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排序方式: 共有10000条查询结果,搜索用时 109 毫秒
921.
922.
Aneta Wgierek-Ciuk Micha Arabski Karol Ciepluch Kamil Brzska Halina Lisowska Malwina Czerwiska Tomasz Stpkowski Krzysztof Lis Anna Lankoff 《International journal of molecular sciences》2021,22(11)
Coralyne is a synthetic analog of berberine related to protoberberine-isoquinoline alkaloids. Isoquinoline derivatives and analogs are renowned as potent radiosensitizers with potential medical application. In the present study, we investigated the effect of coralyne on the cell death, cytoskeletal changes and cell cycle progression of irradiated A549 cells. A clonogenic assay revealed that coralyne pretreatment decreased the viability of A549 cells in a time- and dose-dependent manner. Moreover, exposure to coralyne and ionizing radiation (IR) markedly altered the filamentous actin cytoskeletal architecture and integrin-β binding sites of A549 cells. Treatment with 1–25 µM coralyne in combination with 2 Gy of IR significantly reduced the percentage of cells in G2/M phase compared with 2 Gy IR alone. These results indicate that coralyne is a potent radiosensitizing agent that may find an application in medicine. 相似文献
923.
The preparation of hybrid porous materials by condensation of poly(dimethyl-co-methyl)siloxanes functionalized with side units: i.e., templating –RC(SiMe3)3 [R = (CH2)5, (CH2)2SiMe2], and reactive –Si(OEt)3, of random distribution along the main chain is described. Tetrabutylammonium salts, tetrabutylammonium hydroxide and tetrabutylammonium
fluoride were chosen as the catalytic system. The relationship between the steric hindrance of the carbosilane template, the
type of n-Bu4N+ catalyst and the structure of cross-linked materials was investigated. It was found that bulky carbosilane substituents can
block formation of the porous structure in the cross-linked material. The type of interaction between Si(OEt)3 and the catalyst seems to be an equally important factor for 3D structure formation. Controlled thermolysis of the cross-linked
materials, performed in order to remove carbosilane units by thermal degradation, allowed for the formation of porous materials
having high specific surface area. 相似文献
924.
Anna Halicka 《Construction and Building Materials》2011,25(10):4072-4078
The paper describes the investigations of concrete composite units consisting of two concrete parts. In each test series the interface was differently arranged and characterised by different strength parameters. They were: non-reinforced interface with existing adhesion, reinforced interface with existing adhesion and reinforced interface with broken adhesion. Simply-supported beams were subjected to four point bending. The failure of all beams was the result of exceeding the shear resistance of the support zones, but the cracks pattern in each series was different. The paper presents the results of the tests, in particular: deflection, stresses in the longitudinal and transverse reinforcement and strains of concrete. The distribution of strains along the height of the beam and the slip between the connected parts are also described.On the basis of these data a classification of failure mechanisms of concrete composite beams is proposed, as well as the analytical criteria allowing to predict failure manner of a composite beam. 相似文献
925.
926.
Agneta Hörnell Anna Winkvist Göran Hallmans Lars Weinehall Ingegerd Johansson 《Nutrition journal》2010,9(1):48
Background
Food pattern analyses are popular tools in the study of associations between diet and health. However, there is a need for further evaluation of this methodology. The aim of the present cross-sectional study was to evaluate the relationship between food pattern groups (FPG) and existing health, and to identify factors influencing this relationship. 相似文献927.
Heitor Luiz Ornaghi Jr. Alexandre Sonaglio Bolner Rudinei Fiorio Ademir Jose Zattera Sandro Campos Amico 《应用聚合物科学杂志》2010,118(2):887-896
This work aims to evaluate the performance of glass/sisal hybrid composites focusing on mechanical (flexural and impact) and dynamic mechanical analyses (DMTA). Hybrid composites with different fiber loadings and different volume ratios between glass and sisal were studied. The effect of the fiber length has also been investigated. The densities of the composites were compared with the theoretical values, showing agreement with the rule of mixtures. The results obtained in the flexural and impact analysis revealed that, in general, the properties were always higher for higher overall reinforcement content. By DMTA, an increase in the storage and loss modulus was found, as well as a shift to higher values for higher glass loading and overall fiber volume. It was also noticed an increase in the efficiency of the filler and the calculated activation energy for the relaxation process in the glass transition region. The fiber length did not significantly change the results observed in all analyses carried out in this work. The calculated adhesion factor increased for higher glass loadings, meaning the equation may not be applied for the system studied and there are other factors, besides adhesion influencing energy dissipation of the composites. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 相似文献
928.
To speed up similarity based searches many indexing techniques have been proposed in order to address the problem of efficiency. However, most of the proposed techniques do not admit fast insertion of new elements once the index is built. The main effect is that changes in the environment are very costly to be taken into account.In this work, we propose a new technique to allow fast insertions of elements in a family of static tree-based indexes. Unlike other techniques, the resulting index is exactly equal to the index that would be obtained by building it from scratch. Therefore there is no performance degradation in search time.We show that the expected number of distance computations (and the average time complexity) is bounded by a function that grows with log2(n) where n is the size of the database.In order to check the correctness of our approach some experiments with artificial and real data are carried out. 相似文献
929.
The paper presents an assessment of the influence of selected highbush blueberry pretreatment methods and parameters on the process of osmotic dehydration conducted in 65 °Brix sucrose solution for 5 to 240 min at 30–70 °C. The pretreatment methods used included: fruit immersion in boiling water (15 s) and in 0.5 % NaOH solution (15 s at 95 °C), exposure to ultrasound at atmospheric pressure (vibration frequency of 35?±?5 kHz, 500 W, for 15 min.) and at low pressure (0.92 kg?cm?1), and enzymatic processing; pectinase (enzyme activity of 46,000 PGU/mL; 0.6 mL/90 g of fruits; 30 min at approx. 22 °C) and lipase (enzyme activity of 750 PGU/mL; 0.7 mL/90 g of fruits; 30 min at approx. 22 °C) were used. Dehydration was also conducted in the presence of pectinolytic enzymes. The dehydrated material was analyzed in terms of the content of dry matter, total polyphenols, and particular polyphenols using high performance liquid chromatography. It was observed that dehydration was much more intensive at 60 and 70 °C, but such temperatures led to substantial losses of phenolic compounds (by 15–30 % after 2-h dehydration) and unfavorable changes in the texture of the final product. A promising method of pretreatment is fruit immersion in solutions containing pectinolytic and lipolytic enzymes, which increase dry matter content by 26 % (after 1 h of dehydration at 30 °C) with a low loss of phenolic compounds (4 %). Among the identified anthocyanins, the greatest retention during dehydration at various temperatures was displayed by petunidin-3-galactoside (over 80 % after 1 h of dehydration) and petunidin-3-glucoside (over 78 %). 相似文献
930.
A significant element in the cost of a new building is devoted to fire safety. Energy efficiency drives the replacement of traditional building materials with lightweight insulation materials, which, if flammable can contribute to the fire load. Most fire deaths arise from inhalation of toxic gases. The fire toxicity of six insulation materials (glass wool, stone wool, expanded polystyrene foam, phenolic foam, polyurethane foam and polyisocyanurate foam) was investigated under a range of fire conditions. Two of the materials, stone wool and glass wool failed to ignite and gave consistently low yields of all of the toxic products. The toxicities of the effluents, showing the contribution of individual toxic components, are compared using the fractional effective dose (FED) model and LC50 (the mass required per unit volume to generate a lethal atmosphere under specified conditions). For polyisocyanurate and polyurethane foam this shows a significant contribution from hydrogen cyanide resulting in doubling of the overall toxicity, as the fire condition changes from well-ventilated to under-ventilated. These materials showed an order of increasing fire toxicity, from stone wool (least toxic), glass wool, polystyrene, phenolic, polyurethane to polyisocyanurate foam (most toxic). 相似文献