排序方式: 共有77条查询结果,搜索用时 11 毫秒
41.
Elmira Kh. Lermontova Sergey S. Karlov Andrei V. Churakov Yuri F. Oprunenko Jörg Sundermeyer 《Journal of organometallic chemistry》2006,691(26):5710-5724
The reaction of RN(CH2CH2OH)CHR1CR2R3OH (1-8) with a stoichiometric amount of tetrachloro(bromo)germane leads to the corresponding RN(CH2CH2O)(CHR1CR2R3O)GeHal2 (9-21). Difluorenylgermocane 22 was prepared by treatment of diethoxydifluorenylgermane with N-methyldiethanolamine. Different dialkanolamines were found to be successive precursors of dimethylgermocanes, RN(CH2CH2O)(CHR1CR2R3O)GeMe2 (23-26). The chemical properties of simple and easy to access germocanes RN(CH2CH2O)2GeX2 [X = OH, Br (28), Cl (29)] were studied and the difluoro (27), haloalkoxy (30-32), and dialkoxy (33, 34) derivatives were prepared. The structures of the compounds 16, 20-22, and 26 were confirmed by X-ray diffraction and the structural features in solution of 23 and 26 were studied by NMR spectroscopy (NOEs). The relationship between the nature of substituents at different positions of the germocane skeleton and the strength of the intramolecular Ge ← N bond is discussed. 相似文献
42.
水热合成了基于吡啶-3,5-二羧酸(H2pydc)的含Ag(I)配位聚合物 [Ag2(bpp)2(H2O)]·pydc·7H2O (1) (其中bpp = 1,3-双(4-吡啶)丙烷)。X射线单晶结构分析表明,在一维化合物1中,发现了包含(H2O)12水簇单元的二维氢键层状结构。有趣的是,在该二维层中, 每个pydc2-阴离子作为“桥”连接了两个(H2O)12单元和两个自由水分子。另外,对化合物1的荧光、热重、粉末衍射等也进行了研究和讨论。 相似文献
43.
Gulnara Gaynanova Leysan Vasileva Ruslan Kashapov Darya Kuznetsova Rushana Kushnazarova Anna Tyryshkina Elmira Vasilieva Konstantin Petrov Lucia Zakharova Oleg Sinyashin 《Molecules (Basel, Switzerland)》2021,26(22)
This review focuses on key topics in the field of drug delivery related to the design of nanocarriers answering the biomedicine criteria, including biocompatibility, biodegradability, low toxicity, and the ability to overcome biological barriers. For these reasons, much attention is paid to the amphiphile-based carriers composed of natural building blocks, lipids, and their structural analogues and synthetic surfactants that are capable of self-assembly with the formation of a variety of supramolecular aggregates. The latter are dynamic structures that can be used as nanocontainers for hydrophobic drugs to increase their solubility and bioavailability. In this section, biodegradable cationic surfactants bearing cleavable fragments are discussed, with ester- and carbamate-containing analogs, as well as amino acid derivatives received special attention. Drug delivery through the biological barriers is a challenging task, which is highlighted by the example of transdermal method of drug administration. In this paper, nonionic surfactants are primarily discussed, including their application for the fabrication of nanocarriers, their surfactant-skin interactions, the mechanisms of modulating their permeability, and the factors controlling drug encapsulation, release, and targeted delivery. Different types of nanocarriers are covered, including niosomes, transfersomes, invasomes and chitosomes, with their morphological specificity, beneficial characteristics and limitations discussed. 相似文献
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A general and efficient method for the cross-coupling reaction of diorgano dichalcogenides with terminal alkynes using copper iodide/cryptand-22 (CuI/C22) has been developed. This protocol gave alkynyl chalcogenides in moderate to excellent yields in the presence of K3PO4 as the base under aerobic conditions. 相似文献
46.
Bromand Nourozi Arash Boochani Ahmad Abdolmaleki Elmira Sartpi Pezhman Darabi Sirvan Naderi 《理论物理通讯》2018,69(1):101-106
The electronic and optical properties of 2D Cu_2Si and Cu_2Si:Ti are investigated based on the density functional theory(DFT) using the FP-LAPW method and GGA approximation. The 2D Cu_2Si has metallic and non magnetic properties, whereas adding Ti impurity to its structure changes the electronic behavior to the half-metallic with 3.256μB magnetic moment. The optical transition is not occurred in the infrared and visible area for the 2D Cu_2Si in x-direction and by adding Ti atom, the real part of dielectric function in the x-direction, Re(ε(ω))_x is reached to a Dirac peak at this energy range. Moreover, the absorption gap tends to zero in x-direction of the 2D Cu_2Si:Ti. 相似文献
47.
Bakherad Mohammad Moosavi Fatemeh Keivanloo Ali Doosti Rahele Moradian Elmira Armaghan Mahsa 《Research on Chemical Intermediates》2019,45(5):2981-2997
Research on Chemical Intermediates - In this work, magnetized water is applied as a green-promoting medium for the catalyst-free, one-pot, practical, efficient, and environmentally benign... 相似文献
48.
Li Yicheng Moradi Iman Kalantar Mahdi Babadi Elmira Malekahmadi Omid Mosavi Amirhosein 《Journal of Thermal Analysis and Calorimetry》2021,144(6):2587-2603
Journal of Thermal Analysis and Calorimetry - Nanofluid refers to the mixture of fluid and solid nanoparticles. If this mixture contains more than one NP or fluid, it is called “hybrid... 相似文献
49.
Paul Damien Alexander Galenko Elmira Popova Timothy Hanson 《European Journal of Operational Research》2007
We address the problem of a finite horizon single item maintenance optimization structured as a combination of preventive and corrective maintenance in a nuclear power plant environment. We present Bayesian semiparametric models to estimate the failure time distribution and costs involved. The objective function for the optimization is the expected total cost of maintenance over the pre-defined finite time horizon. Typically, the mathematical modeling of failure times are based on parametric models. These models fail to capture the true underlying relationships in the data; indeed, under a parametric assumption, the hazard rates are treated as unimodal, which, as shown in this paper, is incorrect. Importantly, assuming an increasing failure rate, as is typically done, we show, is way off the mark in the present context. Since hazard and cost estimates feed into the optimization phase, from a risk management perspective, potentially gross errors, resulting from purely parametric models, can be obviated. We show the effectiveness of our approach using real data from the South Texas Project Nuclear Operating Company (STPNOC) located in Bay City, Texas. 相似文献
50.
Dulat Dzhumabaev Elmira Bakirova Sandugash Mynbayeva 《Mathematical Methods in the Applied Sciences》2020,43(4):1788-1802
A nonlinear loaded differential equation with a parameter on a finite interval is studied. The interval is partitioned by the load points, at which the values of the solution to the equation are set as additional parameters. A nonlinear boundary value problem for the considered equation is reduced to a nonlinear multipoint boundary value problem for the system of nonlinear ordinary differential equations with parameters. For fixed parameters, we obtain the Cauchy problems for ordinary differential equations on the subintervals. Substituting the values of the solutions to these problems into the boundary condition and continuity conditions at the partition points, we compose a system of nonlinear algebraic equations in parameters. A method of solving the boundary value problem with a parameter is proposed. The method is based on finding the solution to the system of nonlinear algebraic equations composed. 相似文献