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81.
关新民 《新疆大学学报(理工版)》2002,19(1):95-99
介绍了采用MATLAB V5.2提供的模糊逻辑工具箱来设计研究电孤纺电极调节系统中的模糊--PD控制器,讨论了在SIMULINK环境下模糊-PD控制器的参数自调速原理、结构、建立模糊控制规则库和模糊推论方法,并给出仿真结果与结论。 相似文献
82.
《Journal of separation science》2017,40(8):1674-1685
It is difficult to identify unknown impurities in nucleotide analogues by mass spectrometry because mass‐spectrometry‐incompatible mobile phases need to be used to separate the major ingredient from impurities. In this study, vidarabine monophosphate was selected, and unknown impurities were identified by online heart‐cutting two‐dimensional high‐performance liquid chromatography and linear ion trap mass spectrometry. The one‐dimensional reversed‐phase column was filled with a mobile phase containing nonvolatile salt. In two‐dimensional high‐performance liquid chromatography, we used an Acclaim Q1 column with volatile salt, and the detection wavelength was 260 nm. The mass spectrum was scanned in positive‐ and negative‐ion mode. The online heart‐cutting and online demineralization technique ensured that the mobile phase was compatible with mass spectrometry; seven impurities were identified by MS2 and MS3 fragments. The mass fragmentation patterns of these impurities were investigated. The two isomers were semiprepared and complemented by nuclear magnetic resonance. The results were further compared with those of normal‐phase high‐performance liquid chromatography with mass spectrometry. The online heart‐cutting two‐dimensional high‐performance liquid chromatography with mass spectrometry was superior in identifying more impurities. The method solves the problem of incompatibility between the mobile phase and mass spectrometry, so it is suitable for identifying unknown impurities. This method may also be used for investigating impurities in other nucleotide analogues. 相似文献
83.
From conductance and viscosities measurements on Pr4NCl, Et4NBr, and AgNO3 in acetonitrile and Et3NBr in nitrobenzene, the Walden products of the anion at infinite dilution were determined in presence of various concentrations of substituted benzoic acids. From these data it was possible to compute the values of the Walden products of the once complexed anions and to estimate the order of magnitude of the Walden products of twice complexed anions. Stokes' law is not obeyed, and the Walden products are not proportional to the third root of the molar volume of the complexed ions, as a consequence of their lack of sphericity. The assumption that the drag force which acts on the ions is proportional to the volume of the substituents results in a linear expression between the reciprocals of the Walden products and the molar volume of the ligands. The experimental results fit this expression within the limits of the experimental errors, and the slopes of the lines are nearly the same for all the anions and for the two solvents studied here, namely, 2.5×10–4 ohm-cm–5 mole-cP–1. 相似文献
84.
85.
Infrared Spectra,Structures and Bonding of Binuclear Transition Metal Carbonyl Cluster Ions 下载免费PDF全文
Binuclear transition metal carbonyl clusters serve as the simplest models in understanding metal-metal and ligand bonding that are important organometallic chemistry catalysis. Binuclear first row transition metal carbonyl ions are produced via a pulsed laser vaporization/supersonic expansion cluster ion source in the gas phase. These ions are studied by mass-selected infrared photodissociation spectroscopy in the carbonyl stretching frequency region. Density functional theory calculations have been performed on the geometric structures and vibrational spectra of the carbonyl ions. Their geometric and electronic structures are determined by comparison of the experimental IR spectra with the simulated spectra. The structure and the metal-metal and metal-CO bonding of both saturated and unsaturated homonuclear as well as heteronuclear carbonyl cluster cations and anions are discussed. 相似文献
86.
《International journal of quantum chemistry》2018,118(4)
The electron affinities of organic molecules obeying Hückel's rule of aromaticity are vanishingly small, if not negative. For example, benzene, a classic example of an aromatic molecule, has an electron affinity of −1.15 eV. Using density functional theory, we have systematically calculated the electron affinities and vertical detachment energies of C6H6 by substituting H with halogen (F) and superhalogen (BO2) moieties, as well as replacing one of the C atoms with B. The ground state geometries were obtained by examining about 330 isomers. The electron affinities are found to steadily increase with these substitutions/replacements, even surpassing that of Cl, the element with the highest electron affinity in the periodic table, in the case of C5BH(BO2)5. In some special cases such as C6H5(BO2) the electron affinity and vertical detachment energy differ by as much as 5 eV, indicating substantial changes in the geometry as the electron is removed from the anion. We hope that the ability to change the negative electron affinity of C6H6 to large positive values by substituting H and/or replacing C atom will motivate experimental studies. 相似文献
87.
以晶体硅金刚线切割废料为原料,通过氮化反应制得氮化硅,既回收了金刚线切割废料,又解决了环境污染的问题。 通过X射线衍射仪(XRD)、扫描电子显微镜(SEM)和X射线能量色谱仪(EDS)等技术手段研究了原料经HCl和HF酸洗净化后制备氮化产物的物相组成、组分质量分数和微观形貌的影响。 结果表明,HCl酸洗后切割废料制备的氮化产物中主要物相为Si2N2O和Si3N4,而HF酸洗后切割废料制备的氮化产物中主要物相为Si3N4。 氮化产物中Si2N2O的形成与切割废料中SiO2的质量分数有关,降低原料中SiO2的质量分数是切割废料经过高温氮化制得氮化硅的前提。 相似文献
88.
Data about the existence of native HO? CH2? CH2? OH (MEG) in natural wines and champagne has led to delicate questions because of legal decisions already made to declare wine or champagne illegal for sale if the MEG concentrations found are above 10 mg/liter. Action has been taken because of the DEG (diethylene glycol) disaster in European wines of 1985…86. An incorrect legal decision was made due to the belief that MEG cannot be produced biochemically by grape vines. A further reason may be lack of correct data on native MEG trace concentrations, as a result of the special behavior of this diol. As first member of a homologous series whose higher members (C4) are normally found in all wines at quite high concentration levels, MEG shows extremely adsorptive behavior. The solution of the chromatographic problems is summarized in this paper. MEG concentrations in Riesling as example are in the range of 2 to 6 mg/liter and can easily be increased by biotechnological steps to a level of around 10 to 60 mg/liter. This is again due to the specific adsorptive behavior of MEG, which can be enriched on filter surfaces and displaced when the wine acidity changes with changing types. In order to control and guarantee the qualitative and quantitative results of MEG analyses we used a combination of Deans heart cutting on-line with Multi-Chromatography. It was easy to produce false data by many otherwise useful single column or two-dimensional separation processes, etc. 相似文献
89.
The surface pressure-molecular area curve of the mixed monolayer of 16-(9-anthroyloxy) palmitic acid (16AP) and fatty acid (palmitic or stearic acids) showed various kink points which indicated the phase transitions of the monolayer. On the basis of the surface phase rule, the phase diagrams of the mixed monolayer were elucidated. The bifunctional molecule, 16AP, takes two orientations in a monolayer state, that is, horizontal and vertical ones. Horizontally oriented 16AP and vertically oriented fatty acid form a mixed monolayer but this exhibits deviation from the ideal mixing, which was interpreted in terms of the surface regular solution theory. On the other hand, the 16AP molecule in the vertical state was found to be immiscible with the fatty acid molecule in a monolayer de spite both molecules being vertical to the surface and parallel to each other. This was caused by the participation of the 9-anthroyloxy moiety of 16AP in the interaction of 16AP and fatty acid in the hydrophobic region of the monolayer. 相似文献
90.
为掌握生物质中钾对生物质超临界水降解过程的影响,选择生物质气化转化过程中生成的重要小分子中间产物甲醛作为研究对象,研究不同工艺条件下(反应温度400~650℃、压力23~29 MPa、停留时间4~12 s),单一钾成分(KHCO3/K2CO3/KCl)或混合钾成分(KHCO3、K2CO3、KCl)对甲醛超临界水降解气体产物的影响。结果表明,KHCO3、K2CO3、KCl、混合钾均降低了气体产物中CO的体积分数,提高了CO2的体积分数,但KCl的影响程度弱于其他三种钾成分。此外,由于不同钾成分均不利于气体产物中CO和H2体积分数的提高,从而使得气体产物的热值降低。KHCO3、K2CO3、KCl、混合钾均降低了H2、CO、CO2的产率以及气化率,其对H2产率以及气化率的抑制程度从大到小依次为:混合钾、KHCO3、K2CO3、KCl,且提高反应温度、延长反应停留时间时抑制气体生成的作用相对越明显。而当反应压力改变时,钾成分对H2产率及气化率的影响程度变化较小。较高反应温度、较高反应压力、较长停留时间时,混合钾中各成分出现协同作用,明显抑制了气体产物的生成。 相似文献