Seed Germination Characteristics of 14 species in the Hilly-gullied Loess Plateau of Northern Shannxi The Characteristics of Low Temperature Tolerance during Seed Germination of the Ephemeral  Plant Lepidium apetalum (Cruciferae) Studies on the Esterase and Protein in the Seeds of Ural Licorice (Glgcuralensis)During the Process of Primary Germination