Methods from october 2002 to april 2004 , a total of 4 534 hospitalized children with acute respiratory tract infection were studied . Nasopharyngeal aspirates were screened for virus by direct immunofluorescent ( dif ) assay .
In this paper the author uses capps model system to make simulation exper iments . It aims at studying the influence of dustpan shaped ferrain on dilution and dif fusion of main pollutants such as so2 , no x and pm10in taiyuan city und er the control of different circulations .