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排序方式: 共有1797条查询结果,搜索用时 15 毫秒
71.
72.
Cyanopolyynes, H(CC)nCN (n = 3–6), were formed by laser ablation of carbon particles in liquid acetonitrile. The molecules were separated according to the size n and characterized by UV absorption spectroscopy, mass spectroscopy in combination with gas-chromatographic separation, and nuclear magnetic resonance (NMR) spectroscopy. For the study of nascent carbon cluster distribution during the growth of the long carbon chain molecules, isotopomer distribution was analyzed by NMR spectroscopy for the product molecules. Two cyanopolyynes of HC7N and HC9N were isolated from solutions after laser ablation of isotope-enriched carbon powder (99% 13C) in liquid acetonitrile, CH3CN, of natural isotopic abundance (1.1% 13C). With the observed chemical shift, δ, and spin–spin coupling constants, JCH and JCC, spectral simulation was made to determine relative abundance of possible isotopomeric forms for HC9N. We found that the isotope of 12C, mostly from solvent molecules, contributes substantially for the part of carbon in the cyano group, –CN, in HC9N. The isotopomer distribution observed for the sequence of H–CC–CC– was fairly explainable by a binomial, random distribution of the two carbon isotopes of 12C and 13C, reducing the concentration of 13C to 76–55%. 相似文献
73.
Dusida Tirawat Akiko Meno Hiroshi Fujiwara Keizo Higo Seiji Noma Noriyuki Igura Mitsuya Shimoda 《Innovative Food Science and Emerging Technologies》2010,11(3):458-463
We developed a novel rapid hygrothermal pasteurization (RHP) method using saturated water vapor with a dew point of 100 °C. In the present study, the effects of RHP on microbiological quality and quality attributes such as color changes, firmness and ascorbic acid content on many fresh-cut fruits and vegetables (cabbage, cucumber, carrot, cherry tomato, bell pepper, strawberry, pineapple and melon) were investigated. The RHP was performed within a second by free-falling samples through a cylindrical processing chamber filled with steam. The RHP resulted in a 0.7–2.0 log order reduction in the numbers of naturally inoculated mesophilic bacteria. Furthermore, the RHP induced no significant changes in color and firmness of samples, except on the leafy vegetable, cabbage. Ascorbic acid was also retained approximately 80% and above. These results indicate that the RHP is a clean and effective method for decontaminating mesophilic bacteria on fresh fruits and vegetables with minimal changes in quality.Industrial relevanceIn fresh-cut industry, an effective and risk-free decontamination technology is required for use in place of a conventional method, washing by chlorine that can produce carcinogenic chlorinated by-products. In this study, the rapid hygrothermal pasteurization (RHP) method using saturated water vapor was invented and their ability for applying minimal processing was evaluated. The results showed that RHP, without using chemicals, can reduce microorganism load and preserve quality attributes in many kinds of fresh-cut fruits and vegetables. Therefore, RHP could be used as a novel method, which can be generally applicable to fresh-cut fruits and vegetables in the food industry. 相似文献
74.
Kawano K. Kohtoku M. Wada M. Okamoto H. Itaya Y. Naganuma M. 《IEEE journal of selected topics in quantum electronics》1996,2(2):348-354
In order to develop spotsize-converter-integrated laser diodes (SS-LDs) with high efficiency and large-misalignment tolerances in the 13-μm-wavelength region, spotsize converters (SSCs), which consist of lateral taper, thin-film core and ridge, are investigated employing the three-dimensional (3-D) semivectorial finite-difference beam propagation method (FD-BPM) with nonequidistant discretization. The sum of the spot-conversion loss and coupling loss between the laser diode (LD) eigenmode and the single-mode fiber (SMF) eigenmode are calculated for various structural parameters. Small loss of around 1.5 dB can be achieved by introducing a nonlinear taper. The fabrication tolerances for the SSCs are also clarified. The calculated results agree well with the results for actually fabricated SS-LD's. It is also shown that the radiation loss and coupling characteristics of the SS-LDs with a buried thin-film core structure can be improved using a nonlinear taper 相似文献
75.
Tetragonal to monoclinic phase transformation of yttria-stabilized zirconia, namely plasma-sprayed coatings and sintered bodies containing 4–8 mass % Y2O3 during hydrothermal aging was investigated with respect to Y2O3 distribution using 1 m area from electron probe microanalysis (EPMA) and 20 nm area from transmission electron microscopy (TEM) analysis. Phase transformation at 473 K was prevented only in plasma-sprayed coatings having more than 6.7 mass % Y2O3 in 20 nm microscopic area. Furthermore, it was confirmed influence of Y2O3 distribution on the rate constants of this phase transformation was observed at 368 K. 相似文献
76.
Pongsuriya Komthong Shoichi Hayakawa Tatsuo Katoh Noriyuki Igura Mitsuya Shimoda 《LWT》2006,39(5):472-478
Gas chromatography-olfactometry with headspace gas dilution analysis was used to evaluate the odor potencies of volatile compounds in Fuji apple. To improve the resolution of volatile compounds, the dilution analysis was conducted on two types of capillary columns with different polarities. Thirty three and 20 compounds were identified on DB-WAX and DB-5 columns, respectively. Methyl 2-methylbutanoate, isobutyl acetate, ethyl butanoate, ethyl 2-methylbutanoate, isopentyl formate, butyl acetate and hexyl acetate as well as hexanal were important odor contributors in the headspace gas of apple on the basis of high Flavor Dilution (FD) factors. Threshold values-in-air of these compounds were also estimated from the relationships between their FD factors and concentrations. Methyl 2-methylbutanoate and ethyl 2-methylbutanote were considered as the most potent odorants because of their lowest threshold values. In addition, the threshold values-in-air of isopentyl formate, isopentyl acetate and butyl isobutanoate, which have never been reported, were estimated at 0.149, 1.95 and 0.00607 μl/l, respectively. 相似文献
77.
D Robinette S Wada T Arroll MG Levy WL Miller EJ Noga 《Canadian Metallurgical Quarterly》1998,54(5):467-475
BACKGROUND: A major reduction in the energy demand of the myocardium results from the electromechanical arrest, and cooling contributes to a lesser degree to this reduction. It is from this assumption that strategies of myocardial protection, utilizing warm blood cardioplegic induction, followed by cold cardioplegia with terminal warm reperfusion before removal of the aortic cross clamp, became established as optimal myocardial protection. Continuous normothermic perfusion 'closed the loop' by avoiding myocardial ischemia and linking warm induction and terminal reperfusion. A series of laboratory and clinical data confirmed the benefits of warm heart surgery on myocardial function and metabolism. The disadvantages of continuous warm blood cardioplegia including disturbance of the operative field, led surgeons to administer warm hyperkalaemic blood intermittently as a new cardioplegic strategy. METHODS: This review examines the laboratory and clinical data with reference to the intermittent warm blood cardioplegia, to establish its experimental basis and place in clinical practice. CONCLUSIONS: Experimental observation and clinical application have established intermittent warm blood cardioplegia as a practical, effective and cheap myocardial protection technique, particularly with reference to coronary artery surgery. 相似文献
78.
The literature suggests that seizure disorders are associated with an increased likelihood of intellectual problems, prompting researchers to investigate risk factors of cognitive impairment in epileptic patients. This study examined the contribution of certain variables (age of seizure onset, duration, etiology, seizure location and laterality, sex, handedness, and cerebral speech pattern) to cognitive outcome in patients with medically refractory seizures. Seizure location (temporal or extratemporal), age of onset of seizures, and handedness proved to be the best indicators of general intellectual ability. There was a relatively diverse pattern of relationships when neuropsychological tests of language, visuospatial ability, and memory were considered individually. However, a factor analytic approach revealed a simpler pattern in which location of dysfunction, age at seizure onset, hand preference, cerebral speech dominance, and gender were relevant and independent indicators of verbal and nonverbal ability. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
79.
8,16-Ethanoretinal 3 was synthesized from 2-methylcyclohexanone. From the binding experiments of 3 and 8,18-ethanoretinal 2 with apoproteins of sensory rhodopsin I and phoborhodopsin, it was found that retinal was incorporated as 6s-trans conformation in the both proteins. 相似文献
80.
M Kushiro K Shikata H Sugimoto Y Shikata N Miyatake J Wada M Miyasaka H Makino 《Canadian Metallurgical Quarterly》1998,53(5):1314-1320
Prostacyclin (PGI2) is known to have a relaxative action on vascular smooth muscle, an inhibitory action against platelet activation and neutrophil function. Previous studies showed the preventive effects of PGI2 on lupus nephritis and Thy-1 nephritis, although the mechanism has not been clarified. Glomerular endothelial expression of intercellular adhesion molecule-1 (ICAM-1) is up-regulated in experimental and human glomerular diseases, and is known to facilitate leukocyte infiltration into the glomeruli, which ultimately induces the various glomerular injuries. In the present study, we evaluated the therapeutic effects of PGI2 on a rat model for crescentic glomerulonephritis and investigated its putative mechanism in relation to ICAM-1-mediated leukocyte recruitment. Wistar-Kyoto (WKY) rats were injected with nephrotoxic serum and received continuous intraperitoneal infusion of PGI2. PGI2 dramatically decreased proteinuria (123.0 +/- 18.8 vs. 31.6 +/- 4.5), crescent formation and deposition of fibrinogen in the glomeruli, while the deposition of rabbit IgG, rat IgG and rat C3 along the capillary walls was not changed. Furthermore, intraglomerular expression of ICAM-1 and infiltration of macrophages were significantly suppressed by administration with PGI2. In contrast, influx of CD4 or CD8 positive cells was not altered. The present results suggest that PGI2 shows the preventive effects on experimental crescentic glomerulonephritis by inhibiting intraglomerular coagulation and ICAM-1-mediated macrophage-glomerular endothelial cell adhesive pathway. 相似文献