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正数学是科学的助手,能够提高学生的抽象思维。它能够打开智慧之城的大门,借着数学,我们能勘探宇宙的秘密,可见数学的重要。教学过程中,教师要引导学生动手操作,学习与生活紧密相连,启发学生的思维,激发他们自主学习的敏锐性,帮助学生打好数学的基础。下面我将教学体会略作列举。 相似文献
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刘振宇 《辽宁教育行政学院学报》2010,27(3):127-129
一、农村环境污染问题的主要表现和危害
(一)影响农产品质量和产量
在一些农村,农药瓶、化肥袋、塑料薄膜、塑料袋等到处乱扔,"白色污染"严重.由于不按科学配制,超标使用大量高毒、剧毒农药和化肥,致使农田中鸟类、青蛙、蚯蚓等益虫、益鸟数量大量减少,河流内鱼虾遭受毁灭性毒害,生物多样性遭到严重破坏,使农业生态环境恶化,造成依赖农药的恶性循环. 相似文献
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Effect of different mulch materials on winter wheat production in desalinized soil in Heilonggang region of North China 总被引:10,自引:0,他引:10
Freshwater shortage is the main problem in Heilonggang lower-lying plain, while a considerable amount of underground saline water is available. We wanted to find an effective way to use the brackish water in winter wheat production. Surface mulch has significant effect in reducing evaporation and decreasing soil salinity level. This research was aimed at comparing the effect of different mulch materials on winter wheat production. The experiment was conducted during 2002-2003 and 2003-2004. Four treatments were setup: (1) no mulch, (2) mulch with plastic film, (3) mulch with corn straw, (4) mulch with concrete slab between the rows. The result indicated that concrete mulch and straw mulch was effective in conserving soil water compared to plastic film mulch which increased soil temperature. Concrete mulch decreases surface soil salinity better in comparison to other mulches used. Straw mulch conserved more soil water but decreased wheat grain yield probably due to low temperature. Concrete mulch had similar effect with plastic film mulch on promoting winter wheat development and growth. 相似文献
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"掌握季节,不违农时"是农业生产最基本要求之一。古农书《齐民要术》上曾经写道:"顺天时,量地利,则用力少而成功多,任情返道,劳而无获"。意思是说,按照季节农时去耕作,可以花较少的劳力得到良好收成。如果主观任意去做,就会劳而无获。二十四节气是中国古代订立的一种用来指导农业生产的补充历法,是劳动人民长期经验的积累和智慧的结晶,各地创造出很多流行谚语,把二十四节 相似文献