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   746篇
  免费   64篇
  2023年   20篇
  2022年   11篇
  2021年   8篇
  2020年   42篇
  2019年   36篇
  2018年   48篇
  2017年   41篇
  2016年   42篇
  2015年   47篇
  2014年   35篇
  2013年   112篇
  2012年   51篇
  2011年   44篇
  2010年   36篇
  2009年   36篇
  2008年   33篇
  2007年   32篇
  2006年   31篇
  2005年   12篇
  2004年   11篇
  2003年   15篇
  2002年   7篇
  2001年   16篇
  2000年   7篇
  1999年   8篇
  1998年   7篇
  1997年   2篇
  1996年   4篇
  1994年   3篇
  1993年   3篇
  1991年   2篇
  1990年   2篇
  1989年   1篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1984年   1篇
  1982年   1篇
排序方式: 共有810条查询结果,搜索用时 15 毫秒
61.
Policy Bubbles     
We develop the concept of a policy bubble to capture the notion of long‐term overinvestment in a policy. In sketching the relation of policy bubbles to economic bubbles, we describe how these two concepts have similar origins but different trajectories because they are filtered by different institutions. We examine in some detail three likely instances of ongoing policy bubbles: crime policy, school reform (charter schools and private education vouchers), and the contracting and privatization of public services. We show how these cases differ from the housing bubble of 1997–2007, how they differ from each other, and the extent to which they can be considered policy bubbles. Last, we suggest this concept can help unify the policy process literature with the practice of policy evaluation and outline testable hypotheses for future research.  相似文献   
62.
Recent studies discuss the link between climate change and violent conflict, especially for East Africa. While there is extensive literature on the question whether climate change increases the risk of violent conflict onset, not much is known about where a climate-conflict link is most likely to be found. We address this question by analyzing the spatial distribution of the factors commonly associated with a high exposure and vulnerability to climate change, and a high risk of violent conflict onset in Kenya and Uganda. Drawing on recent literature and quantitative data for the period 1998–2008, we develop various specifications of a composite risk index (CRI) with a spatial resolution of half a degree for Kenya and Uganda in the year 2008. A quantitative comparison with conflict data for the year 2008 provides support for the composite risk index. Finally, the composite risk index is contrasted with the findings of three qualitative case studies, which provide mixed support for the index and help to identify its strengths and weaknesses as well as conceptual needs for further quantitative studies on climate change and violent conflict.  相似文献   
63.
欧美学者普遍认为,角色压力是影响员工服务态度和服务行为的一个极为重要的因素,包括角色负担、角色冲突、角色模糊等3个组成成分.本文对我国11个地区的33个旅游企业进行了一次实证研究,检验部门管理人员感知的组织支持、企业的支持型领导氛围、授权氛围和员工服务行为评估氛围对员工角色模糊的影响.多层次线性模型分析结果表明,部门管理人员感知的组织支持会通过企业的支持型领导氛围,间接影响员工感知的角色模糊.企业的支持型领导氛围会通过企业的授权氛围,间接影响员工感知的角色模糊.此外,部门管理人员感知的企业支持还会调节员工感知的角色负担和角色冲突对他们的角色模糊的影响.  相似文献   
64.
Knowledge and science transfer – introductory remarks. The article presents introductory remarks on the historical study of knowledge and science transfer. Discussion focuses initially on the reasons for speaking of knowledge transfer and not only about science transfer, and the relations of this topic to current research in general history on cultural transfer. Multiple levels of knowledge / science transfer are then discussed, specifically: (1) transfer by means of migration or other movement of people across geographic boundaries; (2) scientific changes related to the transfer of objects (such as plant specimens or instruments) across continents or disciplines; (3) knowledge or science transfer in practical contexts. Addressed throughout is the problematic character of the concept of transfer itself. The author suggests that users of this concept often presuppose a static conception of scientific and cultural contents being more or less successfully transferred; more interesting, however, are the changes in science and culture conditioned or caused by the migration of individuals as well as the transfer of culture by other means.  相似文献   
65.
Issue redefinition and venue shopping have been identified as key strategies for enacting agenda and policy change, but much work remains to be done in elaborating these processes. I argue that an important aspect of issue redefinition involves shifting not only the image of an issue but also the bases for considering those issues—what I call policy principles. Policy principles are the core values, beliefs, or guidelines attached to policies that help direct decision making. The emergence and acceptance of new principles by the public and policymakers can be a vital source of policy change, at times having far greater consequences for policy than redefining an issue. Venue shopping is also a multifaceted undertaking involving efforts by policy entrepreneurs and advocacy groups to keep issues out of venues they would rather not participate in as well as move decision making to new arenas. Moreover, while the literature suggests that shifting venues is usually a sensible strategy, sometimes venue shopping can backfire. A case study of the municipal movement to restrict the nonessential use of lawn and garden pesticides in Canada illustrates these theoretical points and shows the applicability of agenda setting models to contexts outside the United States.  相似文献   
66.
Why do policies change dramatically? Most prominent theories and many empirical studies of policy change address that question with attention to external shocks to policy systems or focusing events. These shocks or events are usually described as unplanned, unpredicted jolts such as global crises or natural disasters. I assert a role for focusing projects. These planned activities continue traditional priorities in an issue but do so to a degree perceived as excessive by enough people to shatter seemingly stable policy systems. I then propose a theoretical framework to explain the varying impacts from such projects. The framework uses two dimensions: one that accounts for the mobilization of pro‐change forces and one that assesses policy learning by members of pro‐status quo coalitions. I examine this framework in the context of changes to dam‐building policies in four diverse political settings: United States, Australia, Canada, and China. I find intriguing similarities between the focusing projects in these different contexts but also considerable variation in the extent to which they produce policy change.  相似文献   
67.
The extent to which North Atlantic Holocene climatic perturbations influenced past human societies is an area of considerable uncertainty and fierce debate. Ireland is ideally placed to help resolve this issue, being occupied for over 9000 yr and located on the eastern Atlantic seaboard, a region dominated by westerly airflow. Irish bog and lake tree populations provide unambiguous evidence of major shifts in surface moisture through the Holocene similar to cycles recorded in the marine realm of the North Atlantic, indicating significant changes in the latitude and intensity of zonal atmospheric circulation across the region. To test for human response to these cycles we summed the probabilities of 465 radiocarbon ages obtained from Irish archaeological contexts and observe enhanced archaeological visibility during periods of sustained wet conditions. These results suggest either increasing density of human populations in key, often defensive locations, and/or the development of subsistence strategies to overcome changing conditions, the latter recently proposed as a significant factor in avoiding societal collapse. Regardless, we demonstrate environmental change is a significantly more important factor in influencing human activity in the landscape than has hitherto been acknowledged.  相似文献   
68.
The Amazon region has long been a place of economic booms and busts. Much attention in the historical literature on Amazonia has focused on the largest and most famous regional economic boom, the Rubber Boom, a period of sustained economic prosperity for some from 1860 to 1920. Other ‘booms’ have occurred in the region as well and this paper describes and discusses one of those others. The paper demonstrates how an export economy in a global periphery (coffee in Brazil) affected economic development in a periphery of that same country and makes a methodological contribution by demonstrating how ethnographic research can contribute to an understanding of a historical period when the paper trail is weak.Jute, a fiber crop, dominated agricultural production along the Amazon River floodplain in the reach between Manaus and Santarém, Brazil, from the late 1930s until the early 1990s. The crop was introduced to the region by Japanese immigrants in order to supply the demand for jute sacking in the south of Brazil where such sacks were used to package commodities, especially coffee. Local smallholder cultivators grew and processed jute, production being mediated initially through Japanese middlemen, later by Brazilians. Poor fiber quality, several external shocks, including the removal of tariffs on imported jute, and especially changes in commodity packaging such as bulk handling and the use of synthetic sacks instead of jute sacks for the transport of coffee beans, the Amazonian jute market collapsed in the early 1990s. Despite its collapse, the legacy of the boom is still evident in the physical and social landscapes in the region.  相似文献   
69.
The marine trophic levels targeted during Swift Creek (AD 300–700) and Savannah (AD 1200–1500) occupations at the Cathead Creek site (9Mc360) and at two sites from the Kings Bay Locality (9CAM171a, 9CAM177), coastal Georgia, USA, differ in a consistent temporal and spatial pattern. Vertebrate and invertebrate remains from these three coastal sites contain similar suites of estuarine animals. However, Swift Creek peoples at these distinct hydrological settings obtained more biomass from fishes and less from molluscs compared to the subsequent Savannah occupants. The two Swift Creek faunal collections are less rich, more diverse, and more equitable than the two subsequent Savannah collections regardless of location. Furthermore, the mean trophic level is higher in the Swift Creek collections compared to the Savannah ones at both locations. These observations apply to both biomass and Minimum Number of Individuals. These differences likely are defining characteristics distinguishing the Swift Creek and the Savannah economies. More research is needed to determine the extent to which these temporal and spatial patterns are attributable to environmental and cultural variables.  相似文献   
70.
经济行为与环境变化:清前期台湾野生鹿消失探析   总被引:3,自引:0,他引:3  
鹿曾经是台湾数量最庞大的野生动物群之一。明末以来,随着台湾贸易交流的活跃,鹿成为大宗出口商品,土著居民由原先捕鹿作为民生用品逐渐发展至为市场服务;清前期大陆移民入台的农业垦殖又破坏了鹿原有的生态环境。人类经济行为引发的环境变化,最终导致了野生鹿在台湾渐趋消失。  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