1 Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049, P.R. China. Electronic address: jhf@sdut.edu.cn.
2 Shandong Provincial Research Center for Bioinformatic Engineering and Technique, Shandong University of Technology, Zibo 255049, P.R. China. Electronic address: shen@sdut.edu.cn.