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排序方式: 共有2501条查询结果,搜索用时 15 毫秒
991.
992.
以伊朗西南部某油田Asmari组砂岩储集层为研究对象,研究其中一口垂直井的井筒稳定性,利用FLAC3D软件,根据钻遇地层地质力学特征建立井筒的有限体积模型,监测井壁岩石塑性状态的形成以确定砂岩层安全钻井液密度的上限值和下限值。评估了岩石强度特性、井筒周围主要地应力和孔隙压力对该井安全钻井液密度窗口的影响,敏感性分析结果表明,井壁岩石内聚力和内摩擦角的减小会导致安全钻井液密度窗口大幅变窄;孔隙压力和最大水平应力与最小水平应力之比的减小则会使安全钻井液密度窗口显著增大。此模型便于量化安全钻井液密度窗口的变化,可作为一种油气井钻井方案设计和监测工具。图11参50 相似文献
993.
994.
Tahereh Gholami Masoud Salavati-Niasari 《International Journal of Hydrogen Energy》2017,42(27):17167-17177
The ZnAl2O4 spinel was synthesized by a facile thermal decomposition method using green chemistry. For the first time, the electrochemical hydrogen storage performances and mechanisms of the ZnAl2O4 was studied by the galvanostatic charge-discharge method in 6 M KOH aqueous medium under 1 mA current. Anionic, cationic and polymeric surfactants were used to increase of hydrogen storage and specific area of ZnAl2O4 spinel. The composition, structure, morphology and specific surface area of the samples were characterized. The maximum measured discharge capacities of ZnAl2O4, ZnAl2O4/CTAB, ZnAl2O4/PVP and ZnAl2O4/SDS were 1250, 3000, 3250 and 4000 mAh/g, respectively. These samples were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), X-ray energy dispersive spectroscopy (EDS), N2 adsorption (BET) and transmission electron microscope (TEM). 相似文献
995.
Sajjad Damiri Yones Mosaei Oskoei Masoud Fouladgar 《Journal of Experimental Nanoscience》2016,11(18):1384-1401
This paper describes the development of 1-methyl-3-butylimidazolium chloride ionic liquid/cobalt hexacyanoferrate nanoparticle modified multi-walled carbon nanotubes nanocomposite paste electrode for the electrocatalytic and adsorptive stripping voltammetric and impedimetric determination of diclofenac (DIC) in real samples. The nanocomposite was prepared by a simple chemical method and was characterised by scanning electron microscopy, Fourier transform infrared spectroscopy and atomic absorption spectroscopy. Also, the electrochemical behaviours of the modified electrode and the electrocatalytic oxidation of DIC were investigated in detail by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy techniques. The kinetic parameters such as electron transfer coefficient, and apparent rate constant for the redox reaction between DIC and the modified electrode were also determined using electrochemical approaches. It was found that the modified electrode exhibited excellent electrocatalytic activity toward the oxidation of DIC, and under the optimised conditions, the linear response range and detection limit were found to be 1.0–100.0 and 0.3 μM, respectively using the differential pulse voltammetry method. The proposed method was applied for the sensitive and selective determination of diclofenac in the urine samples and pharmaceutical formulations with satisfactory results. 相似文献
996.
Poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) samples were synthesized via aqueous atom transfer radical polymerization with DPn of 35, 151, 390, and 546 and dispersity of 1.13, 1.17, 1.20, and 1.18, respectively. All samples were exposed to temperature and pH variations at different concentration of polymer and salt (NaCl). Results indicated that cloud point (Tcl) can be controlled by changing DPn, polymer concentration, and ionic strength of solution. According to results, Tcl of the PDMAEMA chains shifted to lower temperatures with increasing solution pH at all molecular weight ranges due to deprotonation of tertiary amine groups in polymer structure. However, higher molecular weight polymers were more sensitive to pH variation especially in alkaline media. Also, higher polymer concentration acted as driving force to decrease cloud point of samples and formation of aggregates that was more predominant for higher molecular weights at alkaline media. Tcl of PDMAEMA chains decreased with increasing ionic strength even at low pH values for low molecular weight polymers. 相似文献
997.
998.
Synthesis of polyethyleneimine (PEI) and β‐cyclodextrin grafted PEI nanocomposites with magnetic cores for lipase immobilization and esterification
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999.
Characterisation of whey protein isolate–gum tragacanth electrostatic interactions in aqueous solutions
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Nassim Raoufi Rassoul Kadkhodaee Glyn O. Phillips Yapeng Fang Masoud Najaf Najafi 《International Journal of Food Science & Technology》2016,51(5):1220-1227
The main objectives of this study were to measure molecular parameters of gum tragacanth by GPC‐MALLS system and investigate the complexation behaviour of whey protein isolate/gum tragacanth mixed dispersions (0.5 wt% total biopolymer concentration) as a function of pH (7.00–2.00) and the biopolymer mixing ratio (r = 0.1–10) using spectrophotometric, zeta potential and precipitate yield determination methods. GPC‐MALLS revealed that gum tragacanth contains relatively heterogeneous particles with high weight‐average and number‐average (Mw = 7.74 × 105 g mol?1 and Mn = 3.87 × 105 g mol?1) molecular mass and high dispersity index (~2.04 ± 0.3). Results of complexation displayed that as the biopolymer mixing ratio increases, the net neutrality shifts to the higher pHs. The critical values associated with the complex structure formation were found at r = 2 in which the charge density of the mixture was near zero at a wide range of pH (3.0–4.0). However, the highest precipitate yield achieved in pH 3.4. 相似文献
1000.