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   193篇
  免费   10篇
  国内免费   2篇
安全科学   7篇
废物处理   10篇
环保管理   47篇
综合类   43篇
基础理论   26篇
污染及防治   46篇
评价与监测   12篇
社会与环境   7篇
灾害及防治   7篇
  2023年   1篇
  2022年   1篇
  2021年   5篇
  2020年   7篇
  2019年   8篇
  2018年   7篇
  2017年   6篇
  2016年   10篇
  2015年   11篇
  2014年   9篇
  2013年   20篇
  2012年   12篇
  2011年   10篇
  2010年   8篇
  2009年   10篇
  2008年   13篇
  2007年   11篇
  2006年   4篇
  2005年   11篇
  2004年   5篇
  2003年   7篇
  2002年   4篇
  2001年   5篇
  2000年   3篇
  1999年   2篇
  1998年   1篇
  1997年   3篇
  1995年   1篇
  1994年   2篇
  1993年   4篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1981年   1篇
排序方式: 共有205条查询结果,搜索用时 46 毫秒
131.
Resource planning and management in British Columbia, Canada, has been steadily moving towards more active public participation. While government agencies have long been required to consult the general public during the course of land or resource use planning, the 1990s brought in a period of more intense public involvement. In terms of resource planning, this led to the creation of several new planning processes. Given that there is now considerable experience with the Commission on Resources and Environment (CORE) and the Land and Resource Management Plan (LRMP) processes, it is time for an appraisal. In particular, the paper examines the public's perceptions of these processes with respect to 'what works well' and 'what needs improvement'. The results highlight a number of areas to which process designers and managers should direct attention. There are three key items of note. First, there are generally low levels of awareness by respondents of public consultation processes in their community. Second, there is a need for access to timely, relevant and readable information throughout the course of the process in order to keep participants and the public as up-to-date as possible. Finally, there must be greater clarity about the process itself, including mandates, participants and decision-making powers.  相似文献   
132.
133.
134.
135.
The oxidation of SO2 is commonly regarded as a major driver for new particle formation (NPF) in the atmosphere. In this study, we explored the connection between measured mixing ratio of SO2 and observed long-term (duration > 3 hr) and short-term (duration <1.5 hr) NPF events at a semi-urban site in Toronto. Apparent NPF rates (J30) showed a moderate correlation with the concentration of sulfuric acid ([H2SO4]) calculated from the measured mixing ratio of SO2 in long-term NPF events and some short-term NPF events (Category I) (R2 = 0.66). The exponent in the fitting line of J30 ~ [H2SO4]n in these events was 1.6. It was also found that SO2 mixing ratios varied a lot during long-term NPF events, leading to a significant variation of new particle counts. In the SO2-unexplained short-term NPF events (Category II), analysis showed that new particles were formed aloft and then mixed down to the ground level. Further calculation results showed that sulfuric acid oxidized from SO2 probably made a negligible contribution to the growth of >10 nm new particles.  相似文献   
136.
Habitat suitability maps are commonly created by modeling a species’ environmental niche from occurrences and environmental characteristics. Here, we introduce the hyper-envelope modeling interface (HEMI), providing a new method for creating habitat suitability models using Bezier surfaces to model a species niche in environmental space. HEMI allows modeled surfaces to be visualized and edited in environmental space based on expert knowledge and does not require absence points for model development. The modeled surfaces require relatively few parameters compared to similar modeling approaches and may produce models that better match ecological niche theory. As a case study, we modeled the invasive species tamarisk (Tamarix spp.) in the western USA. We compare results from HEMI with those from existing similar modeling approaches (including BioClim, BioMapper, and Maxent). We used synthetic surfaces to create visualizations of the various models in environmental space and used modified area under the curve (AUC) statistic and akaike information criterion (AIC) as measures of model performance. We show that HEMI produced slightly better AUC values, except for Maxent and better AIC values overall. HEMI created a model with only ten parameters while Maxent produced a model with over 100 and BioClim used only eight. Additionally, HEMI allowed visualization and editing of the model in environmental space to develop alternative potential habitat scenarios. The use of Bezier surfaces can provide simple models that match our expectations of biological niche models and, at least in some cases, out-perform more complex approaches.  相似文献   
137.
此文以霸县凹陷文安斜坡和饶阳凹陷留楚构造为研究对象,对比了斜坡区和隆起区断裂密集带的特征及其对不同构造部位油气分布的控制作用。在三维地震资料、钻井资料和已发现油气藏特征的基础上,利用断裂密集带识别方法和分类方案,识别出文安斜坡和留楚构造的断裂密集带,并对其进行了分类。对比两种构造部位断裂密集带发育的差异性及对油气分布的控制作用,认为隆起区(留楚构造)相对于斜坡区(文安斜坡)断裂密集带发育数量较少,规模大,斜坡区断裂密集带主要以顺向背形断裂密集带为主,而隆起区主要以屋脊背形断裂密集带为主,隆起区油气主要分布在顺向背形断裂密集带内,斜坡区主要分布在屋脊背形断裂密集带内部及靠近生烃中心的边部。  相似文献   
138.
139.
This study documents the effects of two consecutive disturbances on coral community structures in the Gulf of Oman (United Arab Emirates); Cyclone Gonu in June 2007 and the Cochlodinium polykrikoides harmful algal bloom (HAB) that persisted from August 2008 until May 2009. Coral cover, colony densities, size class frequency distributions, and geometric growth rates derived from size class transition probability matrices were used to assess the post-Gonu and post-HAB recovery trajectories at four sites. The net effects of these disturbances were fourfold: (i) storm damage caused >50% losses of live branching and tabular coral cover by fragmentation and dislodgment of pocilloporid and acroporid colonies; (ii) Pocillopora damicornis colonies that survived the cyclone experienced mass mortality during the first 3?months of the HAB, resulting in localized extirpation of this species; (iii) variable Acropora mortality during the HAB indicated individual colony, rather than taxa-wide, susceptibility; and (iv) massive colony coral taxa were resistant to both disturbances.  相似文献   
140.
This paper provides an assessment of the tools required to fulfil the air quality management role now expected of local authorities within the UK. The use of a range of pollution monitoring tools in assessing air quality is discussed and illustrated with evidence from a number of previous studies of urban background and roadside pollution monitoring in Leicester. A number of approaches to pollution modelling currently available for deployment are examined. Subsequently, the modelling and monitoring tools are assessed against the requirements of local authorities establishing air quality management areas. Whilst the paper examines UK-based policy, the study is of wider international interest.  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