1. Department of Bioinformatics Institute of Health Service and Transfusion Medicine Beijing 100850 P. R. China
2. School of Informatics Xiamen University Xiamen 361005 P. R. China
3. College of Life Science and Technology Beijing University of Chemical Technology Beijing 100029 P. R. China
4. Department of Computer Science and Engineering University of Shanghai for Science and Technology Shanghai 201210 P. R. China