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151.
152.
李昭华 《华中科技大学学报(自然科学版)》2003,31(6):113-116
研究税务机关和出口公司之间就出口骗税所进行的双人博弈的若干模型,探讨各模型的均衡解,结果表明:在对税务机关无激励的情况下,对骗税公司课征罚款的威胁不能阻止外贸公司骗税;而课征罚款与对税务机关的激励相结合,可以部分地抑制或减少出口骗税,但却不能根除骗税. 相似文献
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154.
非可换的奇异l-群 总被引:2,自引:1,他引:1
吕新民 《纯粹数学与应用数学》2002,18(2):178-181
通过建立奇异元以及奇异l-群的刻划,研究了一般非可换的奇异l-群的性质及相关的结构. 相似文献
155.
苯基异氰酸酯与3,6-二甲基-1,6-二氢-S-四嗪反应生成标题化合物(C18H18N6O2,Mr=350.38)。经X-射线单晶结构分析表明此晶体属于单斜晶系,P21/c空间群,a=9.348(2),b=6.860(6),c=27.929(7) A,β=94.57(2)°,V=1785.3A3,Z=4,μ=0.090mm-1,Dc=1.304g/cm3,F(000)=736。结果表明该化合物的2个酰胺基接在S-四嗪环的1,4位,而四嗪环本身呈船式构象,不具有同芳香性,分子间存在氢键相互作用。 相似文献
156.
Anders Björn 《Potential Analysis》2007,27(4):381-387
We characterize regular boundary points for p-harmonic functions using weak barriers. We use this to obtain some consequences on boundary regularity. The results also
hold for -harmonic functions under the usual assumptions on , and for Cheeger p-harmonic functions in metric spaces.
相似文献
157.
The osmotic swelling in clays has been extensively studied at the physico-chemical scale. The present paper addresses the question of the modelling of this phenomenon from the mechanical point of view. First, the classical macroscopic thermodynamic framework for saturated porous continua is extended in order to take into account the solid-salt interaction through the concept of macroscopic activity coefficient of the salt. The micromechanical approach then incorporates this interaction through the concept of swelling pressure which is used for describing the internal forces in the fluid phase at the microscopic scale. The results of a physico-chemical theory for the solid-salt interaction, such as the e.d.l. theory, can be introduced in both approaches. Each of them leads to the identification of a deviation, of chemical origin, to Terzaghi's effective stress principle. Besides, the micromechanical approach allows us to clearly differentiate the mechanical and the chemical parts of clay materials elasticity. 相似文献
158.
《Comptes Rendus Chimie》2015,18(10):1134-1142
Pharmaceuticals, personal care products and endocrine disruptors demonstrate huge potential to cause adverse ecological health effects at very low concentration in aquatic environment. There is a need to improve current purification technologies used in sewage and drinking-water treatment plants. This article aims at providing new insights into the recent development of natural and modified clay-based sorbents for the removal of aqueous contaminants such as pharmaceuticals and personal care products. The removal of six widely used pharmaceuticals: ibuprofen, diclofenac, ketoprofen, carbamazepine, as well as endocrine disrupting chemicals – bisphenol A and a bactericidal agent, triclosan – was examined by sorption onto eight adsorbents. Sorption was performed using natural and modified clay minerals – montmorillonite (Mt), vermiculite (VER), bentonite (B), kaolinite (K), commercial acid activated montmorillonites K10 and K30, and two carbonaceous-mineral nanocomposites, MtG5%T, BAlG3%C. This study showed that among the tested natural clays, vermiculite is the most promising sorbent for the removal of pharmaceuticals in purification processes. Among the modified clay minerals, the best results were achieved for carbonaceous bentonite and two acid activated montmorillonites K10 and K30. However, the removal of acidic pharmaceuticals on montomorillonite K10 and carbonaceous bentonite was strongly dependent on the pH value. In the case of vermiculite and acid-modified montmorillonite K30, the sorption of the selected compounds was not significantly affected by pH, which is crucial in wastewater treatment. The sorption constant divided by the specific surface area (Kd/A) is proposed to assess whether the surface area or chemical properties of the materials control the sorption process. Kd/A values were relatively high in the case of vermiculite, so it should be noticed that individual and specific surface properties of vermiculite were of crucial importance for sorption. 相似文献
159.
160.
A one‐step strategy for aliphatic poly(carbonate‐ester)s with high performance derived from CO2, propylene oxide and l‐lactide 下载免费PDF全文
To improve the performance of PPC, aliphatic poly(carbonate‐ester)s were prepared in one‐step strategy from the terpolymerization of CO2, propylene oxide (PO), and l ‐lactide (L ‐LA) catalyzed by zinc glutarate. Consequently giving high‐molecular weight terpolymers (PPCLAs) in a very high yield (8450.8–9435.8 g mol?1 of Zn). The resulting terpolymers PPCLAs were characterized by 1H NMR, showing that PPCLAs had an almost alternating structure for the components of CO2, PO, and L‐LA. The influence of molecular weight and L‐LA content on the properties of PPCLAs was also investigated. Differential scanning calorimetry and thermogravimetric analysis (measurements revealed that the glass transition temperature (T g) and thermal decomposition temperature (T d) of PPCLAs are all much higher than those of PPC and increased with increasing molecular weight and L‐LA content. Tensile tests showed that the high mechanical properties of PPCLAs are due to the introduction of L‐LA into the copolymerization of CO2 and PO. Furthermore, PPCLA4 exhibits high degradability, and after 10 weeks, the weight loss increases up to 6.58%, which is significantly higher than that of PPC of 4.58%. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献