7Sundstol F.Improving the nutritive value of straw and other lowquality roughages by treatment with ammonia.World Animal Rev.,1978,26:13～21
8Tarkow H.A mechanism for improving the digestibility of lignocellulosic materials with dilute alkali and liquid ammonia.In:Celluloses and their applications.USA:Amer.Chem.Soc.,1969
