推进STEM教育,已经成为全球许多国家实现教育创新、培养科技人才,增强国家核心竞争力的重要战略。"项目引路"(Project Lead the Way)计划作为美国STEM教育中最重要的课程提供者,通过基于活动、基于项目、基于问题解决的STEM...推进STEM教育,已经成为全球许多国家实现教育创新、培养科技人才,增强国家核心竞争力的重要战略。"项目引路"(Project Lead the Way)计划作为美国STEM教育中最重要的课程提供者,通过基于活动、基于项目、基于问题解决的STEM课程项目,致力于推进STEM跨学科整合的课程与教学方式,旨在提高学生参与STEM学习的兴趣以及选择STEM领域的职业意愿,培养学生STEM素养。通过分析"项目引路"计划的价值动因、课程样态和行动路径,可以对我国STEM课程的开发与实施提供有益的参考与借鉴。其主要特点包括:秉持跨学科整合的基本理念,为培养STEM学习兴趣和职业选择做准备;拓展STEM课程资源,凸显STEM课程内容的先进性;积聚多方力量,保障STEM课程的有效衔接和评价反馈;重视PLTW师资培训,促进STEM教师专业发展。展开更多
The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α＂ occurs upon quenching afte...The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α＂ occurs upon quenching after solution treatment between 960-1000 ℃. The antiphase boundary （APB）-like structure was observed clearly in the α＂ martensite plates. The APB-like contrasts exist along the （001） and （020） planes of α＂ martensite. This APB-like structure of α＂ martensite was identified as a kind of stacking fault with an APB-like morphology induced by martensitic transformation and not by order/disorder transition. During martensitic transformation, martensitic domains nucleate and grow, eventually encounter each other, resulting in the formation of the APBdike contrast.展开更多
文摘推进STEM教育,已经成为全球许多国家实现教育创新、培养科技人才,增强国家核心竞争力的重要战略。"项目引路"(Project Lead the Way)计划作为美国STEM教育中最重要的课程提供者,通过基于活动、基于项目、基于问题解决的STEM课程项目,致力于推进STEM跨学科整合的课程与教学方式,旨在提高学生参与STEM学习的兴趣以及选择STEM领域的职业意愿,培养学生STEM素养。通过分析"项目引路"计划的价值动因、课程样态和行动路径,可以对我国STEM课程的开发与实施提供有益的参考与借鉴。其主要特点包括:秉持跨学科整合的基本理念,为培养STEM学习兴趣和职业选择做准备;拓展STEM课程资源,凸显STEM课程内容的先进性;积聚多方力量,保障STEM课程的有效衔接和评价反馈;重视PLTW师资培训,促进STEM教师专业发展。
基金Project (2011AA030101) supported by the High-tech Research and Development Program of China
文摘The morphology and formation mechanism of the substructure of martensite in TC21 alloy was investigated by XRD and TEM. The results showed that the martensitic transformation from β to α＂ occurs upon quenching after solution treatment between 960-1000 ℃. The antiphase boundary （APB）-like structure was observed clearly in the α＂ martensite plates. The APB-like contrasts exist along the （001） and （020） planes of α＂ martensite. This APB-like structure of α＂ martensite was identified as a kind of stacking fault with an APB-like morphology induced by martensitic transformation and not by order/disorder transition. During martensitic transformation, martensitic domains nucleate and grow, eventually encounter each other, resulting in the formation of the APBdike contrast.
