排序方式: 共有136条查询结果,搜索用时 15 毫秒
71.
A class of spinning magnetic string in 4-dimensional Einstein-dilaton gravity with Liouville type potential which produces a longitudinal nonlinear electromagnetic field is presented. These solutions have no curvature singularity and no horizon, but have a conic geometry. In these spacetimes, when the rotation parameter does not vanish, there exists an electric field, and therefore the spinning string has a net electric charge which is proportional to the rotation parameter. Although the asymptotic behavior of these solutions are neither flat nor (A)dS, we calculate the conserved quantities of these solutions by using the counterterm method. We also generalize these four-dimensional solutions to the case of (n+1)-dimensional rotating solutions with k?[n/2] rotation parameters, and calculate the conserved quantities and electric charge of them. 相似文献
72.
Surfactant‐assisted dispersive liquid–liquid microextraction of nitrazepam and lorazepam from plasma and urine samples followed by high‐performance liquid chromatography with UV analysis
下载免费PDF全文
![点击此处可从《Journal of separation science》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Karam Molaei Ali Akbar Asgharinezhad Homeira Ebrahimzadeh Nafiseh Shekari Niloofar Jalilian Zhara Dehghani 《Journal of separation science》2015,38(22):3905-3913
Surfactant‐assisted liquid–liquid microextraction followed by high‐performance liquid chromatography with UV detection has been developed for the simultaneous preconcentration and determination of lorazepam and nitrazepam in biological fluids. In this study, an ionic surfactant (cetyltrimethyl ammonium bromide) was used as an emulsifier. The predominant parameters affecting extraction efficiency such as the type and volume of extraction solvent, the type and concentration of surfactant, sample pH, and the concentration of salt added to the sample were investigated and opted. Under the optimum conditions (extraction solvent and its volume, 1‐octanol, 70 μL; surfactant and its concentration, 1 mL of ultra‐pure water containing 2 mmol L?1 cetyltrimethyl ammonium bromide; sample pH = 9 and salt content of 10% NaCl w/v), the preconcentration factors were obtained in the range of 202–241 and 246–265 for nitrazepam and lorazepam, respectively. The limits of quantification for both drugs were 5 μg L?1 in water sample and 10 μg L?1 in biological fluids with R2 values higher than 0.993. The suitability of the proposed method was successfully confirmed by the extraction and determination of the target drugs in human urine and plasma samples in the range of microgram per liter. 相似文献
73.
Afshari M Dehghani M Abusara Z Moazzen-Ahmadi N McKellar AR 《The Journal of chemical physics》2007,126(7):071102
A new infrared band at 2069.3 cm-1 is observed and assigned to the long-anticipated polar isomer of the OCS dimer, helping to explain apparent discrepancies among earlier studies. The data reported here should enable direct observation of the microwave spectrum of polar (OCS)2 and motivate new theoretical works on the energetics of OCS dimer isomers and interconversion energy barriers. 相似文献
74.
Hua Wei Roya Ravarian Sabrina Dehn Sebastien Perrier Fariba Dehghani 《Journal of polymer science. Part A, Polymer chemistry》2011,49(8):1809-1820
A novel amphiphilic thermosensitive poly(ethylene glycol)45‐b‐poly(methyl methacrylate46‐co‐3‐(trimethoxysilyl)propyl methacrylate)2‐b‐poly(N‐isopropylacrylamide)429 (PEG45‐b‐P(MMA46‐co‐MPMA2)‐b‐PNIPAAm429) triblock copolymer was synthesized via consecutive atom transfer radical polymerization techniques. The thermoinduced association behavior of the resulting triblock copolymers in aqueous medium was further investigated in detail by 1H NMR, transmission electron microscopy, and dynamic light scattering. The results showed that at the temperature (25 °C) below the LCST, PEG45‐b‐P(MMA46‐co‐MPMA2)‐b‐PNIPAAm429 triblock copolymers self‐assembled into the core crosslinked micelles with the hydrophobic P(MMA‐co‐MPMA) block constructing a dense core, protected by the mixed soluble PEG and PNIPAAm chains acting as a hydrophilic shell simultaneously. With an increase in temperature, the resulting core‐shell micelles converted into a new type of micelles with the hydrophilic PEG chains stretching out from the hydrophobic core through the collapsed PNIPAAm shell. On the other hand, at the temperature (40 °C) above the LCST, such triblock copolymers formed the crosslinked vesicles with the hydrophobic PNIPAAm and P(MMA‐co‐MPMA) blocks constructing a membrane core and the soluble PEG chains building the hydrophilic lumen and the shell. On further decreasing the temperature, the resulting vesicles underwent transformation from the shrunken to the expanded status, leading to the formation of swollen vesicles with enlarged size. This study is believed to present the first formation of two types of hybrid crosslinked self‐assemblies by thermoinduced regulation. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
75.
Hadad Saeed Hamrahjoo Mahtab Dehghani Elham Salami-Kalajahi Mehdi Eliseeva Svetlana N. Roghani-Mamaqani Hossein 《Cellulose (London, England)》2022,29(6):3423-3437
Cellulose - Poly(ethylene oxide) (PEO) is one of the most famous polymer electrolytes; however, its low conductivity and capacity have prevented its commercial applications. This study utilizes... 相似文献
76.
Amir Hashemi Benyamin M.-Alizadeh Mahdi Dehghani Darmian 《Linear and Multilinear Algebra》2013,61(2):265-272
In this article, we study the minimal polynomials of parametric matrices. Using the concept of (comprehensive) Gröbner systems for parametric ideals, we introduce the notion of a minimal polynomial system for a parametric matrix, i.e. we decompose the space of parameters into a finite set of cells and for each cell we give the corresponding minimal polynomial of the matrix. We also present an algorithm for computing a minimal polynomial system for a given parametric matrix. 相似文献
77.
The purpose of this paper is to introduce and to discuss the concept of approximation preserving operators on Banach lattices with a strong unit. We show that every lattice isomorphism is an approximation preserving operator. Also we give a necessary and sufficient condition for uniqueness of the best approximation by closed normal subsets of X+, and show that this condition is characterized by some special operators. 相似文献
78.
The effect of 4,4′-diaminodiphenylsulfone (DADPS) as a co-additives in iodide/triiodide redox electrolyte on the performance of dye-sensitized solar cell based on the 2-cyano-3-(4-(diphenylamino)phenyl)acrylic acid (TPA) and 2-cyano-3-(2΄-(5΄,10΄,15΄,20΄- tetraphenylporphyrinato Zinc (II)yl) acrylic acid (Zn-1) dyes have been investigated. Compared withstandard electrolyte (0.1 M LiI, 0.05 M I2, 0.6 M 1-butyl-2,3-dimethylimidazolium iodide (BDMII) and TBP (0.5, 1 M)), adding 0.5 M of DADPS, as a co-additive, into the electrolyte system has caused increasing short current density (Jsc) and open-circuit potential (Voc) consequently the energy conversion (η) improved. Electrochemical impedance results indicate adsorbing of DADPS on the titanium dioxide surface leads to an increase in the lifetime (τ). Adsorbing of DADPS on the semiconductor surface retards the interfacial charge recombination that has a beneficial effect on the Voc and Jsc. The results showed that amine groups of DADPS attach to the conduction band (CB) of TiO2 film and suppress the electron recombination process and as a result, it can be applied as a promising co-additive in DSSCs. 相似文献
79.
Ardeshir Khazaei Mohammad Ali Zolfigol Mohammad Mokhlesi Abdolkarim Zare Fatemeh Derakhshan‐Panah Maria Merajoddin Hassan Keypour Ahmad Ali Dehghani‐Firouzabadi 《中国化学会会志》2012,59(2):199-207
A highly efficient protocol for the synthesis of β‐acetamido ketone or ester derivatives in the presence of pyrazinium di(hydrogen sulfate) {Py(OSO3H)2} as a novel, green and homogeneous solid acid catalyst at room temperature is described. One‐pot multi‐component condensation of enolizable ketones or alkyl acetoacetates with aldehydes, acetonitrile and acetyl chloride affords the title compounds in high to excellent yields and in relatively short reaction times. In this work, the efficiency of our recently reported solid acid catalyst, saccharin sulfonic acid (Sa‐SO3H), in the synthesis of β‐acetamido ketones/esters is also studied. Moreover, in this research, some new β‐acetamido ketones and esters (i.e. one complex structure) are prepared. 相似文献
80.
Jafari Saeid Dehghani Mohammad Nasirizadeh Navid Akrami Hamid Reza 《Mikrochimica acta》2017,184(11):4459-4468
Microchimica Acta - The article describes a sensor for the voltammetric determination of the azo dye Basic Red 13 (BR13) during its degradation by using sonoelectrochemistry in the presence of TiO2... 相似文献