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   12篇
  免费   0篇
大气科学   1篇
地球物理   4篇
地质学   4篇
海洋学   1篇
自然地理   2篇
  2016年   1篇
  2015年   1篇
  2010年   2篇
  1998年   1篇
  1996年   1篇
  1990年   2篇
  1983年   1篇
  1974年   3篇
排序方式: 共有12条查询结果,搜索用时 812 毫秒
11.
This article examines linkages between recent domestic out-migration from immigrant gateway metropolitan areas and nonmetropolitan migration gains, based on data of the 1990 census, 1996 Current Population Survey, and population estimates for the 1990–1996 period from the Bureau of Census. Our analysis of these data suggests that there is a mirror image of migration patterns between high immigration metropolitan area losses and nonmetropolitan area gains. This is especially evident in the West with the relationship between Los Angeles and San Francisco areas' losses on the one hand, and the region's nonmetropolitan gains on the other. While pre-elderly and elderly retirees have contributed to these nonmetropolitan gains, much of it is attributable to the destination choices of suburban-like populations—Whites with children, not college educated, and with lower incomes—that have been leaving high immigration metropolitan areas. This new, more dispersed form of “White flight” holds the potential for reinvigorating smaller, nonmetropolitan communities, but creating, as well, new demographic divisions across space.  相似文献   
12.
A new structural system for earthquake resistant steel structures is investigated in this paper. This new framing system, called the knee-brace-frame (KBF), is a braced frame with diagonal braces connected to ductile knee members. The diagonal braces provide the lateral stiffness, whereas the knee anchors yield in flexure to dissipate energy during severe seismic excitation. To assess the inelastic characteristics of the KBF, a large scale model of a KBF was tested using the pseudodynamic test procedure. The experimental results are compared with analytical results obtained from a DRAIN-2D model. It is found that, with an appropriate design of knee anchors, the KBF can be made to be ductile to dissipate energy during severe seismic excitation.  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