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排序方式: 共有460条查询结果,搜索用时 46 毫秒
21.
IP Chernikevich EA Gritsenko IM Lisitskaia TA Luchko 《Canadian Metallurgical Quarterly》1995,41(6):36-42
The levels of phosphate esters and the activities of thiamine biotransformation enzymes in the blood and tissues of albino rats were studied during oxythiamine-induced B1 deficiency and after metabolic correction with thiamine and taurine. Among thiamine phosphates, the most informative indicators of thiamine deficiency were shown to be triphosphate esters and free thiamine diphosphate. The biosynthetic enzymes thiamine kinase and thiamine diphosphate kinase played a decisive role in maintaining the initial rate and in recovering the physiologically active forms of vitamin B1. The activation of hydrolytic enzymes of thiamine phosphate esters occurred by producing abundant free thiamine diphosphate and thiamine triphosphate. Within the first hours, taurine favoured the acceleration of phosphoester biosynthesis and, accumulating in the tissues, inhibited vitamin phosphorylation reactions. 相似文献
22.
Peripheral T cell lymphoma encompasses lymphomas with a variety of histologic appearances and clinical patterns. Recently, it has been suggested that almost all of the histologic features described under the name of polymorphic reticulosis(PR), lethal midline granuloma, and midline malignant reticulosis can be included in those generally described for malignant lymphomas of peripheral T cell origin(PTCL). There have been few studies of pathogenesis or tissue damage mechanism in PR patients. The need for a precise mechanism for tissue damage has important therapeutic implications. Using immunohistochemical methods with polyclonal anti IL-6 antibody, the authors describe 5 cases of PR with clinically and pathologically typical PR demonstrating a high expression of IL-6. According to classification, 2 cases of grade 1 PR showed the highest expressions, and 2 cases of grade 2 PR with atypical lymphoid cells showed moderate activity, but one case progressed into frank lymphoma(grade 3) and lost IL-6 expression. This strongly implies that some cases of PR have a different mechanism of tissue damage from frank PTCL, despite the one disease spectrum. Further studies on more cases may help clarify the pathogenesis. 相似文献
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Luciana Katty Figueiredo Sanches Edmea Lodovici Leticia Cristina Cidreira Boaro Leonardo Eloy Rodrigues-Filho 《Journal of Adhesion Science and Technology》2013,27(12):1386-1394
The durability of adhesive interfaces is still a problem in adhesive restorations in dentistry. Laboratorial ageing methods have been proposed to predict the performance of materials, but they still require standardization. The objective of this study was to evaluate the resin-dentin microtensile bond strength of composite restorations subjected to pH cycling and different levels of mechanical loading. Resin blocks were built over a flat superficial dentin of bovine incisors (n = 40), using a three-step adhesive system. Half of the specimens were submitted to 10 cycles of pH cycling, followed by mechanical loading (0, 500,000; 1,000,000; 2,000,000 cycles – 98 N, 4 Hz). The other half was directly subjected to mechanical loading. After ageing, all groups were subjected to a microtensile bond test. Data were analyzed using two-way ANOVA and Tukey’s test (α = 0.05). The frequency of the early de-bonding was compared using the Chi-square test (α = 0.05). The statistical analysis revealed that the cross-product interaction ‘pH cycling’ vs. ‘number of mechanical loading cycles’ (p = 0.72) as well as the main factor ‘pH cycling’ (p = 0.49) was not statistically significant, and they were not able to reduce the resin–dentin bond strength values. Regarding the number of mechanical loading cycles, the groups subjected to 2,000,000 cycles showed lower bond strength values than the others (p = 0.003). The frequency of debonded specimens increased with mechanical loading. Therefore, it can be concluded that in this restorative model, at least 2,000,000 mechanical cycles are need to decrease the microtensile strength and simulate the ageing of the interface. 相似文献
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DE Petrosian SD Arutiunov IP Kolobukhin GIu Pakalns 《Canadian Metallurgical Quarterly》1997,76(5):49-51
Computer-aided milling of ceramic insertions helped more effectively repair the masticatory surface of teeth, minimize the incidence of errors, rule out the laboratory stage of making the insertions and the technological errors made at this stage, retain physical and mechanical characteristics of ceramics, optimize marginal adherence of the insertion to the tooth, retain the height of the lower part of the face, and thus prevent the maxillodental dysfunction. 相似文献
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使正常养护28d的70个镀锌焊接钢丝网水泥试件持续受弯,最外层钢丝的计算应力达到腐蚀下容许值207N/mm^2,再放入自制的以70℃干燥60min和43℃,3.5%NaCl溶液浸渍30min为一周期的忆速模拟海洋环境实验系统中,分别承受荷载-腐蚀共同作用1、3、7和18个月(480 ̄8640个周期),再对这些试件进行弯曲疲劳-腐蚀试验。分析评估了影响钢丝网水泥抗荷载-腐蚀性能的因素,给出了破坏概率 相似文献
30.
A. Sanches Silva J. M. Cruz Freire R. Sendón García R. Franz P. Paseiro Losada 《European Food Research and Technology》2008,226(6):1357-1363
Two methods were tested and compared for the additivation of low density polyethylene (LDPE). The aim was to obtain highly
contaminated plastic films to enable the study of migration (diffusion and partition phenomena). One of the methods involved
immersion of low density polyethylene (LDPE) films in a concentrated solution of the selected substances. The other method
involved achieving close contact of plastic films with a polyethylene wax contaminated with the selected compounds. The PE-wax
method provided better results as regards the final concentration and homogeneity of the contaminants in the plastic films
(deviations between replicates for each plastic film was lower than 10% for both migrants tested). This method was therefore
considered suitable for preparing a homogeneous additive release system. Finally, to test the applicability of the method,
concentration profiles were studied in chocolate spread placed in contact with the contaminated films, and diffusion coefficients
were estimated in this foodstuff. Estimated diffusion coefficients were 4.6 × 10−07 cm2/s for DPBD and 3.2 × 10−07 cm2/s for triclosan in the same conditions. 相似文献