肾糖阈是
A．尿中开始出现葡萄糖时的血糖浓度
B．肾小球开始滤过葡萄糖时的血糖浓度
C．肾小管吸收葡萄糖的最大能力
D．肾小管开始吸收葡萄糖时的血糖浓度
E．肾小球开始滤过葡萄糖的临界尿糖浓度
参考答案：A
解析：[解题思路] 近球小管对葡萄糖的重吸收有一定限度，当血中葡萄糖浓度超过160～180mg/ 100ml时，部分近球小管上皮细胞对葡萄糖的吸收已达极限，部分葡萄糖将随尿排出。尿中开始出现葡萄糖时的最低血糖浓度称为肾糖阈。[命题规律] 考察“近球小管对葡萄糖的重吸收”。必须掌握。
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But beyond just looking dirty, a filthy (肮脏) keyboard might actually make you sick. A 2008 study showed that keyboards can be up to five times dirtier than the average toilet seat. How come? Too often, people don't 2_____ to wash their hands after using the restroom or eating at their desks. In the latter case, sticky fingers transfer sauces and crumbs (食物碎屑)onto and between the keys. Also, our fingers rub skin oils onto the keys. Thus, a keyboard can become a 3_____ place for germs to grow. One common bug that researchers have found is staphylococcus aureus (金黄色葡萄球菌). It is a classic cause of food 4_____, signs of which include nausea (恶心) and diarrhea (腹泻). Stomach sicknesses caused by typing on a dirty keyboard have been dubbed "qwerty tummy" after the "Q-W-E-R-T-Y" keys on a keyboard. The threat posed by a dirty keyboard is quite real, but it can be 5_____. The easiest way is to clean your keyboard regularly. Office cleaning 6_____ say that keyboards should be unplugged, turned upside down and shaken 7_____. By doing so, you can get rid of most of the crumbs. After that, wipe across the keys using a soft cloth with a cleaning solution (清洁剂). Another way to solve the problem is using a silicon (硅胶) keyboard cover. These thin covers are made to 8_____ over the keys. They prevent food from falling through the cracks and dust from 9_____. |