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排序方式: 共有10000条查询结果,搜索用时 812 毫秒
931.
Namsin Park Takeyuki Shiraishi Kazuyoshi Kamisugi Yoshitaka Hara Keita Iizuka Takashi Kado Shuzi Hayase 《Journal of Applied Electrochemistry》2008,38(3):371-375
A direct ethanol fuel cell (DEFC), which is less prone to ethanol crossover, is reported. The cell consists of PtRu/C catalyst as the anode, Nafion® 117 membrane, and Ni–Co–Fe (NCF) composite catalyst as the cathode. The NCF catalyst was synthesized by mixing Ni, Co, and Fe complexes into a polymer matrix (melamine-formaldehyde resins), followed by heating the mixture at 800 °C under inert atmosphere. TEM and EDX experiments suggest that the NCF catalyst has alloy structures of Ni, Co and Fe. The catalytic activity of the NCF catalyst for the oxygen reduction reaction (ORR) was compared with that of commercially available Pt/C (CAP) catalyst at different ethanol concentrations. The decrease in open circuit voltage (Voc) of the DEFC equipped with the NCF catalysts was less than that of CAP catalyst at higher ethanol concentrations. The NCF catalyst was less prone to ethanol oxidation at cathode even when ethanol crossover occurred through the Nafion®117 film, which prevents voltage drop at the cathode. However, the CAP catalyst did oxidize ethanol at the cathode and caused a decrease in voltage at higher ethanol concentrations. 相似文献
932.
933.
构建科学的企业文化体系 总被引:1,自引:0,他引:1
姜军芝 《石油化工管理干部学院学报》2003,(3):18-19
提出在企业文化建设中注意防止两种倾向;明确构建科学企业文化体系的内涵,物质文化、精神文化、制度文化和行为文化。 相似文献
934.
935.
Placid Rodriguez 《Metallurgical and Materials Transactions A》2004,35(9):2697-2705
A critical review of available results on the dependence of grain size on the activation parameters for deformation, specifically,
the activation volume, V*, and the thermal component of flow stress, σ*, has been carried out with a view to verifying the Armstrong prediction that identifies the Hall-Petch (H-P) intercept with
the easy slip system and the H-P slope with the most difficult system in polycrystals. The influence of slip system choice
is demonstrated using results on Cd and Zr. The Armstrong prediction is valid for basal slip hcp metals, such as Cd and Zn,
with V* and σ* determined by the difficult pyramidal slip. For the prism slip metals such as Zr and Ti, V* and σ* are controlled by interstitial solutes and are independent of grain size. The results on Zr are used to highlight the influence
of dynamic strain aging on the H-P parameters. In bcc metals, in which the Peierls-Nabarro barrier is the rate-controlling
obstacle, V* and σ* are again independent of grain size. For fcc metals, correlation of the H-P slope with the cross-slip stress, predicted
by the Armstrong model, has been demonstrated for a few cases. The variation of V* with grain size in Ni as reported by Narutani and Takamura (Acta Metall. Mater., 1991, vol. 227, pp. 2037–49) is newly interpreted in terms of the Armstrong model that associates the H-P intercept in fcc
metals with dislocation intersections and the H-P slope with cross-slip, and provides realistic results for the activation
volumes for the two processes.
This article is based on a presentation given in the symposium “Dynamic Deformation: Constitutive Modeling, Grain Size, and
Other Effects: In Honor of Prof. Ronald W. Armstrong,” March 2–6, 2003, at the 2003 TMS/ASM Annual Meeting, San Diego, California,
under the auspices of the TMS/ASM Joint Mechanical Behavior of Materials Committee. 相似文献
936.
937.
压裂预处理技术的现场实施与评价 总被引:5,自引:1,他引:4
通常,压裂目的层的储层特征、物性及生产史差异较大,为保证压裂施工成功并取得较好的压裂效果,进行油层预处理十分必要。介绍了酸预处理、前置液氮预处理、柴油十互溶剂混合液预处理3种技术,阐述了各种预处理方法的目的及适应性,介绍了各种预处理技术在现场取得的效果,提出了各种预处理技术的适用条件及常用做法。 相似文献
938.
939.
Instrumental characterization of clay by XRF,XRD and FTIR 总被引:2,自引:0,他引:2
Instrumental characterizations of the clay were performed by different techniques such as XRF, XRD and FTIR. XRF shows the
chemical compositions of the clay where Al-oxide and silica oxide are present in major quantity whereas XRD confirms the presence
of these minerals in clay. FTIR studies show the presence of quartz, alumina, haematite and different mineral matters. 相似文献
940.