Cells cannot remain alive outside certain limits of temperature and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only withi

发表于:2018-12-01 / 阅读(201) / 评论(0) 分类 新东方背诵文选

By Peter Fedynsky Kyiv 30 September 2007 Ukrainians cast their ballots in a special parliamentary election, in which domestic and international observers sought to assure an honest vote.Opposition leader Yulia Tymoshenko says she will ask President V

发表于:2018-12-08 / 阅读(86) / 评论(0) 分类 2007年VOA标准英语(九月)

Welcome to This I Believe, an NPR series presenting the personal philosophies of remarkable men and women from all walks of life. Support for NPR Podcasts comes from Visa, offering the Visa signature card, featuring concierge services for travel, din

发表于:2018-12-19 / 阅读(128) / 评论(0) 分类 2007年NPR美国国家公共电台

Some bacteria have adapted to super cold environments for millions of years. And scientists have isolated some of the essential genes that allow bacteria to tolerate their harsh living conditionsbecause these same genes might help in the creation of

发表于:2019-01-11 / 阅读(75) / 评论(0) 分类 英语杂谈

New research suggests ayahuasca, a jungle vine found in the Peruvian rainforest, can have a powerful effect on the human central nervous system when brewed with other plants. Researchers say one of ayahuasca's most promising uses could be in treating

发表于:2019-01-13 / 阅读(61) / 评论(0) 分类 VOA标准英语2010年(三月)

Fusion is how stars produce energy. It occurs when the nuclei of light atoms, such as hydrogen, are fused together under extreme pressure and heat. Tokamak Energy, from Oxfordshire, believes that the third version of their compact, spherical tokamak

发表于:2019-01-17 / 阅读(96) / 评论(0) 分类 2015CRI中国国际广播电台