广州市石井河水质污染及其对水源的影响分析

根据广州市石井河日益发展的水污染及其危害西航道饮用水源的问题，进行了深入的调查研究，剖析了造成水污染的主要原因，有针对性地提出了分期整治石井河以保护饮用水源的对策与建议，本文旨在通过对石井河水污染的分析，使人们认识到水源污染的主要来源，同时对相类似的河流－流溪河引以警惕，加强保护，防止水源上游河流受到污染。     

Selenium metabolism in animals and humans

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Prenatal diagnosis of pericentric inversion of chromosome no. 17 in a twin pregnancy

Although prenatal genetic diagnosis can usually provide prospective parents with information as to whether their fetus is affected with certain genetic conditions, the presence of twins and the uncertainty about the phenotype of some chromosome variations pose a major dilemma and make genetic counselling very difficult. Here, a case report of an unusual chromosome aberration (pericentric inversion of chromosome no. 17) in a twin pregnancy which was originally suspected to be monoamniotic but later proved to have two sacs was presented.