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排序方式: 共有86条查询结果,搜索用时 15 毫秒
1.
Abdolreza Iraj Mansouri Zahra Hassani Mohammad Reza Islami 《Phosphorus, sulfur, and silicon and the related elements》2013,188(8):1753-1758
2-Aminobenzoic acids or 4-aminobenzoic acid react with dimethyl acetylenedicarboxylate/triphenylphosphine in less than 20 min at 15–25°C to produce new organic phosphorus compounds in good to excellent yields. The conversion occurs with selective N- over O-alkylation of the amino group and isolation of the products is accomplished simply by filtration. 相似文献
2.
Ali Golchin Simzar Hosseinzadeh Aytak Jouybar Masumeh Staji Masoud Soleimani Abdolreza Ardeshirylajimi Arash Khojasteh 《先进技术聚合物》2020,31(7):1519-1531
Wound healing, one of the most complex processes of the body involving the cooperation of several important biomolecules and pathways, is one of the major therapeutic and economic issues in regenerative medicine. The present study aimed to introduce a novel electrospun curcumin (Cur)‐incorporated chitosan/polyvinyl alcohol/carbopol/polycaprolactone nanofibrous composite for concurrent delivery of the buccal fat pad‐derived mesenchymal stem cells (BFP‐MSCs) and Cur to a full‐thickness wound on the mouse model. Scaffolds were characterized structurally using scanning electron microscopy (SEM), fluorescence microscopy imaging and Fourier‐transform infrared spectroscopy, and toxicity of the scaffolds was also evaluated after BFP‐MSC seeding by SEM imaging and 3‐(4,5 dimethyiazol‐2‐1)‐2‐5‐diphenyl tetrazolium bromide (MTT) assay. Then, its influence on the wound‐healing process was investigated as a wound dressing for a full‐thickness skin defect in mouse model. Results demonstrated that the designed composite scaffolds have the capability for cell seeding and support their growth and proliferation. Macroscopic and histopathological characteristics were evaluated at the end of the 7 and 14 days after surgery, and their results showed that our designed scaffold groups accelerated the wound‐healing process compared with the control group. Among those, scaffold/Cur, scaffold/Cur/BFP‐MSC and scaffold/BFP‐MSC groups demonstrated more wound repair efficacy. These results indicated that the combined grafts can be used to improve the wound‐healing process, and therefore, the electrospun nanofibers presented in this study, Cur and BFP‐MSC together, were demonstrated to have promising potential for wound‐dressing applications. 相似文献
3.
Abdolreza Rezaeifard Maasoumeh Jafarpour Hossein KavousiMahboubeh Alipour Helen Stoeckli-Evans 《Polyhedron》2011,30(13):2303-2309
Benzyltributylammonium periodate (BzBu3NIO4) was prepared easily in high yield in neat water. The compound crystallized with two cations and two anions per asymmetric unit and a space group of Pna21 was determined by single-crystal X-ray diffraction. It was used practically in the clean and selective epoxidation of olefins and oxygenation of saturated hydrocarbons catalyzed by manganese (III) porphyrins in water/ethanol as a green media. The catalyst could be reused without noticeable loss of activity, and the oxidant’s by-product (BzBu3NIO3) could also be reused. The efficiency of the oxidation system depends critically upon the steric hindrances and electronic structures of both the nitrogen donors and Mn-catalysts. Some evidences suggest the involvement of a high valent Mn-oxo species as well as a six-coordinate [(L)(Por)Mn-OIO3] complex in the oxidation reactions. 相似文献
4.
A new method, based on the concepts of matrix analysis as well as the learning capabilities of neural networks, for the analysis of nonlinear trusses under dynamic loading is presented. The method can be applied to static trusses too. While there have been attempts in the past to use neural networks to identify and model different structures based on data measured on structural response directly, the main feature and advantage of this new method is in its capability to model a nonlinear truss by assembling the data collected on the response of its members. The basics of the method are: (1) for each truss member, a neural network is trained to learn and simulate its load-response behavior, (2) the member neural networks are then assembled to build another neural network which can simulate the load-response behavior of the whole truss. Noticing test at member level is generally easier than at structure level, this can make the building of a neural network to simulate the response of the truss more affordable. Also this has potential application when it is hard to find a mathematical model from experimental data to describe the internal force vector for a truss, as well as identification and control of trusses where precise modeling of the structure is a key point to the success of the application. Prandtl Neural Network, developed recently by the authors for modeling of nonlinear hysteretic materials, has been improved and used in this study too. The improved version has been called Prandtl-2 Neural Network (PNN2) in this paper. The method has been applied to the static and dynamic analysis of a 3-bar and a 10-bar benchmark truss successfully, the results of which are reported in this paper. 相似文献
5.
A very efficient and mild procedure for preparation of silyl ethers from benzylic, allylic, propargilic alcohols, phenols, naphtoles and some of phenolic drugs with trimethylsilylchloride (TMSCl), triethylsilylchloride (TESCl) and t‐buthyldimethylsilyl chloride (TDSCl) ethers in the presence of Fe(HSO4)3/Et3N in room temperature in excellent yields is reported. This procedure also allows the excellent selectivity for silylation of alcohols and phenols. 相似文献
6.
Weaving is a matrix construction developed in 1990 for the purpose of obtaining new weighing matrices. Hadamard matrices obtained by weaving have the same orders as those obtained using the Kronecker product, but weaving affords greater control over the internal structure of matrices constructed, leading to many new Hadamard equivalence classes among these known orders. It is known that different classes of Hadamard matrices may have different maximum excess. We explain why those classes with smaller excess may be of interest, apply the method of weaving to explore this question, and obtain constructions for new Hadamard matrices with maximum excess in their respective classes. With this method, we are also able to construct Hadamard matrices of near‐maximal excess with ease, in orders too large for other by‐hand constructions to be of much value. We obtain new lower bounds for the maximum excess among Hadamard matrices in some orders by constructing candidates for the largest excess. For example, we construct a Hadamard matrix with excess 1408 in order 128, larger than all previously known values. We obtain classes of Hadamard matrices of order 96 with maximum excess 912 and 920, which demonstrates that the maximum excess for classes of that order may assume at least three different values. Since the excess of a woven Hadamard matrix is determined by the row sums of the matrices used to weave it, we also investigate the properties of row sums of Hadamard matrices and give lists of them in small orders. © 2004 Wiley Periodicals, Inc. J Combin Designs 12: 233–255, 2004. 相似文献
7.
8.
Preparation of Nano Silica Supported Sodium Hydrogen Sulfate: As an Efficient Catalyst for the Trimethyl,Triethyl and t‐Butyldimethyl Silylations of Aliphatic and Aromatic Alcohols in Solution and under Solvent‐free Conditions
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Nano silica supported sodium hydrogen sulfate has been prepared by mixing NaHSO4 with activated Nano silicagel. We wish to report a new method for the synthesis of trimethyl (TMS), triethyl (TES) and t‐butyldimethyl silyl (TBS) ethers from benzylic, allylic, propargylic alcohols, phenols, naphtholes and some of phenolic drugs in the solution and under solvent‐free conditions. 相似文献
9.
Abdolreza Rezaeifard Maasoumeh Jafarpour Heidar RaissiEbrahim Ghiamati Aida Tootoonchi 《Polyhedron》2011,30(4):592-598
The oxidation of aryl sulfides by tetra-n-butylammonium peroxomonosulfate (n-Bu4NHSO5) was carried out in the presence of six different manganese (III) tetraarylporphyrins [Mn(Por)s] as biomimetic catalysts and a number of nitrogen donors as co-catalysts. There is no noticeable difference between the reactivity of sulfides, in the presence of electron-rich Mn(por)s, whereas, for electron-deficient catalysts, conversion rates are different. Nevertheless, the over-oxidation of sulfoxide is more sensitive to both the nature of substituents attached to the sulfur atom in substrates as well as porphyrin complex structure. The degree of catalytic activity of Mn(Por)s for the formation of sulfone product increases as the following order: Mn(TPFPP)OAc < Mn[T(4-NO2P)P]OAc < Mn(TDCPP)OAc < Mn(TPP)OAc < Mn(TMP)OAc < Mn[T(4-OMeP)P]OAc. Our results show that in the presence of electron-rich Mn(Por)s, the strong π-donor N-H imidazoles possess co-catalytic activity greater than that of strong σ-donor amines and weak π-donor pyridines. When electron-deficient Mn(Por)s were employed as catalyst, pyridines demonstrated a higher co-catalytic activity than that of N-H imidazoles. The pronounced effect of protic solvents on the rate and selectivity of oxidation reactions, particularly in the presence of electron-deficient Mn(Por)s has been observed. The outcome of our investigations accompanied by UV-Vis and Raman spectral data confirms the involvement of different active oxidant such as a high valent Mn-oxo species as well as a six-coordinate [(L)(Por)Mn-OHSO4] complex. 相似文献
10.
A non-circular Ehlich D-optimal design of order 150 is constructed. Noting that all computer computations so far have not produced a circular D-optimal design of order 150 makes this design quite interesting. 相似文献