Hydrogen-induced cracking (HIC) of Fe3Al alloy was studied by in situ transmission electron microscope (TEM). Electron transparent specimens were mounted onto a constant displacement device. Stress was applied to the ...Hydrogen-induced cracking (HIC) of Fe3Al alloy was studied by in situ transmission electron microscope (TEM). Electron transparent specimens were mounted onto a constant displacement device. Stress was applied to the specimen by using a bolt through the device. The results showed that hydrogen enhanced the dislocation emission and motion in Fe3Al alloy. A dislocation free zone (DFZ) was formed following the dislocation emission. Microcrack initiated in the DFZ or at the main crack tip when the emission reached a critical extension. Hydrogen played an important role in the process of brittle fracture of Fe3Al alloy.展开更多
目的：选择与人类高度相似的大鼠胎盘为研究对象、以血管发育为切入点、经灌胃途径给予妊娠大鼠大、中、小剂量的叶酸干预、选择受精后13.5 d 为时间点，原位、在体观察叶酸对胎盘的作用。方法实验进行时间为2012年9月至2014年1月间，...目的：选择与人类高度相似的大鼠胎盘为研究对象、以血管发育为切入点、经灌胃途径给予妊娠大鼠大、中、小剂量的叶酸干预、选择受精后13.5 d 为时间点，原位、在体观察叶酸对胎盘的作用。方法实验进行时间为2012年9月至2014年1月间，应用免疫细胞化学等技术检测叶酸干预后，胎盘血管内皮生长因子（VEGF）、凝血因子Ⅷ（Ⅷ因子）的表达及游离雌三醇（FE3）的水平。结果叶酸可能通过影响细胞增殖正负向调节因素 VEGF 和Ⅷ因子的表达，促进妊娠大鼠胎盘细胞的增殖活性。叶酸还通过提高胎盘的合成功能，促进胎盘的发育。结论一定剂量的叶酸对胎盘组织结构发育及功能发挥起到有益作用。展开更多
Recently, the Tertiary red clay sequence underlying Pleistocene loess has attracted much attention. The remarkable progress is the recognition that the Tertiary red clay sequence is also wind-blown in origin, thus pro...Recently, the Tertiary red clay sequence underlying Pleistocene loess has attracted much attention. The remarkable progress is the recognition that the Tertiary red clay sequence is also wind-blown in origin, thus providing a good opportunity to reconstruct long-term monsoon changes. In contrast to the loess deposits, the magnetic susceptibility and the pedogenic characteristics are almost independent of each other in the red clay, thus challenging the validity of the readily measurable magnetic susceptibility in describing the monsoon history recorded by the red clay. With the objective to address the long-term East Asia summer monsoon evolution, the free to total Fe2O3 ratios were calculated in a continuous eolian red clay-loess sequence at Lingtai, the Chinese Loess Plateau, which has a thickness of 305 m and a basal age of 7.0 Ma. The seven million-year Fe2O3 ratio record from the red clay-loess sequence indicates that (i) variations of the free to total Fe2O3 ratios of the loess can correlate展开更多
A mild and efficient method for the oxidative deprotection of 1,3-oxathiolanes with Fe（NO3）3·9H2O and Cu（NO3）2·3H2O in the absence of solvent is reported.
文摘Hydrogen-induced cracking (HIC) of Fe3Al alloy was studied by in situ transmission electron microscope (TEM). Electron transparent specimens were mounted onto a constant displacement device. Stress was applied to the specimen by using a bolt through the device. The results showed that hydrogen enhanced the dislocation emission and motion in Fe3Al alloy. A dislocation free zone (DFZ) was formed following the dislocation emission. Microcrack initiated in the DFZ or at the main crack tip when the emission reached a critical extension. Hydrogen played an important role in the process of brittle fracture of Fe3Al alloy.
文摘目的：选择与人类高度相似的大鼠胎盘为研究对象、以血管发育为切入点、经灌胃途径给予妊娠大鼠大、中、小剂量的叶酸干预、选择受精后13.5 d 为时间点，原位、在体观察叶酸对胎盘的作用。方法实验进行时间为2012年9月至2014年1月间，应用免疫细胞化学等技术检测叶酸干预后，胎盘血管内皮生长因子（VEGF）、凝血因子Ⅷ（Ⅷ因子）的表达及游离雌三醇（FE3）的水平。结果叶酸可能通过影响细胞增殖正负向调节因素 VEGF 和Ⅷ因子的表达，促进妊娠大鼠胎盘细胞的增殖活性。叶酸还通过提高胎盘的合成功能，促进胎盘的发育。结论一定剂量的叶酸对胎盘组织结构发育及功能发挥起到有益作用。
基金the National Natural Science Foundation of China (Grant No. 49525203).
文摘Recently, the Tertiary red clay sequence underlying Pleistocene loess has attracted much attention. The remarkable progress is the recognition that the Tertiary red clay sequence is also wind-blown in origin, thus providing a good opportunity to reconstruct long-term monsoon changes. In contrast to the loess deposits, the magnetic susceptibility and the pedogenic characteristics are almost independent of each other in the red clay, thus challenging the validity of the readily measurable magnetic susceptibility in describing the monsoon history recorded by the red clay. With the objective to address the long-term East Asia summer monsoon evolution, the free to total Fe2O3 ratios were calculated in a continuous eolian red clay-loess sequence at Lingtai, the Chinese Loess Plateau, which has a thickness of 305 m and a basal age of 7.0 Ma. The seven million-year Fe2O3 ratio record from the red clay-loess sequence indicates that (i) variations of the free to total Fe2O3 ratios of the loess can correlate
文摘A mild and efficient method for the oxidative deprotection of 1,3-oxathiolanes with Fe（NO3）3·9H2O and Cu（NO3）2·3H2O in the absence of solvent is reported.
