排序方式: 共有154条查询结果,搜索用时 15 毫秒
141.
Shapour Heidarkhani Yulin Zhao Giuseppe Caristi Ghasem A. Afrouzi Shahin Moradi 《Applicable analysis》2017,96(8):1401-1424
In this paper, the existence of infinitely many solutions for perturbed systems of impulsive non-linear fractional differential equations including Lipschitz continuous non-linear terms is discussed. The approach is based on variational methods. In addition, examples are presented to illustrate the feasibility and effectiveness of the main results. 相似文献
142.
Reihaneh Malakooti Ghasem Rezanejade Bardajee Somayyeh Hadizadeh Hassan Atashin Hadiseh Khanjari 《Transition Metal Chemistry》2014,39(1):47-54
An iron Schiff base complex was encapsulated in SBA-15 mesoporous silica to afford a Fe(III)-Schiff base/SBA-15 heterogeneous nanocatalyst for the synthesis of pyridopyrazine and quinoxaline heterocycles. These reactions proceeded in water with excellent yields. The catalyst was characterized by physico-chemical and spectroscopic methods and found to retain the characteristic channel structures of the SBA-15, allowing good accessibility of the encapsulated metal complex. 相似文献
143.
Arash Mouradzadegun Fatemeh Ghasem Hezave Maryam Karimnia 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):84-87
Regiospecific synthesis of some new hexasubstituted 2H-thiopyrans was examined by reductive alkylation of pentaphenylthiopyrylium perchlorate and found to be in quantitative yields. Under our experimental conditions, the formation of unstable thiabenzene intermediates could be observed through detectable color changing during the addition of C-nucleophiles to thiopyrylium perchlorate. Moreover, the effect of phenyl groups on the 3,5-positions of thiopyrylium perchlorate on the regioselectivity were compared with other analogs having methyl groups on the same positions. 相似文献
144.
Polyamide-6/poly(epichlorohydrin - co - ethylene oxide) (PA6/ECO) nanocomposites were prepared with 6 wt.% organoclay and different ECO content from 5 to 40 wt.%,
via two-step melt blending process. The effects of organoclay and rubber content on the morphological and rheological properties
of samples have been studied. Samples have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM),
and rheometry in small amplitude oscillatory shear. XRD results indicate that the nanoclay platelets are partially exfoliated
in both PA6 and ECO phases. The higher rubber content of nanocomposite samples results in higher exfoliation degree of the
nanoclay layers. SEM photomicrographs of samples show that the size of rubber droplets increases by the introducing of nanoclay.
Oscillatory shear measurements show that the storage modulus of nanocomposite samples significantly increases in comparison
with unfilled blends. The formation of physical network is the prime cause of such increase. Moreover, presence of nanoclay
dramatically increases melt yield stress of the samples. Palierne emulsion model has been applied to predict the rheological
behavior of unfilled blends. A quantitative agreement between Palierne model and those of experimental data is found for low
ECO content samples. 相似文献
145.
Ghasem Firouzzadeh Pasha Sakineh Asghari Mahmood Tajbakhsh Mojtaba Mohseni 《中国化学会会志》2019,66(6):660-667
A series of bicyclopyrazolones were synthesized from the condensation reaction of methyl 4‐oxotetrahydro‐2H‐thiopyran‐3‐carboxylate with hydrazine derivatives in ethanol. All synthesized products were characterized by FT‐IR, 1H, and 13C NMR spectral data, elemental analyses, and mass spectrometry. The antibacterial and antifungal activities of these compounds were evaluated against Staphylococcus aureus and Bacillus subtilis as Gram‐positive bacteria, Escherichia coli and Pseudomonas aeruginosa as Gram‐negative bacteria, and the fungus Candida albicans. The results revealed that bicyclopyrazolones including an aryl or aryl sulfonyl group in the N‐2 position of the pyrazolone moiety are the most effective against all the microorganisms studied in this work. 相似文献
146.
Nickel oxide nanoparticle (NiO?NP) and polypyrrole (PPy) composite were deposited on a Pt electrode for fabrication of a urea biosensor. To develop the sensor, a thin film of PPy?NiO composite was deposited on a Pt substrate that serves as a matrix for the immobilization of enzyme. Urease was immobilized on the surface of Pt/PPy?NiO by a physical adsorption. The response of the fabricated electrode (Pt/PPy?NiO/Urs) towards urea was analyzed by chronoamperometry and cyclic voltammetry (CV) techniques. Electrochemical response of the bio‐electrode was significantly enhanced. This is due to electron transfer between Ni2+ and Ni3+ as the electro‐catalytic group and the reaction between polypyrrole and the urease‐liberated ammonium. The fabricated electrode showed reliable and demonstrated perfectly linear response (0.7–26.7 mM of urea concentration, R2= 0.993), with high sensitivity (0.153 mA mM?1 cm?2), low detection of limit (1.6 μM), long stability (10 weeks), and low response time (~5 s). The developed biosensor was highly selective and obtained data were repeatable and reproduced using PPy‐NiO composite loaded with immobilized urease as urea biosensors. 相似文献
147.
Abaee MS Mojtahedi MM Pasha GF Akbarzadeh E Shockravi A Mesbah AW Massa W 《Organic letters》2011,13(19):5282-5285
An aqueous medium containing catalytic amounts of a tertiary amine was employed to direct the chemoselectivity of the reaction of aldehydes with 1a. With DBU, 2 was formed at room temperature as a rare exemplary of Baylis-Hillman reactions in heterocyclic enones. DABCO alternated the pathway toward an aldol reaction to form syn/anti mixtures of 3 with the syn isomers being the major products. With Et(3)N, aldol condensation dominated. 相似文献
148.
Ghasem Rezanejade Bardajee Ali PourjavadiRouhollah Soleyman 《Colloids and surfaces. A, Physicochemical and engineering aspects》2011,392(1):16-24
A novel nano-porous hydrogel (NPH) was synthesized via graft copolymerization of sodium acrylate (Na-AA) and acrylamide (AAm) onto salep backbones and its application as a carrier matrix for oral delivery of tetracycline hydrochloride (TH) was investigated. The Taguchi method as a strong experimental design tool was used for synthesis optimization. The swelling behavior of optimum hydrogel was measured in various media. The hydrogel formation was confirmed by Fourier transform infrared spectroscopy (FT-IR) and thermogravimetrical analysis (TGA). The study of the surface morphology of the hydrogels using SEM and AFM showed a nanoporous (average pore size: 180 nm) structure for the sample obtained under optimized conditions. The drug delivery results demonstrated that this NPH could successfully deliver a drug to the intestine without losing the drug in the stomach, and could be a good candidate as an orally administrated drug delivery system. 相似文献
149.
Ghasem Marandi Malek Taher Maghsoodlou Reza Heydari Sayyed Mostafa Habibi-Khorassani Roya Kabiri Zahra Gharechahi 《Phosphorus, sulfur, and silicon and the related elements》2013,188(7):1395-1403
Protonation of the reactive 1:1 intermediates produced in the reactions between triphenylphosphine and dialkyl acetylenedicarboxylates by 1-amino-anthraquinone or 1,5-diphenylcarbazone as a core dye leads to vinyl phosphonium salts, which undergo Michael addition with conjugate base of NH compounds to produce stable phosphorus ylides as novel dyes in fairly good yields. These ylides can exist in two geometrical isomers (Z) and (E) for 3, because the negative charge of the ylide moiety of these compounds are strongly conjugated with the adjacent carbonyl group. Rotation around the carbon–carbon double bond is slow in the (Z) and (E) geometrical isomers on the NMR time scale at ambient temperature. These compounds are assigned by their IR, 1H, 13C NMR spectral data as well as their mass spectroscopic data. 相似文献
150.