%0 Journal Article %J China Environmental Science %D 2015 %T Effects of emission-sources reduction time and ratios on PM2.5 concentration over Beijing Municipality %A Shixian Zhai %A Xingqin An %A Zhaobin Sun %A Jun Liu %B China Environmental Science %V 35 %P 1921-1930 %G eng %U http://www.cnki.com.cn/Article/CJFDTotal-ZGHJ201507001.htm %N 7