Cd34 used to be used as a prerequisite marker for hscs , but recently , seve 1 laboratory have proved the existence of cd34 - negative hscs independently 新生大鼠体积适中，操作方便，且实验周期相对短，可以成为研究干细胞体内检测的实验模型。
2.
Abstract : the fraction compositions , group compositions and structure compositions of seve n catalytic stocks were determined by means of vacuum distillation , mass spectrum , element analysis and molecular mass measurement 文摘:采用减压蒸馏、质谱分析、元素分析和分子质量测定对辽河原油的7种催化原料油进行了馏分组成、族组成和结构族组成的分析。
3.
But in fact , difficulty in classification has been an obstacle in the utilization , conservation and application of the palm resources for the specialty of their geological distributions and morphological structures , and the lack of research on the physio - ecological principles in cultivation and appliance with the palm resources has not only coursed waste in plant introduction and acclimatization but also seve rely influenced the elaboration of the ecological efficiency of palms as an emblem of tropical plant landscape in the construction of urban green system 然而，由于棕榈科植物地理分布和形态结构的特殊性，分类鉴别上的困难已经成为这类资源科学保护、合理开发利用上的严重障碍；同时也由于对棕榈科植物栽培应用中的生理生态规律缺乏研究，在引种驯化和推广应用的过程中造成了不必要的浪费，并严重影响了这种热带植物景观象征的园林植物资源的生态效益的有效发挥。
