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991.
Lipid composition of supercritical CO2 (SC-CO2) extracts, residual oil in muscle and changes in sarcoplasmic proteins after extraction of Atlantic mackerel were characterized. Dehydration of the muscle to 10.2% (w/w) resulted in high oil yield with minimum changes in protein content and composition. Sarcoplasmic protein content of fish muscle following SC-CO2 treatment was lower than that of original muscles at all moisture levels (3.8–64%, w/w). Analysis of sarcoplasmic proteins by capillary electrophoresis indicated aggregation of low molecular weight proteins during SC-CO2 extraction. SC-CO2-extracted muscle also had lighter color than original samples. The SC-CO2 extraction showed potential to provide high quality oil and protein meal. 相似文献
992.
993.
ZHU Yingdan WANG Jihui TAN Hua GAO Guoqiang 《武汉理工大学学报(材料科学英文版)》2005,20(3):64-66
1IntroductionDue to the difficulty in reliable permeability mea-surements and the potentially large number of tests thathave to be carried out to characterize the range of candi-date fiber reinforcements,much work has to be relatedtothe predication of the… 相似文献
994.
通过陶瓷与酸的相互作用,使钛酸钡基PTCR陶瓷材料烧成样品的阻值上升。酸处理工艺条件对阻值上升幅度有一定影响。酸处理后的样品的综合电性能的变化,确定了用酸处理升高阻值的可行性。运用复阻抗分析法对样品阻值上升前后晶粒、晶界电阻的变化进行了研究。分析了酸处理过程中阻值变化的规律。运用叠加势垒模型分析了酸处理使阻值升高的机理。 相似文献
995.
Robert L. Wolff Corinne C. Bayard Robert J. Fabien 《Journal of the American Oil Chemists' Society》1995,72(12):1471-1483
The successive steps of an integrated analytical procedure aimed at the accurate determination of butterfat fatty acid composition,
includingtrans-18:1 acid content and profile, have been carefully checked. This sequential procedure includes: dispersion of a portion of
butter in hexane/isopropanol (2:1, vol/vol) with anhydrous Na2SO4, filtration of aliquots of the suspension through a microfiltration unit, subsequent preparation of fatty acid isopropyl
esters (FAIPE) with H2SO4 as a catalyst, and analysis of total FAIPE by capillary gas-liquid chromatography (GLC). Isolation oftrans-18:1 isomers was by silver-ion thin-layer chromatography (Ag-TLC), followed by extraction from the gel of combined saturated
andtrans-monoenoic acids with a biphasic solvent system. Analysis of these fractions by GLC allows the accurate quantitation oftrans-18:1 acids with saturated acids (14:0, 16:0, and 18:0) as internal standards. A partial insight in the distribution oftrans-18:1 isomers can be obtained by GLC on a CP Sil 88 capillary column (Chrompack, Middelburg, The Netherlands). All steps of
the procedure are quite reproducible, part of the coefficients of variation (generally less than 3%, mainly limited to butyric
and stearic acids) being associated with GLC analysis (injection, integration of peaks) and, to a lesser extent, to FAIPE
preparation. FAIPE appear to be of greater practical interest than any other fatty acid esters, including fatty acid methyl
esters (FAME), for the quantitation of short-chain fatty acids, because peak area percentages, calculated by the integrator
coupled to the flame-ionization detector, are almost equal (theoretically and experimentally) to fatty acid weight percentages
and do not require correction factors. With this set of procedures, we have followed in detail the seasonal variations of
fatty acids in butterfat, with sixty commercial samples of French butter collected at five different periods of the year.
Important variations occur around mid-April, when cows are shifted from forage and concentrates during winters spent in their
stalls to fresh grass in pastures. At this period, there is a decrease of 4:0–14:0 acids and of 16:0 (−2 and −6%, respectively),
while 18:0 andcis- plustrans-18:1 acids rise suddenly (2 and 5%, respectively). These modifications then progressively disappear until late fall or early
winter. Other variations are of minor quantitative importance. Although influenced by the season, the content of 18:2n-6 acid
lies in the narrow range of 1.2–1.5%.Trans-18:1 acids, quantitated by GLC after Ag-TLC fractionation, are at their highest level in May–June (4.3% of total fatty acids),
and at their lowest level between January and the end of March (2.4%), with a mean annual value of 3.3%. The proportion of
vaccenic (trans-11 18:1) acid, relative to totaltrans-18:1 isomers, is higher in spring than in winter, with intermediate decreasing values in summer and fall, which supports
the hypothesis that the level of this isomer is linked to the feed of the cattle, and probably to the amount of grass in the
feed. 相似文献
996.
A set of accurate surface-tension data for HFC-125 has been obtained experimentally with both an absolute capillary rise technique and a differential capillary rise technique in the temperature range of 233.15–333.15 K. The purity of the experimental HFC-125 sample is 99.98 wt%. The two sets of experimental results with an absolute capillary rise method agree well with each other and, also, with the experimental results with a differential capillary rise method. The absolute deviations of experimental results with these two methods are within 0.01 mN · m–1. The relative deviation are within 0.2%. A van der Waals surface-tension correlation is also proposed. 相似文献
997.
998.
999.
1000.
周绪康 《桂林电子科技大学学报》1989,(1)
近年来,由于电子设备器件的发展,功率密度的迅速提高;电子设备的“短、小、轻、薄”化;电子组装技术从插入安装技术(IMT)向表面安装技术(SMT)发展,印刷线路板(PCB)电子机箱和印刷线路板的散热已成为当前热设计的重要课题,本文就此对国外发展近况作一简要介绍。 相似文献