小学科学低年级室外教学活动探微

小学科学课程是一门基础性课程,课程的学习方式多种多样,对学生的发展起关键性的影响作用。2017年小学新课程改革,低年级学生开始系统地学习科学课教学,低年级学生好奇心强,对周边的环境有强烈的求知欲,他们更乐于在广阔的自然环境中探索和发现。选择恰当的室外教学教学内容,高效的组织课堂,能让学生在愉快的教学环境中更好学习。     

小学低年级学生口语交际能力的培养策略

新课标指出,小学生应具备日常口语交际的基本能力,学会在各种交际活动中倾听、表达、交流并初步学会进行文明的人际交往和社会交往。因此,学生口语交际能力的培养对提高学生的综合素质至关重要。     

Teachers developing practice: Reflection as key activity

The article is based on a research and development project conducted in a Norwegian lower secondary school. The purpose of the text is to show how a project involving a researcher and a teacher team encourages the teachers to reflect on teaching processes, and, furthermore, to show what the form and content of such reflection processes could be. Theories on reflection are presented as the framework in which illustrations from practice are analysed. Findings from the project show that when teachers question their own practice, they can transcend their teaching, meaning they can think of and see new things. In connecting theory and practice, the article concludes that teachers are shown in this way how to reflect before action, reflecting on prior experiences by using theory, and how they can reflect in action and on action, connecting theoretical concepts to their teaching practice. In this way theories can serve as a tool in reflection processes.     

一种求解二阶电路暂态过程的降阶方法

给出了求解二阶电路暂态过程的降阶方法．该方法是一种数学上严格、要求的数学准备知识不多、物理概念明确的方法．     

A vague-set-based fuzzy multi-objective decision making model for bidding purchase

A vague-set-based fuzzy multi-objective decision making model is developed for evaluating bidding plans in a bid- ding purchase process. A group of decision-makers (DMs) first independently assess bidding plans according to their experience and preferences, and these assessments may be expressed as linguistic terms, which are then converted to fuzzy numbers. The resulting decision matrices are then transformed to objective membership grade matrices. The lower bound of satisfaction and upper bound of dissatisfaction are used to determine each bidding plan’s supporting, opposing, and neutral objective sets, which together determine the vague value of a bidding plan. Finally, a score function is employed to rank all bidding plans. A new score function based on vague sets is introduced in the model and a novel method is presented for calculating the lower bound of sat- isfaction and upper bound of dissatisfaction. In a vague-set-based fuzzy multi-objective decision making model, different valua- tions for upper and lower bounds of satisfaction usually lead to distinct ranking results. Therefore, it is crucial to effectively contain DMs’ arbitrariness and subjectivity when these values are determined.     

拉萨河下游河谷不同土地利用方式下土壤有机碳储量格局

以拉萨河下游河谷宽谷区达孜农场为例研究了不同土地利用方式土壤有机碳储量的垂直空间格局,并讨论了农田退耕为弃耕地和人工林等土地利用方式的碳固定功能。结果表明：拉萨河谷土壤有机质含量普遍较低,其中沼泽草甸、人工杨树林有机质含量相对较高。沼泽草甸、杨树林和灌丛草原类型在浅层土壤积累了相对较多的有机碳,而耕作类土壤如农田、弃耕地和苗圃的有机碳垂直分布则相对较均匀。农田退耕为弃耕地、苗圃和建立人工林网后有利于有机质积累和土壤有机碳密度的提高,具有碳固定功能,其中,农田退耕还林积累有机碳的碳固定能力最强。达孜农场土壤有机碳储量为10.71×103 Mg, 其中草甸土和灌丛草原土是达孜农场土壤碳储量最大的土壤类型,在51.9％土地面积上储藏了有机碳总量的77.6％。     

Hausdorff空间中一类广义拟平衡问题解的存在性

文章引入了实Hausdorff线性拓扑空间中一类新的广义拟平衡问题,利用KKM定理,得到了这一类广义拟平衡问题几个解的存在定理。本文的工作改进和推广了近期的一些已知结果.     

Antibacterial potency of methanol extracts of lower plants

Antibacterial potency of methanol extracts of three green lower plants, Pneumatopteris afra, Platycerium bifurcatum and Nephrolepsis bisserata was determined using agar dilution method on clinical strains of Escherichia coli, Staphylococcus aureus, Klebsiella spp. and Salmomelia typhi. Antibacterial activities were observed at concentrations of 12.5, 25.0, 50.0 and 100.0 μg/ml. Their minimum inhibitory concentrations ranged from 12.5~100 μg/ml. Extracts of P. afra and P. bifurcatum were most active. Antibacterial activities observed with N. bisserata were less pronounced with no detectable activity at extract con-centrations of 12.5 and 25.0 μg/ml. E. coli, together with S. aureus appeared to be the most susceptible of the test bacteria while Klebsiella spp. was least sensitive. The significance of our findings is discussed.     

半连续函数的性质

讨论了定义在一般拓扑空间上的半连续函数的性质,建立了有关半连续函数的若干命题.     

中国二叠纪苏铁科新属、种——古生铁花

本文是继中国始苏铁Primocycas chinensis Zhu  et  Du之后，又报道一种古植物文献未见记载的早二叠世晚期苏铁科小孢子叶球，命名为古生铁花(新属、种)Cycadostrobilus  paleozoicus  Zhu，gen. et.sp．nov．标本采自我国山西省太原市东山煤矿的下石盒子组，它是世界迄今已知的一种最古老的小孢子叶球化石。和本新属同层发现的化石，除了中国始苏铁之外，还有楔叶Sphenophyllum、齿叶Tingia，楔羊齿Sphenopteris、楔叶羊齿Sphenopteridium、织羊齿Emplectopteris、栉羊齿Pecopteris、大芦孢穗Macrostachya、科达Cordaites、带羊齿Taeniopteris、角籽Cornucarpus和几种也未见记载而形态又非常特殊的植物。本文认为当前报道的古生铁花(新属、种)很可能和中国始苏铁同属一种植物，其营养叶可能是疏脉带羊齿Taeniopteris norinii Halle。