TQH-3821

Main purpose: Evaluate the safety and tolerability of TQH3821 in healthy subjects after multiple, single and multiple administrations, and the safety and tolerability of TQH3821 in combination with methotrexate tablets; Secondary purpose: Evaluate the pharmacokinetics of TQH3821 in healthy subjects after multiple, single and multiple administrations; Evaluate the drug metabolism and transformation study of TQH3821; Evaluate the effect of food on the pharmacokinetics of TQH3821; Evaluate the drug-drug interaction between TQH3821 and methotrexate tablets and the pharmacokinetic properties after combined use; Preliminary evaluation of pharmacodynamics; Preliminary exploration of the identification of metabolites;