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排序方式: 共有216条查询结果,搜索用时 15 毫秒
1.
Influence of geosynthetic reinforcement on the load-settlement characteristics of two-layer subgrade
The possibility of realistic prediction of two-layer subgrade load-settlement characteristics is discussed. The case of improvement of the soft subgrade properties using the geosynthetic reinforcement placed at the boundary between two different subgrade layers is analysed. In the first part of the paper, a short review of the main conclusions from experimental results dealing with the influence of geosynthetic reinforcement on the load-settlement characteristics of subgrade is presented. Then, the results of using the selected analytical membrane-action model to describe the reinforcement action in soil are discussed. The model is verified on the basis of data obtained from previously published laboratory tests. Particular attention is devoted to influencing some basic initial parameters on the accuracy of obtained results. Important problems which need intensive investigations are identified. 相似文献
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The small angle X-ray scattering (SAXS) was used to examine structural changes of starches after γ-irradiation with 10, 20, 30 kGy doses. The diminution of intensity of small-angle reflexion relating to 100 A spacing indicates destruction of long-range ordering in granules after γ-irradiation. It was observed as well in the case of irradiation of dry pure starches as a starch contained in potatoes. The method suggests possibility of quick identification of irradiated foodstuffs. 相似文献
4.
The LC–MS/MS technique was applied to the stability study of several flavonoids and phenolic acids in honey samples during the ultrasonic extraction (USE) and microwave-assisted extraction (MAE). Phenolic compounds from the standard mixture were stable under ultrasounds action with the mean recovery of (90.4% ± 7.1%), but during microwave-assisted extraction the benzoic acid derivatives and aglycones of flavonoids showed lower recovery (70–80%). In honey matrix, the phenolic acids and the glycosides exhibited the high stability for MAE and USE treatments. However, the recoveries of tested aglycones were below 10%. In the presence of an artificial sugar matrix, flavonols were almost completely degraded after successive treatment under MAE and USE conditions. The obtained results indicated that standard addition method for flavonoids quantification in honey samples should not be recommended. Application of the USE conditions provided higher and/or similar extraction yields for phenolic acids than usually applied shaking with solvent. It also allowed shortening the time required for the whole sample preparation procedure. Phenolic acids and glycosides such as quercetrin, rutin and hesperidin appeared to be stable under such conditions. 相似文献
5.
Krystyna Bogdanowicz-Szwed Andrzej Policht 《Advanced Synthesis \u0026amp; Catalysis》1984,326(5):721-728
The reaction of enamines 1 derivatives of cyclohexanon- or cycloheptanon-2-carboxylic acid anilides with malononitrile gave in the first step 2-phenylcarbamoyl-cycloalkylideno-malononitriles 3 , which in turn were converted into 1-oxo-2-phenyl-3-amino-4-cyano-cycloalkenoisoquinolines 4 . Enamines containing an adjacent diphenylamidino group 6 reacted with malononitrile giving 1-phenylimino-2-phenyl-3-amino-4-cyano-cycloalkenoisoquinolines 7 . The alkaline hydrolysis of 7 yielded 1-phenylamino-3-oxo-4-cyano-cycloalkenoisoquinoline 8 . 相似文献
6.
The influence of post-mortem ageing and roasting on the microstructure, texture and collagen solubility of bovine semitendinosus muscle 总被引:1,自引:0,他引:1
Palka K 《Meat science》2003,64(2):191-198
Bovine semitendinosus (ST) muscles aged for 5 and 12 days at 4?°C were roasted at 170?°C to internal temperatures of 50, 60, 70, 80 and 90?°C. Microstructural changes in meat were evaluated using a scanning electron microscope (SEM). Texture profile analysis (TPA) and measurements of the shear force values of samples were conducted using a texture analyser. The cooking losses and quantity of total and soluble collagen were also estimated. The structure of intramuscular connective tissue and myofibrillar structure of meat after 5 days of ageing was very regular. In 12-day-aged samples fibrous and myofibrillar structures were less distinct, damages of endomysium tubes appeared and fibres of perimysium were swelled. Ageing of ST muscle for 12 days caused a two-fold increase in the quantity of soluble collagen and a two-fold decrease in the value of TPA parameters-hardness and chewiness, as compared to 5-day-aged samples. The decrease in fibre diameter and sarcomere length during roasting started at 60?°C in 5-day-aged meat and at 50?°C in 12-day-aged samples. The shear force values measured after roasting were lower for 12-day-aged meat than for 5-day-aged samples. The quantity of soluble collagen in roasted meat increased at an internal temperature of 80?°C. At a higher temperature of meat this variable depended on the degree of meat ageing. The cooking losses during roasting of meat were about 3% lower for 12-day-aged than for 5-day-aged samples. In the examined range of internal temperature of meat the cooking losses and the sarcomere length were negatively correlated. 相似文献
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8.
Activity of monolithic perovskite catalysts in oxidation of selected hydrocarbons and oxy-derivatives, oxidized individually and in two-component mixtures, as well as the reaction selectivity were investigated. One bulk perovskite (LaMn2O3) catalyst and two catalysts based on LaMn2O3 with addition of silver (25 at.%) coated on cordierite support were prepared for the study. The efficiency of oxy-derivatives oxidation was higher than that of hydrocarbon oxidation, but some by-products (first of all aldehydes) were detected in the flue gases. Addition of silver to the active phase improved catalyst activity and selectivity to CO2 and water. The “mixture effect” on catalyst activity and selectivity depended on composition of the reaction mixture and the catalyst used. The presence of oxy-derivative in the reaction mixture inhibited oxidation of hydrocarbons. Toluene inhibited the process of oxy-derivatives conversion and increased the concentration of incomplete oxidation products. 相似文献
9.
Oracz K Bailly C Gniazdowska A Côme D Corbineau F Bogatek R 《Journal of chemical ecology》2007,33(2):251-264
The aim of this study was to investigate the phytotoxic effect of sunflower on physiological and biochemical processes during
germination of mustard seeds (Sinapis alba L. cv. Nakielska). To exclude the involvement of osmotic stress in seed reaction to phytotoxic compounds, we compared the
effect of 10% (w/v) water extract from sunflower (Helianthus annuus L. cv. Ogrodowy) leaves and 28.4% (w/v) polyethylene glycol (PEG) 8000 solution characterized by an equal Ψ = −1 MPa. We evaluated (1) the amount of hydrogen peroxide (H2O2); (2) activities of antioxidant enzymes: superoxide dismutase, catalase, and glutathione reductase; (3) membrane permeability;
and (4) level of malondialdehyde (MDA). Both, sunflower compounds and PEG solutions inhibited mustard seed germination, but
only phytotoxins caused an increase in the cell membrane permeability, MDA level, H2O2 concentration, and alterations in activities of antioxidant enzymes. Our results demonstrate that despite the activation
of the antioxidant system by sunflower phytotoxins, reactive oxygen species accumulation caused cellular damage, which resulted
in the decrease of germinability and gradual loss of seed vigor. It seems that the negative effect of sunflower on germination
of mustard seeds is mostly because of its toxicity and not to its contribution to osmotic potential. 相似文献
10.
Roman Cichon Krystyna Elkowicz Halina Kozlowska Antoni Rutkowski Willem C. Sauer 《Journal of the science of food and agriculture》1980,31(7):677-684
The nutritive value of protein of blends consisting of meat and soya bean protein products, which replaced either 20 or 40 % of protein of meat, were determined in rat feeding experiments. Protein efficiency ratio (PER) and net protein utilisation (NPU) were significantly lower (P<0.05) in blends containing either 20% protein from soya isolate or 40% protein from soya concentrate or soya flakes than blends containing sirloin only. However, there were no significant differences in PER and NPU when model meat (consisting of 70 and 30% protein from sirloin and connective tissue, respectively) was replaced by up to 20% protein from soya isolate or up to 40% protein from soya concentrate. 相似文献