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81.
黄原胶与魔芋葡甘聚糖马来酸酯的协同相互作用及其凝胶化的研究 总被引:7,自引:1,他引:6
黄原胶-魔芋葡甘聚糖马来酸酯(AME)通过改变各种比例成分制备了混合凝胶.当多糖总浓度为1%,黄原胶对AME的共混质量比例为70/30,并在80℃水浴中恒温0.5h,可达协同相互作用的最大值;研究了制备温度(L)和体系盐离子浓度对凝胶化的影响;并把改性的AME-黄原胶与未改性的魔芋葡甘聚糖(AGM)-黄原胶的混合凝胶性能进行了比较.结果发现,两者均具有相似行为,只不过黄原胶-AGM的凝胶强度、粘度等比较低.同时从其FTIR谱图上分析了这两种多糖分子间相互作用的机理. 相似文献
82.
Gui-xiang Wang Xue-dong Gong Yan Liu He-ming Xiao 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2009,74(2):569-574
The nitro derivatives of phenols are optimized to obtain their molecular geometries and electronic structures at the DFT-B3LYP/6-31G* level. Their IR spectra are obtained and assigned by vibrational analysis and are reliable compared with the experimental results. Based on the frequencies scaled by 0.96 and the principle of statistic thermodynamics, the thermodynamic properties are evaluated, which are linearly related with the number of nitro and hydroxy groups as well as the temperature, obviously showing good group additivity. 相似文献
83.
XIE Hai-ming YAN Xue-dong YU Hai-ying ZHANG Ling-yun YANG Gui-ling XU Yang WANG Rong-shun **. Department of Chemistry Northeast Normal University Changchun P. R. China . Department of Chemistry Inner Mongolia University for Nationalities Tongliao P. R. China 《高等学校化学研究》2006,22(5):639-642
IntroductionLithium ion batteries have attracted a great interestbecause of their commercial applications in portable de-vices[1,2].Great efforts have been made to improve theenergy density of new anode materials.For example,Sn-based compounds,such as SnO… 相似文献
84.
以因肝硬化行门脉高压脾切除术的患者为研究对象,观察并记录患者术后并发门脉血栓(PVT)的情况,收集所有患者的P-选择素、血栓前体蛋白(TPP)和D2聚体(D2)含量(术后第1,3,5,7,14天)的临床观察指标数据,分析各临床观察指标与并发PVT的关系.建立相应的统计模型,并利用受试者工作特征曲线(ROC曲线)方法,比较各指标在单独和联合预测PVT时的价值和意义,确定最佳的术后预测时间和阈值,进而对PVT的形成进行较准确、早期的预测,为临床防治相关患者并发PVT打下基础. 相似文献
85.
Purpose
To determine the feasibility of using R2? map MRI for pretreatment diagnosis and monitoring of tumor response to neoadjuvant chemotherapy (NAC) in patients with breast cancer.Material and Methods
Twenty-eight women with breast cancer, as evidenced by pathology, underwent MR imaging prior to and after chemotherapy. All patients were examined by conventional MRI and R2? map imaging. Subjects were divided into major histological response (MHR) and non-major histological response (NMHR) groups. Mean R2? values of cancerous and normal glandular tissues were measured before and following NAC. Differences in R2? and ΔR2?% values between these two groups were compared with paired or independent t tests. The relationship between ΔR2?% and histological response was examined using Spearman's correlation test.Results
Before NAC, the average R2? values in carcinoma were lower than in normal glandular tissue (P<.05). After two to four cycles of NAC, the R2? values in carcinoma were increased (P<.05 ), but this change was not significant in normal glandular tissue. After NAC, ΔR2?% was significantly higher in MHR as compared to NMHR (P<.05). The ΔR2?% correlated with the histological response (r=0.581, P<.01).Conclusion
In women undergoing NAC for breast cancer treatment, R2? and ΔR2?% appear to provide predictive information of tumor response which is probably associated with changes in tumor angiogenesis and tissue oxygenation. R2? map imaging of breasts may therefore be useful in monitoring tumor response to NAC. 相似文献86.
最大利润流问题及算法 总被引:3,自引:0,他引:3
最大利润流是以运输利润最大为目标的网络优化问题 .一个利润可行流可分解为若干个路流和圈流 ,相应地该可行流的利润也等于这些路流和圈流的利润之和 .本文证明了一个可行流为最大利润流的充要条件是不存在利润增广路 ,并据此提出了求解算法 .文章最后给出了一个计算实例 . 相似文献
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89.
Four acrylamide polymer flocculants, anionic polyacrylamide P(AA-co-AM), cationic poly-acrylamide P(DMB-co-AM), nonionic polyacrylamide P(AM), and hydrophobical polyacry-lamide P(OA-co-AM) have been prepared by copolymerizing with acrylic acid, cationic monomer dimethylethyl (acryloxyethyl) ammonium bromide (DMB) and hydrophobical monomer octadecyl acrylate with acrylamide. The interactions between the flocculants withthe (012) surface of alumina crystal (Al2O3) have been simulated by molecular dynamics method. All the polymers can bind tightly with Al2O3 crystal, the interaction between the O of polymers and Al of the (012) surface of Al2O3 is significantly strong. The order of binding energy is as follows: P(DMB-co-AM)>P(OA-co-AM)>P(AA-co-AM)>P(AM), implying a better flocculation performance of P(DMB-co-AM) than the others. Analy-sis indicates that binding energy is mainly determined by Coulomb interaction. Bonds are found between the O atoms of the polymers and the Al atoms of Al2O3. The poly-mers' structures deform when they combine with Al2O3 crystal, but the deformation en-ergies are low and far less than non-bonding energies. Flocculation experiments in sus-pension medium of 1%Kaolin show a transmittancy of 90.8% for 6 mg/L P(DMB-co-AM) and 73.0% for P(AM). The sequence of flocculation performance of four polymers is P(DMB-co-AM)>P(OA-co-AM)>P(AA-co-AM)>P(AM), which is in excellent agreement with the simulation results of binding energy. 相似文献
90.
Molecular Dynamics Simulation on Scale Inhibition Mechanism of Polyepoxysuccinic Acid to Calcium Sulphate 下载免费PDF全文
Molecular dynamics simulation has been performed to simulate the interaction between PESA and the (001) face of anhydrite crystal CaSO4 at different temperatures with the presence of various number of H2O molecules. The results show that PESA can effectively prevent the growth of CaSO4 scale at 323-343 K. At the same temperature, the binding energy between PESA and the (001) face of CaSO4 for systems with various number of H2O has the order of Ebind(0H2O)>Ebind(200-400H2O)>Ebind(100H2O). For the same system at different temperatures the binding energies are close and are mainly contributed from the Coulomb interaction, including ionic bonds. The bonds are formed between the calcium atoms of anhydrite scale crystal and the oxygen atoms of the carboxyl group of PESA. Hydrogen bonds are formed between the O atoms of the carboxyl group of PESA and the H atoms of H2O. van der Waals interaction is conducive to the stability of the system of PESA, H2O, and CaSO4. The radial distribution functions of O(carbonyl of PESA)-H(H2O),O(CaSO4)-H(H2O), and O(CaSO4)-H(PESA) imply that solvents have effects on the anti-scale performance of PESA to CaSO4. 相似文献