A PhaseⅡ of Injection for Recombinant Human Tissue Plasminogen Kinase Derivative in Treatment of Acute Ischemic Stroke.

The primary purpose of this trial is to compare the efficacy of different doses of investigator product and comparator product in patients with acute ischemic stroke in 4.5 Hours after stroke onset, and provide a basis of drug administration for phase Ⅲ clinical trial. The secondary purpose of this trial is to compare the safety of different dose of investigational product and comparator product in patients with acute ischemic stroke in 4.5 hours afterstroke onset .