??
???????????????2?????????????
???????????????????????????֧????
???2900?12%????????????????????????
?????????????????????Murray Ramanathan?38?8??????????????2.5???m????
?????????????30%60%
19???19??6?????16??5?????????????????
????????????????????4
??????????????????????????????????1b?13M?1?RNA????RNA?DNA??????
???1b?13?1?????????????????????????510?1b????????13?1????Ramanathan???????????????
???????????????30%40%Ramanathan?????
???1???????ɧ?????????????????????????80%
????????????
?????????????????????????