The naming of stars is at the discretion of the International Astronomical Union.给星体命名是由国际天文学联合会决定的。He developed an armillary sphere, on which were carved all the astronomical phenomena known time.经过多年的观察,他研制了一架“浑天仪”.凡是知...
Regular vinyl addition polymers may be obtained from particularly strained endocyclic double bonds.由带特殊张力的桥环双键可以得到规整的乙烯类加成聚合物.Use vinyl seam adhesive where vinyls overlap.塑料布相叠处用塑料封口胶粘起来。This compilation was first issued...