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排序方式: 共有266条查询结果,搜索用时 125 毫秒
31.
Tsuneaki Matsudaira Hideaki Itoh Shigeharu Naka Hiroshi Hamamoto Mikio Obayashi 《Journal of Materials Science》1988,23(1):288-292
TiB2 powder was synthesized by solid state reaction using amorphous boron and TiN as a source of titanium. The TiB2 formation did not occur at all in a nitrogen atmosphere even at 1400° C. TiB2 formed above 1100° C in argon and hydrogen atmospheres. The only crystalline phase of TiB2 powder was favourably synthesized at 1400° C for 360 min in an argon atmosphere from a starting powder with a composition containing excess boron (B/Ti = 2.2). The synthesized powder was well dispersed and had a particle size of 0.5 to 2 µm. The powder activity was evaluated by sintering at 4 G Pa and 1300 to 1600° C for 15 min. 相似文献
32.
Y Katsube H Saro M Naka BH Kim N Kinoshita Y Koretsune M Hori 《Canadian Metallurgical Quarterly》1996,78(9):1007-1010
Although studies have shown that arterial baroreflex sensitivity (BRS) is decreased in patients with acute myocardial infarction, BRS changes in patients with stable coronary artery disease (CAD) have not been studied extensively. We assessed BRS by the phenylephrine method in 55 normotensive and nondiabetic patients with chronic effort angina, old myocardial infarction, or both. The control group consisted of 24 age-matched patients without coronary lesions. To identify factors that determine BRS in stable CAD, we performed multivariate analysis using age, sex, left ventricular ejection fraction, pulmonary artery wedge pressure, resting systolic blood pressure, resting heart rate, the number of stenotic coronary arteries, history of myocardial infarction, and the presence or absence of angina pectoris as variables. BRS was significantly lower in patients with CAD than in control subjects (5.9 +/- 2.9 vs 6.9 +/- 2.4 ms/mm Hg, p < 0.05). In patients with CAD, BRS was inversely correlated with age, the resting heart rate, and the number of stenotic coronary vessels (p < 0.001, p < 0.005, and p < 0.005, respectively), but was independent of other clinical parameters, including the history of myocardial infarction. In control subjects, BRS was significantly correlated only with age. These results indicate that BRS is decreased in patients with stable CAD, and this decrease is correlated with the extent and severity of coronary narrowing. 相似文献
33.
T Tachikawa S Matsumoto A Naka F Endo S Imada S Kaneko Y Ishii A Kubo 《Canadian Metallurgical Quarterly》1997,34(10):933-937
201Tl-99mTc subtraction scintigraphy has been recognized as a useful procedure in the preoperative localization of hyperfunctioning parathyroid glands. We experienced a case which showed 99mTc-pertechnetate uptake in a parathyroid hyperplasia. This case warned us to focus a lot of attention on the detection for preoperative localization. There has been no such case reported in the previous Japanese literatures. Hypervascularity and thick fibrous capsule presumed explanation for a rare case of marked pertechnetate uptake into a parathyroid hyperplasia. 相似文献
34.
35.
The possible influencing factors for diamond formation which prevent non-graphitic carbons from transforming to diamond in the presence of nickel as solvent-catalyst were pursued. The relative amount of nickel to carbon did not affect the behaviour of each starting carbon on diamond formation. The existence of a graphitic structure in the starting carbon was not the major prerequisite for diamond formation. Adsorbed gases on the starting carbon and atmospheric gases in the high pressure cell were found to be the most important influencing factors for diamond formation. Hydrogen and chemical species containing hydrogen atoms were the most harmful. 相似文献
36.
The formation of α-NaFeO2 and β-NaFeO2 below 700°C was found to depend strongly on the structure of starting iron oxide; α-Fe2O3 with hcp of oxygen yielded β-NaFeO2 with hcp and γ-Fe2O3 with ccp of oxygen yielded α-NaFeO2 with ccp by a reaction either with Na2CO3 or Na2O2. The doping of Na-ions into the γ-Fe2O3 structure and its rapid change to α-NaFeO2 were observed. The transformation from the metastable β-NaFeO2 to the stable α-form was very much sluggish in the solid state, but it was accelerated by the presence of the liquid Na2O2. 相似文献
37.
Isotropic spherulites of carbon stable at 2000° C were synthesized by the pressure pyrolysis of divinylbenzene polymer sealed in a capsule. The morphology of the synthesized carbon was pressure and temperature dependent being influenced by the state of polymerization of the starting polymer. Using a polymer prepared at atmospheric pressure and 150° C without catalyst, isolated spherulitic carbon was formed at 700° C and pressures of 1000 to 1250 kg cm–2. These spherulitic carbons were optically isotropic, hard and non-graphitizable after heat treatment at 2000° C. Such carbons originate in the co-existence of higher and lower molecular weight products of pressure pyrolysis and the survival cross-linkages in the original polymer. 相似文献
38.
39.
K Kubo Y Kohara Y Yoshimura Y Inada Y Shibouta Y Furukawa T Kato K Nishikawa T Naka 《Canadian Metallurgical Quarterly》1993,36(16):2343-2349
In order to improve the oral bioavailability (BA) of 2-butyl-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimid azole - 7-carboxylic acid (3: CV-11194) and 2-ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4- yl]methyl]-1H-benzimidazole-7-carboxylic acid (4: CV-11974), novel angiotensin II (AII) receptor antagonists, chemical modification to yield prodrugs has been examined. After selective tritylation of the tetrazole rings in 3 and 4, treatment of N-tritylated benzimidazole-7-carboxylic acids (6, 7) with a variety of alkyl halides, followed by deprotection with hydrochloric acid, afforded esters of 3 and 4. Mainly 1-(acyloxy)alkyl esters and 1-[(alkoxycarbonyl)oxy]alkyl esters, double ester derivatives, were synthesized. Their inhibitory effect on AII-induced pressor response in rats and oral BA were investigated. (Pivaloyloxy)methyl and (+/-)-1-[[(cyclohexyloxy)-carbonyl]oxy]ethyl esters of 3 and 4 showed marked increases in oral bioavailability which significantly potentiated the inhibitory effect of the parent compounds on AII-induced pressor response. Among them, (+/-)-1-[[(cyclohexyloxy)carbonyl]oxy]ethyl 2- ethoxy-1-[[2'-(1H-tetrazol-5-yl)biphenyl-4-yl]methyl]-1H-benzimida zole- 7-carboxylate (10s, TCV-116) was selected as a candidate for clinical evaluation. 相似文献
40.
Fluorinated completely condensed polyhedral oligomeric silsesquioxanes (F-CC-POSSs) are widely utilized as surface modifiers for polymeric materials because of their polyhedral and fluorine-rich structures, which generate polymers with lower surface energies under molecular-level control. In contrast, their derivatives, fluorinated incompletely condensed or open-cage POSSs (F-IC-POSSs), have similarly intriguing structures, but their utilization for polymer synthesis remains undeveloped. Herein, fluorinated network polymers were prepared based on a 3,3,3-trifluoropropyl-substituted IC-POSSs via hydrosilylation polymerization with isobutyl- and phenyl-substituted IC-POSS under optimized conditions. In addition to their good thermal stability and tunable refractive indices, these polymers exhibited solution processability and their casting films showed excellent optical transparency, indicating their potential for constructing fluorinated polymers. Their utilization as surface modifiers was examined by addition to poly(methylmethacrylate) (PMMA) films. Intriguingly, modified PMMA films with 2.0 and 0.5 wt% addition showed similar hydrophobicity and surface energies to the films prepared with only fluorinated network polymers. 相似文献