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931.
932.
IntroductionSnake-cageresin,alsoca1ledsnake-cagepolyelectrolyte['],isaspecialkindofamphotericresin.ItwasfirstinvestigatedbyHatchM.J.etal.in1957[z].Thetypicalandusefulsnake-cageresinisRetardation11A-8(l1A-8inthecon-text)manufacturedbyDowChemicalCoI,TD.Itissynthesizedbypolymerizingacrylicacidinsidethenetworkofastrongbasicanionexchangeresinwith8%crosslinking.Thus,theresinconsistsofacrosslinkedpolymermatrix,cage,andalinearpolymer,socalledsnake,whichisphysicallytrappedinsidethecage.Thecagepol… 相似文献
933.
Anna Rita Campanelli Sofia Candeloro De Sanctis Angelo Antonio D'Archivio Edoardo Giglio Lucid Scaramuzza 《Journal of inclusion phenomena and macrocyclic chemistry》1991,11(3):247-256
Crystals of sodium taurocholate (NaC26H44NO7S · 2.5 H2O) belonging to the triclinic space groupP1 have unit cell parametersa = 12.731 (2),b = 16.104 (2),c = 7.628 (1) A, =83.40 (1), = 101.20 (1), = 105.35 (1)°, and two molecules in the asymmetric unit. The refinement, carried out on 4424 observed reflections, gaveR = 0.059 andR
w = 0.066. The packing is characterized by bilayers, formed by antiparallel monolayers and with nonpolar outermost surfaces, held together by van der Waals interactions. Inside the bilayers there are channels, lined with polar groups, and filled by sodium ions and water molecules. A structural unit has been identified that could provide a reasonable model for the micellar aggregates of this bile salt.
Supplementary Data relevant to this article have been deposited with the British Library under the reference number SUP 82125 (38 pages). 相似文献
934.
Control on Crystal Forms of Ultrafine Barium Carbonate Particles and Study on its Mechanism 总被引:4,自引:0,他引:4
HUO Ji-Chuan ② LIU Shu-Xin YANG Ding-Ming WANG Hai-Bin 《结构化学》2005,24(11):1290-1297
1 INTRODUCTION Barium carbonate is one of the important che- mical materials as well as one of the most important barium salts. Its application covers multitudinous in- dustries and fields such as building material, meta- llurgy, electron, chemical industry and so on[1]. With the fast development of science and technology, it is becoming more and more demanding with barium carbonate’s quality, and more and more scientific workers do researches on the control of Barium car- bonate’s crys… 相似文献
935.
936.
Na7I2(OH)5: A Hydroxide Iodide in the System NaOH/NaI The pseudobinary system NaOH/NaI is investigated by X-ray methods. The crystal structure of the compound Na7I2(OH)5 was solved by single crystal data: Na7I2(OH)5: P4/nmm, Z = 2, a = 7.748(2) Å, c = 10.260(3) Å, Z(Fo) = 443 with (Fo)2 ≥ 3σ(Fo)2, Z(parameter) = 28, R/Rw = 0.044/0.059 Na7I2(OH)5 crystallizes in a new type of structure which contains puckered layers of ∞2[Na7(OH)52+] connected via iodide ions. 相似文献
937.
938.
Reaction energies were determined for reductive ring-opening reactions of Li+-coordinated ethylene carbonate (EC) and vinylene carbonate (VC) by using various density functional theory (DFT) and ab-initio methods applying the basis sets up to Dunnings aug-cc-pVQZ. The methods examined include the local density functional (SVWN), the pure gradient-corrected density functionals (BLYP and BPW91), and the hybrid density functionals (B3LYP, B1LYP, B3PW91, and mPW1PW91). Comparison of the DFT results with ab-initio results indicates that the mPW1PW91 approach introduced by Adamo and Barone, is superior to all the other DFT methods (including B3LYP). The performance of more cost-effective Pople-type basis sets ranging from 6-31G(d,p) to 6-311++G(3df,3pd) was assessed at DFT levels of theory by calibrating them with the aug-cc-pVQZ results 相似文献
939.
Molybdosphoric Acid Mixed with Titania Used as a Catalyst to Synthesize Diphenyl Carbonate via Transesterification of Dimethyl Carbonate and Phenol
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Tong Chen Huajun Han Zhiping Du Jie Yao Gongying Wang Dachuan Shi Desheng Zhang Zhiming Chen 《天然气化学杂志》2006,15(4):303-306
The 12-molybdosphoric acid mixed with titania (MPA-TiO2) was found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate (DPC) via transesterification of dimethyl carbonate (DMC) and phenol. The X-ray diffraction (XRD) and infrared (IR) techniques were employed to characterize the prepared catalysts. The effect of the weight ratio of the 12-molybdosphoric acid to titania on the transesterification was investigated. A 13.1% yield of DPC and an 11.6% yield of methyl phenyl carbonate (MPC) were obtained over MPA-TiO2 with the weight ratio of MPA to TiO2 as 5:1. 相似文献
940.
Gao-Qi Zhang Liu-Sheng Zha Mei-Hua Zhou Jing-Hong Ma Bo-Run Liang 《Colloid and polymer science》2005,283(4):431-438
In this study, temperature-/pH-responsive semi-interpenetrating polymer network (semi-IPN) hydrogels based on linear sodium alginate (SA) and cross-linked poly(N-isopropylacrylamide) (PNIPAAm) were prepared. The semi-IPN hydrogels reached an equilibrium deswelling state within 6 h in response to temperature or pH stimuli. Compared with the conventional PNIPAAm hydrogel, their dewelling rate in response to temperature was improved significantly, owing to the formation of a porous structure within the hydrogels in the presence of ionized SA during the polymerization process. Moreover, the deswelling process could be well described with a first-order kinetics equation and it is possible to design any hydrogel with the desired deswelling behavior through the control of the SA content in the semi-IPN hydrogels. 相似文献