单能窄束γ射线垂直通过吸收物质时，其强度按照哪种规律衰减

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SQL Error: select id,body,options from ***_enewstiku where sourceid='29509' and id < 2400271 and id<>'2400271' order by id desc limit 5 SQL Error: select id,body,options from ***_enewstiku where sourceid='29509' and id > 2400271 and id<>'2400271' order by id asc limit 5