用亲脂性有机溶剂提取总生物碱时,一般
A.先用酸水湿润药材
B.先用碱水湿润药材
C.先用石油醚脱脂
D.用正丁醇、乙醇等溶剂提取
E.用氯仿、苯等溶剂提取
参考答案:B,D
The journey around the world took the old sailor nine months, _________the sailing time was 226 days.
A. of which
B. during which
C. from which
D. for which
增加电极与体表间的距离,可以增加有效作用深度和热分布的均匀性,但会使,高频电场对人体作用强度降低,故必须调高电压档,增大机器输出功率。()