利用碱性差异进行分离的是()
A. 小檗碱和小檗胺
B. 麻黄碱和伪麻黄碱
C. 苦参碱和氧化苦参碱
D. 莨菪碱和东莨菪碱
E. 吗啡和可待因
6-甲氧基-7-羟基香豆素的H-3信号是()
A. δ7.60(1H,d,J=9.5Hz)
B. δ6.85(1H,brs)
C. δ6.26(1H,d,J=9.5Hz)
D. δ3.95(3H,s)
E. δ6.91(1H,s)
有27个C原子,F环开裂成直链的是()
A. β-香树脂烷型
B. α-香树脂烷型
C. 羽扇豆醇型
D. 呋甾烷醇型
E. 异螺旋甾烷型
Questions 17-20 are based on the following passage. You now have 20 seconds to read the questions 17-20 Why is insulation required in new houses
A. To limit discussion on heating bills.
B. To determine temperature in homes.
C. To prevent heat loss.
D. To convert homes to electric heat.