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排序方式: 共有354条查询结果,搜索用时 78 毫秒
71.
Alireza Bahadori Saeid Mokhatab Brian F. Towlera 《天然气化学杂志》2007,16(4):349-353
Natural gases containing sour components exhibit different gas compressibility factor(Z) behavior than do sweet gases.Therefore,a new accurate method should be developed to account for these differences.Several methods are available today for calculating the Z-factor from an cquation of state. However,these equations are more complex than the foregoing correlations,involving a large number of parameters,which require more complicated and longer computations.The aim of this study is to develop a simplified calculation method for a rapid estimating Z-factor for sour natural gases containing as much as 90% total acid gas.In this article,two new correlations are first presented for calculating the pseudo- critical pressure and temperature of the gas mixture as a function of the gas specific gravity.Then,a simple correlation on the basis of the standard gas compressibility factor chart is introduced for a quick estimation of sweet gases' compressibility factor as a function of reduced pressure and temperature.Finally,a new corrective term related to the mole fractions of carbon dioxide and hydrogen sulfide is developed. 相似文献
72.
Saboury AA Bagheri S Ataie G Amanlou M Moosavi-Movahedi AA Hakimelahi GH Cristalli G Namaki S 《Chemical & pharmaceutical bulletin》2004,52(10):1179-1182
Thermodynamic studies were carried out to evaluate the binding of theophylline on adenosine deaminase (ADA) in 50 mM sodium phosphate buffer pH 7.5, at 300 K, using isothermal titration calorimetry (ITC). A simple method for determination of binding isotherm in the drug--ADA interaction was applied using ITC data. ADA has two binding sites for theophylline, which show positive cooperativity in its sites. The intrinsic association equilibrium constants are 6 and 52 mM(-1) in the first and second binding sites, respectively. Hence, occupation of the first site has produced an appreciable enhancement by 8.7 of the binding affinity of the second site. The molar enthalpies of binding are -12.2 and -14.9 kJ/mol in the first and second binding sites, respectively. 相似文献
73.
Ray L. Withers Thomas Höche Saeid Esmaeilzadeh Brian Sales 《Journal of solid state chemistry》2004,177(10):3316-3323
High-purity Rb2V3O8 has been grown and temperature-dependent electron and single-crystal X-ray diffraction used to carefully investigate its fresnoite-type reciprocal lattice. In contrast to other recently investigated representatives of the fresnoite family of compounds, Rb2V3O8 is not incommensurately modulated with an incommensurate basal plane primary modulation wave vector given by q∼0.3 〈110〉*. A careful low-temperature electron diffraction study has, however, revealed the existence of weak incommensurate satellite reflections characterized by the primitive primary modulation wave vector q1∼0.16c*. The reciprocal space positioning of these incommensurate satellite reflections, the overall (3+1)-d superspace group symmetry, as well as the shapes of the refined displacement ellipsoids determined from single-crystal XRD refinement, are all consistent with their arising from a distinct type of condensed rigid unit modes (RUMs) of distortion of the Rb2V3O8 parent structure. 相似文献
74.
Farrokh Gharib Saeid Taghvaei Sara Ghazi 《Russian Journal of Inorganic Chemistry》2007,52(12):1915-1917
The synthesis and complexing abilities of 26,28-bis-benzyloxy-25,27-dihydroxy-5,11,17,23-tetra-tertbutyl-calix[4]arene towards
alkali earth metal ions Mg2+, Ca2+, Sr2+, and Ba2+ in a methanol-chloroform mixture have been evaluated at 25°C, using UV-Vis spectrophotometric techniques. The results showed
that the ligand is capable to complex all alkali earth cations by 1:1 metal to ligand ratios. The selectivity presented considering
the calculated stability constants are in the order Mg2+ > Ca2+ > Sr2+ > Ba2+ towards the ligand. 相似文献
75.
The paper studies the existence of infinitely many solutions for a Neumann problem involving the p(x)-Laplacian-like depending on two parameters. Our approach is based on variational methods. 相似文献
76.
Abbas Dechal Mostafa Khoshsefat Saeid Ahmadjo Seyed Mohammad Mahdi Mortazavi Gholam Hossein Zohuri Hossein Abedini 《应用有机金属化学》2018,32(6)
Polymerization of 1‐hexene was carried out using a mononuclear (MN) catalyst and two binuclear (BN1 and BN2) α‐diimine Ni‐based catalysts synthesized under controlled conditions. Ethylaluminium sesquichloride (EASC) was used as an efficient activator under various polymerization conditions. The highly active BN2 catalyst (2372 g poly(1‐hexene) (PH) mmol?1 cat) in comparison to BN1 (920 g PH mmol?1 cat) and the MN catalyst (819 g PH mmol?1 cat) resulted in the highest viscosity‐average molecular weight (Mv) of polymer. Moreover, the molecular weight distribution (MWD) of PH obtained using BN2/EASC was slightly broader than those obtained using BN1 and MN (2.46 for BN2 versus 2.30 and 1.96 for BN1 and MN, respectively). These results, along with the highest extent of chain walking for BN2, were attributed to steric, nuclearity and electronic effects of the catalyst structures which could control the catalyst behaviour. Differential scanning calorimetry showed that the glass transition temperatures of polymers were in the range ? 58 to ?81 °C, and broad melting peaks below and above 0 °C were also observed. In addition, longer α‐olefins (1‐octene and 1‐decene) were polymerized and characterized, for which higher yield, conversion and molecular weight were observed with a narrower MWD. The polymerization parameters such as polymerization time and polymerization temperature showed a significant influence on the productivity of the catalysts and Mv of samples. 相似文献
77.
Faramarz Rostami-Charati Rahimeh Hajinasiri Seyyed Zahra Sayyed Alangi Saeid Afshari Sharif Abad 《Chemical Papers》2016,70(7):907-912
4-amino-2-iminodithiole derivatives were synthesised via multi-component reactions of tetramethyl thiourea, isothiocyanates and alkyl bromides in the presence of ZnO nanorods (ZnO-NR) as the catalyst in water at ambient temperature. These reactions provide low yields without catalysts. The catalyst exhibited significant reusable activity. 相似文献
78.
79.
Saeid Shokooh 《复变函数与椭圆型方程》2019,64(8):1310-1324
We apply a three critical points theorem of B. Ricceri to establish the existence of at least three weak solutions for a class of non-homogeneous Neumann problems. Furthermore, by using another theorem of him, we prove that an appropriate oscillating behaviour of the nonlinear term ensures the existence of infinitely many weak solutions. Our analysis is based on recent variational methods for smooth functionals defined on Orlicz-Sobolev spaces. 相似文献
80.
Meccanica - The wastewater of steel production factories consists of a large amount of very small metal particles. The metal particles in this wastewater enter a large sedimentation tank and are... 相似文献