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以“活用”贯穿数学教学活动
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作者 黄秀银 《教育实践与研究(小学版)(A)》 2012年第2期50-51,共2页
学生是学习的主人,数学教学应是学生获得人生体验、激发生命活力的殿堂。教师要活用教材、教法、评价和应用,让数学课堂充满生机和活力。
关键词 数学课堂 活用教材 活用学法 活用评价 活用应用
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Rose Essential Oil Extraction from Fresh Petals Using Synergetic Microwave & Ultrasound Energy: Chemical Composition and Antioxidant Activity Assessment 被引量:2
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作者 Mariana Patrascu Marilena Radoiu 《Journal of Chemistry and Chemical Engineering》 2016年第3期136-142,共7页
The aim of the present work was to investigate the synergetic effect of microwave and ultrasound treatment on the production, chemical composition and antioxidant activity of rose essential oil. The rose essential oil... The aim of the present work was to investigate the synergetic effect of microwave and ultrasound treatment on the production, chemical composition and antioxidant activity of rose essential oil. The rose essential oil was extracted from fresh Rosa x damciscena Mill. petals by four methods, hydrodistillation, steam distillation, organic solvent extraction and ultrasounds followed by microwave hydrodistillation. The chemical composition of the extracts was analysed by GC-MS, and the antioxidant capacity by DPPH. It was found that both chemical composition and the antioxidant activity of the extracts depend on the extraction method. Overall it was found that microwaves coupled with ultrasonic treatment can be used effectively for the intensification of the extraction of monoterpenes and sesquiterpenes--fragrance bearing molecules--and equally, for increased antioxidant activity while using about 4 time shorter extraction time. The scale-up of the method was also evaluated. The results obtained in this research support the possible use of the US/MW method for the extraction of rose essential oil for the pharmaceutical and fragrance industry. 展开更多
关键词 2.45 GHz microwaves ULTRASOUNDS rose petals essential oil scale-up hydrodistillation.
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