拉沙热和其他病毒性出血症

病毒性出血热包括一系列不同的热带病,其所以可怕,是因为它容易传染、一经传染的爆发性和高死亡率。再者,控制前景仍然是暗淡的,而且流行区也不具备必要的财力和监测计划。     

《当代》最佳二奖

第四届“《当代》长篇小说年度（2007）最佳奖”日前在京开奖：艾米的《山楂树之恋》以获得群众投票1484票荣获“年度最佳读者奖”，著名作家刘震云的《我叫刘跃进》在专家现场投票中获得“年度最佳专家奖”。     

力量训练中协调性的作用

引言人类肌肉的力量常作为一种容易说明和容易测定的量来讨论。然而,即使在一简单的运动中,一块肌肉(如股四头肌)所表现出来的力量都是多种因素结合的结果。这些因素大致分为中枢性和外周性两类。中枢性因素包括意识、运动神经的活动和那些对肢体起稳定作用的肌肉的协调性。外周性因素则是     

植物病原的生物防治

生物防治是通过一种或多种生物来降低病原接种体数量或减弱病原的致病能力的一种防病途径,它包括运用对病原有害的生物,破坏病原的接种体,减少其侵染来源,利用抗病育种或生物工程手段培育高抗的植物品种,以及用农业栽培措施调节病原生物与其拮抗生物之间的生态关系,使之不利于病原物,有利于拮抗生物,以至于寄主植物,同时本文揭示了土壤中一些潜在的天然生物防治现象,如抑菌土壤,及其利用的可能性。     

知识经济时代图书馆员应具备的素质

本文在论述图书馆员在知识经济时代的重要作用的基础上，分析了知识经济时代图书馆员应具备的能力结构．探讨了当前图书馆员队伍素质的现状及提高素质的基本途径。     

《太阳能》单元(一)

这是美国小学科学教育专家乔治·Z·托基塔博士撰写的关于“探究——研讨”教学法专著中的一章——“太阳能”单元教学设计。本文对这一单元涉及的概念和从属概念体系,教学材料的准备,学生实验和探究的过程,研讨会,学生可能提出的问题等等,都有详尽的论述。原文近万字,由译者和编者进行了部分删减,将分三期连载,本期刊登的是第一部分。     

灯片演示 化解难点

我在教学“一个数除以分数”例1“李师傅(3/4)小时做6个零件,1小时做几个零件”时,使用电化教学,帮助学生突破知识的难点,收到了理想的教学效果。教学过程是这样的。     

襄樊市图书馆现状、问题及对策

通过对襄樊市图书馆现状详尽的分析，阐明了地方图书馆生存、发展和为地方社会进步、经济发展、服务的方向与具体途径。     

Across the great divide: bridging the gap between understanding of toddlers' and older children's thinking

Research on very young children's cognitive development differs greatly from research on cognitive development in older children. The differences include the questions that are asked, the methods that are used to address them, the measures that are employed to provide relevant evidence, and the level of detail at which children's knowledge is represented. The research approaches are so different that they create an impression that infants' and toddlers' thinking differs qualitatively from that of preschoolers and older children. This impression, however, may reflect differences in research approaches rather than differences in children's thinking. In the present study, we attempted to bridge this gap by applying to toddlers a type of process analysis that has proved fruitful in studies of older children. Overlapping waves theory, trial-by-trial strategy assessments, and microgenetic methods were used to analyze 1.5- and 2.5-year-olds' problem solving and learning. The results demonstrated that changes in toddlers' strategies could be assessed reliably on a trial-by-trial basis, that the changes followed the basic form predicted by the overlapping waves model, and that analyses of toddlers' strategies could tell us a great deal about both qualitative and quantitative aspects of their learning. A componential analysis of learning that previously had been applied to older children also proved useful for understanding toddlers' learning. The analysis specified that cognitive change frequently involves five components: acquisition of new strategies; strengthening of the strategies in their original context; improved mapping of strategies onto novel problems; increasingly refined choices among variants of the strategies; and increasingly skillful execution of the strategies. Independent measures of these components indicated that strategic development in toddlers involves improvements in all five components. Analyses of individual differences in learning showed that the effects of distal variables, such as age and sex, could be partially explained in terms of their influence on mastery of the components, but that the distal variables exercised additional direct effects as well. The process of learning in toddlers closely resembled that of older children in other ways as well. Like older children, toddlers use multiple strategies over the course of learning; their choices among strategies are quite adaptive from early on; their choices become progressively more adaptive as they gain experience with the task; they switch strategies not only from trial to trial but within a single trial; their transfer of learning from one problem to the next is primarily influenced by structural relations between problems but also is influenced by superficial features; they show utilization deficiencies early in learning that they gradually overcome; and they show individual differences in learning that fall into a few qualitatively distinct categories. Perhaps most striking, the 1.5- and 2.5-year-olds emerged as active learners, who continued to work out the lessons of previous instruction in the absence of further instruction. That is, they integrated the lessons of their own problem-solving efforts with the previous instruction in ways that magnified the initial effects of the instruction. Overall, the findings indicated that the gap can be bridged; that theories, methods, measures, and representations of knowledge typically used with older children can improve our understanding of toddlers' problem solving and learning as well.