短语词组短語maser r beam 微波激射束molecular beam maser 分子束微波激射器ammonia -beam maser 氨束微波激射器monia beam maser 氨束微波激射器ammonia beam maser 氨束微波激射器beam type maser 分子束微波激射器molecular beam type maser 分子束式脈澤 返回 maser beam