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111.
Anna I. Suvorova Lyudmila Yu. Demchik Aza L. Peshekhonova Olga A. Sdobnikova 《Macromolecular chemistry and physics.》1993,194(5):1315-1321
The phase equilibrium of plasticized polymer systems on the basis of cellulose diacetate and ethylene glycol esters of dibasic aliphatic acids (from oxalic acid to 1,10-decanedicarboxylic acid) was studied and the solubility parameters and the thermodynamic interaction parameters of the components were calculated. It is shown that an increase in molecular weight of the plasticizers leads to a lower miscibility of the components, a fact which is reflected in a regular rise of the upper critical solution temperature (UCST), a tendency of the systems for gelation, a decrease of the solubility parameter of the plasticizer δ1, and a growth of the interaction parameters χH and χ12. The results are discussed in terms of the existing theories for polymer solutions. 相似文献
112.
Alcohol effects on the percentage of beta waves in the electroencephalograms of twins 总被引:2,自引:0,他引:2
Electroencephalogram (EEG) recordings were made from 26 pairs of monozygotic (MZ) and 26 pairs of dizygotic (DZ) adult male twins, before and after alcohol ingestion. After a baseline EEG and a light breakfast, 1.2 ml/kg of ethanol was given orally over 15 min and the EEG repeated four times at hourly intervals. Alcohol caused a significant drop in the percentage of beta waves (14-30 cycles/sec) during the 1st hr. For the percentage of beta waves in 38 pairs of twins with complete data, MZ twin beta-wave intraclass correlations (RMZ) ranged between 0.85 and 0.91 before and after alcohol, but the DZ intraclass correlations (RDZ) started at 0.54 and fell to 0.05 at 2 hr after alcohol before recovering to baseline levels. These correlations resulted in heritability estimates [2(RMZ-RDZ)] of 0.68 at baseline and 1.73 at 2 hr. A heritability of 1.43 was found for the 1st hr drop in percentage of beta waves (RMZ = 0.78, RDZ = 0.06). These unrealistically high heritabilities, due to RDZ's approaching 0.0, suggest a failure of assumptions in the linear twin model that was used. Also, these findings are similar to, but more exaggerated than, findings in resting EEG's and visually evoked EEG potentials of twins and are compatible with the influence of gene interactions. 相似文献
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用动态扭摆法测试聚丙烯酸丁酯橡胶增韧环氧树脂的动态力学行为,研究在环氧树脂低固化度和高固化度时,橡胶活性官能团种类(环氧基官能团与羧基官能团)和数量(官能度)对其影响。研究体系中橡胶玻璃化转变温度(Tg)的移动大小,与橡胶和基体树脂健合程度之间的关系。 相似文献
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根据生物代谢状态方程和代谢反应一般表达式,解析由葡萄糖生成乙醇的生物代谢过程。结果表明,该过程是一个可达到热力学最大可能性的过程,该代谢过程的热力学最大可能性转化率为51.1%,方程的解与依据代谢途径直接核算的结果一致,说明这些代谢途径已实现了热力学上的最大可能性。研究表明由葡萄糖生成乙醇的代谢过程具有非连续的能级特征。研究结果为深入解析代谢过程的物理意义奠定了基础。 相似文献
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The effect of prolonged treatment with amitriptyline on the secretory activity of rat salivary glands evoked by parasympathetic nerve stimulation and isoprenaline administration has been studied. Low doses of amitriptyline (10 mg/kg per day for 2 or 4 weeks), did not significantly affect salivary flow evoked by either parasympathetic nerve or isoprenaline stimulation. Higher doses of amitriptyline (50 mg/kg/day for 2 or 4 weeks) however, markedly decreased parasympathetic-evoked salivary secretion (flow and volume) from both parotid and submandibular glands, while isoprenaline-evoked secretions were unaffected. Sodium, potassium, and calcium concentrations of nerve-elicited or isoprenaline-evoked saliva were not significantly altered by amitriptyline treatment. Protein concentration and amylase activity of nerve-elicited parotid saliva were, however, greatly increased by chronic amitriptyline administration. Possible mechanisms for drug-induced increase in nerveelicited salivary protein concentration include changes in cholinergic receptor binding, release of neuropeptides and variations in phosphatidylinositol turnover, which need further study. 相似文献