HMQC---Heteronuclear Multiple Quantum  Correlation，异核多量子相关; HSQC---Heteronuclear Single Quantum Correlation，异核单量子相关; HMBC---Heteronuclear Multiple Bond Correlation，异核多键相关。 前两者看到的都是碳氢直接相连的相关信号；后者看到的是相隔2、3根键的碳氢相关。 纠正一下楼上，上述看到的都是C-H相关信号。H-H的是H-H COSY谱，至于C-C的貌似没听过啊！ 另外，关于前两者的区别文献上是这样说的：Both the HSQC and HMQC provide the exact same  information. The differences are technical and involve signal-to-noise ratio.  The  HSQC has a sensitivity-enhanced version that provides a factor of two of improvement in sensitivity for methine protons (only) and amide nitrogen. If you are interested in  CHs and NHs then choose the HSQC，