Obtained and Cold Resistance Identification of Tobacco Plants Transformed by siCOR of Saussurea involucrata Kar.et Kir. Cloning and Sequence Analysis of CBF1 Gene in Vitis amurensis Cloning and Sequence Analysis of a Cold-regulated Gene BnCOR14 from Brassica napus Drought-tolerance Analysis of Tobacco Plant Transformed with Sasussured involucrata siCOR Gene