期刊文献+
共找到3篇文章
< 1 >
每页显示 20 50 100
新版课间视力操在预防小学生近视上的作用
1
作者 徐杰 王婧雯 李大帅 《新乡学院学报》 2022年第6期59-62,共4页
为了验证新版课间视力操在保护学生视力中的作用,以某小学的学生为研究对象,分别安排他们做新版课间视力操和眼保健操,并在春季开学、暑假前和暑假后3个时间节点对他们进行了视力检查,基于影响学生视力的主要因素分析了学生视力变化的... 为了验证新版课间视力操在保护学生视力中的作用,以某小学的学生为研究对象,分别安排他们做新版课间视力操和眼保健操,并在春季开学、暑假前和暑假后3个时间节点对他们进行了视力检查,基于影响学生视力的主要因素分析了学生视力变化的原因。结果表明:新版课间视力操与眼保健操对保护学生视力均有积极作用,暑假期间学生的视力下降比较明显。 展开更多
关键词 新版课间视力操 小学生 电子产品
下载PDF
Unique influences of reboiler inventory control on the operation of totally reboiled reactive distillation columns
2
作者 Kejin Huang Yang Yuan +3 位作者 Liang Zhang Haisheng Chen Shaofeng Wang Nian Liu 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2017年第1期103-115,共13页
In this work,the dynamics and operation of the totally reboiled reactive distillation columns are visualized in terms of transfer function based process models.This kind of processes is found to be characterized by un... In this work,the dynamics and operation of the totally reboiled reactive distillation columns are visualized in terms of transfer function based process models.This kind of processes is found to be characterized by underdamped step responses due to the special topological configuration and the intricate interplay between the reaction operation and the separation operation involved.The under-dampness can be substantially alleviated through the tight inventory control of bottom reboiler and this presents beneficial effects to process dynamics and operation.Two totally reboiled reactive distillation columns,separating,respectively,a hypothetical synthesis reaction from reactants A and B to product C,and a real decomposition reaction from 1,4-butanediol to tetrahydrofuran and water,are employed to demonstrate these uncommon behaviors.The results obtained give full support to the above qualitative interpretation.Despite the strong influences of reaction kinetics and thermodynamic properties of the reacting mixtures,the totally reboiled reactive distillation columns are generally considered to present such unique behaviors and require tight inventory control of bottom reboiler to facilitate their control system development. 展开更多
关键词 Reactive distillation column Totally reboiled operation Reboiler inventory control Process dynamics Process control
下载PDF
热闹的街头
3
《智力(提高版)》 2010年第6期4-5,39,共3页
这幅漫画描绘了一个有点过度热闹的街头。本期“视力操”的问题非常简单:请你用最短的时间找出画面中一共有多少只动物(人类当然不能算)。
关键词 “热闹的街头” 漫画 "视力操" 故事
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部