共查询到20条相似文献,搜索用时 31 毫秒
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Alessandro Vetere 《加拿大化工杂志》2007,85(1):118-121
A simple modification of the Pitzer relation to calculate second virial coefficients of polar compounds is proposed. The proposed modification is based on the use of a new parameter, β, which embodies both the contributions of acentricity and polarity to second virial coefficient values. The analytical form of the Pitzer relation is preserved and its performances are improved. Rules are given to calculate β for several classes of compounds which require only the knowledge of a few well known properties of pure compounds. A comparison between the new method and the Pitzer-Tsonopoulos relation is made on the basis of the experimental Bi data of nearly 50 compounds. 相似文献
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Kenneth T. Hartman Lucien C. Rose Raymond L. andaveer 《Journal of the American Oil Chemists' Society》1971,48(4):178-182
A simple procedure has been developed for the isolation, concentration and gas liquid chromatographic detection of the volatile
compounds in vegetable oils. The volatile compounds are isolated by bubbling purified helium through a measured quantity of
vegetable oil heated in an oil bath having a temperature of 350 F. These compounds are collected on activated charcoal and
then extracted from the charcoal with carbon disulfide containing an internal standard. The distribution of the volatile compounds
is determined with a flame ionization detector. A 400-fold concentration of the volatile compounds is achieved with this procedure.
The technique provides good reproducibility (94.3% to 105.5%) and has been successfully used for measuring the increase of
volatile compounds in vegetable oils during storage and food production. 相似文献
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组合化学,不仅可用于化合物的合成,还可用于化合物的纯化,介绍了一种新型清除剂-乙酰乙酸基甲基丙烯酸乙酯,用于提纯仲胺。 相似文献
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The volatile flavor compounds in a reverted soybean oil with a peroxide number of 4.3 meq/kg were isolated by a semicontinuous counter-current vacuum steam-distillation process, fractionated by repeated gas chromatography, and identified by infrared and mass spectrometry. A total of 71 compounds were identified, which included 19 acids, 39 nonacidic compounds, and 13 tentatively identified compounds. The acids consisted of eight normal saturated acids, nine α,β-unsaturated acids, a branch-chain acid, one hydroxy acid, two keto acids, three lactones, and one aromatic acid. The nonacidic compounds consisted of two esters, eight normal saturated aldehydes, two branched-chain aldehydes, five 2-enals, three dienals, eight ketones, eight alcohols, six hydrocarbons, and four aromatic compounds. The mechanism of formation of the identified compounds indicated that they were mostly primary or secondary autoxidation products of the hydroperoxides of the unsaturated fatty esters. Since many of the identified compounds were produced from oleic and linoleic acids, it is doubtful that linolenic acid was solely responsible for the reversion flavor. Of the compounds identified two are of unusual interest. They are 1-decyne and 2-pentyl furan. The former is the first acetylenic compound reported as the autoxidation products of unsaturated fatty esters which contained only double bonds. The latter imparts to an oil at concentrations of 5–10 ppm a beany and grassy flavor reminiscent of that of a reverted soybean oil. Since this compound is postulated as being produced by the autoxidation of linolenic acid, it is suggested that the presence of linolenic acid catalyzes the autoxidation of linoleic acid and possibly alters the decomposition pattern of its hydroperoxides. 相似文献
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A new correlation is introduced for desk calculation of gas phase heat of formation of aromatic energetic compounds that contain the elements of carbon, hydrogen, nitrogen and oxygen. Predicted gas phase heats of formation for 26 energetic compounds have a root mean square of deviation from experiment of 20.67 kJ/mol, which is in good agreement with respect to measured values of oxygen‐lean and oxygen‐rich aromatic energetic compounds. 相似文献
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Nitrogen compounds in natural soils are studied in relation to their effect on the soil removal mechanism in detergency.
Nitrogen compounds in various forms and in fairly large amts are found in natural soils, and more than 24% of these nitrogen
compounds are presumed to be high mol wt nitrogen compounds or proteins. These high mol wt nitrogen compounds which cannot
be removed by water can be removed by the detergent action of sodium dodecyl benzene sulfonate (DBS). When the detergency
of DBS was compared with nonyl phenol-polyoxyethylene adduct, the detergency for artificial soil cloths did not coincide with
results obtained with naturally soiled cloths.
These data suggest that some interaction between DBS and nitrogen compounds might have contributed to the detergent action.
If proteins were added to the present artificial soil formulation, better correlation might be expected between artificial
and natural soil detergency results in DBS evaluation. 相似文献
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Dr. David T. Manallack Dr. Richard J. Prankerd Gemma C. Nassta Dr. Oleg Ursu Prof. Tudor I. Oprea Dr. David K. Chalmers 《ChemMedChem》2013,8(2):242-255
Chemogenomics methods seek to characterize the interaction between drugs and biological systems and are an important guide for the selection of screening compounds. The acid/base character of drugs has a profound influence on their affinity for the receptor, on their absorption, distribution, metabolism, excretion and toxicity (ADMET) profile and the way the drug can be formulated. In particular, the charge state of a molecule greatly influences its lipophilicity and biopharmaceutical characteristics. This study investigates the acid/base profile of human small‐molecule drugs, chemogenomics datasets and screening compounds including a natural products set. We estimate the acid‐ionization constant (pKa) values of these compounds and determine the identity of the ionizable functional groups in each set. We find substantial differences in acid/base profiles of the chemogenomic classes. In many cases, these differences can be linked to the nature of the target binding site and the corresponding functional groups needed for recognition of the ligand. Clear differences are also observed between the acid/base characteristics of drugs and screening compounds. For example, the proportion of drugs containing a carboxylic acid was 20 %, in stark contrast to a value of 2.4 % for the screening set sample. The proportion of aliphatic amines was 27 % for drugs and only 3.4 % for screening compounds. This suggests that there is a mismatch between commercially available screening compounds and the compounds that are likely to interact with a given chemogenomic target family. Our analysis provides a guide for the selection of screening compounds to better target specific chemogenomic families with regard to the overall balance of acids, bases and pKa distributions. 相似文献
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Paul E. Rider 《应用聚合物科学杂志》1980,25(12):2975-2984
A two-parameter equation is developed that allows for the estimation of the enthalpies of hydrogen formation between two compounds. The compound acting as a proton donor is assigned a donating parameter, and the compound acting as a proton acceptor is assigned an accepting parameter. The compounds described can be assigned both a donating and an accepting parameter. These parameters are derived either from the observed linear relationship between measured hydrogen bond enthalpies and the shift in the OH stretching frequency of alcohols or from the estimated contribution of hydrogen bonding to the cohesive energy density of liquids. The donating parameters correlate well with observed autoprotolysis constants for the several compounds, and the accepting parameters correlate well with observed equilibrium constants for the protonation reaction in which a compound (base) gains a proton. The ability to estimate enthalpies is important in predicting polymeric resin solubilities in solvents. 相似文献
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介绍一类新型稳定剂——环状二硫代二氧化物。讨论了该类化合物的结构、应用条件及范围。该类化合物可防止因老化或贮存而引起的灰雾增加。性能最好的化合物是 1, 2-苯并硫代- 3’-酮- 1’ ,1’-二氧化物。该化合物的用量范围是( 0.001~ 100) mg/mol Ag,最好的用量范围是 ( 1~ 50) mg/mol Ag。该化合物可以溶解在除甲醇以外的大多数普通有机溶剂中 ,适宜的溶剂有乙腈和丙酮。它可以以液体或液体分散物的形式加入 ,也可以以固体颗粒形式加入。原则上讲可以在乳剂制备过程中的任何时间加入到卤化银乳剂中 ,但最好是在化学增感期间或者化学增感之后加入 ,卤化银乳剂可以由任何卤化物组成 ,但最好是 含 AgCl为 95%以上的乳剂。卤化银乳剂颗粒大小和几何形状可以是任意的。实验结果表明该二氧化物是性能优良的稳定剂。 相似文献
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L. L. Blyler H. E. Bair P. Hubbauer S. Matsuoka D. S. Pearson G. W. Poelzing R. C. Progelhof W. G. Thierfelder 《Polymer Engineering and Science》1986,26(20):1399-1404
A new capillary rheometer incorporated in an instrumented transfer molding press has been developed. This rheometer is effective for determining the viscosity characteristics of thermoset molding compounds under both isothermal and typical molding conditions. In examples of the rheometer's utility, the power law indices of two commercial epoxy molding compounds have been determined to be approximately 0.7. Additionally it has been shown that preconditioning typical epoxy compounds at 47 percent relative humidity causes a viscosity decrease of about 40 percent owing to plasticization of the epoxy resin. 相似文献
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The specifics of application of organic compounds in glass modification technology (aliphatic alcohols and ketones, organic acids and their salts, and organosilicon compounds) compared to the use of inorganic compounds are considered. It is demonstrated that treatment of the glass surface with organic compounds can improve mechanical, chemical, calorimetric, biochemical, and other properties of glasses. 相似文献
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A. Pëarez De Diego Martïanez 《Propellants, Explosives, Pyrotechnics》1993,18(2):93-99
This work shows an electrochemical study about triaminoguanidine nitrate, estimating the influence of the reaction compounds for the formation of TAGN and secundary compounds and hydrolysis products of this formation reaction. The conditions to determine polarographically the content of TAGN in a propellant without the interference of those compounds are verified. The method used is the differential pulse polarography in aqueous medium, due to the high solubility of TAGN in water. We have used three different media as electrolyte support, verifying the influence of different variables, as pH, drop time etc., to obtain the optimum work conditions. 相似文献
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Continuous thermodynamics is extended to the calculation of vapor-liquid equilibria with UNIFAC. For many mixtures of discrete compounds, the UNIFAC model is an efficient method for calculating vapor-liquid equilibria of systems when experimental data are scarce or non-existent. Such constraints are especially important in continuous mixtures. The continuous distribution is characterized by model compounds chosen to reproduce the TBP analysis. The UNIFAC model is extended to systems including several gases, and the new parameters for several light gases are given. The new algorithm is described in detail. Sample calculations are shown for several semi-continuous systems. 相似文献
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Twenty-seven selected equations were tested on 162 compounds with 1958 calorimetric data for their abilities to reflect the
temperature influence on the heat of vaporization of pure compounds. A new equation is recommended (overall percent deviation
0.27% and percent deviation 0.59% above 0.9T
r
). 相似文献
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Seri Jo Luca Signorile Suwon Kim Mi-Sun Kim Oscar Huertas Raúl Insa Núria Reig Dong Hae Shin 《International journal of molecular sciences》2022,23(12)
The outbreak of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) wreaked havoc all over the world. Although vaccines for the disease have recently become available and started to be administered to the population in various countries, there is still a strong and urgent need for treatments to cure COVID-19. One of the safest and fastest strategies is represented by drug repurposing (DRPx). In this study, thirty compounds with known safety profiles were identified from a chemical library of Phase II-and-up compounds through a combination of SOM Biotech’s Artificial Intelligence (AI) technology, SOMAIPRO, and in silico docking calculations with third-party software. The selected compounds were then tested in vitro for inhibitory activity against SARS-CoV-2 main protease (3CLpro or Mpro). Of the thirty compounds, three (cynarine, eravacycline, and prexasertib) displayed strong inhibitory activity against SARS-CoV-2 3CLpro. VeroE6 cells infected with SARS-CoV-2 were used to find the cell protection capability of each candidate. Among the three compounds, only eravacycline showed potential antiviral activities with no significant cytotoxicity. A further study is planned for pre-clinical trials. 相似文献
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本文提出一种专用于硅化合物的分子蒸发热(沸点时,一大气压下)估计法。 本文试将Joshi沸点-折射关系式应用于硅化合物的分子R_T值的计算,并求出若干原子团及键的R_T值。 相似文献
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Mohammad H. Keshavarz 《Propellants, Explosives, Pyrotechnics》2013,38(6):754-760
This paper describes an improved simple model for prediction of impact sensitivity of different classes of energetic compounds containing nitropyridines, nitroimidazoles, nitropyrazoles, nitrofurazanes, nitrotriazoles, nitropyrimidines, polynitroarenes, benzofuroxans, polynitroarenes with α‐CH, nitramines, nitroaliphatics, nitroaliphatic containing other functional groups, and nitrate energetic compounds. The model is based on some molecular structural parameters. It is applied for 90 explosives, which have different molecular structures. The predicted results are compared with outputs of complex neural network approach as one of the best available methods. Root mean squares (rms) of deviations of different energetic compounds are 24 and 49 cm, corresponding to 5.88 and 12.01 J with 2.5 kg dropping mass, for new and neural network methods, respectively. The novel model also predicts good results for eight new synthesized and miscellaneous explosives with respect to experimental data. 相似文献