Clinical Study to Evaluate the Efficacy and Safety of Huperzine A Controlled-Release Tablets in Patients With Mild-to-Moderate Dementia of the Alzheimer's Type

During the trial, the patients should take huperzine A controlled-release tablets in the morning

During the trial, the patients should take donepezil hydrochloride tablets before going to bed in the evening

During the trial, the patients should take huperzine A controlled-release tablets placebo in the morning and donepezil hydrochloride tablets placebo before going to bed in the evening