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The relationship between chemical structures and biodegradation rates (k b) of 22 polycyclic aromatic hydrocarbons (PAHs) was studied using density functional theory (DFT) and stepwise multiple linear regression analysis (SMLR) method.The equilibrium geometries and vibration frequency have been investigated at the B3LYP/6-31+G(d,p) level by thinking Solvent effects using a selfconsistent reaction field (SCRF) based on the polarizable continuum model (PCM).It was concluded that the biodegradation rate was closely related to its molecular structure,and there is one high correlation coefficient between the in-plane bending vibration frequency of the conjugated ring of PAHs (Freq) and k b.By means of regression analysis,the main factors affecting the biodegradation rate were obtained and the equation of quantitative structure-activity relationship (QSAR) was successfully established kb =-0.653+0.001Freq+0.068CQ+0.049N1.Statistical evaluation of the developed QSAR showed that the relationships were statistically significant and the model had good predictive ability.The fact that a bending frequency is more important than the HOMO or LUMO energies in predicting k b suggests that the bending of benzene ring might play an important role in the enzymatic catalysis of the initial oxidation step. 相似文献
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采用水热法合成了碱式硫酸镁晶须,利用扫描电镜、透射电镜、X射线能谱仪和X射线衍射仪等对产物的形貌和组成进行表征。通过考察不同温度下SO42-浓度随时间的变化,对碱式硫酸镁晶须的结晶动力学进行了研究。利用MATLAB软件和Runge-Kutta数值解法对实验数据进行处理,得出不同温度下晶须的结晶动力学方程。对晶须的几种生长机理模型进行分析发现,低温和高温的动力学模型不同,反应温度为170℃、180℃、190℃时的动力学模型分别为MB-1、MB-2和MB-3,结晶机理为多核控制表面生长,结晶速率由表面反应控制;反应温度为200℃和210℃时,结晶机理发生了变化,为单核控制表面生长,结晶动力学模型分别为MC-2和MC-3。 相似文献
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针对产品具有一定替代性的两个竞争企业(分别为企业1和企业2)和存在规模效应的上游供应商的外包决策问题, 构建了企业1 外包前后各方的利润模型,求解了下游企业的外包和自产的最优策略以及供应商的最佳批发价格,分析了企业1 的外包策略对企业2 和供应商的外包决策的影响,比较了产品替代性对外包前后各决策变量的影响。研究发现:当企业的单位生产成本高于外包成本时,企业也可能选择自产;而当企业的单位生产成本低于外包成本时,企业也可能选择产品外包。并对模型进行进一步的拓展,比较了下游企业作顺序和同时外包决策两种情景的异同。 相似文献
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铁基超细粒子催化剂的F—T反应性能研究:Ⅲ.反应条件的影响,稳定性… 总被引:2,自引:2,他引:0
详细考察了反应条件,包括温度、压力、空速、原料气组成对Fe-Mn超细粒子催化剂F-T反应性能的影响。结果表明,反应条件对催化剂活性,低碳烯烃、CO2以及CH4选择性等都有一定的影响。在所考察的时间范围(840h)内,即使在很宽的作用范围操作,催化剂的稳定性仍能保持良好。硫中毒使催剂的F-T反应活性逐渐下降,产物向轻质组分偏移,C2~C4组分中烯/烷比值下降,但C2~C4烯占总烃的质量百分比略有升高 相似文献
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