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排序方式: 共有146条查询结果,搜索用时 15 毫秒
71.
Beata Jarmołowska Edyta Szłapka‐Sienkiewicz Elżbieta Kostyra Henryk Kostyra Dagmara Mierzejewska Katarzyna Marcinkiewicz‐Darmochwał 《Journal of the science of food and agriculture》2007,87(12):2247-2250
Recent investigations have suggested that novel food should be evaluated not only from the nutritional but also from the physiological point of view. Opioid peptides derived from milk belong to compounds whose physiological importance has not yet been fully recognized. The commercial Humana formula for newborns sold on the Polish market was assayed in the study. Four opioid peptides with agonistic and antagonistic activity were found in a peptide extract from the Humana formula and its pepsin–trypsin hydrolysate: β‐casomorphin‐5, casoxin C and 6 and lactoferroxin A. The opioid activity of the peptide extracts was determined by examining their influence on the motor activity of isolated rabbit intestine. In conclusion, it was suggested that the opioid activity of the formulas could be an additional indicator of their diversity. Copyright © 2007 Society of Chemical Industry 相似文献
72.
73.
Edyta?Nalewajko-SieliwoniukEmail author Julita?Malejko Aneta?Pawlukiewicz Anatol?Koj?o 《Food Analytical Methods》2016,9(4):991-1001
An automatic flow procedure based on a multicommuted flow analysis (MCFA) for the determination of the total polyphenolic content in food samples employing chemiluminescence (CL) as a detection technique is described. The concept of applying three-way solenoid valves in flow injection analysis was chosen in order to develop an environmentally friendly system which enables minimal consumption of reagents and waste generation. The method was based on the enhancing effect of polyphenolic antioxidants on CL of Mn(IV)–formaldehyde–hexametaphosphate system. The calibration graph obtained for standard solutions of gallic acid was linear in the range 5–150 μg L?1 with a detection limit of 1.5 μg L?1. The relative standard deviation for 20 measurements was between 1.1 and 2.4 %. The sampling rate was 60 determinations per hour. The proposed method was found to be selective to polyphenol detection and was successfully applied to the determination of the total polyphenol index in 27 diverse plant-derived food samples (wine, tea, coffee, fruit and vegetable juices, herbs, spices and extracts of olive oil). A significant correlation between the total phenolic contentment determined by the MCFA-CL method and the total reducing capacity determined by Folin–Ciocalteu method and total antioxidant activity estimated by the DPPH method was observed. 相似文献
74.
Stec E Pistorius D Müller R Li SM 《Chembiochem : a European journal of chemical biology》2011,12(11):1724-1730
Aurachins are quinoline alkaloids isolated from the myxobacterium Stigmatella aurantiaca. They are substituted with an isoprenoid side chain and act as potent inhibitors in the electron transport chain. A biosynthetic gene cluster that contains at least five genes (auaA-auaE) has been identified for aurachin biosynthesis. In this study, auaA, the gene encoding a putative prenyltransferase of 326 amino acids, was cloned and overexpressed in Escherichia coli. Biochemical investigations showed that AuaA catalyzes the prenylation of 2-methyl-4-hydroxyquinoline in the presence of farnesyl diphosphate (FPP), thereby resulting in the formation of aurachin D. The hydroxyl group at position C4 of the quinoline ring is essential for an acceptance by AuaA; this was concluded by testing 18 quinoline derivatives or analogues with AuaA and FPP. (1) H NMR and HR-EI-MS analyses of six isolated enzyme products revealed the presence of a farnesyl moiety at position C3 of the quinoline ring. K(M) values of 43 and 270 μM were determined for FPP and 2-methyl-4-hydroxyquinoline, respectively. Like other known membrane-bound prenyltransferases, the reaction catalyzed by AuaA is dependent on the presence of metal ions such as Mg(2+) , Mn(2+) and Co(2+) , although no typical (N/D)DXXD binding motif was found in the sequence. 相似文献
75.
Radiant temperature has crucial significance in the evaluation of thermal conditions in a structure heated by high-temperature gas-fired radiant heaters. Its value can be influenced by various factors. The article presents the methods of calculating radiant temperature encountered in the literature and contains an analysis of the relation of radiant temperature and the mounting angle of the radiant heater as well as the relation of its power output and dimensions of the burning surface, based on the authors’ research. Formulae are given for calculation of radiant temperature and their correct usage is indicated. An example of distribution of radiant temperature in a hall heated by six gas-fired direct radiant heaters with the power output of 12 kW is presented.Examinations of gas-fired radiant heaters conducted so far provide insufficient information about creating thermal conditions at work stands heated by high temperature radiant heaters located in industrial spaces. Hence, the results presented here are of special importance as they refer to parameters characterizing the thermal comfort of people in large capacity halls. 相似文献
76.
A new genotype of flax (Linum usitatissimum L.) with decreased susceptibility to fat oxidation: consequences to hematological and biochemical profiles of blood indices 下载免费PDF全文
77.
Pawe? Karasiński Janusz Jaglarz Manuela Reben Edyta Skoczek Jacek Mazur 《Optical Materials》2011,33(12):1989-1994
The paper presents a simple fabrication method of porous silica xerogel films. By adding a surface active agent Triton X-100™ to the starting solution, we can considerably reduce the surface tension, which, in turn, allows to fabricate silica films of high porosity. The paper presents the influence of surfactant content and the influence of heating temperature on the refractive index and thickness of the fabricated films. We fabricated silica films of the minimum refractive index below 1.3 and corresponding porosity ∼50%. Due to low refractive index, the elaborated porous silica xerogel films can be applied to reduce the light reflection coefficient in optical systems. In this work the spectral characteristics of the refractive index, extinction coefficients, the reflection and transmission coefficients and also depolarization factor are presented. The paper also provides results of surface morphology of produced layers, obtained using an atomic force microscope. 相似文献
78.
Work stations in industrial spaces are frequently arranged at a significant distance from each other. Local heating applying, among others, the gas-fired direct radiant heaters, is a viable alternative to the central heating. Radiant heaters provide heat comfort to workers and guarantee the maintenance of higher temperatures of the surrounding walls at a lower indoor temperature. The advantage of heating by gas-fired radiant heaters is the lower operational cost comparing to another systems. It uses less energy to obtain 2-3 K lower indoor temperature than in case of heating by conventional systems.The radiant temperature at work stations should be high enough to eliminate thermal discomfort, which in particular, is a result of radiant temperature asymmetry that may be caused by excessive and asymmetric overheating of the human body by a radiant heater.This paper includes formulas, based on the results of the self-designed test, which are then used in the calculation of the radiant temperature and the radiant temperature asymmetry, depending on the radiant heater position and the indoor temperature.This paper presents also the most recognized interrelations between the radiant temperature and its asymmetry. The discussed parameters are particularly significant in the heating process using high-temperature radiant heaters. 相似文献
79.
Krol M Lankoff A Buraczewska I Derezinska E Wojcik A 《Radiation protection dosimetry》2007,123(4):483-489
Biological dosimetry relies on the assessment of dose in peripheral blood lymphocytes (PBL) of a victim. Variability in the individual radiosensitivity of PBL has an impact on the precision of dose estimate and radiation-induced micronuclei show a strong individual variability. A factor which can influence the radiosensitivity of PBL is the hormonal status of female donors, which shows a regular pattern during the menstrual cycle. The aim of the present investigation was to verify whether the position within the menstrual cycle has an impact on the level of micronuclei in PBL. Blood was collected from 19 donors during the first and second half of the menstrual cycle and exposed to 2 Gy. Although statistically significant differences between the MN frequencies in PBL collected during the different time points were observed in the case of some donors, no reproducible trend that could find application in biological dosimetry could be detected. 相似文献
80.
Edyta Blaszczyk Agnieszka Töpper Luisa Schmacht Felix Wanke Andreas Greiser Jeanette Schulz-Menger Florian von Knobelsdorff-Brenkenhoff 《Magma (New York, N.Y.)》2017,30(1):85-91