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71.
72.
Ethanol suppressed, in a dose-related manner, glucose-induced insulin (IRI) release and thus delayed the disappearance of glucose from the blood of rats. Pretreatment with pyrazole, an alcohol dehydrogenase inhibitor, exacerbated the effect of ethanol on IRI release, glucose tolerance and glucagon (IRG) release. These results suggest that ethanol produces glucose intolerance by inhibiting glucose-induced IRI release and by augmenting IRG release. Moreover, these findings indicate that ethanol does not have to be metabolized completely in order to produce these effects.  相似文献   
73.
Sodium beta-alumina solid electrolytes were prepared containing up to 7.5 wt% SiO2 and their density, soda content, micro-structure, and ionic resistivity were studied. The resulting microstructures have glassy sodium ahminosilicate phases inhomogeneously distributed. The glassy phase collects preferentially at triple grain junctions, but occasionally penetrates along some grain boundaries as a thin layer (10 to 20 Å). Alpha-alumina is also present, especially with high silica content and when the samples are not protected with β-alumina powder during sintering. The total specific ionic resistivity follows a dependence on silicate content typical of 2-phase mixtures.  相似文献   
74.
75.
Some solutions which involve iterative optimization techniques are given to improve adaptation transients in adaptive systems. Two suboptimal controllers are developed and applied to an equivalent discrete-time system valid for describing the behaviour of a recent adaptive control scheme when one of the (time-varying) parameters entering the adaptation algorithm varies within a closed domain admissible from a convergence point of view. The resulting suboptimal control strategies are translated into corrections of this parameter in order to recompute the adaptation algorithm over a finite horizon. Some numerical simulations illustrate the usefulness of the proposed scheme.  相似文献   
76.
Factors are summarised which led to the development of screen and copper–roller techniques as two complementary systems for textile printing, and problems are explained which delayed the commercial exploitation of the rotary screen. Features of the print–paste applicator and the screen construction are studied. Recent improvements in durability and versatility of screens are examined, and novel fields of application for the rotary screen, particularly in duplex printing, are reviewed.  相似文献   
77.
Arsenic is a natural tasteless and odourless element,existing in the earth’s crust at average levels of between two and five thousands micrograms per liter (parts per million) . Arsenic is highly toxic to humans, who are exposed to it primarily from air,food and water. The occurrence of arsenic in groundwater is due to geological composition of soil. High concentrations of arsenic in water are the result of dissolution or desorption of ferric oxides and the oxidation of mineral arsenopyrites. Arsenic in drinking water has an important impact on the human health,especially in the less developed countries. Different methods exist to remove arsenic from aquatic media,and one of them is by adsorption. In this work,the adsorption of both As(III) and As(V) by means of novel microspheres has been investigated. In particular,TiO2 has been embedded into polymeric microspheres PES (PolyEtherSulphone) and PEEK-WC (PolyEtherEther-Ketone) . The main advantages of this encapsulation adsorption material are: no loss of adsorbents into the water stream,easy to be used and scaled-up.  相似文献   
78.
ABSTRACT

Asymmetries in three-phase windings of rotating-field a.c, machines may cause homopolar currents in delta-connected phase windings. End-winding particulars can have an Important quantitative influence on these currents and on the connected phase current inequalities.  相似文献   
79.
纤维的结构和性能(Ⅲ)   总被引:1,自引:0,他引:1  
本文介绍了PET高速纺丝纤维的热性能,低速纺丝领域中纤维的大分子取向以及纤维结晶相和非结晶相的取向,指出:纤维的沸水收缩率在纺速为2000-3000m/min内达最大值,其后随纺速增加急剧减少;纤维结晶相取向度随纺增加而增大;非晶向取向在600m/min纺速以随纺速增加而增大,6000m/min纺速以上随纺增加而减少。另外指出纺丝速度在7000m/min以上时,PET纤维横断面上存在一个内部结构分  相似文献   
80.
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