西安市空气质量评价分析

针对西安市的环境质量问题,首先分析和对比空气污染指数(API)与环境质量指数(AQI)对西安市空气质量的影响.建立AQI与API比较模型,得到两种标准基本一致,但两个指标的值有所不同,因此得出需实施新标准的结论.其次分析影响西安市空气质量的原因.运用灰色关联度等方法,得出结论即工业污染为主要原因,其次是交通、生活污染.最后根据问题的分析和模型的求解结果,对环境空气质量的监测与控制对西安市环保部门提出均衡监测点的选取及其规模大小、环保部门应加强宣传力度、鼓励政府调整能源产业结构等具有建设性的意见.     

English secondary students’ thinking about the status of scientific theories: consistent,comprehensive, coherent and extensively evidenced explanations of aspects of the natural world – or just ‘an idea someone has’

Teaching about the nature of science (NOS) is seen as a priority for science education in many national contexts. The present paper focuses on one central issue in learning about NOS: understanding the nature and status of scientific theories. A key challenge in teaching about NOS is to persuade students that scientific knowledge is generally robust and reliable, yet also in principle always open to challenge and modification. Theories play a central role, as they are a form of conjectural knowledge that over time may be abandoned, replaced, modified, yet sometimes become well established as current best scientific understanding. The present paper reports on findings from interviews with 13–14 year olds in England where target knowledge presents theories as ‘consistent, comprehensive, coherent and extensively evidenced explanations of aspects of the natural world’. Student thinking reflected a two-tier typology of scientific knowledge in which largely unsupported imaginative ideas (‘theories’) became transformed into fairly definitive knowledge (such as laws) through relatively straightforward testing. These results are considered in relation to research into intellectual development which indicates that effective teaching in this area requires careful scaffolding of student learning, but has potential to contribute to supporting intellectual development across the curriculum.