排序方式: 共有159条查询结果,搜索用时 46 毫秒
91.
Asadi Sara Zebarjad Maedeh Masoudi Hamidreza Mehrabi Hossein 《Research on Chemical Intermediates》2022,48(1):251-265
Research on Chemical Intermediates - The aim of present investigation is survey reactivity of 2-aminopyridine and Meldrum’s acid in the presence of aryl glyoxals or aryl aldehydes. The ethyl... 相似文献
92.
Fedor M. Miloserdov David McKay Bianca K. Muoz Hamidreza Samouei Stuart A. Macgregor Vladimir V. Grushin 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(29):8586-8590
[(Ph3P)3Ru(L)(H)2] (where L=H2 ( 1 ) in the presence of styrene, Ph3P ( 3 ), and N2 ( 4 )) cleave the Ph X bond (X=Cl, Br, I) at RT to give [(Ph3P)3RuH(X)] ( 2 ) and PhH. A combined experimental and DFT study points to [(Ph3P)3Ru(H)2] as the reactive species generated upon spontaneous loss of L from 3 and 4 . The reaction of 3 with excess PhI displays striking kinetics which initially appears zeroth order in Ru. However mechanistic studies reveal that this is due to autocatalysis comprising two factors: 1) complex 2 , originating from the initial PhI activation with 3 , is roughly as reactive toward PhI as 3 itself; and 2) the Ph I bond cleavage with the just‐produced 2 gives rise to [(Ph3P)2RuI2], which quickly comproportionates with the still‐present 3 to recover 2 . Both the initial and onward activation reactions involve PPh3 dissociation, PhI coordination to Ru through I, rearrangement to a η2‐PhI intermediate, and Ph I oxidative addition. 相似文献
93.
Amin Zeinali Zeinab Hosseini Dastgerdi Farshad Kheiri 《Journal of Macromolecular Science: Physics》2020,59(5):263-283
AbstractGelatin/montmorillonite bionanocomposite hydrogels containing 0, 5 and 10?wt.% of montmorillonite were prepared via two different techniques, either a cooling or drying method. In addition, gelatin/polyvinyl alcohol/montmorillonite bionanocomposite hydrogels having gelatin/polyvinyl alcohol ratios of 1/1, 1/2 and 2/1, loaded with 0, 5 and 10?wt.% of montmorillonite, were prepared via a cyclic freezing-thawing technique. The microstructural properties of both types of the prepared bionanocomposite hydrogels were investigated using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The gel fraction, swelling behavior and drying kinetics of all prepared bionanocomposite hydrogels were also studied. The XRD and SEM results showed a porous structure with a possible exfoliated morphology for both types of the prepared bionanocomposite hydrogels. In addition, the gel fraction of the bionanocomposite hydrogels increased and a more entangled and crosslinked network with a decreased pore size was obtained by increasing the loading level of montmorillonite for both types of the bionanocomposite hydrogels. The swelling ratio and drying rate of both types of the bionanocomposite hydrogels could be increased by decreasing the PVA portion or MMT loading level, while the swelling and drying ability of the gelatin/montmorillonite bionanocomposite hydrogels prepared via the cooling method was higher than those of the corresponding samples prepared via the drying method. 相似文献
94.
Eirinaios I. Vrettos Dr. Ibai E. Valverde Dr. Alba Mascarin Dr. Patrick N. Pallier Dr. Linda Cerofolini Prof. Marco Fragai Prof. Giacomo Parigi Baydaa Hirmiz Nick Bekas Nathalie M. Grob Evgenios Κ. Stylos Hamidreza Shaye Prof. Mark Del Borgo Prof. Marie-Isabel Aguilar Prof. Francesca Magnani Dr. Nelofer Syed Prof. Timothy Crook Emal Waqif Dr. Essam Ghazaly Prof. Vadim Cherezov Prof. Robert E. Widdop Prof. Claudio Luchinat Prof. Adina T. Michael-Titus Prof. Thomas L. Mindt Prof. Andreas G. Tzakos 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(47):10690-10694
Mutating the side-chains of amino acids in a peptide ligand, with unnatural amino acids, aiming to mitigate its short half-life is an established approach. However, it is hypothesized that mutating specific backbone peptide bonds with bioisosters can be exploited not only to enhance the proteolytic stability of parent peptides, but also to tune its receptor subtype selectivity. Towards this end, four [Y]6-Angiotensin II analogues are synthesized where amide bonds have been replaced by 1,4-disubstituted 1,2,3-triazole isosteres in four different backbone locations. All the analogues possessed enhanced stability in human plasma in comparison with the parent peptide, whereas only two of them achieved enhanced AT2R/AT1R subtype selectivity. This diversification has been studied through 2D NMR spectroscopy and unveiled a putative more structured microenvironment for the two selective ligands accompanied with increased number of NOE cross-peaks. The most potent analogue, compound 2 , has been explored regarding its neurotrophic potential and resulted in an enhanced neurite growth with respect to the established agent C21. 相似文献
95.
Bifurcation of limit cycles in small perturbations of a hyper-elliptic Hamiltonian system with two nilpotent saddles
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Rasool Kazemi Hamidreza Zohouri Zangeneh 《Journal of Applied Analysis & Computation》2012,2(4):395-413
In this paper we study the first-order Melnikov function for a planar near-Hamiltonian system near a heteroclinic loop connecting two nilpotent saddles. The asymptotic expansion of this Melnikov function and formulas for the first seven coefficients are given. Next, we consider the bifurcation of limit cycles in a class of hyper-elliptic Hamiltonian systems which has a heteroclinic loop connecting two nilpotent saddles. It is shown that this system can undergo a degenerate Hopf bifurcation and Poincarè bifurcation, which emerges at most four limit cycles in the plane for sufficiently small positive ε. The number of limit cycles which appear near the heteroclinic loop is discussed by using the asymptotic expansion of the first-order Melnikov function. Further more we give all possible distribution of limit cycles bifurcated from the period annulus. 相似文献
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Safar Irandoust-pakchin Hossein Kheiri Somayeh Abdi-mazraeh 《Computational Mathematics and Mathematical Physics》2013,53(7):920-932
In this paper, we introduce a modification of He’s variational iteration, homotopy analysis and optimal homotopy analysis methods for solving fractional boundary value problems. It is illustrated that the proposed methods are powerful fast numerical tools to find accurate solutions. It is illustrated that efficiency of these methods is based on proper choosing of initial guess. 相似文献
98.
Boroujeni K. P. Shahrokh M. Kiani K. Farokhnia A. Kazemi R. Kheiri F. 《Russian Journal of Organic Chemistry》2020,56(10):1823-1831
Russian Journal of Organic Chemistry - Some bimetallic and trimetallic magnetic nanoalloys based on cobalt, copper, and silver have been synthesized and used as and green catalysts for the... 相似文献
99.
Evaluation of UiO‐66 metal organic framework as an effective sorbent for Curcumin's overdose
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Hossein Molavi Mostafa Zamani Mozhgan Aghajanzadeh Hamidreza Kheiri Manjili Hossein Danafar Akbar Shojaei 《应用有机金属化学》2018,32(4)
Metal organic frameworks (MOFs) UiO‐66 (UiO stands for University of Oslo) and NH2‐UiO‐66 were prepared and characterized as sorbent (antidotal agents) for curcumin (CUR) adsorption. The structure of products were characterized by X‐ray powder diffraction (XRD), Field emission scanning electron microscopy (FESEM), thermogravimetric analysis (TGA), Attenuated Total Reflectance‐Fourier transform infrared spectroscopy (ATR‐FTIR), and N2 adsorption–desorption measurements. FESEM showed NH2‐UiO‐66 displayed symmetrical crystals with triangular base pyramid morphology, with the particle size around 100 nm and uniform size distribution. Adsorption capacities of CUR/MOFs with different mass ratios in the feed were investigated in the present study, and this investigation revealed that when the CUR/MOFs with mass ratio was around 0.4, the absorption capacity of NH2‐UiO‐66 had tended to maximum. Although, functionalization reduced the specific surface area and free volume, introducing polar amine groups could improve the affinity of NH2‐UiO‐66 respect to CUR. Kinetic studies showed that the kinetic data are well fitted with the pseudo‐ second‐order model. MTT assay revealed that MOFs at the concentration range of 0–560 μg/ml had no cytotoxic effect on the Human Foreskin Fibroblast normal cell line (HFF‐2). These results suggest that these MOFs could be safe as sorbent for adsorb CUR from the body. 相似文献
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