黃禹錫 幹細胞 胚胎幹細胞研究守則 告知後同意 倫理委員會 捐贈者補償 補助 胚胎的地位 研究性複製 Woo-Suk Hwang Stem cell Ethical guideline for the conduct of human embryonic stem cell research Informed consent Ethics committee Reimbursement of donor Public funding Status of embryo Cloning for research purpose