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121.
GangWEI HaiYahHUANG RongChunXIONG 《中国化学快报》2003,14(8):877-880
TiO2 nanoparticles were synthesized by using micro-reactors. The shape and size of the nanoparticles produced from the original micro-reactors and the five times recycled micro-reactorsmother liquor were investigated on transmission electron microscopy (TEM) by using the original sample, freeze prepared sample, and dyeing treated sample, respectively. UV-VIS spectrometry was used to study the growth process of TiO2 nanoparticles in main reactors. The results showed that micro-reactors with nanometer magnitude had spherical or oval structures, and could restore to their original structure after they were destroyed. The products prepared in the original micro-reactors were similar to that in the micro-reactors recycled for many times, suggesting that the micro-reactors had memory function. 相似文献
122.
吸热碳氢燃料裂解镧改性混合型催化剂的研究 总被引:3,自引:0,他引:3
制备了吸热型碳氢燃料NNJ-150和镧离子交换改性的USY、ZSM-5分子重申及混合分子筛,考察了NNJ-150在USHY、HZSM-5和两者混合物以及镧改性单分子筛和混合分子筛催化剂上的裂解反应。结果表明,ZSM-5分子筛中添加镧,对NNJ-150的单分子裂解反应有明显影响;混合分子两种分子筛之间存在协同作用,低温(500℃)下,LaUSY LaZSM-5(75:25)混合分子筛对低碳烯烃的选择性较高(41.48%),催化剂寿命较长(35min以上),能有效提高吸热型碳氢燃料NNJ-150的吸热能效。 相似文献
123.
Yao Zu Liao Mei Hua Xin Ming Chun Li Sheng Su College of Materials Science Engineering Huaqiao University Quanzhou China 《中国化学快报》2007,18(2):213-216
O-Lauroyl chitosan/poly(L-lactide) (OCS/PLLA) blend membranes with different compositions were prepared by solution-casting approach using chloroform as common solvent. The experimental results of FT-IR, DSC and WAXD indicated that inter-association hydrogen-bond interactions existed between OCS and PLLA in the blend membranes. And SEM observation confirmed that the blend membranes with suitable compositions were compatible. 相似文献
124.
Xing Yong Wang Jing Nan Cui Wei Min Ren Feng Li Chun Liang Lu Xu Hong Qian State Key Laboratory of Fine Chemicals Dalian University of Technology Dalian China School of Chemical Engineering Technology China University of Mining & Technology Xuzhou China Shanghai Key Laboratory of Chemical Biology East China University of Science Technology Shanghai China 《中国化学快报》2007,18(6):681-684
Baker's yeast mediated reduction of acenaphthenequinone within 4-10 h afforded mono-hydroxyacenaphthenone mainly with low enantioselectivity, the substrate and mono-hydroxyacenaphthenone product almost converted to dihydroxyacenaphthene after 48 h. By control of the reaction time and in the presence of DMF as co-solvent, the reduction of 6-substituted acenaphthenequinones under vigorous agitation afforded the corresponding 2-hydroxyacenaphthenones in 24-84% yields with 10-93% ee. 相似文献
125.
126.
Unsaturation was introduced at Delta(4,6) and Delta(6) of the sphingoid chain of naturally occurring ceramide 1 via a beta-keto sulfoxide (12) and sulfone (18) derived from N-Boc-L-serine methyl ester acetonide (9), affording two novel ceramide analogues, (2S,3R)-2-octanoylamidooctadeca-(4E,6E)-diene-1,3-diol (2) and (2S,3R)-2-octanoylamidooctadec-(6E)-ene-1,3-diol (3). After C-alkylation of 12 with (E)-1-bromo-2-tetradecene (8), a trans double bond was installed by elimination of PhS(O)H, providing conjugated dienone oxazolidine 13. Reaction of 18 with 8, followed by desulfonation (Al(Hg)), afforded keto-oxazolidine 20, which bears a (E)-Delta(6) double bond. The syntheses of analogues 2 and 3 from ketones 13 and 20, respectively, were completed by the following sequence of reactions: diastereoselective reduction (NaBH(4)/CeCl(3) or DIBAL-H), hydrolysis of the oxazolidine ring, liberation of the amino group, and installation of the N-amide group. 相似文献
127.
JiangBinXIA FuYouLI ShuMingYANG ChunHuiHUANG 《中国化学快报》2004,15(5):619-622
Composite nanoporous electrode SnO2/TiO2 was fabricated for the dye sensitized solar cell (DSSC) with N3 (Cis-Ru). After introducing of TiO2, the open-circuit photovoltage (Voc) was higher than that of the pure SnO2 electrode, while short-circuit photocurrent (Isc) was varied with the ratio of the TiO2. Appropriate content of the TiO2 can be beneficial to the efficiency of the solar cell, and it gives negative impact on the composite electrode when the content of TiO2 is higher. 相似文献
128.
129.
Jo‐Nan Chen Fang‐Ming Hsu Hui‐Chun Wang Chung‐Wen Wu Pao‐Swu Cheng Wen‐Liang Tsai 《中国化学会会志》2006,53(4):931-938
Four series of compounds 11?50 containing terminal alicyclic rings such as cyclohexylmethyl, cyclopentylmethyl, cyclobutylmethyl, and cyclopropylmethyl rings were synthesized and their liquid crystal behavior studied. The ring size and the length of flexible alkoxy chain influence the phase formation in different ways. While the smaller ring and the shorter alkoxy chain tend to favor the formation of the N phase, the larger ring and the longer alkoxy chain tend to favor the formation of the SmC phase. All the compounds except 11 and 21 exhibit SmA phases. The widest temperature range of the N, SmA, and SmC phases are found in the compounds 41 , 46 , and 20 , respectively, which are 75 °C for 41 , 115 °C for 46 , and 100 °C for 20 . 相似文献
130.
Paul W. Chun 《International journal of quantum chemistry》2001,85(6):697-712
This communication will demonstrate the existence of a thermodynamic molecular switch in the pairwise, sequence‐specific hydrophobic interaction of Ile–Ile, Leu–Ile, Val–Leu, or Ala–Leu over the temperature range of 273–333 K reported by Nemethy and Scheraga in 1962. Based on Chun's development of the Planck–Benzinger methodology, the change in inherent chemical bond energy at 0 K, ΔH°(T0), is 3.0 kcal mol?1 for Ile–Ile, 2.4 for Leu–Ile, 1.8 for Val–Leu, and 1.2 kcal mol?1 for Ala–Leu. The value of ΔH°(T0) decreases as the length of the hydrophobic side chain decreases. It is clear that the strength and stability of the hydrophobic interaction is determined by the packing density of the side chains, with Ala–Leu being the most stable. At 〈Tm〉, the thermal agitation energy, $\int^{T}_{0}\Delta Cp^{\circ}(T)\,dT$, is about five times greater than ΔH°(T0) in each case. Additionally, the thermal agitation energy for the same series, evaluated at 〈Tm〉, decreases in the same order, that is, as the length of the side chain decreases. This pairwise, sequence‐specific hydrophobic interaction is highly similar in its thermodynamic behavior to that of other biological systems, except that the negative Gibbs free energy change minimum at 〈Ts〉 occurs at a considerably higher temperature, 355 K compared to about 300 K. The melting temperature, 〈Tm〉, is also high, 470 K compared to 343 K in a biological system. The implication is that the negative Gibbs free energy minimum at a well‐defined 〈Ts〉 has it origin in the hydrophobic interactions, which are highly dependent on details of molecular structure. In addition to the four specific dipeptide interactions described, we have shown in our unpublished work the existence of a thermodynamic molecular switch in the interactions of 32 dipeptides wherein a change of sign in ΔCp°(T)reaction leads to a true negative minimum in the Gibbs free energy of reaction, and hence, a maximum in the related Keq. Indeed, all interacting biological systems that we have thus far examined using the Planck–Benzinger approach point to the universality of thermodynamic molecular switches. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001 相似文献