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每个青少年都有创造的潜力,如何让学生在获得基础知识的同时,积极发展智力和创造力,是值得我们探讨的问题。笔者在教学实践中发现、巧设实验题目,由学生独立思索、设计、完成实验,可使学生的创造力得以充分的发挥。 相似文献
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郗钦文 《大地测量与地球动力学》2006,26(2):134-135
我们居住的星球——地球到底是什么样子?是崎岖不平、奇形怪状、非常丑陋还是美轮美奂?近来,有人乃至许多网站(包括科技网站)都说地球是梨形或是越来越像梨形。看来,不说明真相不仅会在科技文化界造成误解,还会贻误青少年。地球表面自然是崎岖不平的,因为它上面有高山、平原、大海、湖泊,这是众所周知的事实。但是太空人从太空观察地球,它还是一个非常美丽的球状天体! 相似文献
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Black rockfi sh Sebastes schlegelii juveniles(30–40 mm total length) were immersed in a range of calcein(CAL) solutions at concentrations ranging from 50 to 250 mg/L and alizarin red S(ARS) solutions at concentrations ranging from 100 to 500 mg/L in fi ltered seawater(salinity 30) for 24 h. Fluorescent marks were detected in otoliths(sagittae, asteriscus), scales, fi n rays(dorsal, pectoral, ventral, anal, and caudal fi n rays), and fi n spines(dorsal, ventral, and anal fi n spines) after a 60-d growth experiment. With the exception of 50–100 mg/L CAL, acceptable marks were produced in the otoliths and fi n spines by all concentrations of CAL and ARS. In particular, marks were clearly visible under normal light in the sagittae, asteriscus, and fi n spines of fi sh immersed in 200–500 mg/L, 300–500 mg/L, and 200–500 mg/L ARS, respectively. Scales and fi n rays had acceptable marks at much higher concentrations(≥50 mg/L CAL, ≥300 mg/L ARS for scales and ≥50 mg/L CAL, ≥200 mg/L ARS for fi n rays). The mark quality was highest(i.e., acceptable marks were observed in all sampled structures after immersion marking) in fi sh immersed in 150–250 mg/L CAL or 300–500 mg/L ARS. In addition, there was no signifi cant difference in survival and growth of marked fi sh compared with controls 60 d post-marking( P 0.05). 相似文献
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北京市朝阳区青少年活动中心科技策划部、社会大课堂办公室一直致力于朝阳区中小学生的社会实践活动和科技创新能力的培养。 相似文献