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   477篇
  免费   49篇
  2024年   4篇
  2023年   15篇
  2022年   6篇
  2021年   4篇
  2020年   17篇
  2019年   20篇
  2018年   69篇
  2017年   45篇
  2016年   45篇
  2015年   34篇
  2014年   41篇
  2013年   84篇
  2012年   25篇
  2011年   18篇
  2010年   14篇
  2009年   14篇
  2008年   17篇
  2007年   5篇
  2006年   4篇
  2005年   3篇
  2004年   4篇
  2003年   2篇
  2002年   5篇
  2001年   3篇
  2000年   2篇
  1999年   2篇
  1998年   1篇
  1997年   2篇
  1996年   4篇
  1995年   4篇
  1994年   1篇
  1993年   3篇
  1992年   1篇
  1990年   1篇
  1988年   1篇
  1985年   2篇
  1984年   1篇
  1982年   1篇
  1981年   1篇
  1973年   1篇
排序方式: 共有526条查询结果,搜索用时 0 毫秒
521.
Up until the late 1990s, the Balanta of Guinea‐Bissau constituted what could be described as a ‘deep rural society’, whose central identity was linked with rice production and cattle accumulation. At the same time, it could be argued that even in the early days after Independence in 1974, the social aspirations of Balanta young men matched those of other Guinean youths in their shared desire to get away from the strictures of gerontocracy and of rural life. Surprisingly, however, this study documents the agency of many rural Balanta young men in changing oppressive social rules, and in using agriculture as a means to fund their education, to feed their families and as a route to prosperity. The authors conclude that the persistent political instability in the country (most acutely felt in the capital city) and the national and global economic crises, together with the Balanta agricultural ethos and the softening of gerontocratic power, are at the root of this revaluing of rural livelihoods. This article challenges current dominant narratives about the crisis of young men in contemporary Africa and highlights the need to study the aspirations and achievements of youth in their rural–urban nexus from a historical and holistic perspective.  相似文献   
522.
The dhole (Cuon alpinus) has been documented on the Iberian Peninsula throughout the Middle and Upper Pleistocene in archaeological and palaeontological contexts. However, this is an uncommon species among the Iberian quaternary faunae as a whole. This paper focuses on the remains of the genus Cuon recovered in three different sites of the Iberian Mediterranean region and their morphological and osteometrical study. By comparing these with fourteen complete skeletons of Canis lupus, as well as with other remains of C. alpinus, we intend to highlight some anatomical and metrical differences between Cuon and Canis that, added to those already published, could be a functional base-line for the identification of this genus. The identification of this species is complex, especially in archaeological contexts, and in some cases the dhole has been identified as Canis or Canidae. Furthermore, this paper explores the chronology of the presence of the dhole in the Iberian Peninsula and the different contexts where these animals have been recovered from.  相似文献   
523.
Sub-national economic policies increasingly use labor market areas (LMAs) rather than administrative areas for analysis and implementation. How a set of LMAs was defined influences the results of such analyses, and so accurate policy delivery needs appropriately defined LMAs. Multinational bodies need comparable LMA definitions in many countries, calling for a definition method that is transferable across national boundaries. This article applies quantitative metrics to evaluate LMAs defined in three contrasting countries by three methods that represent the main methodological approaches. The deductive approach—based on a center and hinterland—is too inflexible to deal with differing geographical circumstances and cannot cope with statistical zones that are very small, or do not respect settlement structure. The alternative inductive methods tested define appropriate LMAs in each country, with the newer method performing slightly better in statistical terms. The article also exemplifies the usefulness of the metrics for comparisons of alternative regionalizations.  相似文献   
524.
525.
526.
In this paper has been derived the most relevant propagation of error formula in the case when argon peaks are measured. The most frequently cited formula published by Cox and Dalrymple deals with the isotope ratios, instead of isotope peaks heights, considered as independent variables.  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