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   153篇
  免费   9篇
  2021年   1篇
  2020年   1篇
  2019年   7篇
  2018年   13篇
  2017年   8篇
  2016年   10篇
  2015年   3篇
  2014年   5篇
  2013年   46篇
  2012年   5篇
  2011年   4篇
  2010年   10篇
  2009年   4篇
  2008年   8篇
  2007年   3篇
  2006年   3篇
  2005年   3篇
  2004年   3篇
  2003年   2篇
  2002年   2篇
  2001年   4篇
  1999年   2篇
  1998年   3篇
  1997年   3篇
  1996年   2篇
  1994年   1篇
  1978年   1篇
  1977年   1篇
  1976年   1篇
  1974年   2篇
  1954年   1篇
排序方式: 共有162条查询结果,搜索用时 0 毫秒
111.
Moseley’s (1975) Maritime Foundations of Andean Civilization hypothesis challenges, in one of humanity’s few pristine hearths of civilization, the axiom that agriculture is necessary for the rise of complex societies. We revisit that hypothesis by setting new findings from La Yerba II (7571–6674 Cal bp) and III (6485–5893 Cal bp), Río Ica estuary, alongside the wider archaeological record for the end of the Middle Preceramic Period on the Peruvian coast. The La Yerba record evinces increasing population, sedentism, and “Broad Spectrum Revolution” features, including early horticulture of Phaseolus and Canavalia beans. Yet unlike further north, these changes failed to presage the florescence of monumental civilization during the subsequent Late Preceramic Period. Instead, the south coast saw a profound “archaeological silence.” These contrasting trajectories had little to do with any relative differences in marine resources, but rather to restrictions on the terrestrial resources that determined a society’s capacity to intensify exploitation of those marine resources. We explain this apparent miscarriage of the Maritime Foundations of Andean Civilization (MFAC) hypothesis on the south coast of Peru by proposing more explicit links than hitherto, between the detailed technological aspects of marine exploitation using plant fibers to make fishing nets and the emergence of social complexity on the coast of Peru. Rather than because of any significant advantages in quality, it was the potential for increased quantities of production, inherent in the shift from gathered wild Asclepias bast fibers to cultivated cotton, that inadvertently precipitated revolutionary social change. Thereby refined, the MFAC hypothesis duly emerges more persuasive than ever.  相似文献   
112.
113.
Standort - Seit Jahrzehnten wird Bier größtenteils in standardisierten Wertschöpfungsketten produziert, wobei die Kontexte der Rohstofferzeugung kaum mehr nachvollziehbar erscheinen....  相似文献   
114.
The elucidation of spatial variation in the landscape can indicate potential wildlife habitats or breeding sites for vectors, such as ticks or mosquitoes, which cause a range of diseases. Information from remotely sensed data could aid the delineation of vegetation distribution on the ground in areas where local knowledge is limited. The data from digital images are often difficult to interpret because of pixel-to-pixel variation, that is, noise, and complex variation at more than one spatial scale. Landsat Thematic Mapper Plus (ETM+) and Satellite Pour l'Observation de La Terre (SPOT) image data were analyzed for an area close to Douna in Mali, West Africa. The variograms of the normalized difference vegetation index (NDVI) from both types of image data were nested. The parameters of the nested variogram function from the Landsat ETM+ data were used to design the sampling for a ground survey of soil and vegetation data. Variograms of the soil and vegetation data showed that their variation was anisotropic and their scales of variation were similar to those of NDVI from the SPOT data. The short- and long-range components of variation in the SPOT data were filtered out separately by factorial kriging. The map of the short-range component appears to represent the patterns of vegetation and associated shallow slopes and drainage channels of the tiger bush system. The map of the long-range component also appeared to relate to broader patterns in the tiger bush and to gentle undulations in the topography. The results suggest that the types of image data analyzed in this study could be used to identify areas with more moisture in semiarid regions that could support wildlife and also be potential vector breeding sites.  相似文献   
115.
116.
117.
118.
119.
120.
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