共查询到20条相似文献,搜索用时 93 毫秒
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运用Langmuir等温线方程和理想吸附溶液理论(IAST)两种方法计算了SAPO-34在混合气体中的单个物种表面浓度,并对比了计算值与实验值的吻合程度. 考察了两个二元混合体系,分别为80 ℃的甲醇和二甲醚以及25 ℃的二甲醚和乙烯混合气,发现IAST计算值在实验压力范围内均与实验结果吻合;但是Langmuir理论计算值仅在酸性位覆盖率低于1/3时与实验值吻合较好,随着压力增加严重偏离实验值,而且Langmuir理论不能描述随压力增加低饱和吸附量物种覆盖率降低的现象. 因此,针对包含不同饱和吸附量组分的混合气,Langmuir理论仅适用于描述表面浓度低时的反应动力学,当表面浓度高时应该采用IAST方法. 相似文献
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噻吩低聚物能级结构的量子化学研究 总被引:2,自引:0,他引:2
用量子化学方法计算了系列EDOT低聚物的紫外-可见吸收光谱和前线分子轨道,得到了相应的能级结构参数.与实验值进行对比发现,计算值与实验值具有相同的变化趋势.计算结果表明,通过选择性地改变共轭主链的长度、取代基的位置和取代基的类型,可以规律性地改变化合物光谱性质和能级结构. 相似文献
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应用价键理论研究直链烷烃体系的电子转移过程, 直接计算得到的耦合能与实验值以及其它的理论计算结果一致. 对于阳离子系列, BOVB方法和VBCIS方法都给出了与实验相符的计算结果, 但对于阴离子系列, VBCIS方法的β值基本一致, 而BOVB方法的β值较大. 计算结果表明, 价键理论可以应用于电子转移的理论研究, 而VBCIS方法是研究电子转移问题的一种合适的价键计算方法. 相似文献
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用双重孔模型计算变换催化剂内扩散效率因子 总被引:2,自引:0,他引:2
本文将双重孔模型应用于WB~2、B109变换催化剂多组分反应系统内扩散效率因子的计算,并与平行交联孔模型进行比较。对WB-2加压变换催化剂用双重孔模型计算,计算值与实验值相对偏差在3.86%~53.94%;对B109变换催化剂,计算值与实验值偏差在-28.24%~-3.31%。 相似文献
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硝酸酯化合物生成热的分子轨道研究 总被引:5,自引:1,他引:4
用MINDO/3, MNDO和AM1三种SCF-MO方法, 在全优化分子几何构型的基础上, 系统地计算研究了32个硝酸酯化合物的生成热, 与实验值相比, MNDO计算结果偏大很多; MINDO/3计算值与凝聚相实验值符合较好, 由于克服了MNDO法过高地估算原子之间Van der Waals核排斥能的缺点, AM1法给出了较满意的结果: 与七个气态实验值之间存在良好的线性关系(相关系数为0.992), 其间的平均绝对差值和平均差值分别只有10.28和-1.01kJ/mol。 相似文献
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食盐与高血压发病 总被引:1,自引:0,他引:1
秦俊法 《广东微量元素科学》2014,(5):31-56
限盐被许多国家推荐作为一项降压措施,但盐与血压之间存在复杂的相关关系。从原发性高血压的危险因素、食盐与血压的关系,以及盐-血压关系分布模式3个方面综述了食盐在高血压发病中的地位。 相似文献
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Reasonable agreement is obtained in the relationship between intensities of Raman lines as measured experimentally and as calculated from an equation derived on the basis of absorbancy laws. A direct relationship between Raman intensity and concentration exists with excitation outside an absorption band, and an inverse relationship over some or all concentration ranges is found with excitation within an absorption band. 相似文献
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The relationship between the calculated energy of the HOMO-LUMO gap, where (epsilonLUMO - epsilonHOMO)/2 is defined as DeltaHL, and of the longest wavelength transition in the UV-visible spectrum, DeltaE, was examined for a series of aromatic and antiaromatic cations and dications. TD-DFT calculations accurately modeled the energies of a series of dications including fluorenylidene dications whose UV-visible spectra are reported, as well as the energies of a series of aromatic and antiaromatic monocations whose spectra were previously reported. There is a linear correlation of the energy of the longest wavelength transition, DeltaEcalc, with DeltaHL. There is no linear relationship between DeltaEcalc and the sum of the NICS values, but there is a linear relationship between DeltaEcalc multiplied by the number of atoms in the conjugated system, DeltaEcalcT, and the sum of the NICS values. There is also an approximate linear relationship between the average 1H NMR shift and the sum of the NICS values. These relationships give further support to the suggestion that the magnetic and energetic criteria of aromaticity and antiaromaticity are related. Furthermore, the data suggest that species that have DeltaEcalcT < 20 are antiaromatic whereas those with DeltaEcalcT > 30 are aromatic. 相似文献
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利用标准吉布斯自由能变化ΔrGm与标准电极电势和标准反应平衡常数间的联系,分析不同标态下电极标准电极电势间的关系。根据这一思想,以水解离平衡为例,讨论了设计原电池求化学反应平衡常数的一般方法。 相似文献
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Yoshioki S 《Journal of computational chemistry》2002,23(3):402-413
Internal and rigid-body motions of bovine pancreatic trypsin inhibitor (BPTI) and of water molecules surrounding the BPTI are studied in a vicinity of an energy minimum using a normal mode analysis proposed as the independent molecule model. Water's rigid-body motion is predominant in comparison to its internal motions. We have derived information about the relationship between the magnitude of a thermal ellipsoid of an H-bonding atom and the anisotropy of its ellipsoid, and the relationship between the magnitude of the ellipsoid and the H-bond strength. We see a relationship between vibrational frequencies (assuming rigid-body motion of the water molecules) and the H-bond strength of the water taking part in this H-bonding. Analyzing the H-bond strength, we found that a hydrogen in water is likely to H-bond to oxygen in the protein, whereas an oxygen in water has a less strong preference to H-bond to the protein. For water molecules acting as the hydrogen acceptor, strong H-bonding has longer lifetimes than weak H-bonding. 相似文献
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The effects of molecular collisions between the mobile phase and the solute in gas–solid chromatography 下载免费PDF全文
In chromatographic processes, molecular collisions between the mobile phase and the solute result in the transfer of kinetic energy. Based on these interactions, the relationship between the gauge pressure of the carrier gas at the column inlet and the partition frequency of the solute is derived; consequently, the relationship between the column temperature and partition frequency can be obtained. These relationships have been experimentally validated. The change in the peak shape described herein has been successfully explained using this relationship: the partition frequency was calculated from the theoretical plate number of a tailing peak. We propose a new mechanism for peak tailing using plate theory, which states that as the number of plates increases, the symmetry of the peak increases. 相似文献
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Relationship between salt-bridge identity and 14-helix stability of beta3-peptides in aqueous buffer
[STRUCTURE: SEE TEXT] We report a systematic analysis of the relationship between salt bridge composition and 14-helix structure within a family of model beta-peptides in aqueous buffer. We find an inverse relationship between side-chain length and the extent of 14-helix structure as judged by CD. Introduction of a stabilizing salt bridge pair within a previously reported beta-peptide ligand for hDM2 led to changes in structure that were detectable by NMR. 相似文献
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Nikulicheva O. N. Fadeeva V. P. Logvinenko V. A. 《Journal of Thermal Analysis and Calorimetry》1999,55(1):47-56
This paper reports a linear relationship between kinetic characteristics from the Arrhenius equation describing a decomposition
process found when studying the kinetics of thermolysis of spatially hindered phenols. This relationship between the coefficients
is known in the literature as a 'compensation effect'. The existence of the compensation effect permits some conclusions concerning
the decomposition mechanism and thermal characteristics of the compounds under investigation.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
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The relationship between monomer chirality and polymer structure has been studied using both theoretical and experimental methods. Atomistic models, such as the ones employed in computational protein folding and design, can be used to study the relationship between monomer chirality and the properties of polypeptides. Using a simulated evolution approach that combines side-chain epimerization with backbone flexibility, we recapitulate the relationship between basic forces that drive secondary structure formation and sequence homochirality. Additionally, we find heterochiral motifs including a C-terminal helix capping interaction and stable helix-reversals that result in bent helix structures. Our studies show that simulated evolution of chirality with backbone flexibility can be a powerful tool in the design of novel heteropolymers with tuned stereochemical properties. 相似文献