排序方式: 共有109条查询结果,搜索用时 15 毫秒
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A simple and efficient method has been developed for the synthesis ofα-amino nitriles from aldehydes,amines and trimethylsilyl cyanide(Me3SiCN) in the presence of a catalytic amount of cyanuric acid at room temperature. 相似文献
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Ammar Sheykhi-Estalkhjani Nosrat O. Mahmoodi Asieh Yahyazadeh Meysam Pasandideh Nadamani Hossein Taherpour Nahzomi 《Tetrahedron》2019,75(6):749-756
A facile two-directional synthesis of new pyrimido[5,4-d]pyrimidine-2,8-dione was reported via an efficient reaction of premade bis-aldehydes and 1-(2-amino-1,2-dicyanovinyl)-3-phenylurea in the presence of triethylamine as the base and Cu (II) as catalyst. As there is controversy about the formation of two types of products, that is, purine or pyrimidine ring containing compounds in the reaction of diaminomaleonitrile with isocyanates and aldehydes, the computational model chemistry has been employed to obtain new insight about this reaction and determining the dominant pathway of the process. Using DFT model, two alternative pathways have been explored and geometrical isomerization of central double bond has been considered. Accordingly, the evaluated energy barriers affirm the formation of six-membered pyrimidine ring as the major product in the presence of CuCl2 as the catalyst and MeOH as solvent. 相似文献
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Farhad Shirini Meysam Alipour Khoshdel Masoumeh Abedini Seyyed Vahid Atghia 《中国化学快报》2011,22(10):1211-1214
Nanocrystalline TiO2 was used as an efficient and recyclable catalyst for the chemoselective trimethylsilylation of primary and less hindered secondary alcohols and phenols with hexamethyldisilazane(HMDS).All reactions were performed under mild and completely heterogeneous conditions in good to excellent yields. 相似文献
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Farzaneh Asadpour Xin-Wei Zhang Mohammad Mazloum-Ardakani Meysam Mirzaei Soodabeh Majdi Andrew G. Ewing 《Chemical science》2021,12(30):10273
The release of the cargo from soft vesicles, an essential process for chemical delivery, is mediated by multiple factors. Among them, the regulation by the interaction between the chemical cargo species and the vesicular membrane, widely existing in all vesicles, has not been investigated to date. Yet, these interactions hold the potential to complicate the release process. We used liposomes loaded with different monoamines, dopamine (DA) and serotonin (5-HT), to simulate vesicular release and to monitor the dynamics of chemical release from isolated vesicles during vesicle impact electrochemical cytometry (VIEC). The release of DA from liposomes presents a longer release time compared to 5-HT. Modelling the release time showed that DA filled vesicles had a higher percentage of events where the time for the peak fall was better fit to a double exponential (DblExp) decay function, suggesting multiple kinetic steps in the release. By fitting to a desorption–release model, where the transmitters adsorbed to the vesicle membrane, the dissociation rates of DA and 5-HT from the liposome membrane were estimated. DA has a lower desorption rate constant, which leads to slower DA release than that observed for 5-HT, whereas there is little difference in pore size. The alteration of vesicular release dynamics due to the interaction between the chemical cargo and vesicle membrane lipids provides an important mechanism to regulate vesicular release in chemical and physiological processes. It is highly possible that this introduces a fundamental chemical regulation difference between transmitters during exocytosis.The release of the cargo from soft vesicles, an essential process for chemical delivery, is mediated by multiple factors. 相似文献
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Hybrid HA/Ge hydrogel particles are embedded in a secondary HA network to improve their structural integrity. The internal microstructure of the particles is imaged through TEM. CSLM is used to identify the location of the Ge molecules in the microgels. Through indentation tests, the Young's modulus of the individual particles is found to be 22 ± 2.5 kPa. The overall shear modulus of the composite is 75 ± 15 Pa at 1 Hz. The mechanical properties of the substrate are found to be viable for cell adhesion. The particles' diameter at pH = 8 is twice that at pH = 5. The pH sensitivity is found to be appropriate for smart drug delivery. Based on their mechanical and structural properties, HA-Ge hierarchical materials may be well suited for use as injectable biomaterials for tissue reconstruction. 相似文献
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In the present investigation, a novel bifunctional oxyammonium-based ionic liquid, namely, 2,2′-(ethane-1,2-diylbis[oxy])bis(ethan-1-aminium)-2,2,2-trifluoroacetate, was designed and synthesized. The structure of the titled ionic liquid was characterized using Fourier-transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance (1HNMR), carbon nuclear magnetic resonance (13CNMR), fluorine nuclear magnetic resonance (19FNMR), homonuclear COSY nuclear magnetic resonance (NMR), thermogravimetry (TG), derivative thermogravimetry (DTG) analysis, X-ray diffraction patterns (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The described ionic liquid demonstrated robust catalytic performance in the synthesis of pyrano[4,3-b]pyrans and tetrahydrobenzo[b]pyran derivatives. The ionic liquid presents a high potential of recycling and reusing capability in both types of model reactions. 相似文献
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Seyed Meysam Baghbanian Maryam Farhang 《Journal of the Iranian Chemical Society》2013,10(5):1033-1037
A simple and efficient method has been developed for the synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines in the presence of CuFe2O4 nanoparticles as a heterogeneous recyclable catalyst at room temperature in high yields. 相似文献
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Golmohammadi Farhad Amiri Masoud Gharibi Hussein Yousefi Ali Safari Meysam 《Journal of solution chemistry》2020,49(1):16-33
Journal of Solution Chemistry - The aggregation behavior was investigated in mixtures of sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) (anionic-rich catanionic) solutions.... 相似文献
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Meysam Najafi 《结构化学》2013,(9):1374-1386
ABSTRACT The antioxidant activity of ortho and meta substituted Enterolactone derivatives has been investigated in the gas phase and water.The reaction enthalpies of antioxidant activity of the studied derivatives have been calculated and compared with the corresponding values of Enterolactone.Results show that EWG substituents increase the BDE and IP,while the EDG ones rise in the PA.The Enterolactone derivatives with the lowest BDE,IP and PA values were identified as the compounds with high antioxidant activity.Results show that the substituents in the ortho position have high potential for the synthesis of novel Enterolactone derivatives.Results show that Enterolactone derivatives can processes their protective role via HAT and SPLET mechanism in gas phase and solvent,respectively.The calculated reaction enthalpies of the substituted Enterolactones have linear dependence with Hammett constants and EHOMO that can be utilized in the selection of suitable substituents for the synthesis of novel antioxidants based on Enterolactone. 相似文献