For years 很多年以来no one could make this particular therapy 没有人可以将这种疗法work in animals 运用在larger than rodents ,比啮齿动物更大的动物上（？）but now two research groups have demonstrated its efficacy.
For years 是时间状语But连接两个并列分句，表转折关系第一个分句：no one could make this particular therapy work in animals larger than rodents 其中no one 是主语 make+宾语（this particular therapy ）+宾语补足语（ work in animals larger than rodents）第二个分句：now two research groups have demonstrated its efficacy.主谓宾简单句，现在完成时整句译为：许多年来，还没有人能使这个特殊的治疗方法在啮齿动物以外的其它动物身上发挥更大的作用，但是现在的两个研究小组已经成功地论证了它的功效。
