Butter, margarine, and oily fish are all good sources of vitamin D.黄油、人造黄油和多脂鱼都含有丰富的维生素D。Milk, oily fish and egg all contain vitamin D.牛奶、油性鱼类和鸡蛋都含有维生素D.This special form of vitamin D is naturally present in breast milk....
Age structure is a foundational base to study the population dynamics.年龄结构是研究种群动态的重要基础.Objective To search for triterpene glycoside with new structure.目的:寻找结构新颖的三萜皂苷类化合物.The photosphere has a granular structure.光球还有颗粒结构。...