A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical pr...A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical properties and microstructures were determined under basic thermodynamics conditions of aging forming. The results show that pre-deformation shortens the time of primary creep and raises the second steady-state creep rate. Then, the total creep strain is greater, but in the range of test parameters it is still smaller than that without pre-deformation. In addition, transmission electron microscopy(TEM) observation shows that pre-deformation promotes the formation of T1 phase and θ′ phase and makes them distribute more dispersively, while inhibits the generation of δ′ phase, which leads to the improvement of mechanical properties of the alloy. A unified constitutive model reflecting the effects of aging mechanism, stress levels and different pre-deformations was established. The fitting results agree with the experimental data well.展开更多
以六水合硝酸钴(Co(NO_3)_2·6H_2O)为钴源,硫脲(CS(NH_2)_2)为硫源,采用溶剂热法和低温固相硫化的方法制备出了介孔Co_3S_4纳米棒。采用X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)等手段对于介孔Co_3S_4纳米棒进行表征,同时对介...以六水合硝酸钴(Co(NO_3)_2·6H_2O)为钴源,硫脲(CS(NH_2)_2)为硫源,采用溶剂热法和低温固相硫化的方法制备出了介孔Co_3S_4纳米棒。采用X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)等手段对于介孔Co_3S_4纳米棒进行表征,同时对介孔Co_3S_4纳米棒进行了电催化产氧性能测试。结果表明:介孔Co_3S_4纳米棒的起始过电位为0.37 V,塔菲尔斜率为76.95 m V/dec,具有高的电催化产氧性能。展开更多
综述了近20年日本梨中与自交亲和和自交不亲和有关的S4基因的研究进展.这些结果包括:'二十世纪'(基因型为S2S4)为自交不亲和品种,其突变品种'奥嗄二十世纪'(基因型为S2S4SM,SM=stylar part mutant;花柱部分突变)为自交...综述了近20年日本梨中与自交亲和和自交不亲和有关的S4基因的研究进展.这些结果包括:'二十世纪'(基因型为S2S4)为自交不亲和品种,其突变品种'奥嗄二十世纪'(基因型为S2S4SM,SM=stylar part mutant;花柱部分突变)为自交亲和型.'奥嗄二十世纪'自交亲和的原因有三点:(1)S4SM 基因被删除或者是低水平表达.(2)S4SM基因仅在柱头表达.(3)S4SM基因表达较迟.这主要是由于'二十世纪'S基因座上的S4等位基因发生了高度突变成为S4SM基因或者S4等位基因被删除,导致其基因产物花柱中的S4-RNase受到高度抑制或缺乏的缘故.S4基因由997bp组成,其中85~768bp为684bp的阅读框,925~931bp和943~950bp为多聚腺苷酸信号.S4基因的表达产物为S4蛋白,S4蛋白由228个氨基酸残基组成,其中N端的27个氨基酸残基为信号肽,成熟的S4蛋白由201个氨基酸残基组成.S4蛋白的生理功能是抑制花粉的萌发和花粉管的伸长.展开更多
基金Project(2014CB046602)supported by the National Basic Research Program of ChinaProject(51235010)supported by the National Natural Science Foundation of China
文摘A set of uniaxial tensile creep tests at different pre-deformations, aging temperatures and stress levels were carried out for Al-Li-S4 alloy, and the creep behavior and the effects of pre-deformation on mechanical properties and microstructures were determined under basic thermodynamics conditions of aging forming. The results show that pre-deformation shortens the time of primary creep and raises the second steady-state creep rate. Then, the total creep strain is greater, but in the range of test parameters it is still smaller than that without pre-deformation. In addition, transmission electron microscopy(TEM) observation shows that pre-deformation promotes the formation of T1 phase and θ′ phase and makes them distribute more dispersively, while inhibits the generation of δ′ phase, which leads to the improvement of mechanical properties of the alloy. A unified constitutive model reflecting the effects of aging mechanism, stress levels and different pre-deformations was established. The fitting results agree with the experimental data well.
文摘以六水合硝酸钴(Co(NO_3)_2·6H_2O)为钴源,硫脲(CS(NH_2)_2)为硫源,采用溶剂热法和低温固相硫化的方法制备出了介孔Co_3S_4纳米棒。采用X射线衍射(XRD),扫描电镜(SEM)和透射电镜(TEM)等手段对于介孔Co_3S_4纳米棒进行表征,同时对介孔Co_3S_4纳米棒进行了电催化产氧性能测试。结果表明:介孔Co_3S_4纳米棒的起始过电位为0.37 V,塔菲尔斜率为76.95 m V/dec,具有高的电催化产氧性能。
文摘综述了近20年日本梨中与自交亲和和自交不亲和有关的S4基因的研究进展.这些结果包括:'二十世纪'(基因型为S2S4)为自交不亲和品种,其突变品种'奥嗄二十世纪'(基因型为S2S4SM,SM=stylar part mutant;花柱部分突变)为自交亲和型.'奥嗄二十世纪'自交亲和的原因有三点:(1)S4SM 基因被删除或者是低水平表达.(2)S4SM基因仅在柱头表达.(3)S4SM基因表达较迟.这主要是由于'二十世纪'S基因座上的S4等位基因发生了高度突变成为S4SM基因或者S4等位基因被删除,导致其基因产物花柱中的S4-RNase受到高度抑制或缺乏的缘故.S4基因由997bp组成,其中85~768bp为684bp的阅读框,925~931bp和943~950bp为多聚腺苷酸信号.S4基因的表达产物为S4蛋白,S4蛋白由228个氨基酸残基组成,其中N端的27个氨基酸残基为信号肽,成熟的S4蛋白由201个氨基酸残基组成.S4蛋白的生理功能是抑制花粉的萌发和花粉管的伸长.