题干

关于电磁波与现代通信,下列说法中错误的是(   )

A:赫兹第一次用实验证实了电磁波的存在

B:微波属于电磁波,而光波不属于电磁波

C:卫星通信具有覆盖面大、通信距离长、不受地理环境限制等优点

D:光纤通信是利用光波在光纤中传播信息的一种通信方式

上一题 下一题 0.0难度 选择题 更新时间:2018-03-07 08:40:05

答案(点此获取答案解析)

B

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    A drug that is used to treat serious bleeding could save thousands of lives of mothers giving birth. A world test of the drug found it reduced (降低) the risk of bleeding deaths during childbirth by nearly one third. The study included 20,000 women in 21 countries, mainly in Africa and Asia. The test was carried out by London School of Hygiene and Tropical Medicine. The drug is called tranexamic acid (凝血酸). It is low-cost and researchers said it does not cause serious side effects (副作用) for mothers or babies.

    The drug is used to treat mothers for serious bleeding during childbirth. Postpartum hemorrhage (产后出血) is the main cause of mothers' death around the world, according to the World Health Organization.

    Haleema Shakur is the project director for the test. She said though medical condition is improved in many countries, serious bleeding after childbirth remains a big problem in some parts of the world. “It's one of the biggest killers of mothers. In Africa and Asia, about 10% of women will end up with serious bleeding.” The drug works after a mother gives birth.

    Shakur said the best results were reported when the drug was given to women as soon as possible after childbirth. “The earlier you give it — within the first three hours after giving birth — the better the result is.”

    The next step will be to provide training for doctors and nurses on how to use it and then to find where the drug is needed. During the test, women were given the drug in a hospital. But researchers are looking for easier ways to use the drug so it can be more widely used in small clinics and the countryside.