丰度比

The thorium abundance ratio measured for the star in the Ursa Minor dwarf galaxy is as low as that found in the oldest stars in the Milky Way, suggesting that this star could be at least 12 billion years old.

钍丰度比测得的星在URSA患者小矮星系是低至那被发现在古老的恒星在银河系中，暗示这颗恒星可能至少有12亿年之久。

Lead ; atmospheric aerosols ; isotope abundance ratio

铅； 大气颗粒物；同位素丰度比

The differential eguations and boundary conditions are established, based on these hypotheses. The theoretical formulary about sample atom number with different diffusion coefficient are reasoned out; the relationship between the isotope abundance ratio and the sample wastage of melting and solid samples and the samples simultaneously at evaporation and decomposition are discussed in theory.

根据这三条假设建立了样品原子数的微分方程及边界条件，推导出了不同扩散系数的样品原子数的理论公式，从理论上讨论了熔融态、固态样品以及蒸发分解同时发生的样品同位素丰度比与样品消耗量间的关系。

The sample was digested by high-pressure vessel with HNO3/H2O2 as the solvent. By measuring 200Hg/202Hg abundance ratio and adding quantity of the spike, the content of Hg was determined. Moreover, the uncertainty of results were also analyzed and evaluated.

样品处理采用高压密封焖罐酸溶样技术，将样品与202Hg稀释剂混合，通过所加稀释剂的量和测量混合样品中200Hg/202Hg的丰度比，准确计算出样品中Hg元素的含量，同时对测量结果的不确定度进行分析和评定。

The MS showed that the ratio of relative abundance ratio of two main Se isotopes is about 2:1, which can give important information for identifying molecular or fragile ions of selenium.

所有化合物均可获得特徵质谱，表现出含单个硒原子的分子离子或碎片离子特徵峰簇，硒的两种主要同位素在峰簇中表现为主要峰M与(M-2)的相对丰度比约为2：1，可为鉴定含硒分子离子或碎片离子提供重要信息。

Models of element synthesis during the supernova explosions predict that the abundance ratios of actinides with respect to other stable elements heavier than iron are very sensitive to the environment of the explosion, such as the entropy and the ratios of protons, neutrons and electrons.

模型元素的合成，在超新星爆炸预言的丰度比锕对于其他稳定更重的元素，比铁很敏感，对环境造成的爆炸，如熵和比例的质子，中子和电子。

Research of neodymium isotopic abundance measurement provides experimental and technical support of determination of neodymium atomic weight.

采用浓缩同位素进行丰度比的测量可以提高丰度测量的不确定度，减小最终结果的测量偏差。

The isotopic ratio of the sample is finally obtained by correction of the IDMS measured value with the correction factor.

用校正因子校正样品和稀释剂的同位素丰度比的测量值，得到准确值。同时，评定了方法的不确定度。

It is an absolute measurement method based on gravimetry.

它可用于准确测定铀样品中的丰度比，这是一种基于重量法的绝对测量方法。

Models of element synthesis during the supernova explosions predict that the abundance ratios of actinide s with respect to other stable elements heavier than iron are very sensitive to the environment of the explosion, such as the entropy and the ratios o

模型元素的合成，在超新星爆炸预言的丰度比锕对于其他稳定更重的元素，比铁很敏感，对环境造成的爆炸，如熵和比例的质子，中子和电子。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。