Structure and Antitumor and Immunomodulatory Activities of a Water-Soluble Polysaccharide from Dimocarpus longan Pulp oleh Fa-Yan Meng, Yuan-Ling Ning, Jia Qi, Zhou He, Jiang Jie, Juan-Juan Lin, Yan-Jun Huang, Fu-Sen Li, Xue-Hua Li