用信噪比法确定定量限时，进行测定的浓 度S/N为

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SQL Error: select id,body,options from ***_enewstiku where sourceid='30783' and id < 2478922 and id<>'2478922' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='30783' and id > 2478922 and id<>'2478922' order by id asc limit 5