Cloning and Function Analysis of SiLEA14 from Saussurea involucrata Kar.et Kir. Clone and Aluminum Tolerance Analysis of Unknown Gene from Saussurea involucrata Kar.et Kir. Obtained and Cold Resistance Identification of Tobacco Plants Transformed by siCOR of Saussurea involucrata Kar.et Kir. Application of macroporous absorption resin in purification for active constituents from Saussurea involucrata