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   239篇
  免费   1篇
  国内免费   2篇
安全科学   13篇
废物处理   5篇
环保管理   23篇
综合类   79篇
基础理论   47篇
污染及防治   56篇
评价与监测   9篇
社会与环境   10篇
  2023年   3篇
  2022年   3篇
  2020年   4篇
  2019年   2篇
  2018年   7篇
  2017年   6篇
  2016年   11篇
  2015年   8篇
  2014年   5篇
  2013年   17篇
  2012年   6篇
  2011年   16篇
  2010年   4篇
  2009年   14篇
  2008年   11篇
  2007年   17篇
  2006年   15篇
  2005年   15篇
  2004年   9篇
  2003年   9篇
  2002年   9篇
  2001年   8篇
  1999年   3篇
  1997年   1篇
  1996年   3篇
  1995年   1篇
  1994年   3篇
  1992年   2篇
  1991年   3篇
  1989年   2篇
  1986年   2篇
  1985年   2篇
  1984年   1篇
  1982年   3篇
  1981年   1篇
  1978年   1篇
  1977年   2篇
  1975年   1篇
  1964年   1篇
  1963年   1篇
  1962年   1篇
  1961年   1篇
  1953年   1篇
  1951年   3篇
  1948年   1篇
  1942年   1篇
  1941年   1篇
  1914年   1篇
排序方式: 共有242条查询结果,搜索用时 15 毫秒
71.
This paper situates livelihood adaptations in two coastal villages within the broader context of Belize's colonial and post-colonial history and environmental processes of change. Through observations, qualitative interviews, and archival reviews, we explore the dynamics of livelihood change and analyse the diverse factors that have been influencing options and adaptation over time. The results reveal that both villages have undergone profound changes in livelihoods and productive activities on several occasions. While the villages' histories, geographies, and cultures are different, similarities in long-term trends include the transition from land-based to marine resources and the decline of small-scale agriculture. Our analysis illuminates the deep connections between local livelihoods and national as well as global political–economic processes, which favour extraction and export of natural resources throughout the period investigated, whereby resource access and market mechanisms create and constrict adaptation options for the villagers. Gradual environmental changes, such as erosion, and episodic events, such as hurricanes, have also influenced livelihood shifts and adaptations in combination with a wide range of political–economic factors. Despite the demonstrated importance of the influence of history and dimensions of political economy on contemporary adaptation options in the communities studied, the literature on climate change adaptation inadequately accounts for these factors. This paper adds new perspectives to current debates in climate change research by emphasising that longer temporal dimensions of livelihood change are important for understanding the current context for adaptation.  相似文献   
72.
ABSTRACT

The Norwegian urban growth agreement (UGA) is a governance platform combining transport-infrastructure development with land-use and transport policy. It is a policy package of measures involving network cooperation between national, regional and local government levels established to coordinate transport and land-use development. Shared responsibility for goal achievement, autonomy and learning and adaptation as new knowledge and experience arise are clear prerequisites for the UGAs. This makes it relevant to investigate the conditions for the UGAs to work as an adaptive governance strategy because their central features are in line with the attributes of adaptive governance. Further, adaptive governance is an approach to handle complex problems like transport development issues. The study shows that UGAs have several strengths in terms of autonomy and learning. However, the multi-level cooperation in the UGAs is framed by complex underlying structures of roles and powers, which challenge the working and legitimacy of the governance structures. Multi-level adaptive governance processes like the UGAs require attention to issues of power and legitimacy. Securing transparency and democratic anchorage is paramount in bringing such processes in line with the intended benefits of adaptive governance.  相似文献   
73.
Diadromous aquatic species that cross a diverse range of habitats (including marine, estuarine, and freshwater) face different effects of climate change in each environment. One such group of species is the anadromous Pacific salmon (Oncorhynchus spp.). Studies of the potential effects of climate change on salmonids have focused on both marine and freshwater environments. Access to a variety of estuarine habitat has been shown to enhance juvenile life-history diversity, thereby contributing to the resilience of many salmonid species. Our study is focused on the effect of sea-level rise on the availability, complexity, and distribution of estuarine, and low-freshwater habitat for Chinook salmon (Oncorhynchus tshawytscha), steelhead (anadromous O. mykiss), and coho salmon (O. kisutch) along the Oregon Coast under future climate change scenarios. Using LiDAR, we modeled the geomorphologies of five Oregon estuaries and estimated a contour associated with the current mean high tide. Contour intervals at 1- and 2-m increments above the current mean high tide were generated, and changes in the estuary morphology were assessed. Because our analysis relied on digital data, we compared three types of digital data in one estuary to assess the utility of different data sets in predicting the changes in estuary shape. For each salmonid species, changes in the amount and complexity of estuarine edge habitats varied by estuary. The simple modeling approach we applied can also be used to identify areas that may be most amenable to pre-emptive restoration actions to mitigate or enhance salmonid habitat under future climatic conditions.  相似文献   
74.
75.
76.
77.
78.
79.
We assessed the discriminatory efficiency and cost-effectiveness of a novel way of organising first trimester screening for Down syndrome (DS), contingent testing, where a serological test (PAPP-A and β-hCG: the double test) is made in early first trimester and followed by nuchal translucency testing (NT) only in women with an intermediate risk, e.g. <1:65 and >1:1000, and not in all women as in normal first trimester screening (NFTS). Using Monte Carlo simulation contingent testing had a detection rate (DR) of 78.9% and a false-positive rate (FPR) of 4.0% for DS with 19.4% of women offered NT testing. The DR of NFTS was 85.5% and the FPR 4.4%. The decrease in NT screening was associated with an increase from 23% to 29% in the proportion of DS cases born. The cost of the contingent testing programme was £53 000 per DS case not born and £91 000 in NFTS. The number of aborted fetuses per DS case were 0.35 and 0.36, respectively. Thus, contingent testing is an organisation of first trimester screening where costs can be reduced with a marginal decrease in performance. Contingent testing is attractive in areas where NT screening is the bottleneck preventing the introduction of first trimester screening. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
80.
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