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排序方式: 共有337条查询结果,搜索用时 15 毫秒
21.
Hooshmandi Kaveh Bayat Farhad Jahedmotlagh Mohamadreza Jalali Aliakbar 《Nonlinear dynamics》2020,100(1):731-748
Nonlinear Dynamics - This paper addresses the guaranteed cost sampled-data controller synthesis and analysis problems with application to nonlinear chaotic systems. A linear parameter-varying (LPV)... 相似文献
22.
Milani Saeideh Ghaemimanesh Fatemeh Salimi Ali Hadavi Reza Bayat Ali Ahmad Alirezapour Behrouz Rabbani Hodjattallah 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(1):267-273
Journal of Radioanalytical and Nuclear Chemistry - Receptor tyrosine kinase Ror1 is widely expressed during embryogenesis but it is absent within most mature tissues. However, expression of Ror1... 相似文献
23.
In this article, we give a necessary condition for the existence of periodic solutions of certain three dimensional autonomous systems. This may become useful in further investigations. Our claims are proved and supported by certain examples for the third order autonomous systems. 相似文献
24.
Ozonolysis reactions of alkenes are suggested to play major roles in the chemistry of the troposphere. Rate constants for the gas‐phase reactions of O3 with a series of alkenes were determined using relative rate technique based on GC/FID measurements of alkene decays. Experiments were carried out in air over the temperature range of 278–353 K at an atmospheric pressure of 760 Torr. An excess of 1,3,5‐trimethylbenzene was used as a HO radical scavenger in all experiments. Arrhenius parameters were calculated for ozonolysis of 1‐butene, 1‐pentene, 1‐hexene, 1‐heptene, 2‐methyl‐1‐butene, isobutene, trans‐2‐butene, trans‐2‐pentene, cis‐2‐pentene, trans‐2‐hexene, cis‐2‐hexene, 3‐chloropropene, 1,1‐dichloroethene, and isoprene from temperature‐dependent studies of the rate constants. The rate constants obtained in this study are compared with previous literature data. A good linear correlation between the logarithms of the rate constants and calculated HOMO energies of selected alkenes is observed. However, no clear correlation could have been drawn for chlorinated substituted alkenes. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 678–684, 2002 相似文献
25.
A new fused heterocyclic derivatives of pyrrole containing acetonitrile or cyanoacetonitrile moiety at 3-position is described by a one-pot multicomponent reaction. The reaction of dimedone, various aniline, aryl glyoxal with malononitrile/ethyl cyanoacetate/methyl cyanoacetate under mild conditions. The present method does not involve any hazardous organic solvents or catalysts. The significant features of this method are readily available starting materials, good yields, and easy purification. 相似文献
26.
Z. Bayat J. Movaffagh 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2010,84(13):2293-2299
The partition coefficients (logP) of nucleoside analogs determined by the difference in the free energies of hydration and solvation in water-saturated octanol
using the thermodynamic integration method are reported. The logP values calculated in this approach are closer to the experimental values compared to other ab initio methods. Solvation free
energy in water and octanol, free energy of cavity formation in water and Henry’s constants, and some other parameters are
estimated at the density functional theory (DFT) and Hartree-Fock level with 6–31G*, 6–31G, and 6–31+G basis sets. Surface
area, mass, refractivity, volume, polarizability, and dipole moment are calculated for some drugs with HF and DFT methods.
The results show that log P decreases with the decrease in polarizability and the increase in dipole moment. 相似文献
27.
Mohammad Bayat Hossein Imanieh Nader Zabarjad Shiraz Mohammad Shah Qavidel 《Monatshefte für Chemie / Chemical Monthly》2010,15(2):333-338
Abstract
Isocyanides, dialkyl acetylenedicarboxylates, and non-cyclic anhydrides, for example acetic anhydride or benzoic anhydride, react in one-pot to afford 2,5-diaminofuran derivatives and dialkyl (E)-2-[(N-acyl-N-alkylamino)carbonyl]-2-butenedioates in fairly good yields at room temperature. 相似文献28.
In the present study a second-order calibration strategy for high performance liquid chromatography with diode-array detection (HPLC-DAD) has been developed using parallel factor analysis (PARAFAC) and has been applied for simultaneous determination of aflatoxins B1, B2, G1 and G2 in pistachio nuts in the presence of matrix interferences. Sample preparation was based on solvent extraction (SE) followed by solid phase extraction (SPE) on Bond Elut C18 cartridges. Since the sample preparation procedure was not selective to the analytes of interest, exploiting second-order advantage to obtain concentrations of individual analytes in the presence of uncalibrated interfering compounds seemed necessary. Appropriate pre-processing steps have been applied to correct background signals and the effect of retention time shifts. Transferred calibration data set obtained from standardization of solvent based calibration data has been used in prediction step. The results of PARAFAC on a set of spiked and naturally contaminated pistachio nuts indicated that the four aflatoxins could be successfully determined. The method was validated and multivariate analytical figures of merit were calculated. The advantages of the proposed method are using a low-cost SPE step relative to standard method of aflatoxin analysis (immune affinity column assay), a unique and simple isocratic elution program for all samples and a calibration transfer for saving both chemicals and time of analysis. This study show that coupling of SPE-HPLC-DAD with PARAFAC as a powerful second-order calibration method can be considered as an alternative method for resolution and quantification of aflatoxins in the presence of unknown interferences obtained through analysis of highly complex matrix of pistachio samples and cost per analysis can be reduced significantly. 相似文献
29.
Mohammad Bayat Nader Zabarjad Shiraz Seyyed Hajar Hosseini 《Helvetica chimica acta》2010,93(11):2189-2193
A novel, efficient one‐pot approach for the synthesis of furopyrimidine and oxobenzofuran derivatives 4 by a multicomponent reaction of an isocyanide, an aldehyde, and a CH‐acid compound in CH2Cl2 is reported (Scheme 1 and Table). The reactions were completed after 20 h at room temperature. This method has the advantages of high yields, simple methodology, and easy workup. 相似文献
30.
Mercuric fluoride (HgF2), as a light-sensitive inorganic compound, in the presence of dioxygen is able to convert various α-aryl- and α,α-diarylcarboxylic acids into the corresponding aldehydes and ketones selectively under photoirradiation via trapping of the benzylic radical by O2. 相似文献