使用圆形单晶片探头时，近场长度i与探头 半径r的关系为

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SQL Error: select id,body,options from ***_enewstiku where sourceid='31793' and id < 2541686 and id<>'2541686' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='31793' and id > 2541686 and id<>'2541686' order by id asc limit 5