研究目的和意义我国是一个高原辽阔的国家,尤其是青藏高原,占全国总面积23％,平均海拔4,000米左右,是世界上面积最大、地势最高的高原,有“世界屋脊”之称。这里由于海拔高、空气稀薄、大气压低、气候寒冷、昼夜温差大、紫外线强等,直接影响 Research Purpose and Significance Our country is a vast plateau, especially the Qinghai-Tibet Plateau, accounting for 23% of the total area in the country with an average elevation of about 4,000 meters. It is the largest plateau in the world with the highest terrain, and is called “roof of the world.” Here due to high altitude, thin air, low atmospheric pressure, cold climate, large temperature difference between day and night, a strong ultraviolet light, a direct impact