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   340篇
  免费   18篇
  国内免费   14篇
安全科学   60篇
废物处理   5篇
环保管理   116篇
综合类   120篇
基础理论   29篇
污染及防治   18篇
评价与监测   8篇
社会与环境   9篇
灾害及防治   7篇
  2023年   3篇
  2022年   8篇
  2021年   9篇
  2020年   11篇
  2019年   10篇
  2018年   5篇
  2017年   9篇
  2016年   7篇
  2015年   10篇
  2014年   16篇
  2013年   35篇
  2012年   25篇
  2011年   34篇
  2010年   26篇
  2009年   26篇
  2008年   11篇
  2007年   21篇
  2006年   23篇
  2005年   16篇
  2004年   5篇
  2003年   20篇
  2002年   7篇
  2001年   7篇
  2000年   7篇
  1999年   6篇
  1998年   3篇
  1997年   1篇
  1995年   3篇
  1994年   1篇
  1993年   3篇
  1988年   1篇
  1987年   1篇
  1986年   1篇
  1981年   1篇
排序方式: 共有372条查询结果,搜索用时 390 毫秒
71.
Abstract: The search for generalities in ecology has often been thwarted by contingency and ecological complexity that limit the development of predictive rules. We present a set of concepts that we believe succinctly expresses some of the fundamental ideas in conservation biology. (1) Successful conservation management requires explicit goals and objectives. (2) The overall goal of biodiversity management will usually be to maintain or restore biodiversity, not to maximize species richness. (3) A holistic approach is needed to solve conservation problems. (4) Diverse approaches to management can provide diverse environmental conditions and mitigate risk. (5) Using nature's template is important for guiding conservation management, but it is not a panacea. (6) Focusing on causes not symptoms enhances efficacy and efficiency of conservation actions. (7) Every species and ecosystem is unique, to some degree. (8) Threshold responses are important but not ubiquitous. (9) Multiple stressors often exert critical effects on species and ecosystems. (10) Human values are variable and dynamic and significantly shape conservation efforts. We believe most conservation biologists will broadly agree these concepts are important. That said, an important part of the maturation of conservation biology as a discipline is constructive debate about additional or alternative concepts to those we have proposed here. Therefore, we have established a web‐based, online process for further discussion of the concepts outlined in this paper and developing additional ones.  相似文献   
72.
This paper adds to the literature on skills for sustainable communities by examining the role and processes of learning in “communities of practice” that exist within a “grassroots association”. Interviews were conducted with participants in the communities of practice of a student group called Green Action, which engages with environmental issues in practical ways. The findings demonstrate how learning occurred in the communities of practice, how participants gained skills and knowledge for sustainable consumption, and how learning in the communities of practice appeared to help Green Action to sustain itself in the long-term. This paper could serve as a useful demonstration to others as to how to apply the theories and concepts from the literature on communities of practice when researching skills and knowledge for sustainable communities. It also has some value for grassroots associations themselves in understanding their own activities.  相似文献   
73.
Targeting of agricultural conservation practices to cost‐effective locations has long been of interest to watershed managers, yet its implementation cannot succeed without meaningful engagement of agricultural producers who are decision makers on the lands they farm. In this study, we engaged 14 west‐central Indiana producers and landowners in an adaptive targeting experiment. Interviews carried out prior to targeting provided rich spatial information on existing conservation practices as well as producers' preferences for future conservation projects. We targeted six of the most accepted conservation practices using the Soil and Water Assessment Tool and spatial optimization using a genetic algorithm approach. Fairly optimal conservation scenarios were possible with even the most limiting constraints of farmer‐accepted practices. We presented in follow‐up interviews a total of 176 conservation practice recommendations on 103 farm fields to 10 farmers whose lands were targeted for conservation. Primary findings indicated producers were interested in the project, were open to hearing recommendations about their lands, and expressed a high likelihood of adopting 35% of targeted recommendations. Farmers generally viewed the interview process and presentation of results quite favorably, and the interviews were found to build trust and make the targeting process more acceptable to them.  相似文献   
74.
建立和完善生态补偿机制,是新时期中国生态环境保护政策创新的重要内容,也是新时期中国推进生态文明建设的必然选择.文章首先介绍了生态补偿的概念和内涵,重点阐述了国外的欧盟、美国、德国-捷克以及国内的浙江省、深圳市和苏州市在生态补偿机制方面的做法和经验,在此基础上提出对常州市的借鉴和启示,主要包括:依靠政府的大力推动、完善生态补偿政策和法律法规的制度,为常州市生态补偿相关管理制度和办法的制定提供理论基础.  相似文献   
75.
安全工程本科的“工程型大安全”教学方案构建   总被引:12,自引:11,他引:12  
“大安全”在安全科学技术教育界广为推崇。它的含义是指广泛适用于解决各个行业、各类组织安全问题的科学理论和方法。“大安全”是我国高等学校安全工程专业本科教育的基本目标之一 ,构建适当的课程教学方案是实现这一目标必需的途经。笔者围绕安全科学技术的研究对象———事故、研究内容———事故的发生发展规律、预防策略和救援方法 ,构建出一种安全工程专业本科的“大安全”课程教学方案。所构建的教学方案由通用于各行业的基础课、专业基础课和针对特定行业的专业课组成。方案中工程技术类课程占有主导地位 ,所以 ,可称为“工程型大安全”课程方案。统计分析表明 ,应用该方案所培养的学生就业面宽广 ,这种类型的课程教学方案符合市场需求  相似文献   
76.
The US Army Engineering Research Development Center (ERDC) uses a modified form of the Revised Universal Soil Loss Equation (RUSLE) to estimate spatially explicit rates of soil erosion by water across military training facilities. One modification involves the RUSLE support practice factor (P factor), which is used to account for the effect of disturbance by human activities on erosion rates. Since disturbance from off-road military vehicular traffic moving through complex landscapes varies spatially, a spatially explicit nonlinear regression model (disturbance model) is used to predict the distribution of P factor values across a training facility. This research analyzes the uncertainty in this model's disturbance predictions for the Fort Hood training facility in order to determine both the spatial distribution of prediction uncertainty and the contribution of different error sources to that uncertainty. This analysis shows that a three-category vegetation map used by the disturbance model was the greatest source of prediction uncertainty, especially for the map categories shrub and tree. In areas mapped as grass, modeling error (uncertainty associated with the model parameter estimates) was the largest uncertainty source. These results indicate that the use of a high-quality vegetation map that is periodically updated to reflect current vegetation distributions, would produce the greatest reductions in disturbance prediction uncertainty.  相似文献   
77.
泰兴生态市建设的实践与思考   总被引:3,自引:2,他引:1  
本文从泰兴生态市建设实际出发,总结了生态建设的指导思想、生态建设规划的原则、生态功能区的划分,展示了黍兴生态市建设的成果;并依据当前的形势,提出了一些建设生态市工作的建议。  相似文献   
78.
This study was undertaken to determine the importance of riparian buffers to stream ecology in agricultural areas. The original Maryland Biological Stream Survey (MBSS) data set was partitioned to represent agricultural sites in Maryland's Coastal Plain and Piedmont regions. ANOVA, multiple linear regression (MLR), and CART regression tree models were developed using riparian and site catchment landscape characteristics. MBSS data were both stratified by physiographic region and analyzed as a combined data set. All models indicated that land management at the site was not the controlling factor for fish IBIs (FIBI) at that site and, hence, using FIBI to evaluate site-scale factors would not be a prudent procedure. Measures of instream habitat and location in the stream network were the dominant explanatory factors for FIBI models. Both CART and MLR models indicated that forest buffers were influential on benthic IBIs (BIBI). Explanatory variables reflected instream conditions, adjacent landscape influence, and chemistry in the Coastal Plains sites, all of which are relatively site specific. However, for Piedmont sites, hydrologic factors were important, in addition to adjacent landscape influence, and chemistry. Both Coastal Plain and Piedmont CART models identified several hydrologic factors, emphasizing the dominant control of hydrology on the physical habitat index (PHI). Riparian buffers were a secondary influence on PHI in the Coastal Plain, but not in the Piedmont. Between 40% and 70% of the variation in FIBI, BIBI, and PHI was explained by the “easily obtainable” variables available from the MBSS data set. While these are empirical results specific to Maryland, the general findings are of use to other locations where the establishment of forest buffers is considered as an aquatic ecosystem restoration measure.  相似文献   
79.
80.
在文献检索和访谈的基础上,提出有关编制适用于我国小学生水域安全调研的知信行(KAP)问卷的理论构想。以此为基础,编制小学生水域安全知信行初始问卷。经初测(N=495)和正式测量(N=2 554),运用探索性因素分析方法筛选条目,用克朗巴赫法评价同质性信度,据内容效度比评价内容效度,用探索性和验证性因素分析方法评价结构效度。问卷包含4个维度(水域安全知识、技能、态度和高危行为)共39个条目。问卷的信效度检验结果表明,问卷的因素结构、同质性信度、内容效度和结构效度均达到心理测量学的要求。小学生水域安全知信行问卷具有较为满意的信、效度,较好地反映了问卷设计的理论构想。  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