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   754篇
  免费   27篇
  2023年   4篇
  2020年   16篇
  2019年   20篇
  2018年   24篇
  2017年   33篇
  2016年   29篇
  2015年   15篇
  2014年   18篇
  2013年   268篇
  2012年   17篇
  2011年   13篇
  2010年   7篇
  2009年   12篇
  2008年   19篇
  2007年   9篇
  2006年   12篇
  2005年   9篇
  2004年   16篇
  2003年   9篇
  2002年   7篇
  2001年   7篇
  2000年   8篇
  1999年   12篇
  1998年   8篇
  1997年   12篇
  1996年   6篇
  1995年   12篇
  1994年   5篇
  1993年   7篇
  1992年   4篇
  1991年   7篇
  1990年   8篇
  1989年   8篇
  1988年   3篇
  1987年   7篇
  1986年   3篇
  1985年   10篇
  1984年   9篇
  1983年   8篇
  1982年   11篇
  1981年   8篇
  1980年   5篇
  1979年   7篇
  1978年   5篇
  1977年   5篇
  1976年   14篇
  1975年   4篇
  1974年   5篇
  1969年   3篇
  1968年   2篇
排序方式: 共有781条查询结果,搜索用时 19 毫秒
11.
This paper provides a complete comparative-static analysis of the simplest model of urban household behavior that incorporates time explicitly. Results involving the housing-price function and the effects on housing consumption and location (radial distance from the CBD) of exogenous changes in preferences for housing, housing price, and money costs of transportation are the same as in models not incorporating time explicitly. In addition, it is found that housing consumption and location are negatively related to commuting time, positively related to nonwage income, and ambiguously related (both a priori and empirically, for reasonable values of the relevant variables) to the wage rate.  相似文献   
12.
Excavations by the joint University of Khartoum/Southern Methodist University Butana Project in the area just north of Khashm el Girba on the upper Atbara River have uncovered a series of preceramic and early ceramic occupations by hunters and gatherers which date fromca 10,000 bp toca 6200 bp. The earlier sites show no direct relations with those of similar age in the northern Sudan, while the later, early ceramic sites show only minor similarities with contemporary occurrences in the central Nile Valley. Thus, it appears that the upper Atbara River Valley played no role in the development of the Khartoum Mesolithic and that Nilotic influences were late reaching the eastern Sudan.
Résumé Des fouilles entreprises par le projet Butana dirigé en commun par l'université de Khartoum et le Southern Methodist University dans la région juste au nord de Khashm el Girba sur le cours supérieur de l'Atbara, ont découvert une série d'occupations précéramiques et céramiques anciennes de chasseurs-cueilleurs, qui datent deca 10,000 bp àca 6200 bp. Les gisements les plus anciens ne semblent pas avoir eu de relations directes avec ceux de la même période dans le nord du Soudan, tandis que les gisements plus tardifs à céramiques ne montrent que de petites analogies avec des occupations contemporaines dans la vallée centrale du Nil. Il semble donc que la haute vallée de l'Atbara n'a joué aucun rôle dans le développement du Mésolithique de Khartoum et que des influences nilotiques n'atteignirent que bien plus tard le Soudan oriental.
  相似文献   
13.
14.
15.
16.
17.
Changes in the grain-size distribution and the lithologi-cal I mineralogical properties of sandy-gravel sediments are used to discriminate between sources for the alluvial valley-fill of Bella Coola River, coastal British Columbia. Spatially variable bedrock sources, ranging from highly resistant quartz monzonites to easily weathered basalts, yield sediments that reflect parent rock characteristics. Local increases in the D95 fraction of bulk gravel samples and the D50 fraction of sand samples can be related to inputs from steeper, heavily glaciated tributaries, or those underlain by fractured basalts of the Fraser Plateau. Where there are similarities in the grain-size properties of the source and the sampled deposit, however, grain-size information alone cannot be used to discriminate between sources. The lithology of Bella Coola alluvium shows a close correspondence with the general distribution of rock types in the basin, suggesting proportional contributions from most tributary sources over the long term. However, sand samples from the floodplain have a mostly volcanic affinity, indicating the dominance of sediment derived from headwater tributaries underlain by this rock type. Admixture of plutonic source sediments is evident in lower Bella Coola River adjacent to alluvial fans, heavily glaciated tributary creeks or rock walls comprised mainly of quartz monzonite. Les changements dans la granulometrie et les proprietes lithologiques et mineralogiques des sediments de gravel sablonneux servent d differencier les sources des depéts alluviaux de la Riviere Bella Coola sur la céte de la Colombie-Britannique. La variation spatiale des sources fondamentales donnent des sediments qui refletent les caracteristiques de la roche-mbe variant des quartz rnonzonites très résistants aux basaltes superficiellement altérés par les agents atmospheriques. Les augmentations locales dans la fraction D95 des echantillons de gravel et la fraction D50 des echantillons de sable peuvent être reliees la contribution des tributaires aux pentes plus escarpees et fortement glaciaires ou ceux qui traversent les basaltes fractures du Plateau Fraser. Cependant, quand il y a des similitudes dans la granulometrie de la source et le dépôt-échantillon, l'information granulometrique seule ne peut pas 6tre employee pour differencier les sources. La lithologie des alluvions de Bella Coola montre une correspondance avec la distribution générale des types de roches dans le bassin, suggérant des contributions proportionnelles des sources tributaires a long terme. Cependant, les échantillons de sable des plaines sujettes à inondations ont en grande part une affinité volcanique, indiquant que la dominance du sédiment provient des tributaires qui traversent ce type de roche. Une addition de sediments de sources plutonique est evidente dans le bas de la Riviere Bella Coola adjacent aux eventails alluviaux, aux ruisseaux tributaires affect& par une forte glaciation, ou aux murs de roches qui comprennent principalement des quartz monzonites.  相似文献   
18.
The Americans with Disabilities Act was pushed through Congress with far less attention from the media than has accompanied other major civil rights bills. This was part of a deliberate and unconventional strategy by disability rights lobbyists who believed that media portrayals of disability were so cliched that journalists would impede, not further, the public's understanding of disability rights issues. Despite the success of the strategy, there is a price to pay for having been a 'stealth' civil rights movement: Now that the law is in place, disabled people face a backlash from Americans who neither understand the ADA nor the need for civil rights protection for disabled people.  相似文献   
19.
20.
Abstract. This article considers the debate that has recently developed in studies of nationalism between those scholars who see the nation as a modern and constantly changing construction ex nihilo and those who see it as an immemorial, unchanging communal essence. It outlines the so-called ‘gastronomical’ and ‘geological’ metaphors of nation formation and suggests a synthetic model which balances the influence of the ethnic past and the impact of nationalist activity. It shows that the central question which has divided theorists of nationalism is the place of the past in the life of modern nations. The author recognises the role of nationalists in national mobilisation but stresses that nationalists are not social engineers or mere image makers as modernist and post-modernist accounts would have it, but rather social and political archaeologists whose activities consist in the rediscovery and reinterpretation of the ethnic past and through it the regeneration of their national community.  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