单萜的基本碳架含有的碳原子数目是() ["10","15","20","25","30"]
正弦稳态电路如题10图所示电压表读数均为有效值,电压表内阻可视为无限大,其中V、V1、V2的读数分别为50V、35V和5V,则电压表V3的读数应为()V。 ["50","40","30","45"]
膳食中最常见的多不饱和脂肪酸是() ["EPA(二十碳五烯酸)","DHA(二十二碳六烯酸)","油酸","亚油酸","亚麻酸"]
非苷类萜室温下析出结晶最难的是() ["A.单萜","B.倍半萜","C.二萜","D.二倍半萜","E.三萜"]
出口替代
国际贸易额