题目内容
简单香豆素母核上的1H-NMR特征有
2021-10-23
A.H-3δ6.1-6.4
B.H-4δ7.5-8.3
C.H-3δ7.0-7.5
D.H-4δ6.5-7.0
E.H-3和H-4的偶合常数（J）约为9Hz
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