Lacking prior information, the person may elect to visit perceived possible locations until an appropriate one is found. Alternatively, an address may first be ascertained and then visited by finding a path to it. Clearly, there is a substantial difference between these two methods in terms of the amount of spatial movement they require in order to satisfy the searcher's needs. In this paper, this difference is modeled for situations that vary in terms of the density of acceptable end points of the search, as well as in characteristics of the signs of these end points, their patterns, and the level of information with which the searcher may begin.  相似文献   
3.
This article examines the introduction of blood transfusion into general practice from the end of the First World War to the Second World War. Developments during most of this period were not the result of new discoveries but rather the spread of ideas and the establishment of donor organizations to secure an adequate blood supply. The identification, testing, and organization of potential donors were done in a wide variety of settings that reflected differences in political and cultural experiences. At the end of the 1930s, with war approaching, the resolution of problems with storage of blood and the discovery of new techniques for separating and storing plasma dramatically changed transfusion practice. Thus, the innovations of the Second World War were very much based on the development of broad donor organizations plus the new technical discoveries that had occurred during the interwar period.  相似文献   
4.
5.
6.
7.
8.
Ohne Zusammenfassung  相似文献   
9.
10.
A number of recent allegations of scientific misconduct in Germany have led to judicial proceedings. Two examples are analyzed in depth, showing evidence for mutual incompatibilities between the legal system and the scientific system. In particular, it seems doubtful whether basic rules of good scientific practice are adequately and consistently taken into account by the courts when assessing the burden of proof. Strengths and weaknesses of some alternatives to judicial proceedings in such cases are discussed.  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