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   8207篇
  免费   447篇
  2023年   57篇
  2020年   165篇
  2019年   202篇
  2018年   308篇
  2017年   300篇
  2016年   347篇
  2015年   229篇
  2014年   208篇
  2013年   2199篇
  2012年   256篇
  2011年   282篇
  2010年   255篇
  2009年   248篇
  2008年   213篇
  2007年   206篇
  2006年   188篇
  2005年   121篇
  2004年   106篇
  2003年   107篇
  2002年   125篇
  2001年   154篇
  2000年   111篇
  1999年   121篇
  1998年   101篇
  1997年   86篇
  1996年   90篇
  1995年   75篇
  1994年   63篇
  1993年   82篇
  1992年   78篇
  1991年   66篇
  1990年   67篇
  1989年   61篇
  1988年   57篇
  1987年   64篇
  1986年   67篇
  1985年   70篇
  1984年   80篇
  1983年   84篇
  1982年   70篇
  1981年   69篇
  1980年   66篇
  1979年   62篇
  1978年   66篇
  1977年   70篇
  1976年   61篇
  1975年   71篇
  1974年   42篇
  1973年   38篇
  1972年   41篇
排序方式: 共有8654条查询结果,搜索用时 15 毫秒
141.
142.
143.
The possibility of lead isotope fractionation in ancient lead production is examined. Kinetic theory relating to isotopic fractionation in non-equilibrium evaporation is considered and the feasibility of the alteration of lead isotope abundance ratios in ore roasting and smelting is assessed. Previous experimental work is shown to have been inconclusive and conclusions are drawn on the need for further research to quantify the possible extent of fractionation in practice.  相似文献   
144.
Accelerator mass spectrometry radiocarbon ages have been taken for a test suite of small samples of material removed from some of the ‘beeswax’art figures found in rock shelters in northern Australia. The results indicate that we can reliably date this unique form of rock art with no noticeable damage. We had not expected to find figures of any great antiquity, and so we were surprised to find that the ages obtained spanned the time period from the recent past to about 4000 BP.  相似文献   
145.
A Roman archaeological site in northern Spain (La Maja, province of La Rioja) includes pottery workshops, part of an important ceramic industry that developed from about the first century BC to the first century AD. A geophysical study was planned to determine the extent of the industrial complex in the vicinity of an excavated kiln. Magnetic observations were done on a grid of 30 × 36m, with a sampling interval of 1m. Two dipolar-shaped anomalies were found: one in the north-east and the other in the south-west of the area. Low-pass and band-pass filters were used in the Fourier domain to enhance the characteristics of the magnetic data and to remove noise and undesirable shallow features. Three-dimensional polygonal prisms were used to model the magnetic anomalies based on palaeomagnetic measurements performed over an uncovered kiln that helped to constrain the induced and remanent parameters of the magnetizing fields.  相似文献   
146.
In recent decades, many Appalachian households have experienced declining incomes due to the loss of traditional male jobs in the mining and manufacturing sectors. One response to this decline has been an increase in female employment in formal sector activities. Another response is homework, or the home-based production of goods and services for sale in the formal and informal sectors. In rural Appalachia, where formal jobs are often unavailable or inadequate to support a household, many women are engaging in homework as an economic strategy. Consequently, economic restructuring cannot be fully understood without analyzing household strategies and gender relations. This paper examines the intersection of gender, households, and economic restructuring as it relates to women's homework and employment shifts in rural Appalachia. Research for this paper entailed qualitative interviews with 50 West Virginia women who are engaged in the home-based production of goods and services. The study analyzes the variety of homework activities done by rural women, their contribution to household incomes, and the effect of these activities on gender relations and divisions of labor in the home. The research forwarded in this study advances a conceptual understanding of household economic strategies and has some practical applications for women and economic development in underdeveloped regions .  相似文献   
147.
"A hedonic migration model is developed where regional amenities are viewed as influencing household production within the framework of the new demand theory. The inputs to household production are goods, time and housing. It is shown that economic growth in the economy as a whole will increase the relative attractiveness of regions that are relatively time-saving, in the sense that they have a lower time elasticity of household production. Hence, migration will flow into time saving regions and housing costs in those regions will rise as real GDP grows." The implied geographical focus is on the United States.  相似文献   
148.
149.
The Pacific Coast of North America was occupied by many distinctive groups of coastal hunter-gatherers at the times of early contacts with Europeans. Despite significant cultural diversity, Pacific Coast peoples shared lifeways oriented toward generally similar marine, nearshore, littoral, and estuarine habitats. In this paper, we examine some major issues that guide much of the archaeology done along the Pacific Coast, then discuss some of the theoretical and methodological problems that limit the efficacy of archaeological reconstructions. Most archaeological research conducted on North America's Pacific Coast has been oriented toward the search for the origins and development of a variety of cultural patterns. A comparative review of California and Northwest Coast sequences provides interesting parallels and discrepancies in the approaches taken in studying some of the major issues in Pacific Coast prehistory.  相似文献   
150.
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