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991.
992.
植物油与氨基醇在催化剂、在偏低于正常反应温度下进行酰胺化反应,以P2O3为磷酸化剂制成混合磷酸酯。 相似文献
993.
994.
离子交换层析快速高效分离低聚糖 总被引:2,自引:0,他引:2
采用001×7阳离子交换树脂柱层析分离提纯低聚半乳糖(GOS)混合物,研究了阳离子型式、树脂粒径等因素对分离的影响,并优化了分离条件。结果筛选出150~180μm的钙型树脂为最佳分离介质;操作温度70℃,洗脱流速20mL/h,层析柱90cm×1cm,当进料量由1mL增至10mL,GOS的产量提高了4.6倍,整个洗脱过程只需180min,可以有效地去除葡萄糖,得到纯度为86.2%的含少量乳糖的GOS混合物。此混合物经过二次上柱后,分离效果明显优于1次上柱,GOS质量分数达95.1%。 相似文献
995.
Yu-Hsuan Lan Fang-Rong Chang Mei-Jung Pan Chin-Chung Wu Shu-Jing Wu Su-Li Chen Shyh-Shyan Wang Ming-Jung Wu Yang-Chang Wu 《Food chemistry》2009
Investigation of the extracts of Physalis peruviana L. has led to the isolation of seven new withanolides, phyperunolide A (1), phyperunolide B (2), phyperunolide C (3), phyperunolide D (4), peruvianoxide (5), phyperunolide E (16), and phyperunolide F (17) together with ten known withanolides. The structure and absolute stereochemistry of all compounds were elucidated on the basis of CD and NMR spectral analysis, respectively. Compounds 1, 6, 7, and 9 showed cytotoxicity against lung cancer (A549), breast cancer (MDA-MB-231 and MCF7), and liver cancer (Hep G2 and Hep 3B) cancer cell lines. The presence of 5β,6β-epoxy-2-en-1-ones in withanolides is greatly helpful in cytotoxicity, it is a key known important factor to cytotoxicity; however, interestingly, the unusual 5-chloride withanolide, 9, displayed significant activity. 相似文献
996.
Four acid treatments: acetic acid (FA), citric acid (FC), hydrochloric acid (FH) and lactic acid (FL) were used in this study to extract the pepsin-solubilised collagen (PSC) containing melanin from silky fowl feet. The collagen content, melanin content, electrophoresis and ultraviolet (UV) absorption spectra (200–400 nm) were determined in order to develop a collagen with UV protection. Among four acid extractions, the acetic acid treatment had both the highest extracting yield (7.3%) and collagen content (516.6 mg/g). PSCs obtained from silky fowl feet using four acid extractions exhibited melanin content; whereas no similar observations were found in that of broiler feet by acetic acid extraction (FB). Moreover, the PSC via acetic acid extraction resulted in the significantly highest melanin content (210 mg/g) (P < 0.05), which contributed to UV absorption. In electrophoresis, three subunits were found in PSCs from silky fowl feet using the four acid extractions, which were different from typical type I collagen and assumed that the PSCs obtained from silky fowl feet consisted of more than two types of collagens. 相似文献
997.
Mei Jing Piao Kyoung Ah Kang Rui Zhang Dong Ok Ko Zhi Hong Wang Keun Hwa Lee Weon Young Chang Sungwook Chae Youngheun Jee Taekyun Shin Jae Woo Park Nam Ho Lee Jin Won Hyun 《Food chemistry》2009
The antioxidant potential of 1,2,3,4,6-penta-O-galloyl-β-d-glucose (PGG), isolated from Elaeocarpus sylvestris var. ellipticus, was investigated by various established systems based on cell-free and cell system experiments, such as radical detection, antioxidant enzyme assay, lipid peroxidation detection, and cell viability assay. PGG was found to quench the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical and intracellular reactive oxygen species. PGG recovered the cellular antioxidant enzyme activities of superoxide dismutase, catalase, and glutathione peroxidase, which were reduced by H2O2 treatment, thereby resulting in the inhibition of lipid peroxidation. Cytoprotective effects of PGG were based on the results of DNA fragmentation, mitochondrial membrane potential (Δψ), apoptotic body formation, and caspase-3 activity. The results suggest that PGG protects cells against H2O2-induced cell damage via antioxidant properties. 相似文献
998.
本文以不同土壤弹簧和依时性阻尼系数 ,配合波动方程有限差分解仿真基桩反应。由t-z和Q-z曲线方程式所推求的弹性土层弹簧系数和依据三维波传递动力阻抗函数所建立之转换阻尼 ,可仿真桩载重反应。基桩位移量和位移历史和土 -桩界面模式相关。本研究模式和其它学者建议模式之差异显现于单调载重的桩顶位移量和冲击载重作用后桩顶位移之衰减 ,调整转换阻尼参数和土壤弹簧系数值可减少分析差异。透过土层弹簧系数修正 ,该项分析模式可仿真桩设计位移曲线和现场桩载重试验数据。 相似文献
999.
1000.
B Wostmann E Bruckner-Kardoss L Chang M Beaver D Madsen 《Canadian Metallurgical Quarterly》1976,106(12):1782-1790
In recent years, the use of milk products and the concomitant intake of lactose have been tentatively linked to the etiology of cardiovascular disease. An effect of lactose on the microbial modification of acid and neutral sterols has been suggested. In the present study lactose intake, ranging up to 30% of total diet increased beta-muricholic (beta-MC) but not cholic acid concentrations in conventional (CV) rat small intestine to the extent that at the 20% and 30% intake level, the intestinal cholic: beta-MC ratio approached that in germ-free (GF) rats. Total intestinal bile acid (BA) content increased by approximately 1/3, but remained at less than half the value found in GF rats. At lactose intake levels within a range corresponding to the consumption of dairy products often recommended for adult man (5% to 10%) only moderate changes in intestinal, and little change in fecal BA were found during and after the 3 months experimental period. Intestinal beta-MC was increased in the presence and in the absence of an intestinal microflora. Experiments with GF rats fed 10% lactose or 10% maltose indicated that this increase is evoked similarly by both carbohydrates. The slight increase in serum cholesterol levels seen with disaccharide feeding, which became evident only in the GF rats, was again not specific for lactose. No influence was found of lactose feeding on liver cholesterol values. Comparison of CV rats fed nonsterile and radiation-sterilized lactose-containing diets suggested that this mode of sterilization has only a minor influence on the resulting data. When GF experiments are to be incorporated, sterilazation of diet by irradiation with 3.5 to 4.0 X 10(6) Rad is preferable to autoclaving. The present data indicate that no major effect specifically related to a normal dietary intake of lactose on cholesterol and BA metabolism of the adult rat could be demonstrated for the duration of these experiments. 相似文献