在气相色谱定量分析时,“单点外标法”比较适合的情形是()。
A.组成比较相近的大批量样品
B.待测物含量变化较大
C.使用自动进样器进样
D.使用高灵敏度检测器
参考答案:A, C
The news of the first successful cloning of a sheep has sent shock waves around the world.As a result, in many countries, officials and even some scientists are calling for new or strengthened legislation to outlaw human cloning, although at this early date, no concrete measures have been proposed.In the United States, which currently has no law prohibiting the procedure, President Clinton announced an urgent inquiry into the potential ethical and legal implications bythe National Bioethics Advisory Commission, which will report its conclusions by the end of May. Meanwhile, Clinton has banned federal funding for human cloning research and asked for a moratorium on nonfederally funded efforts. In addition, both houses of the U. S. Congress had held holding hearings on the issue. Scientists have cloned embryos for the first time from patients with serious diseases and injuries. It is believed that the day will come when some of mankind’s most destructive diseases and injuries can be effectively treated through the use of therapeutic stem cells.
钢管内壁涂层保护常采取哪些措施?