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   252篇
  免费   9篇
  国内免费   5篇
安全科学   75篇
废物处理   4篇
环保管理   55篇
综合类   49篇
基础理论   36篇
污染及防治   11篇
评价与监测   19篇
社会与环境   9篇
灾害及防治   8篇
  2024年   1篇
  2023年   2篇
  2022年   2篇
  2021年   7篇
  2020年   11篇
  2019年   9篇
  2018年   3篇
  2017年   10篇
  2016年   9篇
  2015年   5篇
  2014年   12篇
  2013年   9篇
  2012年   11篇
  2011年   18篇
  2010年   13篇
  2009年   20篇
  2008年   10篇
  2007年   7篇
  2006年   10篇
  2005年   6篇
  2004年   6篇
  2003年   13篇
  2002年   7篇
  2001年   8篇
  2000年   3篇
  1999年   7篇
  1998年   12篇
  1997年   6篇
  1996年   5篇
  1995年   3篇
  1993年   3篇
  1992年   2篇
  1990年   1篇
  1988年   2篇
  1986年   2篇
  1984年   1篇
  1983年   1篇
  1981年   1篇
  1979年   2篇
  1978年   1篇
  1972年   3篇
  1971年   1篇
  1970年   1篇
排序方式: 共有266条查询结果,搜索用时 234 毫秒
101.
范瑜 《环境科技》1999,12(3):28-29
根据对污染物污染分担率,在确定地面水体主要污染物的基础上,计算相应水体不平均综合污染指数、对地面水污染程度进行分级。  相似文献   
102.
Soil erosion is a major environmental problem and threat to rural development in Kenya. Numerous attempts to address the problem have apparently had little success. There are however some districts that have been very successful, notably Machakos. In this study we search for the factors that determine successful development in soil conservation such as social capital, human capital and market integration. One of our main results is that social capital measures are significant determinants of investment in soil conservation. A better understanding of the relevant mechanisms is essential for developing policies targeting improvement in natural resource management.
Wilfred NyangenaEmail:
  相似文献   
103.
We examine issues to consider when reframing conservation science and practice in the context of global change. New framings of the links between ecosystems and society are emerging that are changing peoples’ values and expectations of nature, resulting in plural perspectives on conservation. Reframing conservation for global change can thus be regarded as a stage in the evolving relationship between people and nature rather than some recent trend. New models of how conservation links with transformative adaptation include how decision contexts for conservation can be reframed and integrated with an adaptation pathways approach to create new options for global‐change‐ready conservation. New relationships for conservation science and governance include coproduction of knowledge that supports social learning. New processes for implementing adaptation for conservation outcomes include deliberate practices used to develop new strategies, shift world views, work with conflict, address power and intergenerational equity in decisions, and build consciousness and creativity that empower agents to act. We argue that reframing conservation for global change requires scientists and practitioners to implement approaches unconstrained by discipline and sectoral boundaries, geopolitical polarities, or technical problematization. We consider a stronger focus on inclusive creation of knowledge and the interaction of this knowledge with societal values and rules is likely to result in conservation science and practice that meets the challenges of a postnormal world.  相似文献   
104.
一种新型的矿井突水分析与预测的支持向量机模型   总被引:2,自引:0,他引:2  
针对矿井突水样本数少,信息不完整的特点,提出了矿井突水分析的线性核H-SVMs模型。推导模型的理论推广误差公式,设计自顶向下基于SVM最大间隔逐层分类构造H-SVMs的新方法,并应用于实际的矿井突水预测。实验结果表明,线性核H-SVMs模型结构简单、泛化能力强,不仅能很好地预测矿井突水,而且其层次结构能正确反映突水的等级关系,各判别函数的法向量还可以指示各突水影响因素的权重,通过判决函数能有效分析突水影响因素并提取突水预测规则,为矿井突水预测提供了新的方法。  相似文献   
105.
System-based approaches such as Functional Resonance Analysis Model (FRAM) are developed to model the complex interactions of system variables and their performance variabilities that may lead to a hazardous scenario in a complex system. However, they have limitations to be applied in process industries for hazard identification since they are heavily based on qualitative analysis and expert elicitations. To overcome the limitations of the system-based hazard identification, the study developed a FRAM-based framework to integrate a human performance model, an equipment performance model, and a first-principle based chemical process model into a hybrid simulator, which will be able to aid hazard analysis in the process industries. The simulator is capable of simulating the performance variabilities of the functions through the aggregation of mathematical models within a complex system, which can be used to simulate potential hazard situations and identify the corresponding interactions. Interaction analysis is conducted by applying association rule mining to the simulated data. The impact of the interactions among upstream functions on the performance of downstream functions can be identified by interpreting the rules, whose antecedents contain upstream functions and consequents contain downstream functions.  相似文献   
106.
我国环境侵权规范分散于相关立法,存在体系性不足和制度性缺陷等问题,因此,必须出台环境侵权专门立法。在构成要件方面,必须构建环境侵权二元规则,即人身损害适用无过错责任,财产损失适用过错推定责任;在责任承担方面,故意违法排污应当引入惩罚性赔偿。《侵权责任法》第67条适用于环境共同侵权内部责任份额的确定。环境侵权专门立法应当规定环境公益诉讼。  相似文献   
107.
Abstract: Assessing species survival status is an essential component of conservation programs. We devised a new statistical method for estimating the probability of species persistence from the temporal sequence of collection dates of museum specimens. To complement this approach, we developed quantitative stopping rules for terminating the search for missing or allegedly extinct species. These stopping rules are based on survey data for counts of co‐occurring species that are encountered in the search for a target species. We illustrate both these methods with a case study of the Ivory‐billed Woodpecker (Campephilus principalis), long assumed to have become extinct in the United States in the 1950s, but reportedly rediscovered in 2004. We analyzed the temporal pattern of the collection dates of 239 geo‐referenced museum specimens collected throughout the southeastern United States from 1853 to 1932 and estimated the probability of persistence in 2011 as <6.4 × 10?5, with a probable extinction date no later than 1980. From an analysis of avian census data (counts of individuals) at 4 sites where searches for the woodpecker were conducted since 2004, we estimated that at most 1–3 undetected species may remain in 3 sites (one each in Louisiana, Mississippi, Florida). At a fourth site on the Congaree River (South Carolina), no singletons (species represented by one observation) remained after 15,500 counts of individual birds, indicating that the number of species already recorded (56) is unlikely to increase with additional survey effort. Collectively, these results suggest there is virtually no chance the Ivory‐billed Woodpecker is currently extant within its historical range in the southeastern United States. The results also suggest conservation resources devoted to its rediscovery and recovery could be better allocated to other species. The methods we describe for estimating species extinction dates and the probability of persistence are generally applicable to other species for which sufficient museum collections and field census results are available.  相似文献   
108.
ITS数据质量控制技术及应用研究   总被引:8,自引:1,他引:7  
通过总结智能交通系统 (ITS)数据质量控制中所涉及的数据属性 ,提出了ITS数据质量控制算法 :根据阈值理论和交通流理论 ,针对错误数据、丢失数据和不精确数据设计相应的判别规则 ,利用数值计算方法对其进行修正 ,并提出了针对数据中的不规则时间点的修正算法。在对北京市和美国圣安东尼奥市的两组不同时间序列的ITS数据进行实践应用后 ,比较质量控制前后的数据特征 ,证明所提出的算法能够有效地解决数据质量问题 ,提高数据的精确度。最后 ,对国内外ITS数据进行质量控制后的结论和经验作了总结。  相似文献   
109.
从事故统计分析结果表明,90%以上的事故是由操作者违章作业造成的。因而提出了安全预案预控活动的有效方法,并介绍了实现这一方法的阶段及效果。  相似文献   
110.
Vlado Vivoda   《Resources Policy》2011,36(1):49-59
The aim of this paper is to assess the conditions that influence foreign direct investment in the mineral industries of China and India. The paper first surveys literature on the determinants of foreign direct investment to identify key conditions, under which host countries attract mining FDI. It then builds an evaluative framework which allows for comparative analysis. The paper then comparatively evaluates the performance of foreign investment regimes that govern mineral industries in China and India. Its findings show that the overall conditions for foreign mining investment in China and India are not favourable and that substantial policy, regulatory and other changes in both countries need to be made if more investment is to flow.  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