在核磁共振谱分析中,当质子核外的电子云密度增加时()
A. 屏蔽效应减弱,化学位移值大,峰在高场出现;
B. 屏蔽效应减弱,化学位移值小,峰在高场出现;
C. 屏蔽效应增强,化学位移值小,峰在高场出现;
D. 屏蔽效应增强,化学位移值大,峰在低场出现。
查看答案
核磁共振谱法与红外吸收光谱法一样,都是基于吸收电磁辐射的分析法。
HSQC detects correlations of two nuclei separated by one bond, while HMBC detects correlations of two nuclei over longer ranges of about 2-4 bonds.
Both 13C-1H HSQC and HMBC are heteronuclear correlation spectroscopy between proton and carbon