排序方式: 共有16条查询结果,搜索用时 31 毫秒
11.
Ni-Zr-Al基非晶合金催化剂的苯加氢催化性能 总被引:4,自引:0,他引:4
利用快速凝固技术制备了Ni23.3Zr6.7Al64Cu2.3Ce3.7非晶态合金,用碱洗抽Al的方法进行活化,制成了Ni-Zr基非晶态合金催化剂(A>50 m2/g), 并考察了其对苯加氢反应的催化性能. 结果发现,这种新型催化材料的比活性高出常规Raney Ni催化剂约375%. 反应动力学分析表明,苯加氢反应级数对氢基本上表现为一级,表观反应活化能约为31.2 kJ/mol, 并推导出苯加氢反应的动力学方程. 相似文献
12.
13.
电子设备和无线技术不断向K/Ka波段发展以及电子系统集成度的不断提高给电子系统的电磁屏蔽设计带来了严峻挑战。提出一种将频率选择表面(FSS)用于电子系统屏蔽的新方法,可以替代传统散热孔阵,在满足通风散热性能的同时确保电子系统在5G毫米波段的电磁屏蔽性能。基于金属腔中心点屏蔽效能和全局屏蔽效能,分析了FSS孔阵排布方式、电磁波极化与入射角度对金属外壳电磁屏蔽效能(SE)的影响。结果表明:FSS孔阵排布方式对金属腔屏蔽性能的影响较小,并且SE不受入射电磁波极化方式影响;含FSS通风孔阵的金属外壳在23.0~25.5 GHz范围内屏蔽效能约为30 dB,比含传统散热孔阵金属腔屏蔽效能提高15 dB。 相似文献
14.
15.
南五味子中五味子甲素的薄层扫描色谱定量分析 总被引:1,自引:0,他引:1
南五味子是2000年中国药典开始收录的中药材。南五味子与北五味子的性状完全不同,所含化学成分亦不同,功能主治各有侧重。南五味子为木兰科植物华中五味子的干燥成熟果实,性味酸、甘、温,具有收敛固涩,益气生津,补肾宁心之功效。现代研究表明,南五味子的活性成分主要包括五味子甲素和五味子酯甲等木脂素成分。五味子甲素具有显著的功效,但药典仅有五味子酯甲的含量测定,未有五味子甲素的含量测定,相关研究报道也很少,因此有必要研究建立南五味子中五味子甲素含量测定方法。 相似文献
16.
As new catalytic materials, amorphous alloys have attracted much attention since 1980s. Rapid solidification is one of the main techniques to prepare amorphous alloys.However, as-cast rapidly solidified alloys usually can not be directly used as the catalyst for their poor surface area, oxide film on their surface, etc. Therefore, activation pretreatment must be carried out. Recently, leaching aluminum has been attempted to activate rapidly solidified amorphous catalytic alloys containing aluminum. In order to carry out such an activation pretreatment, the Al-rich amorphous precursor alloys must be obtained first, in which the content of active component must be sufficiently high so that the catalytic activity of the activated catalyst can be attained. On the other hand, the chemical composition of the precursor must approach eutectic point or contribute to the range of low liquidus temperature so that the glass transition can be easily achieved according to the solidification theory[1]. So far Al-based alloys which meet the dual confinement have not been found yet. For Ni-Al and Cu-Al systems,only the microcrystalline alloys can be obtained through rapid solidification[2,3].In the present study, glass formation was achieved by introducing promotion elements in Ni-Al system precursor alloys. 相似文献