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   301篇
  免费   17篇
  2024年   1篇
  2023年   3篇
  2022年   1篇
  2021年   1篇
  2020年   8篇
  2019年   14篇
  2018年   14篇
  2017年   17篇
  2016年   15篇
  2015年   12篇
  2014年   9篇
  2013年   83篇
  2012年   8篇
  2011年   18篇
  2010年   12篇
  2009年   7篇
  2008年   7篇
  2007年   2篇
  2006年   3篇
  2005年   6篇
  2004年   11篇
  2003年   4篇
  2002年   6篇
  2001年   6篇
  2000年   5篇
  1999年   4篇
  1998年   5篇
  1996年   1篇
  1993年   4篇
  1992年   2篇
  1991年   3篇
  1989年   2篇
  1988年   1篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1983年   4篇
  1980年   3篇
  1979年   1篇
  1978年   4篇
  1977年   1篇
  1976年   2篇
  1974年   1篇
  1972年   1篇
排序方式: 共有318条查询结果,搜索用时 15 毫秒
281.
282.
Diminishing returns and advances in telecommunications have prompted large video game firms to seek new locations, outsource production, and develop niche studios, including on Canada's East Coast. In this paper, we examine emerging occupational cultures and trace the origins and evolution of video game production in Canada's Atlantic provinces—a critical yet peripheral space economy in the gaming sector. Our findings are drawn from 30 interviews with gameworkers, studio managers, government officials, and other industry experts. We find this industry to be driven by the confluence of three major factors: (i) provincial governments have supported video game development as a strategic industry via financial incentives; (ii) firms are benefiting from a return migration effect and are repatriating Atlantic Canadian talent from media hubs by selling “home,” work‐life balance, and an alternative to the punishing gamework culture associated with Silicon Valley; and (iii) post‐secondary institutions in the region have improved their talent pipelines through computer science, digital media, and video game development programs.  相似文献   
283.

Coastal adaptations have become an important topic in discussions about the evolution and dispersal of Homo sapiens. However, the actual distribution and potential relevance of coastal adaptations (broadly, the use of coastal resources and settlement along shorelines) in these processes remains debated, as is the claim that Neanderthals exhibited similar behaviors. To assess both questions, we performed a systematic review comparing coastal adaptations of H. sapiens during the African Middle Stone Age (MSA) with those of contemporaneous Neanderthals during the European Middle Paleolithic. In both species, systematic use of marine resources and coastal landscapes constitutes a consistent behavioral signature over?~?100,000 years (MIS 6–3) in several regions of Africa and Europe. We found more similarities than differences between Neanderthals and modern humans, with remaining disparities all in degree rather than kind. H. sapiens exploited a wider range of marine resources—particularly shellfish—more intensively. MSA shellfish-bearing sites are also more often associated with intense occupations on coastal landscapes, and more evidence of complex material culture such as shell beads. In terms of broader ramifications, Pleistocene coastal adaptations are best conceived of as an ‘add-on’ to previous adaptive strategies, complementing more frequently exploited inland resources and landscapes. Still, Neanderthals and modern humans increased their dietary breadth and quality, and added options for occupation and range expansion along coastlines. Potential evolutionary implications of these multi-generational behaviors include higher intakes of brain-selective nutrients as a basis for neurobiological changes connected to increased cognitive capacities, but also greater reproductive success, dispersal abilities and behavioral flexibility. Whether gradual differences between modern humans and Neanderthals stimulated different evolutionary trajectories is a question for future research.

  相似文献   
284.
William Charles Wells retained an interest in vision throughout his life. His first book was on single vision with two eyes; he integrated vision and eye movements to determine principles of visual direction. On the basis of experiments and observations he formulated three principles of visual direction, which can readily be demonstrated. In the course of these studies, he also examined visual acuity, accommodation and convergence, visual persistence, and visual vertigo. Insights into visual processing were mainly derived from observations of afterimages that were used to provide an index of how the eyes moved. His experiments enabled him to distinguish between the consequences of active and passive eye movements (later called outflow and inflow) as well as describing nystagmus following body rotation. After providing a brief account of Wells's life, his neglected research on vision is described and assessed.  相似文献   
285.
Rice and millet were staple crops at Liangchengzhen, a late Neolithic Longshan site in Shandong, China, but the degree of dietary variation is not known. This study uses stable isotope analysis of human and faunal skeletal remains to quantitatively address the importance of these crops as well as terrestrial domesticates and aquatic resources in the diet at Liangchengzhen. Although no collagen could be extracted from the poorly preserved human bones, the δ13C stable isotope results for 2 apatite sample and 16 tooth enamel samples averaged −9.8‰ suggesting that diet was based on foods averaging from −24‰ to −18‰, with millet and millet-fed animals comprising at most approximately 25–30% of the diet. Pig faunal δ13C isotope values suggested that during the earlier Longshan period pigs were fed mainly millet with more C3 foods such as rice included by the later Longshan period. Solid ceramic residues from two guan jar sherds produced δ13C values averaging −18‰ and δ15N values averaging +16‰, suggesting both vessels contained fish. The results of the study indicate that by the Longshan period, people in southeastern Shandong no longer relied as heavily on millet and that the agricultural crop of rice had increased in importance at Liangchengzhen. Unfortunately, without human collagen samples to provide nitrogen isotope results, we cannot estimate the relative contribution of aquatic and terrestrial protein to the diet of people at Liangchengzhen. In general, however, the pattern of a diverse agricultural system on the basis of the macrobotanical remains from Liangchengzhen is supported by the isotopic results.  相似文献   
286.
In the Wahiba Sands of eastern Oman, luminescence dating of sands enables us to relate wind activity to climatic variations and the monsoon cycle. These changes resulted from Polar glacial/interglacial cyclicity and changes in global sea levels and wind strengths. Luminescence dates show that development of the Sands began over 230 ka ago when the sand-driving winds were the locally arid, northward-blowing SW Monsoon.  相似文献   
287.
Paleolithic research often assumes that environmental conditions played a major role in shaping human evolution. To study this relationship we present a spatially explicit approach based on the assumption that the distribution of water within the landscape is an essential component of local environmental conditions. Here, we analyze the relation of wetness and human landuse patterns from the Upper Paleolithic (UP) and Epipaleolithic (EP) of Western Syria. In particular the spatially explicit character of the approach enables the detection of a significant change in landuse patterns during the UP and EP accompanied by a significant shift in the wetness characteristics of the preferentially used areas. These results are discussed against the background of published data on climatic conditions in order to identify both a possible time frame and triggers for this change in landuse. While we conclude an increased influence of natural conditions on the spatial behavior for the UP, we suggest an additional influence of cultural circumstances in shaping EP spatial behavior. For the region studied we argue that the bounded pattern observed during the UP changes to a spatially flexible pattern during the Late Natufian.  相似文献   
288.
Technological and morphological variability in lithic artifacts is commonly used to identify taxonomic entities in Paleolithic research contexts. Assemblages are mainly studied using either linear distance measurements or qualitative assessments of morphologies. Here, we present a method to quantify morphological variability in lithic artifacts using 3D models of stone artifacts. Our study on the sequence of the Upper Paleolithic layers V–I from the site Yabroud II in western Syria, demonstrates that utilizing 3D models provides a new insight into the variability of lithic technologies. We use quantitative data on convexities, twist and scar patterns on cores and blades, attributes previously not readily quantifiable, to trace technological change through the archaeological sequence. We are able to identify differences and translate these findings into a grouping of the layers. While layers VI–II are characterized by technological continuity and were grouped together, layers V and I can be separated from this group and represent technologically different groups chronologically before and after. Our results demonstrate the potential of 3D models for studying morphological variability in lithic assemblages.  相似文献   
289.
Both David Clarke and Martin Wobst have had a significant impact on archaeological theory and practice through their critical insights into the nature of archaeological inquiry and their respective challenges to assumptions about what we know and how we know it. This paper examines the development and historical context of some of their ideas, and highlights how their notions of responsibility, self-awareness, and relevance influence or intersect with contemporary archaeological practice.  相似文献   
290.
Fiber internet expansion represents a path to improved economic vitality for Americans, but it is unclear who benefits from it and by how much. We examine the effects of subsidized fiber internet expansion on home prices and homebuyer demographics using data from Wisconsin and an IV approach to correct for fiber network endogeneity. We find fiber internet increases urban and rural housing values by 1.83% ($3,462) and decreases the likelihood a homebuyer is white by 2.88%, but in urban areas only. Fiber internet therefore does not appear to drive minority homebuyers away but may contribute to the urban-rural racial divide.  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