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   476篇
  免费   13篇
  2023年   4篇
  2020年   11篇
  2019年   12篇
  2018年   14篇
  2017年   27篇
  2016年   16篇
  2015年   9篇
  2014年   7篇
  2013年   148篇
  2012年   14篇
  2011年   15篇
  2010年   9篇
  2009年   10篇
  2008年   12篇
  2007年   9篇
  2006年   6篇
  2004年   8篇
  2003年   9篇
  2002年   13篇
  2001年   13篇
  2000年   9篇
  1999年   4篇
  1998年   7篇
  1997年   7篇
  1996年   5篇
  1995年   6篇
  1994年   10篇
  1993年   3篇
  1992年   6篇
  1991年   2篇
  1990年   2篇
  1989年   2篇
  1988年   2篇
  1986年   2篇
  1985年   7篇
  1984年   6篇
  1983年   4篇
  1982年   2篇
  1981年   4篇
  1979年   7篇
  1978年   2篇
  1976年   5篇
  1975年   3篇
  1974年   2篇
  1973年   1篇
  1972年   2篇
  1970年   3篇
  1969年   1篇
  1966年   1篇
  1964年   1篇
排序方式: 共有489条查询结果,搜索用时 31 毫秒
91.
92.
Estimates of slope and aspect are commonly made from digital elevation models (DEMs), and are subject to the uncertainty present in such models. We show that errors in slope and aspect depend on the spatial structure of DEM errors. We propose a general-purpose model of DEM errors in which a spatially auto-regressive random field is added as a disturbance term to elevations. In addition, we propose a general procedure for propagating such errors through GIS operations. In the absence of explicit information on the spatial structure of DEM errors, we demonstrate the potential utility of a worst-case analysis. A series of simulations are used to make general observations about the nature and severity of slope and aspect errors.  相似文献   
93.
Spatial correlations are replaced by ordinary correlations by projecting the two-dimensional coordinates of a map onto a single axis making angle θ with the horizontal (east-west) axis. This calculation permits the use of exact test statistics. Moreover, the correlations can be plotted in polar coordinate form and the significance of the maximum correlation can be tested. The plot is a useful aid in assessing the reasonableness of the isotropy assumption.  相似文献   
94.
95.
96.
Three Latin mistranslations of Josephus' Jewish War I.61 between the fourth and the seventh centuries ce reflect the expansion of a series of charitable institutions, called xenodocheia and nosokomeia, around the Mediterranean in late antiquity and the early medieval period. In the late fourth century, authors known as pseudo‐Rufinus and pseudo‐Hegesippus independently mistranslated Josephus' report that the Hasmonean ruler John Hyrcanus hired mercenary troops at the conclusion of a Seleucid siege of Jerusalem. In their confusion, these authors both interpreted this as a charitable action and pseudo‐Hegesippus anachronistically imported the xenodocheion into the Hellenistic period. In the early seventh century Isidore of Seville expanded upon pseudo‐Hegesippus' mistake to transform the hiring of mercenaries into the genesis of both the xenodocheion and the nosokomeion. Isidore's inclusion of these institutions in his Etymologiae indicated their ubiquity and popularity by the seventh century, while for later writers his work canonized the mistaken origin.  相似文献   
97.
98.
Australia is at risk of being left behind by the pace of India's emergence as a regional and global power and its lack of engagement with India during this emergence. The Rudd Labor government is developing a framework which may make Australia a significant partner with India. There is the potential for a thoroughgoing engagement of interests and ideals in proposals Australia has put forward in three areas. Australia's vision of an Asia Pacific Community, with cooperation as its habitual operating principle, and with a membership that includes India and the USA as well as China and Japan, fills a multilateral gap. Secondly, the International Commission on Nuclear Non-Proliferation and Disarmament may provide a global framework assisting the development of Australian and Indian initiatives in the controlling and winding back of nuclear proliferation. Thirdly, Australia's national carbon pollution reduction program is intended to demonstrate international leadership and engagement in climate change, and opens the prospect for Australia of a substantial bilateral partnership with India (and others) to advance common interests around climate change. Australia, while emphasising its close relationship with the USA, is preparing to live in a region where the USA will, over time, be less influential as its relative power declines. As other great powers rise, Australia can actively pursue a hedging strategy to diversify its dependencies, and develop a much deeper engagement with that other emerging Asian giant.  相似文献   
99.
Recent years have witnessed a proliferation of state government policies addressing immigration‐related issues. This article addresses an example of state policy regarding immigration: since 2001, 11 state legislatures have granted undocumented high school graduates in‐state tuition status should they wish to attend public post‐secondary schools, while 18 others have considered, and rejected, the same policy. We argue that these outcomes are largely explicable by the manner in which the policy is presented and debated within state legislatures, especially the terms in which policy targets are socially constructed and state jurisdictional authority is framed. We apply this framework to two states (Kansas and Arkansas) that, in spite of demographic institutional similarities, reached different outcomes on in‐state tuition bills. The different outcomes can be traced to the manner in which policy deliberations in Kansas focused on positive evaluations of undocumented high school students, portraying them as “proto‐citizens,” while in Arkansas debate became centered on the state's jurisdictional authority to enact such a policy, an issue frame that effectively killed the legislation. This article suggests the importance of both social constructions and issue framing when state legislatures become the lead actors in crafting immigration policies.  相似文献   
100.
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