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排序方式: 共有1420条查询结果,搜索用时 15 毫秒
81.
Shohei Tada Ochieng James Ochieng Ryuji Kikuchi Takahide Haneda Hiromichi Kameyama 《International Journal of Hydrogen Energy》2014
The effect of CeO2 loading amount of Ru/CeO2/Al2O3 on CO2 methanation activity and CH4 selectivity was studied. The CO2 reaction rate was increased by adding CeO2 to Ru/Al2O3, and the order of CO2 reaction rate at 250 °C is Ru/30%CeO2/Al2O3 > Ru/60%CeO2/Al2O3 > Ru/CeO2 > Ru/Al2O3. With a decrease in CeO2 loading of Ru/CeO2/Al2O3 from 98% to 30%, partial reduction of CeO2 surface was promoted and the specific surface area was enlarged. Furthermore, it was observed using FTIR technique that intermediates of CO2 methanation, such as formate and carbonate species, reacted with H2 faster over Ru/30%CeO2/Al2O3 and Ru/CeO2 than over Ru/Al2O3. These could result in the high CO2 reaction rate over CeO2-containing catalysts. As for the selectivity to CH4, Ru/30%CeO2/Al2O3 exhibited high CH4 selectivity compared with Ru/CeO2, due to prompt CO conversion into CH4 over Ru/30%CeO2/Al2O3. 相似文献
82.
K. Sueki K. Kobayashi K. Kikuchi K. Tomura Y. Achiba H. Nakahara 《Fullerenes, Nanotubes and Carbon Nanostructures》1994,2(3):213-221
HPLC elution behaviors of La-fullerenes were investigated by use of the radiochemical methods. Elution curves of La-fullerenes could be observed in detail for the first time, and the persistent presence of La in the whole elution curve was demonstrated. Production of La-fullerenes containing a radioactive 140La could be achieved for the first time. 相似文献
83.
Using an Al-Mg-Cu alloy developed for auto body panels, strip sheets are experimentally produced by various cold-rolling and annealing procedures. Tensile and metallographic properties of the sheets and their relations are examined to attain high formability. The elongation is closely related to the grain size, and increases with the final annealing temperature. The rolling texture influences the plastic anisotropy, the Lankford value of the sheets. The comparatively high Lankford values are obtained under the condition that both the intermediate and the final annealing temperatures are higher and the reduction ratio after the intermediate annealing is smaller. 相似文献
84.
To investigate the relationship between serum Se contents and the risk of cancer, 4857 serum samples were obtained from cancerous (2730) and non-cancerous patients (2127). In this cohort, the incidence of cancer in the non-cancerous patients was followed for the subsequent 3 years. The serum Se level of non-cancerous patients who later developed cancer during the 3 years was determined and compared with that of the non-cancerous patients. A high incidence of cancer was observed in the lower serum Se patients of the non-cancerous group. The serum Se levels of cancerous patients were significantly lower than in non-cancerous patients. These results suggest that the low serum Se level in cancerous patients may not be induced by the tumor but it was more likely already present before the tumor. To calculate the odds ratio, cancerous and non-cancerous patients were divided into group of less than 110 ppb and more than 111 ppb group in serum Se. The odds ratio was estimated to be 1.95, suggesting the high risk of cancer in the low serum Se group. 相似文献
85.
Four derivatives of the insuln B-chain COOH-terminal pentapeptide Arg-Gly-Phe-Phe-Tyr (B22-26) were synthesized and shown to be inactive alone. In the presence of submaximal concentrations of insulin or desoctapeptide insulin, peptides at concentrations of 10(-4) M and higher, markedly stimulated the actions of insulin on rat adipocytes including labeled glucose oxidation, activation of glycogen synthase, and stimulation of 2-deoxyglucose transport. The B-chain COOH-terminal heptapeptide, Gly-Phe-Phe-Tyr-Thr-Pro-Lys (B23-29) was inactive alone or in the presence of submaximal concentrations of insulin or desoctapeptide insulin, suggesting that argnine is required. Dose response curves of insulin, and desoctapeptide insulin for labeled glucose oxidation by rat adipocytes were shifted 1 log concentration unit to the left in the presence of peptide. Peptide shortened the lag time of labeled glucose oxidation and markedly enhanced the rate of 14CO2 production following the lag time. Peptides also enhanced insulin-like activities of concanavalin A and nonsuppressible insulin-like activity P. 相似文献
86.
Kishino K. Kikuchi A. Yoshizawa M. Fujita N. Kushi K. Sasamoto H. 《IEEE journal of selected topics in quantum electronics》1998,4(3):550-556
Novel growth technologies of III-nitrides for fabricating optical devices by molecular beam epitaxy using RF-plasma excited nitrogen (RF-MBE) were investigated. A relatively high-growth rate, up to 1.4 μm/h of GaN with high-electrical and high-optical quality was obtained. The concept of AlGaN quasi-ternary (QT) compounds, consisting of GaN-AlGaN short period superlattice, was demonstrated and the Al composition was controlled with a shutter control method in the range of 0-0.47. Using the QT technology, a GaN-Al0.07Ga0.933N-Al0.3Ga0.7 N multiquantum-well heterostructure was fabricated to show the effectiveness of the method 相似文献
87.
Masaru Ogura Susumu Kage Masayoshi Hayashi Masahiko Matsukata Eiichi Kikuchi 《Applied catalysis. B, Environmental》2000,27(4):L213-L216
Effect of second components on the catalytic performance of Pd/H-ZSM-5 zeolite (Pd: 0.4 wt.%) was evaluated by a durability test of NO reduction with CH4 at a relatively high temperature of 500°C in the presence of water vapor for a prolonged period. The Pd/H-ZSM-5 showed high stable activity for this reaction without H2O in the reactant feed, while immediate and irreversible deactivation was observed in the presence of H2O, resulting in no activity after 7 h. The second components such as Co, Rh, Ag, Ce, and Fe introduced individually to the Pd/H-ZSM-5 enhanced the durability, and in particular the addition of 3.3 wt.% Co led to a stable NO conversion for more than 40 h in the presence of H2O. 相似文献
88.
Yukito Murakami Jun-Ichi Kikuchi Kazunari Akiyoshi Nobuyuki Shiratori 《Israel journal of chemistry》1987,28(1):23-28
The transamination reaction of l-phenylalanine with pyruvate as catalyzed by the artificial transaminase formed with synthetic bilayer aggregates was examined in aqueous media under mild kinetic conditions. Each catalyst system was constructed with a combination of a synthetic peptide lipid, a hydrophobic vitamin B6 derivative, and metal ions. Modification of the active site in the present artificial transaminase was performed by changing a combination of molecular components constituting the catalytic system. While the catalytic activity was scarcely influenced by differences in aggregate structure, single- or multi-walled bilayer, and in copper-(II) concentration, molecular structures of the hydrophobic vitamin B6 and an amino acid residue of the peptide lipid had significant effects on the reactivity. 相似文献
89.
90.