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- Radium and uranium are radioactive elements. 镭和铀是放射性元素。
- A naturally occurring or artificially produced radioactive element. 放射性元素自然产生或人为制造的放射性元素
- Radium is a radioactive element. 镭是个放射性元素。
- Radium and uraniumare radioactive elements. 镭和铀是放射性元素。
- How many radioactive elements do you know? 你知道多少种放射性元素?
- Polonium is a highly radioactive element and a metalloid. 钋是高放射性的元素,金属。
- The rate at which radioactive elements disintegrate varies from one element to another. 放射性元素的衰变速度随元素种类的不同而不同。
- Radioactive elements are at the normal background level, causing no deleterious pollution. 环境辐射在正常范围之内，不存在任何人为造成的放射性污染。
- Other radioactive elements have been discovered since: actinium, radiothorium and mesothorium, ionium , etc. 自那以后发现的其他放射性元素有：锄、放射性钍和新针、镍，等等。
- I shall now speak to you of the experiments which have led us to obtain by transmutation new radioactive elements. 我现在跟诸位讲讲那些使我们通过蜕变法获得新的放射性元素的实验。
- The decomposition of a radioactive element is the simplest example of a true first order reaction. 放射性元素的衰变是真正一级反应最简单的实例。
- Other radioactive elements have been discovered since: actinium,radiothorium and mesothorium,ionium ,etc. 自那以后发现的其他放射性元素有：锄、放射性钍和新针、镍，等等。
- Radioactive elements are at the normal background level,causing no deleterious pollution. 环境辐射在正常范围之内，不存在任何人为造成的放射性污染。
- Petrographically and mineralogically similar rocks quite often have different concentrations of radioactive elements. 岩石学矿物学上类似的岩石，其放射性元素丰度却往往有所不同。
- Other radioactive elements have been discovered since: actinium, radiothorium and mesothorium, ionium, etc. 自那以后发现的其他放射性元素有：锄、射性钍和新针、，等等。
- Could you tell me the name of the scientist who discovered two new radioactive elements, radium and polonium? 你能告诉我发现了两种新放射性元素，镭和钋的科学家名字吗?
- Any of a series of chemically similar,radioactive elements with atomic numbers ranging from 89(actinium) through103(lawrencium). 锕类任何化学性质相似，原子序数在89（锕）与103（铹）之间变化的放射性元素
- There are many toxic (poisonous) pollutants,but the best studied are radioactive elements and certain chemical compounds used to kill insects. 污染物质有许多是有毒物质，其中对放射性元素和一些特定的用来杀灭昆虫的化学化合物的污染研究得最多。
- If heavy atoms could be split, scientists reasoned, this energy could be released, as it is when the radioactive elements disintegrate spontaneously. 于是，科学家们推断，如果重原子能够被分裂的话，这种能量就可以被释放出来，放射性元素自然衰变时情况就是这样。
- I will remind you at the outset that one of the most important properties of the radioactive elements is that of ionizing the air in their vicinity(Becquerel). 我想从一开始就提醒大家，放射性元素最重要的属性之一就是将其附近的空气电离(贝克勒尔)。
