天麻钩藤汤联合硝苯地平控释片治疗原发性高血压肝阳上亢证疗效及安全性研究-Study on Efficacy and Safety of Tianma Gouteng Decoction Combined with Nifedipine Controlled-Release Tablets in the Treatment of Hyperactivity of Liver-Yang in Patients with Essential Hypertension