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排序方式: 共有482条查询结果,搜索用时 15 毫秒
461.
论文以四川省石棉县为例,对空间数据库支持下的树种分布知识的发现进行了研究。利用GIS技术建立相关空间数据库,主要有森林资源二类调查GIS数据库、树种GIS数据库,以及10 m分辨率的DEM、多年平均大于10 ℃的年积温和多年平均年降雨量等栅格数据库。利用GIS的叠加统计分析等方法,发现了各树种分布的的海拔、年平均大于10 ℃的积温、年平均降雨量等带谱知识。利用GIS的拓扑空间分析方法,挖掘了各树种间的空间配置知识。该知识可用于退耕还林、造林绿化中,因地制宜地选择树种,以及配置树种。该知识对于辅助数据协同下的各树种遥感识别也具有重要意义。此外,对其他区域也有示范意义。  相似文献   
462.
Transport of engineered antibiotic resistance plasmids in porous media has been reported to potentially cause significant spreading of antibiotic resistance in the environment. In this work, transport of an indigenous resistance plasmid pK5 in porous media was investigated through packed column experiments. At identical ionic strengths in CaCl2 solutions, the breakthroughs of pK5 from soil columns were very close to those from quartz sand columns, indicating that transport of pK5 in quartz sand and soil was similar. A similarity in transport behavior was also found between pK5 and an engineered plasmid pBR322 that has approximately the same number of base pairs as pK5. The influence of surfactants, a major group of constituents in soil solutions, was examined using an engineered plasmid pcDNA3.1(+)/myc-His A. The impact of an anionic surfactant, sodium dodecyl sulfate (SDS), was negligible at concentrations up to 200 mg·L–1. Cetyltrimethyl ammonium bromide (CTAB), a cationic surfactant, was found to significantly enhance plasmid adsorption at high concentrations. However, at environmentally relevant concentrations (<1 mg·L–1), the effect of this surfactant was also minimal. The negligible impact of surfactants and the similarity between the transport of engineered and indigenous plasmids indicate that under environmentally relevant conditions, indigenous plasmids in soil also have the potential to transport over long distances and lead to the spreading of antibiotic resistance.
  相似文献   
463.
Ecology and culture comprise interacting components of landscapes. Understanding the integrative nature of the landscape is essential to establish methods for sustainable management. This research takes as a unifying theme the idea that ecological and cultural issues can be incorporated through management. As a first step in developing integrative management strategies, information must be collected that compares and contrasts ecological and cultural issues to identify their areas of intersection. Specifically how can local cultural knowledge enable water resource management that reflects cultural and ecological values? This research examines Native American cultural knowledge for setting water resource management priorities in the Wind River Indian Reservation in central Wyoming. A cross-cultural approach is adopted to assess the relationship between indigenous cultural knowledge and Euro-American perspectives through a comparative examination of the Wind River Water Code and Wyoming Water Law. This research indicates that cultural perspectives provide a rich arena in which to examine management issues. Understanding and identifying cultural practices may be an important first step in collaborative resource management between different cultural groups to prevent conflict and lengthy resolution in court.  相似文献   
464.
The terms used to describe and negotiate environmental quality are both ambiguous and value-laden. Stakeholders intimately and actively involved in the management of forested lands were interviewed and found to use ambiguous, tautological, and value-laden definitions of terms such as health, biodiversity, sustainability, and naturalness. This confusing language hinders public participation efforts and produces calls to regulate and remove discretion from environmental professionals. Our data come from in-depth interviews with environmental management professionals and other stakeholders heavily vested in negotiating the fate of forested lands. We contend that environmental science and management will be more effective if its practitioners embrace and make explicit these ambiguous and evaluative qualities rather than ignore and disguise them.  相似文献   
465.
466.
燃煤电厂袋式除尘专家系统开发研究   总被引:1,自引:0,他引:1  
开发了一种袋式除尘系统故障专家诊断方法,用于诊断整个袋式除尘系统的故障现象,通过现场数据采集、操作人员与专家系统的人机对话对故障现象进行分析、推理,并做出相应的解决方案指导操作人员排查故障.燃煤电厂袋式除尘专家系统以知识库、推理机为核心,实现整个袋式除尘系统的设备故障诊断功能和维修故障指导功能,辅以解释机构,人机界面来指导用户如何准确无误地操作运行本系统和袋式除尘控制系统.系统被划分为4个模块:专家系统简介模块,在线故障诊断模块,离线故障诊断模块和专家指导模块.  相似文献   
467.
节约用水是缓解水资源紧缺的有效途径,涉及社会心理层面认知、意愿的复杂状态。设计问卷对312名北京市中学生的节水知识、意识和行为进行现状评估,系统分析三者相互关系,为推行更为有效的节水管理措施提供支持。结果显示,节水知识、意识和行为问卷的信度指标(Cronbach’sα)值分别为0.82、0.77和0.84。中学生群体缺乏对节水的精确定量认知,难以判别用水的合理程度;电视是当前的主要知识来源。水资源的稀缺性被广泛认同,中学生群体具有一定的敏感度和节水责任感,能够感知水资源条件的变化;但缺乏深入理解,尤其存在"口号化"的倾向。中学生群体在节水行为方面有待改进。通过改变自身用水方式达到节水目的的行为发生频次超过半数,而改变他人用水方式的人际行为发生率较低。节水意识显著影响节水行为,节水知识对节水意识的影响不具统计意义。节水知识除直接影响节水行为外,还通过节水意识的中介效应影响节水行为,两者效果比例大约9∶1。  相似文献   
468.
知识员工的工作关键不在于数量而在质量,难度是表征质量的重要变量。本文在综述工作特征研究的基础上,提出从工作难度这一基础管理变量出发研究知识员工工作特征。通过对从事典型知识型岗位的工作者进行问卷调查,采用结构方程模型分析形成的知识工作难度因素结构,不仅为知识工作的评级和测量提供了可行框架,而且为进一步研究知识员工工作特征提供了有利途径。  相似文献   
469.
Coping with ambiguities in natural resources management has become unavoidable. Ambiguity is a distinct type of uncertainty that results from the simultaneous presence of multiple valid, and sometimes conflicting, ways of framing a problem. As such, it reflects discrepancies in meanings and interpretations. Under the presence of ambiguity it is not clear what problem is to be solved, who should be involved in the decision processes or what is an appropriate course of action. Despite the extensive literature about methodologies and tools to deal with uncertainty, not much has been said about how to handle ambiguities. In this paper, we discuss the notions of framing and ambiguity, and we identify five broad strategies to handle it: rational problem solving, persuasion, dialogical learning, negotiation and opposition. We compare these approaches in terms of their assumptions, mechanisms and outcomes and illustrate each approach with a number of concrete methods.  相似文献   
470.
The international shelter response to the Jogjakarta earthquake in Indonesia in May 2006 is widely regarded as a success story, especially when compared with the response to the Indian Ocean tsunami 16 months earlier. This evaluation is largely in terms of the international aid system itself, which emphasises statistical measures of ‘success’ and internal coordination and efficiency. From the perspective of those closer to the ground, however, it was less successful, especially in terms of coordination and communication with and participation of local agencies and affected communities. This paper, by an aid worker resident in Jogjakarta and an anthropologist, examines the response from a perspective grounded both within and outside the aid system, local as well as global. It recognises the relative success of the response, but argues for an approach more grounded in local knowledge and responsive to local concerns, while also providing practical suggestions for improvement.  相似文献   
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