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排序方式: 共有1199条查询结果,搜索用时 15 毫秒
61.
黄焕山 《江汉石油职工大学学报》2002,15(3):38-39
将名牌以不同空间领域为对象的专门领域 (如城市 )统一起来 ,产生名牌空间经济学。名牌空间经济学的中心议题是研究名牌集中魅力的机制。发展中国家把城市化道路抽象为人口城市化 ,这种集中不是“市”的集中。经济全球化时期科技可“兴城”但难以“兴市” ,唯有名牌的集中体现“市”的本质 ,“名牌兴市”是最终选择 相似文献
62.
通过气体在玻璃态高分子膜中的吸收过程分析,认为在膜中气体分子与膜之间的相互作用将影响吸收等温线。假设气体在膜中的溶解过程类似于在溶液中的溶解过程,推导得出了普遍化双方式吸收模型。该模型中考虑了气体吸收浓度对气体在玻璃态膜中吸收过程的影响,几乎能够描述各种吸收过程。 相似文献
63.
Effects of impeller characteristics have been studied in the hydrogenation of aniline on Ru/C catalyst. Dual impellers were
employed and the experiments were performed at 300 rpm using a lab-scale reactor. Reaction with disk turbines (DT) resulted
in the higher cyclohexylamine (CHA) selectivity and higher reaction rate compared to that with pitched blade turbines (PBT).
When a combination of PBT and DT impellers was employed, high product selectivity and reaction rate were obtained and the
selectivity was maintained constant. Changes in the product selectivity with the impeller geometry were explained in terms
of the relative rates of the side reactions depending on the hydrogen concentration in the reaction mixture. 相似文献
64.
多溴联苯醚(PBDEs)是一类具有生态风险的新型环境有机污染物。PBDEs作为阻燃剂已经被愈来愈广泛地添加到工业产品中,对大气、水体、沉积物、土壤等环境介质产生污染,并最终危害生物和人类健康。鉴于这一环境新问题的产生,本文概述了环境介质中PBDEs的来源、含量,并对其分布特征进行了探讨。 相似文献
65.
66.
Dong Kyun YimIn-Sun Cho Chan Woo LeeJun Hong Noh Hee Suk RohKug Sun Hong 《Optical Materials》2011,33(7):1036-1040
Novel whitish-blue phosphors based on a phosphate host matrix, γ-KCaPO4: Eu2+, were prepared by a conventional solid-state reaction method using slightly phosphorus deficient conditions and their photoluminescence properties were investigated. The concentration quenching process, temperature dependence of the luminescence and decay curve were also investigated. The γ-KCaPO4: Eu2+ phosphor was efficiently excited by UV-Visible light at wavelengths of 200-450 nm and exhibited a bright whitish-blue emission with a maximum peak wavelength of 473 nm. All of these characteristics suggest that the γ-KCaPO4: Eu2+ phosphors combined with red phosphors could be applicable to near UV-based white LEDs, i.e., only two kinds of phosphor powders are needed for the formation of white light. 相似文献
67.
Cameron Jennifer M.; Leon Matthew R.; Correia Christopher J. 《Canadian Metallurgical Quarterly》2011,19(4):295
The present study extended the Simulated Drinking Game Procedure (SDGP) to obtain information about different types of drinking games. Phase I participants (N = 545) completed online screening questionnaires assessing substance use and drinking game participation. Participants who met the selection criteria for Phase II (N = 92) participated in laboratory sessions that consisted of three different periods of drinking game play. Sixty-two percent (N = 57) of the sample was female. Data from these sessions was used to estimate the peak Blood Alcohol Concentration (BAC) a participant would achieve if they consumed alcohol while participating in the SDGP. Total consumption and estimated BAC varied as a function of game type. The total consumption and estimated BAC obtained while playing Beer Pong and Memory varied significantly as a function of group. Total ounces consumed while playing Three Man varied significantly as a function of group; however, the variation in estimated BAC obtained while playing Three Man was not significant. Results indicated that estimated BACs were higher for female participants across game type. Previous experience playing the three drinking games had no impact on total drink consumption or estimated BAC obtained while participating in the SDGP. The present study demonstrated that the SDGP can be used to generate estimates of how much alcohol is consumed and the associated obtained BAC during multiple types of drinking games. In order to fully examine whether previous experience factors in to overall alcohol consumption and BAC, future research should extend the SDGP to incorporate laboratory administration of alcohol during drinking game participation. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
68.
Riad Taha Al-Kasasbeh 《Advances in Engineering Software》2012,45(1):137-143
A new software technique for determining emotional tension on humans is developed by means of psychological tests connected with the psycho-emotional sphere and on indicators characterizing the state of a subject’s visual attention. Each of these two areas determines several factors for psycho-emotional tension. The level of tension is determined as an aggregate of these two components with the rules of fuzzy logic. The membership functions and solving rules for the psychological tests, and for the state of visual attention, are constructed using fuzzy logic theory. It is shown that the resulting method can be used as an informative feature for prediction of many properties, such as the situational awareness (training and experience) of an operator and the operator’s individual capacity to function (mental-physiological limits). The second group of indicators characterize properties such as switchable attention (the ability to switch attention) (SWA), concentration (ability to concentrate) (CNA), stability of visual attention (STA) and parameters determining the state of memory. One of the most important issues for man-machine systems is to evaluate the performance of operators under abnormal conditions such as stress or tension. 相似文献
69.
《Journal of Hydro》2014,8(1):62-73
Solute transport in streams with diffusive transfer in the hyporheic zone is studied. Analytical solution of the diffusive transfer model is obtained by means of Laplace transform. Solutions are derived for a general situation, in which the concentration at the injection point is a function of time. In order to illustrate the use of present analytical solution, physical transport parameters are estimated for the observed data of Uvas Creek tracer experiment for chloride concentration and also of Wkra river tracer experiment. The concentration–time breakthrough curves obtained from the analytical solutions are found to be in good agreement with the observed as well as numerical concentration–time breakthrough curve. Step concentration–time profile and continuous concentration–time profile are considered as upstream boundary conditions for conservative solute. An instantaneous injection of solute is taken as an upstream boundary condition for reactive solute. It is noticed that with the increase in the value of porosity, the solute concentration in the main channel decreases. With the decrease in the value of Péclet number in the hyporheic zone, the overall solute concentration in the main channel decreases. Due to increase in the value of the sorption rate coefficient in the hyporheic zone, solute particles once enter into the hyporheic zone, reside for a longer time in the hyporheic zone. A sensitivity analysis is performed in order to identify the critical parameters for conservative as well as for reactive solute. It is found that the ratio of cross-sectional areas is much more sensitive compared to the other parameters for conservative solute. The Damköhler number in the hyporheic zone is the most sensitive parameter among all the parameters for reactive solute. The above observations indicate that the analytical solution can be reliably applied for the analysis of tracer experiments. 相似文献
70.
We consider a model of directed crystallization. We write the boundary-value problem to a curvilinear coordinate frame attached to the interface. The theory of perturbations is formulated for small perturbations of temperature and component concentration. We study stability of the interface of a binary alloy. In this paper, we show the manner in which the known phenomenon of the lamination of the components in a melt, result in formation of regular eutectic structure. We also give a conclusion of analytical expression for period of this structure. 相似文献