简介:摘 要:L-组氨酸是一种非必需碱性氨基酸,也是L-肌肽化学合成法和生物酶法转化中的重要原料之一。本方法采用离子对高效液相色谱法直接测定含量。优选十八烷基硅烷键合硅胶柱为分析柱,流动相采用甲醇-异丙醇-离子对试剂。具体方法:流动相1g庚烷磺酸钠,加水900ml(高氯酸调pH至2.10土0.01)加入甲醇135ml,异丙醇20ml,柱温30℃,最适检测波长210nm,进样量20ul,经验证方法的线性关系良好,线性回归相关度R =1.0,回收率大于99.6%,实验重复性RSD 0.14%(n=6),实验稳定性RSD 0.77%(n=4)。本方法具有操作便捷、快速定量、重复性好、结果准确的优点,可以满足常规科学研究和工艺过程中对L-组氨酸含量精准检测。
简介:【摘要】词汇教学是语言教学的重要组成部分,也是语言教学的基础。整体语言教学是西方语言教育界长期以来最为重要的一种理论思潮。进行单词教学时,教师应关注单元目标,基于单元整体,做到教学设计基于单元整体
简介:摘要:本教学设计案例围绕 预备单元(Starter Unit 3What color is it ? )展开。通过复习句型(What’s this/that? It’s an apple. What color is it? t’s red. Spell it ,please.It’s red)谈论物体颜色学习语法(an/a/the),同时训练学生听,说的能力 .本教学设计依据新课程标准要求,通过希沃游戏,大转盘游戏激发学生学习兴趣,采用图片直观教学法, 通过师生练习,小组练习,双人练习呈现新句型(It’s a red apple.The apple is red.),让学生观察发现总结 规律学习语法。通过完成听力任务培养学生抓住关键词寻找答案的听力技能,培养学生好的听力习惯 。同时以教材为本,结合实际,采用小组合作表演培养学生的口语技能和初步写作能力。本教学案例教学手段多样,使用希沃游戏教学,大转盘游戏,图片插入直观教学,图片裁剪,多媒体希沃白版5手机拍照视频上传,音乐剪辑插入播放等多种信息技术教学手段提高学生学习兴趣,调动学生积极性, 尽力让学生全体参与。教学过程中贯穿课程思政的理念,作业设计注重学生能力的培养。
简介:identification and classification of learning strategy. The problems are reviewed concerning the definition and classification of learning strategies and then the paper tentatively introduces Cohen’s approach to defining learning strategies in terms of prototypicality of features of learning strategies.,Cohen’s attempt to describe the prototypicality of strategies is a step forward concerning defining learning strategies. It might reflect the nature of learning strategies to a large extent because the answers to the questionnaire come from strategy experts. It is true that some problems still exist. For example,all-or-nothing feature but in terms of how far along a continuum a feature could possibly go before it stopped being descriptive of a strategy. This is an approach of defining learning strategies in terms of how prototypical the feature was. These features as follows are arranged in a descending order of agreement