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小学数学教学中量感的培养 被引量:3
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作者 尹力 郭修瑾 《教育视界》 2022年第5期12-14,共3页
量感是关于量的大小的一种感觉,往往让人觉得难以捉摸。量感也非自发生成的,教学中需要有意识地干预与引导,科学地培养学生的量感。具体来说,可以通过积累量的表象、沟通单位联系、丰富感量方式、运用估量方法等有效引导量感的生成。
关键词 量感 量的表象 单位联系 感量方式 估量策略
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Assessing Nitrogen Fertilization Strategies in Winter Wheat and Cotton Crops in Northern Greece 被引量:4
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作者 E. POLYCHRONAKI C. DOUMA +1 位作者 C. GIOURGA A. LOUMOU 《Pedosphere》 SCIE CAS CSCD 2012年第5期689-697,共9页
The management of fertilizer application is crucial for agricultural production and environmental safety. The objective of this study was to assess the efficiency of different fertilization strategies, applying fertil... The management of fertilizer application is crucial for agricultural production and environmental safety. The objective of this study was to assess the efficiency of different fertilization strategies, applying fertilizers with and without nitrification inhibitors (NIs) in split application, in Greece. The assessment criteria used were based on crop yield, soil nitrogen (N) concentrations and economic efficiency. For this purpose two crops (winter wheat and cotton) were selected in order to explore the optimum fertilization strategy for each crop. Three treatments combining fertilizers with NIs were tested compared with conventional fertilization (CF). Slight differences in the quantity and the combination of fertilizers with NIs applied resulted in variable effects on crop yield, soil N and economic return. Split N application of 102 kg ha^(-1), with half of the total amount applied at seeding, resulted in higher grain yield of winter wheat, lower NO3-N in soil and higher economic return. This result reveals the importance of N application at seeding in wheat crop. Fertilization strategy with 109.5 kg N ha^(-1) and split P application resulted in higher cotton yield and higher economic profit. Split P application seemed to increase yield, even though it is not a common practise in the area. 展开更多
关键词 Mediterranean nitrification inhibitors split application
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