电针刺激上巨虚、天枢对溃疡性结肠炎模型大鼠Th17相关特异性因子及Treg的影响-Effects of electroacupuncture at 'Shangjuxu' (ST37) and 'Tianshu' (ST25) on Th17-related specificity factors and Treg cells in rats with ulcerative colitis