Thrombolysis With rhPro-UK in 4.5-6 Hours After Acute Ischemic Stroke in a Double-blinded,Controlled Trial

Inclusion Criteria: 1. Ischemic stroke with symptoms of neurological deficits. 2. Aged 18 to 80 years,male or famale. 3. NIH Stroke Scale（NIHSS）scores of 4 to 25. 4. Treatment 4.5 to 6 hours after stroke onset.(Stroke onset time is defined as the last time a patient with no clinical neurological deficit,for patients who wake up with stroke symptoms, consider that stroke occurs when the patient begins to fall asleep). 5. The symptoms of stroke last at least 30 minutes without significant improvement before treatment. 6. CT showed negative or signs of early infarction. 7. Patients and/or their families are willing to participate in this study and agree to sign informed consent. Exclusion Criteria: 1. Patients with premorbid modified Rankin Scale(mRS) score ≥2 2. CT showed multiple infarctions（low density\> 1/3 cerebral hemisphere）. 3. Transient ischemic attack. 4. Epileptic seizure when stroke onset. 5. Intracranial tumor, arteriovenous malformation and aneurysm. 6. Iatrogenic Stroke. 7. Thrombectomy is planned. 8. Cardioembolism and atrial fibrillation. 9. Myocardial infarction history within 3 months. 10. Severe cerebral trauma or stroke history within 3 months. 11. Blood pressure is still out of control after aggressive antihypertensive treatment.Uncontrolled blood pressure is defined as systolic blood pressure≥ 180mmHg or diastolic blood pressure≥100mmHg. 12. High density lesions (bleeding) and subarachnoid hemorrhage is revealed by emergency CT examination. 13. Active visceral hemorrhage. 14. Patients with intracerebral hemorrhage history. 15. Patients with diabetic retinopathy history. 16. Puncture in 1 week which can not be oppressed. 17. Major surgery or severe trauma within 2 weeks. 18. Intracranial surgery, intraspinal surgery or solid organ biopsy within 30 days. 19. Heparin treatment within 48 hours (APTT above normal upper limit). 20. Taking anticoagulant drugs orally, and PT \>15s or INR \>1.7. 21. High risk of acute hemorrhage include platelet count\<10\^9/L. 22. Taking thrombin inhibitors or factor Xa inhibitor with abnormal results of sensitive laboratory examination(e.g. APTT, INR, PLT, FIB、TT or appropriate Ⅹ a factor activity test, etc.). 23. Blood glucose \< 2.7 mmol/L or \> 22.2 mmol/L. 24. Pregnancy, lactating or menstrual women. 25. Patients who have difficulty swallowing and are unable to take medications orally. 26. Clinician thinks patient doesn't fit to participate in the test of other diseases or conditions.