19.2.3单糖的构象 CH2OH CHO CH2OH H-OH H HO-H OH H H-OH HO H-OH HO CH2OH D-(+)葡萄糖 CH CH2OH HO Lr O HO OH OH OH OH BD-(十)吡喃葡萄糖 aD-(+)吡喃葡萄糖 20 20 [B]D=+112 a JD =+19°19.2.3 单糖的构象 CHO CH2OH H OH H OH HO H H OH O CH2OH H OH H H OH HO H OH H O CH2OH H OH H H OH HO H H OH O OH OH HO HO CH2OH O OH OH HO HO CH2OH α -D-(+)-吡喃葡萄糖 α D-(+)-葡萄糖 β-D-(+)-吡喃葡萄糖 [ β ] D 20 + 112 o [ ] D 20 + 19 o