共查询到20条相似文献,搜索用时 31 毫秒
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镧热还原氧化钐过程镧的非平衡扩散的研究 总被引:1,自引:1,他引:0
运用化学分析法和热重法对镧热还原氧化钐的反应产物镧渣进行分析,得到坩埚不同部位镧渣的镧的扩散量△La和实际反应物料的Sm2O3∶La的比值,并把理论反应物料的Sm2O3∶La和实际的比值相比较。结果表明:真空高温条件下,还原剂金属镧在反应过程中发生了有固定方向的扩散迁移。金属镧从反应物料中的由内向外的非平衡扩散,造成金属镧在反应物料中的分布不均,表面富集而芯部贫乏,降低了还原剂金属镧利用率及产物金属钐收率。 相似文献
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Magnetic Coupling in La0.67 Ca0.33 MnO3/La0.67 Sr0.33 CoO3/La0.67 Ca0.33MnO3 Trilayer Films 总被引:1,自引:0,他引:1
The perovskite La0.67 Ca0.33 MnO3/La0.67 Sr0.33 CoO3/La0.67 Ca0.33 MnO3 trilayers were fabricated by a facing-target sputtering technique and their magnetotransport properties were investigated. The magnetoresistance is dependent on spacer thickness and dramatically decreases when La0.67 Sr0.33 CoO3 layer is thick enough because of its short-circuiting effect. Different from La0.67 Ca0.33 MnO3 single layer, trilayer films with thin La0.67 Sr0.33 CoO3 spacer have the enhanced metal-semiconductor transition temperature (TMS) of La0.67 Ca0.33 MnO3 layers. The magnetic coercivity Hc shows a nonmonotonic behavior with changing the spacer layer thickness at 230 K. The waist-like hysteresis indicates that there is an indirect exchange coupling between the top and bottom Lao.67 Ca0.33 MnO3 layers across the spacer La0.67 Sr0.33 CoO3 layer. 相似文献
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镧参与金属胎体/金刚石复合材料界面反应的热力学及动力分析 总被引:3,自引:0,他引:3
通过分析镧参与金属胎体/金刚石复合界面反应的热力学及动力学条件,指出在本试验烧结条件下,镧参与反应的热力学条件已得到满足呵以直接或间接参与金属胎体与金刚石颗粒之间的界面反应,但在不同的工艺条件下,镧的作用程度不同。 相似文献
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A sketch is made of the historical developments of the Faculty of Psychology and Education of the University of Ottawa. In the last 18 years the teaching of Psychology has taken major proportions at the University. What was a department of the Faculty of Arts until 1949 has now become an autonomous Faculty. Since July of 1967, Education has separated itself from the Faculty of Psychology although through cross-appointments of staff and through courses that are common to both Psychology and Education students, the two Faculties remain close to one another. To complete an M.A. in Psychology, a student must put in three years of residence during which he attends classes, undergoes internship training and finally prepares a thesis. At the Ph.D. level, the residence requirements are of two years (post M.A.). Specialization is offered in the following areas: Counselling, Educational Psychology, General Psychology, Clinical Psychology, School Psychology and Child Psychology. More recently (in 1964) the Faculty instituted a research centre in psychophysiology. This centre has developed a section of animal psychology and very recently a cybernetics laboratory which has concentrated its efforts on the electronic measurement of intelligence. Projects are under way for expansion in the form of new buildings and new research centres. The first of these, a Centre for Child Study is being built this year at the cost of $2.5 million. Plans are also drawn for more buildings to house classrooms and laboratories, and these are expected to be completed by 1970. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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Preparations of La Crosse virus, a member of the California encephalitis group of bunyaviruses, were found to possess three major virion proteins. Two of the proteins were glycosylated (G1 and G2) and were located on the surface of the virus particles. These two glycoproteins were present in equimolar amounts and possessed apparent molecular weights of 120 X 10(3) and 34 X 10(3). Virion nucleocapsids, isolated by a nonionic detergent and salt treatment, contained another major protein, N (molecular weight = 23 X 10(3)). A large, but minor, protein species L (molecular weight = 180 X 10(3)) was also found in virus preparations. The approximate number of protein molecules per virion has been determined. Electron microscopy of purified La Crosse virus indicated that the virus particle (mean diameter, 91 nm) is enveloped and possesses irregular surface projections (length, 10 nm). 相似文献
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