问题
问答题 简答题
简述甲基红试验的原理。
答案
参考答案：
某些细菌能分解葡萄糖产生丙酮酸，并进一步分解丙酮酸产生甲酸、乙酸、乳酸等使pH下降至4.5以下，加入甲基红试剂后呈红色，为阳性。若分解葡萄糖产酸量少，或产生的酸进一步分解为其他非酸性物质，则pH在6.2以上，加入甲基红试剂后呈黄色，为阴性。
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简述甲基红试验的原理。
参考答案：
某些细菌能分解葡萄糖产生丙酮酸，并进一步分解丙酮酸产生甲酸、乙酸、乳酸等使pH下降至4.5以下，加入甲基红试剂后呈红色，为阳性。若分解葡萄糖产酸量少，或产生的酸进一步分解为其他非酸性物质，则pH在6.2以上，加入甲基红试剂后呈黄色，为阴性。
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| You have waited 45 minutes for the valuable 10 minutes' break between classes.But when the bell for the next class rings, you can't __1__ how quickly time has passed. If you are familiar with this __2__, you'll know how time flies when you are having fun and__3__ when you are bored.Now scientists have __4__ a reason why this is the case. Scans have shown that patterns of activity in the brain __5__ according to how we focus on a task. When we are __6__, we concentrate more on how time is passing.And this makes our brains __7__ the clock is ticking more slowly. In an experiment __8__ by a French laboratory,12 volunteers watched an image __9__ researchers monitored their brain activity. The volunteers were told to __10__ concentrate on how long an image appeared for, then __11__ the color of the image, and thirdly, study both duration and color.The results showed that__12__ was more active when the volunteers paid attention to__13__ subjects. It is thought that if the brain is __14__ focusing on many aspects of a task, it has to__15__its resources, and pays less attention to the clock.__16__, time passes without us really __17__ it, and seems to go quickly.If the brain is not so active, it concentrates its __18__ energies on monitoring the passing of time.__19__, time seems to drag. Next time you feel bored __20__, perhaps you should pay more attention to what the teacher is saying! | ||||
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