Isozyme Studies of Elytrigia Hybrids(E. elongate×E. intermedia) and Their Parents A research on Ephedra cultivation in saline-alkali land GC-MS Analysis of Constituent of Essential Oils from Stems of Ephedra sinica Stapf,E.intermedia Schrenk et C.A.Mey. and E.equisetina Bge. A Study on Induction of Emdryogenic Callus and Plant Regeneration from Mature Embryos of Elytrigia hybrid(E. elongata×E. intermedia)