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171.
Elizabeth?Gutierrez Tong?WangEmail author 《Journal of the American Oil Chemists' Society》2004,81(10):971-977
Soybeans are believed to be a rich source of sphingolipids, a class of polar lipids that has received attention for their
possible cancer-inhibiting activities. The effect of processing on the sphingolipid content of various soybean products has
not been determined. Glucosylceramide (GlcCer), the major sphingolipid type in soybeans, was measured in several processed
soybean products to illustrate which product(s) GlcCer is partitioned into during processing and where it is lost. Whole soybeans
were processed into full-fat flakes, from which crude oil was extracted. Crude oil was refined by conventional methods, and
defatted soy flakes were further processed into alcohol-washed and acid-washed soy protein concentrates (SPC) and soy protein
isolates (SPI) by laboratory-scale methods that simulated industrial practices. GlcCer was isolated from the samples by solvent
extraction, solvent partition, and TLC and was quantified by HPLC. GlcCer remained mostly within the defatted soy flakes (91%)
rather than in the oil (9%) after oil extraction. Only 52, 42, and 26% of GlcCer from defatted soy flakes was recovered in
the acid-washed SPC, alcohol-washed SPC, and SPI products, respectively. All protein products had a similar GlcCer concentration
of about 281 nmol/g (dry wt basis). The minor quantity of GlcCer in the crude oil was almost completely removed by water degumming. 相似文献
172.
Summary: Wear behavior correlations with morphology have been established from polytetrafluoroethylene (PTFE) drawn at 200, 327, and 375 °C with draw ratio about 4. The friction coefficient and wear rate for PTFE drawn at 327 °C are lower and the wear rate is lower than that of undrawn PTFE by about 30%. The structures of samples were characterized by scanning electron microscope (SEM), DSC, and wide angle X‐ray diffraction (WAXD). Results indicate that the debris morphologies of samples are different. The differences in the tribological behavior of undrawn and drawn samples were attributed to the improvement of the degree of the crystalline, fibrillation, and orderliness by drawing, especially, for PTFE drawn at 327 °C. The orderliness of molecular arrangement along the drawn direction is also higher for PTFE drawn at 327 °C than those of PTFE drawn at 200 and 375 °C, respectively. Therefore, the intensity of covalent bond along drawn direction is higher. The shear resistance and the deformability of the material are greatly improved and the size of the wear breakage unit decreases, which results in a good tribological property for PTFE drawn at 327 °C.
173.
有机试剂的pKa是其重要物化参数,是有机试剂酸碱性的度量,直接决定配合物的稳定性。应用改进的Hammett方程处理取代基常数与pKa的关系,得到满意的结果。 相似文献
174.
响应面优化褶皱假丝酵母脂肪酶催化合成木质甾醇油酸酯 总被引:1,自引:0,他引:1
以木质甾醇转化率为指标,考察了10种常见商业化脂肪酶催化合成木质甾醇油酸酯的效果,确定褶皱假丝酵母脂肪酶(CRL)为优选生物催化剂,进一步筛选出正己烷为优选反应介质.在脂肪酶用量、油酸和木质甾醇的物质的量比、反应温度和反应时间这4个单因素考察基础上,通过响应面分析法对酶催化木质甾醇油酸酯合成工艺条件进行优化,并对优化条件进行验证和放大实验.CRL催化合成木质甾醇油酸酯的优化工艺参数为:CRL添加量为木质甾醇质量的10%,油酸与木质甾醇的物质的量比为3.8:1,反应温度为46℃,反应时间为28 h,木质甾醇的转化率为91.56%±0.25%. 相似文献
175.
176.
The carboxyl‐terminated butadiene‐a‐acrylonitrile rubber (CTBN) has been proved to be the most effective toughener for cyanate ester (CE) resin. This work mainly focuses on the different modification effects caused by the addition of CTBN with different acrylonitrile content. The phase separation, morphology of fracture surface, and physical properties of the blends are studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), dynamic mechanic analysis (DMA), and thermogravimetric analysis (TGA). It is testified that the compatibility and toughness between CE and CTBN had a positive correlation with the acrylonitrile content of CTBN. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
177.
178.
179.
双道原子荧光光谱法测定水中痕量Hg、As、Se、Sb 总被引:2,自引:0,他引:2
介绍了应用双道原子荧光光谱法测定水中的汞、砷、硒、锑等痕量元素的原理、过程,并讨论测定条件的优化、干扰的去除方法。 相似文献
180.
提出了一种基于动态加权的数据选取方法, 并应用到连续语音识别的声学模型区分性训练中. 该方法联合后验概率和音素准确率选取数据, 首先, 采用后验概率的Beam算法裁剪词图, 在此基础上依据候选词所在候选路径的错误率, 基于后验概率动态的赋予候选词不同的权值; 其次, 通过统计音素对之间的混淆程度, 给易混淆音素对动态地加以不同的惩罚权重, 计算音素准确率; 最后, 在估计得到弧段期望准确率分布的基础上, 采用高斯函数形式对所有竞争弧段的期望音素准确率软加权.实验结果表明, 与最小音素错误准则相比, 该动态加权方法识别准确率提高了0.61%, 可有效减少训练时间. 相似文献