$s=<<<txt
","bdSourceName":"","bdFromPageTitlePrefix":"","token":"8095"},{"thumbURL":"http://t2.baidu.com/it/u=2984778172,1478112097&fm=0&gp=0.jpg","middleURL":"http://t2.baidu.com/it/u=2984778172,1478112097&fm=51&gp=0.jpg","largeTnImageUrl":"http://t2.baidu.com/it/u=2984778172,1478112097&fm=52&gp=0.jpg","hasLarge" : 0,"pageNum":40,"objURL":"http://www.che51.com/UploadFiles/image/Gallery/2_Pic_200912250127432009.jpg ","fromURL":"http://www.che51.com/picture/carinfo.aspx?car_id=1781&carserialsid=227 ","fromURLHost":"http://www.che51.com ","currentIndex":"28638 ","width":174,"height":121,"type":"jpg","filesize":"52","bdSrcType":"0","di":"64754191000","is":"0,0","bdSetImgNum":0,"bdImgnewsDate":"1970-01-01 08:00","fromPageTitle":"新<strong>bmw<\/strong> <strong>530li<\/strong>典雅型 ","bdSourceName":"","bdFromPageTitlePrefix":"","token":"9011"},{"thumbURL":"http://t3.baidu.com/it/u=167097252,823550504&fm=0&gp=0.jpg","middleURL":"http://t3.baidu.com/it/u=167097252,823550504&fm=51&gp=0.jpg","largeTnImageUrl":"http://t3.baidu.com/it/u=167097252,823550504&fm=52&gp=0.jpg","hasLarge" : 0,"pageNum":41,"objURL":"http://www.2sauto.net/db/upload/s_20081013200290.jpg "
txt;
preg_match_all('/"objURL":"(.+)"/sU',$s,$m);
print_r($m[1]);