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   1869篇
  免费   60篇
  2020年   11篇
  2019年   20篇
  2018年   128篇
  2017年   103篇
  2016年   122篇
  2015年   26篇
  2014年   30篇
  2013年   433篇
  2012年   73篇
  2011年   125篇
  2010年   109篇
  2009年   64篇
  2008年   50篇
  2007年   117篇
  2006年   55篇
  2005年   27篇
  2004年   25篇
  2003年   22篇
  2002年   20篇
  2001年   24篇
  2000年   18篇
  1999年   11篇
  1998年   15篇
  1997年   7篇
  1996年   12篇
  1995年   15篇
  1994年   12篇
  1993年   12篇
  1992年   9篇
  1989年   11篇
  1988年   9篇
  1987年   7篇
  1986年   8篇
  1985年   9篇
  1984年   9篇
  1983年   14篇
  1982年   8篇
  1981年   8篇
  1980年   14篇
  1979年   12篇
  1978年   9篇
  1977年   7篇
  1976年   7篇
  1974年   12篇
  1973年   5篇
  1972年   6篇
  1971年   8篇
  1968年   10篇
  1967年   6篇
  1966年   7篇
排序方式: 共有1929条查询结果,搜索用时 31 毫秒
991.
Einkorn (Triticum monococcum L.) was one of the first cereals to be domesticated in the Old World ca. 10,000 years ago and to spread towards Europe and North Africa. Its cultivation declined before the Iron Age and it remains today only as a relic crop in remote areas. To investigate if the geographic distribution of genetic diversity in modern einkorn landrace accessions could be informative about the movement of this crop during prehistory, we genotyped 50 accessions of einkorn from Europe, North Africa and the Near East. Using nuclear and chloroplast microsatellites and clustering methods, we detected two main gene pools in einkorn. The distribution of these lineages revealed differences between accessions from Morocco and the Iberian Peninsula from the rest of Europe and the Near East and suggests different regional dynamics in the spread of this crop.  相似文献   
992.
993.
994.
Huss‐Ashmore, Rebecca and Solomon H. Katz, eds. African Food Systems in Crisis: Part II. Contending with Change. New York: Gordon and Breach, 1990. xiii + 292 pp. including chapter references and index. $78.00 cloth.

Whiteford, Scott and Ann E. Ferguson, eds. Harvest of Want: Hunger and Food Security in Central America and Mexico. Boulder, CO: Westview Press, 1991. 264 pp. including chapter references and index. $48.00 cloth.  相似文献   
995.
This article examines how Maoist theory and practice were imported to France during the 1960s. A syncretic phenomenon, as notions developed in the Chinese cultural context were adapted to the very different Gallic situation, French Maoism proved to be especially influential among students at the École normale supérieure at the rue d’Ulm in Paris, where the Marxist theoretician, Louis Althusser, was teaching. Maoist philosophy facilitated critiques of the Moscow-aligned French Communist Party and its student union; it enabled Althusser's rethinking of the Marxist tradition, and it ultimately provided ammunition for his students’ eventual break with his “theoreticism.” Maoism's fecund contribution to French intellectual culture in the 1960s, helping to lay the groundwork for the events of May 1968, derived principally from its dual theoretical and practical nature. This article highlights two specific Maoist tenants—the inevitably violent nature of revolution and the ersatz-empiricist method of the “investigation”—and suggests how, after 1968, French Maoism ultimately surrendered the former as the latter proved more useful to direct democratic politics.  相似文献   
996.
997.
Diverse shallow water assemblages dominated by brachiopods, molluscs, sponges and stromatoporoids, and a tabulate coral, in the Wahringa Limestone Member (Darriwilian-Gisbornian), and Yuranigh Limestone Member (Gisbornian, or early Late Ordovician) of the Fairbridge Volcanics, are documented from the northern Molong Volcanic Belt in central N.S.W. New species described include Billingsaria spissa, Shlyginia printhiensis and Sowerbyites? wahringaensis. Elements of the Wahringa Limestone Member assemblage such as Labechia banksi, Labechiella regularis, and Maclurites cf. M. florentinensis are biogeographically significant in displaying strong similarities with contemporaneous Tasmanian faunas. The brachiopods Ishimia and Shlyginia from the Yuranigh Limestone Member are recognised for the first time outside Kazakhstan and Sibumasu. The presence of the brachiopod Anoptambonites in allochthonous limestone breccia within the lower Fairbridge Volcanics provides evidence of a regionally significant hiatus of 10–15 Ma duration separating this unit from the underlying Hensleigh Siltstone, of Early Ordovician (Bendigonian) age. The sponge Archaeoscyphia?, from allochthonous limestones in the latter formation, is the oldest macrofossil yet described from the Lachlan Fold Belt in central N.S.W.  相似文献   
998.
999.
The archaeological record of Eastern Hungary indicates that settlement patterns, subsistence strategies, ceramic style, trade patterns and mortuary customs changed from the Late Neolithic to the Copper Age (5000–2700 cal BC). Despite a rich archaeological tradition, questions remain regarding the management and use of domesticated animals and the role animal husbandry played in social change during this transition. Some researchers have hypothesized that these changes reflect a shift towards an economy that intensified its focus on primary and perhaps secondary animal products. Here we synthesize isotope data from human and animal remains and residue analysis from pottery sherds from Neolithic and Copper Age assemblages. Results indicate that the consumption and use of animal protein and fat was relatively high for both periods, with an increase in animal fats in ceramic vessels during the Middle Copper Age; however, milk products do not appear to have played an important dietary role. We conclude that livestock management remained small-scale during the Neolithic and Copper Age and that dairy use was minimal. It is proposed that the cultural changes that occurred at this time were associated with the emergence of smaller, independent farmsteads and perhaps the innovative use of secondary products like manure.  相似文献   
1000.
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