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   313篇
  免费   19篇
  2023年   3篇
  2022年   2篇
  2020年   8篇
  2019年   18篇
  2018年   22篇
  2017年   19篇
  2016年   18篇
  2015年   12篇
  2014年   7篇
  2013年   93篇
  2012年   8篇
  2011年   9篇
  2010年   5篇
  2009年   2篇
  2008年   7篇
  2007年   9篇
  2006年   7篇
  2005年   5篇
  2004年   6篇
  2003年   6篇
  2002年   2篇
  2001年   3篇
  2000年   2篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1995年   4篇
  1994年   4篇
  1993年   2篇
  1992年   1篇
  1991年   3篇
  1990年   1篇
  1989年   1篇
  1988年   1篇
  1987年   3篇
  1986年   2篇
  1985年   1篇
  1984年   1篇
  1983年   2篇
  1982年   3篇
  1981年   2篇
  1980年   1篇
  1979年   2篇
  1977年   3篇
  1976年   4篇
  1975年   5篇
  1974年   1篇
  1973年   1篇
  1969年   2篇
排序方式: 共有332条查询结果,搜索用时 15 毫秒
51.
52.
Organizational recovery has traditionally been considered animportant factor in any explanation of the Conservative Party'selectoral recovery during the fifteen years after 1945. Thisarticle examines the extent of this recovery in three marginalseats, which the Conservatives either held or regained to formtheir new parliamentary majority. It demonstrates that, in anumber of constituencies, whatever the wider community mighthave thought, the reality of local organization—whetherin terms of financial health, membership numbers, the deliveryof political education, election campaigning, the effectivenessof party agents, or level of activity—was considered tobe less than impressive to those involved intimately. The articleconcludes that although the value of the Conservative Party'sextensive grass roots should not be denied, the precise roleand effectiveness of local organization should be reconsidered.  相似文献   
53.
54.
55.
56.
Lithic artifacts from the lowest strata of the Debra L. Friedkin site, located on Buttermilk Creek in central Texas, have been interpreted as an undisturbed pre-Clovis assemblage (Waters et al., 2011a). Stone tools and debitage were recovered from sediments stratified just below diagnostic Clovis artifacts and dated by OSL to between 13.2 and >15.5 cal kya. Invoking commonly observed cultural and natural site formation processes, we offer an alternative explanation of the “Buttermilk Creek Complex” as a Clovis assemblage in secondary association with the dated sediments.  相似文献   
57.
Stable carbon (δ13C) and nitrogen (δ15N) isotope analyses of dog (Canis familiaris), island fox (Urocyon littoralis), and human bone collagen from CA-SRI-2 (AD 130–1830) on Santa Rosa Island, California provide a proxy of diet and the relationships between humans and these animals. Carbon isotopic signatures indicate that Native Americans and their dogs at CA-SRI-2 subsisted almost exclusively on marine resources, while the island fox ate primarily terrestrial foods. Nitrogen isotopes and archaeofaunal remains indicate that humans and dogs also ate higher trophic level foods, including finfishes, marine mammals, and seabirds with smaller amounts of shellfish. The CA-SRI-2 island foxes appear to have eaten higher amounts of terrestrial foods, similar to the diets observed in modern fox populations. These data generally confirm the commensal relationship assumed to exist between domesticated dogs and people, but the carbon isotopic composition of dogs is enriched ∼2‰ compared to humans. We hypothesize that the difference in carbon isotopes between dogs and humans may have resulted from a higher consumption of C3 plants with lower δ13C values by humans, or less likely from the ingestion by dogs of significant amounts of bone collagen, which is enriched by ∼4‰ over associated muscle.  相似文献   
58.
59.
60.
Pending the publication of new Soviet population data based on the 1979 census, to be hald next January, the author reviews population trends in the 1970's. After a steady decline through much of the Soviet period, birth rates and death rates have stabilized for the country as a whole, although marked regional differences continue. An unexplained rise in infant mortality and an apparent reduction of life expectancy have led to the suppression of data in these areas. No ready explanation is found for a recent increase in female fertility and age-specific death rates. Abnormalities in the age-sex structure, resulting from past population catastrophes, continue to persist and indicate future labor shortages. Geographical differences in population growth rates, resulting from differential rates of natural increase and migration, are analyzed. Urbanization, a typical phenomenon of the Soviet period, continues apace, with the biggest increases in large cities despite a policy designed to discourage big-city growth. A crucial question is the optimal disposition of the growing labor pool in the Central Asian region-whether to foster local employment or encourage migration from Central Asia to labor deficit areas elsewhere in the Soviet Union.  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