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41.
Vvedenskaya IO Rosen RT Guido JE Russell DJ Mills KA Vorsa N 《Journal of agricultural and food chemistry》2004,52(2):188-195
Flavonoids were extracted from cranberry powder with acetone and ethyl acetate and subsequently fractionated with Sephadex LH-20 column chromatography. The fraction eluted with a 60% methanol solution was composed primarily of phenolic constituents with maximum absorbance at 340 nm. A high-performance liquid chromatography procedure was developed, which resolved 22 distinct peaks with UV/vis and mass spectra corresponding to flavonol glycoside conjugates. Six new constituents not previously reported in cranberry or in cranberry products were determined through NMR spectroscopy to be myricetin-3-beta-xylopyranoside, quercetin-3-beta-glucoside, quercetin-3-alpha-arabinopyranoside, 3'-methoxyquercetin-3-alpha-xylopyranoside, quercetin-3-O-(6' '-p-coumaroyl)-beta-galactoside, and quercetin-3-O-(6' '-benzoyl)-beta-galactoside. Quercetin-3-O-(6' '-p-coumaroyl)-beta-galactoside and quercetin-3-O-(6' '-benzoyl)-beta-galactoside represent a new class of cranberry flavonol compounds with three conjugated components consisting of a flavonol, sugar, and carboxylic acid (benzoic or hydroxycinnamic acids). This is also the first report identifying quercetin-3-arabinoside in both furanose and pyranose forms in cranberry. Elucidation of specific flavonol glycosides in cranberry is significant since the specificity of the sugar moiety may play a role in the bioavailability of the flavonol glycosides in vivo. 相似文献
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Hydrocortisone is necessary for the formation of rough endoplasmic reticulum in mammary alveolar epithelial cells. This membrane system is required for the synthesis of the milk protein, casein, but it is not required for the synthesis of a nonmilk protein fraction. 相似文献
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Ravishankara AR Turnipseed AA Jensen NR Barone S Mills M Howard CJ Solomon S 《Science (New York, N.Y.)》1994,263(5143):71-75
Hydrofluorocarbons, many of which contain a CF(3) group, are one of the major substitutes for the chlorofluorocarbons and halons that are being phased out because they contribute to stratospheric ozone depletion. It is critical to ensure that CF(3) groups do not cause significant ozone depletion. The rate coefficients for the key reactions that determine the efficiency of the CF(3) radical as a catalyst for ozone loss in the stratosphere have been measured and used in a model to calculate the possible depletion of ozone. From these results, it is concluded that the ozone depletion potentials related to the presence of the CF(3) group in hydrofluorocarbons are negligibly small. 相似文献
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Mills TJ 《Science (New York, N.Y.)》1958,127(3295):431-435
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McBride JM Segmuller BE Hollingsworth MD Mills DE Weber BA 《Science (New York, N.Y.)》1986,234(4778):830-835
Organic single crystals provide an ideal model for studying the factors that influence chemical processes in structured media. Reaction trajectories are well defined and reveal the influence of spontaneous mechanical stresses equivalent to tens of thousands of atmospheres. Analysis of molecular and crystal structures helps to explain both local mechanical properties, which influence reactions, and bulk properties such as melting point, compressibility, and surface energy. 相似文献
50.
The Namibian cheetah population has recently undergone serious decline due to human-mediated removals, and investigating the rates and causes of such removals is an important aspect of the future management of cheetah populations outside protected areas. We examined cheetahs that were reported live-trapped or killed on Namibian farmlands between 1991 and 1999. A perceived threat to livestock or game led to the vast majority of live captures and to almost half of the cheetah deaths investigated. Despite this, livestock predation from cheetahs appeared to be minimal, and was usually perpetrated by cheetahs with injuries. Most of the cheetahs were trapped in groups, and cheetahs’ relative sociality leads to the easy removal of entire social units. Long-term monitoring must include detailed consideration of these indiscriminate removals, as they involve many cheetahs, fluctuate between years, often go unreported, and are likely to have a serious impact on cheetah populations outside protected areas. 相似文献