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991.
992.
Y-α-sialon ceramics with different compositions were hot-press sintered. Varying the m or n value in theα-Sialon general formula, both the α-sialon grain morphology and phase assemblages present diversification, therefore, affecting the toughness and hardness. Meanwhile, varying the compositional parameters also influenced the composition and structure of the intergranular glass phase, as well as its oxidation behavior at 1100-1200 ℃. The oxidation of the intergranular phase Mt in the Y-α-sialon ceramics was significantly enhanced with further rising the oxidation temperature to 1300 ℃. 相似文献
993.
In February 2016, China’s State Council released a set of guidelines representing a change in the country’s approach toward neighbourhood design: to move away from superblock neighbourhoods and create a finer network of urban blocks and streets. The paper traces the circumstances that prompted this change, drawing on a comparative review of international literature and practice, and explores the opportunities and challenges for urban design. While modifications of the superblock are somewhat overdue, this current mode of organization should not be entirely abandoned. The suggestions and overall blueprint warrant a more circumspect approach and should be adopted with discretion. 相似文献
994.
995.
A new kind of acetylene terminated silazanes, N‐(3‐acetylenephenyl)‐diorganosilazanes (abbreviated as APSZs) with three kind of substituents, were synthesized by the aminolysis of dichlorosilane with 3‐aminophenylacetylene (3‐APA). Structure of APSZs was confirmed by Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance (NMR). Thermal behavior of the cured silazanes was determined by thermogravimetry analysis (TGA), revealing that cured silazanes exhibited high temperature resistance. The ceramic yields of APSZ‐Me2, APSZ‐MeVi, and APSZ‐Ph2 at 1000°C under nitrogen were 77.6, 81.9, and 68.7%, respectively. The peak separation of derivative thermogravimetric data was employed to evaluate the three major regions of the thermolysis, and the kinetic parameters of thermolysis were calculated by the method of Kissinger from dynamic thermogravimetric measurement in nitrogen atmosphere at several different heating rates. Influence of substituents on the thermal behavior of cured silazanes in each separated region was discussed. The results showed that the vinyl derivative exhibit higher thermal stability than methyl and phenyl derivatives due to the high decomposition activation energy and small pendant group. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
996.
当前在建筑工程施工招投标中有许多突出问题亟待解决,如低价中标、借资质围标、难以择优选择施工企业,以及招标人、投标人缺少应有权利等问题.为此,从招投标相关政策法规、政府职能及从业者行为,到具体招投标方法,以及建筑行业和社会问题对招投标的影响等方面分析问题之所以产生的原因,探讨解决问题的途径和方法.力求揭示问题深刻,分析问题准确深入,方法合理有效. 相似文献
997.
With the increasing burden of chronic diseases on the health care system, Markov-type models are becoming popular to predict the long-term outcomes of early intervention and to guide disease management. However, statisticians have not been actively involved in the development of these models. Typically, the models are developed by using secondary data analysis to find a single “best” study to estimate each transition in the model. However, due to the nature of secondary data analysis, there frequently are discrepancies between the theoretical model and the design of the studies being used. This paper illustrates a likelihood approach to correctly model the design of clinical studies under the conditions where (1) the theoretical model may include an instantaneous state of distinct interest to the researchers and (2) the study design may be such that study data cannot be used to estimate a single parameter in the theoretical model of interest. For example, a study may ignore intermediary stages of disease. Using our approach, not only can we accommodate the two conditions above, but more than one study may be used to estimate model parameters. In the spirit of “If life gives you lemon, make lemonade”, we call this method “Lemonade Method”. Simulation studies are carried out to evaluate the finite sample property of this method. In addition, the method is demonstrated through application to a model of heart disease in diabetes. 相似文献
998.
999.
A. V. Zakharov M. Ye Ilchenko L. S. Pinchuk 《Radioelectronics and Communications Systems》2014,57(5):217-223
There are researched specificities of electromagnetic coupling coefficients at main and higher resonance frequencies between step-impedance resonators, fabricated from symmetric stripe transmission lines with open ends. It is shown, modification of step resonators parameters can result in modification of the coupling coefficient at main resonance frequency in wide range, that allows to realize band-pass filters of array type. It is stated in case of several values of parameters of stripe resonators their coupling coefficients values at frequencies higher than main one are zero. It is proposed a new method of expansion of suppressed frequency band of pass-band filters of array type, which is based on suppression of the first parasitic pass band due to zero coupling coefficient. 相似文献
1000.
Ye Sheng Xuechun Xu Wenyong Jiang Yanhua Song Shucai Gan Haifeng Zou 《Journal of surfactants and detergents》2012,15(4):393-398
Oxidized cornstarch, which is only composed of carbon, hydrogen and oxygen elements, was used as a builder in detergent formulations to reduce the hardness of water. Therefore, the calcium binding capacity of these oxidized cornstarch samples was tested and the relative detersive efficiency of the self-made detergent with oxidized cornstarch builder was also evaluated. The results show that higher Ca2+ binding capacities 104.5?mg/g can be obtained when the synthesis is carried out at 100?°C for 3?h in conjunction with the addition of 21?g NaOH. The detersive efficiency can reach 1.28 which is equivalent to the other detergent powders. In addition, the biodegradability of the oxidized cornstarch was judged as being adequate by the China National Center for Quality Supervision and Test of Plastic Products. Compared with the traditional detergent builders, the oxidized cornstarch is water-soluble, environmentally friendly, and cheap, with an equivalent performance to traditional detergent builders. 相似文献