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   3607篇
  免费   186篇
  2023年   24篇
  2020年   87篇
  2019年   68篇
  2018年   158篇
  2017年   158篇
  2016年   148篇
  2015年   93篇
  2014年   98篇
  2013年   1170篇
  2012年   106篇
  2011年   103篇
  2010年   86篇
  2009年   80篇
  2008年   79篇
  2007年   54篇
  2006年   65篇
  2005年   41篇
  2004年   52篇
  2003年   50篇
  2002年   37篇
  2001年   38篇
  2000年   28篇
  1999年   32篇
  1998年   30篇
  1997年   27篇
  1996年   21篇
  1995年   28篇
  1994年   29篇
  1993年   28篇
  1992年   29篇
  1991年   24篇
  1990年   24篇
  1989年   26篇
  1988年   24篇
  1987年   24篇
  1986年   27篇
  1985年   24篇
  1984年   29篇
  1983年   31篇
  1982年   25篇
  1981年   25篇
  1980年   25篇
  1979年   30篇
  1978年   28篇
  1977年   29篇
  1976年   23篇
  1975年   24篇
  1973年   25篇
  1971年   22篇
  1969年   24篇
排序方式: 共有3793条查询结果,搜索用时 15 毫秒
61.
62.
63.
This paper demonstrates that the morphology of ordinary rural roads tells much about regional development. It uses southern Ontario as a case study, but the principles may be applied widely. It is a plea for recognition of a deep heritage in unspectacular things: ditches, fence-lines, culverts, jogs in the survey, and more. This paper also encourages local and regional planners to conserve signs of change in the roadscape and to celebrate them. Roadside evolution is worth publicizing, and unnecessary destruction of elements that enhance the story must be discouraged.
Cet essai démontre que la morphologie des routes rurales ordinaires en dit beaucoup au sujet du développement regional. On peut employer cet exemple de /'Ontario du sud mais les principes peuvent s'appliquer d'une manière plus large. Dans ce manuscrit on doit reconnaître /'heritage profond des elements communs: des caniveaux, des clotures, des aqueducs, des irrégularity de I'arpentage, etc. Cet essai encourage aussi les planificateurs i conserver ces signes du paysage routier et à les mettre en Évidence. On doit les faire connaître au public, et décourager leur déstruction.  相似文献   
64.
65.
Tráfico de Indias y política oceánica. By Fernando Bordejé Y Morencos. Madrid: MAPFRE, 1992. Pp. 341.

Relaciones económicas entre España y América hasta la independencia. By John R. Fisher. Madrid: MAPFRE, 1992. Pp. 280.

Las comunicaciones en América. By Secundino‐José Gutiérrez Alvarez. Madrid: MAPFRE, 1993. Pp. 424.

Piratas, bucaneros, filibusteros y corsarios en América. Perros, mendigos y otros malditos del mar. By Manuel Lucena Salmoral. Madrid: MAPFRE, 1992. Pp. 306.

El dinero americano y la política del imperio. By María Emelina Martín Acosta. Madrid: MAPFRE, 1992. Pp. 333.

Cargadores a Indias. By Julian B. Ruiz Rivera and Manuela Cristina García Bernal. Madrid: Mapfre, 1992. Pp. 395.  相似文献   

66.
A trial, monitored release on the Wingecarribee River over 27 days had a peak discharge below the Wingecarribee Dam of 1090 ML/d, which had a flow duration of 0.95 per cent. Morphological impacts on 29 km of channel below the dam included bank erosion, concentrated neck overflow, bed degradation and channel widening at recent cutoffs, sedimentation in weir pools and overbank flow, particularly at discharges greater than 800 ML/d. Prolonged operational releases at bankfull discharge (400–800 ML/d) will have the greatest morphologic impacts and should be avoided. Pulses which dissipate stream power over a broad, well-vegetated floodplain should be incorporated in the operational release policy, provided such pulses are phased to facilitate channel and vegetation recovery.  相似文献   
67.
68.
The Early Historic Period in the Mun Valley occupies a critical three centuries, from A.D. 500 to A.D. 800, a period often known as that of Zhenla, a name derived from early Chinese accounts. This article first describes early findings of fieldwork designed to illuminate the prehistory of the upper Mun Valley, a period which covers approximately two millennia, with initial settlement now dated between 1500 and 1000 B.C. It then considers the nature of the transition to the complex polities of Zhenla. This involves a combination of archaeological and documentary evidence. Sources for the latter are rare for the Mun Valley, but by broadening the area considered, it is possible to integrate archaeological and historical sources in order to portray the intensifying social changes which characterize the Early Historic Period. It is suggested that most of the Mun Valley was occupied by Khmer speakers during the Iron Age, people responsible for the transition to increasingly centralized polities of the Early Historic Period. In the upper reaches of the Mun catchment, and in the Chi Valley to the north, the late prehistoric inhabitants spoke Mon. They had close affinities with the Dvaravati polities of Central Thailand. If confirmed, this hypothesis would indicate a series of local trends towards increasing social complexity which we can recognize in the early epigraphic record.  相似文献   
69.
Concepts of unemployment or of the labour market are not abstract, but develop from each society's own particular logic. Taking the examples of Germany and France at the end of the nineteenth century, it is possible to see how these concepts were constructed in specific national contexts, and how they were then used in practice. This analysis leads us to rethink current ideas about work and unemployment, and to ask what their future will be in a united Europe.  相似文献   
70.
Cultural resource management (CRM) work accounts for most of the archaeology conducted in the United States. A diverse and somewhat fragmented field, CRM has nonetheless achieved a degree of institutional and organizational maturity. CRM archaeology has produced important contributions to archaeological methodology and has established and refined knowledge of regional cultural-historical sequences and settlement and subsistence patterns. The current florescence of historical archaeology is attributable to CRM. Yet the maintenance of high quality in CRM is a pervasive and enduring problem. Academic institutions need to reestablish alliances with the CRM community. The future viability of CRM archaeology depends on factors both internal and external to the discipline: regulatory and statutory “reform,” agency funding levels, looting and other destructive forces, and Native American and other public involvement.  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