60钴射线全挡所需要的低熔点铅的厚度约为

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SQL Error: select id,body,options from ***_enewstiku where sourceid='29411' and id < 2394815 and id<>'2394815' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29411' and id > 2394815 and id<>'2394815' order by id asc limit 5