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   5654篇
  免费   260篇
  2020年   86篇
  2019年   129篇
  2018年   169篇
  2017年   205篇
  2016年   187篇
  2015年   137篇
  2014年   144篇
  2013年   1800篇
  2012年   127篇
  2011年   145篇
  2010年   153篇
  2009年   137篇
  2008年   120篇
  2007年   105篇
  2006年   90篇
  2005年   70篇
  2004年   75篇
  2003年   79篇
  2002年   81篇
  2001年   76篇
  2000年   91篇
  1999年   72篇
  1998年   61篇
  1997年   71篇
  1996年   50篇
  1995年   56篇
  1994年   44篇
  1993年   42篇
  1992年   45篇
  1991年   54篇
  1990年   38篇
  1989年   43篇
  1988年   47篇
  1987年   45篇
  1986年   46篇
  1985年   72篇
  1984年   54篇
  1983年   71篇
  1982年   52篇
  1981年   63篇
  1980年   55篇
  1979年   61篇
  1978年   61篇
  1977年   45篇
  1976年   53篇
  1975年   38篇
  1974年   39篇
  1973年   35篇
  1972年   28篇
  1969年   27篇
排序方式: 共有5914条查询结果,搜索用时 140 毫秒
101.
Current federal hazardous and low-level radioactive waste management policies (under conjoint federalism) fail to balance national concerns for consistency with state concerns for equity, discretion, and adequate resources. Congress should expand conjoint federalism to permit states to charge differential fees on imported hazardous waste as it does for low-level radioactive waste. For low-level radioactive waste, clarification of the "take title" issue makes the present framework for state discretion implementable, given sufficient time.  相似文献   
102.
103.
An important line of research concerning historical fertility patterns in currently developed countries of Europe has concluded that, prior to the fertility transition, marital fertility was essentially constant over time, and deliberate fertility control was virtually unknown. It has been argued that variations over time in overall fertility were largely the consequence of variations in nuptiality. Other researchers have challenged these views and present evidence for the existence of a significant minority of fertility controllers in pretransition populations. In this article, we find support for this second view and argue that (1) there was significant, non-random variation in marital fertility over time, prior to the transition; (2) in many cases, this variation in marital fertility was large relative to contemporaneous variations in nuptiality; and (3) in a substantial minority of the cases, the variation over time in pretransition marital fertility was so large that it is suggestive of deliberate fertility control. Thus, our findings question the view of fertility transition as an innovation in deliberate marital fertility control. While most of our evidence is based on data from England and Wales, we find corroboration of our key results in other European data.  相似文献   
104.
David Schmid 《对极》1995,27(3):242-269
Radical geographers often discuss how contemporary urban space is becoming increasingly violent and dangerous. They pay much less attention to the question of how to make this space safe. In contrast, detective fiction focuses precisely on how to take danger out of the city. It therefore provides radical geographers with imaginative models of how different levels of space are linked through forms of violence. Detective fiction challenges accounts of the urban spatialization of power that over-simplify relations between city inhabitants as a clash between “oppressor” and “oppressed.” By suggesting how a subject can simultaneously oppress through and be oppressed by volence, detective fiction shows the contradictory multiplicity of people's spatial identifications.  相似文献   
105.
The possibility of lead isotope fractionation in ancient lead production is examined. Kinetic theory relating to isotopic fractionation in non-equilibrium evaporation is considered and the feasibility of the alteration of lead isotope abundance ratios in ore roasting and smelting is assessed. Previous experimental work is shown to have been inconclusive and conclusions are drawn on the need for further research to quantify the possible extent of fractionation in practice.  相似文献   
106.
107.
108.
The need for experiments to study physical aspects of craft of the past is stated, as well as the necessity for them to have clear aims and to follow the established principles of scientific enquiry. These principles are discussed in this joint paper by ten maritime archaeologists and others, together with methods and some points of management critical to their application in this field.  相似文献   
109.
110.
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