摘要
Stroke ranks fourth among all causes of death and is the major cause of long-term disability in the United States.Furthermore,it is associated with significant morbidity/mortality and a direct/indirect cost of approximately$65 billion annually（Roger et al.,2012）.Other than thrombolysis by tissue plasminogen activator（t PA）,which offers only a short window of treatment（-3–4 hours）,
Stroke ranks fourth among all causes of death and is the major cause of long-term disability in the United States.Furthermore,it is associated with significant morbidity/mortality and a direct/indirect cost of approximately$65 billion annually（Roger et al.,2012）.Other than thrombolysis by tissue plasminogen activator（t PA）,which offers only a short window of treatment（-3–4 hours）,
