排序方式: 共有103条查询结果,搜索用时 15 毫秒
61.
Maleki Ali Valadi Kobra Gharibi Saideh Taheri-Ledari Reza 《Research on Chemical Intermediates》2020,46(9):4113-4128
Research on Chemical Intermediates - Herein, a volcanic-based mesoporous catalytic system is precisely characterized by various analytical methods and suitably used for facilitating the organic... 相似文献
62.
In this research, a solvent‐free four‐component one‐pot reaction of phenyl isothiocyanate, phenylacetylene, various kinds of aldehydes, and amines was interpreted to obtain the desired five‐membered heterocycles named thiazolidin‐2‐imines. The promotor of this transformation is a novel magnetite‐based multilayered inorganic–bioorganic nanohybrid prepared via embedding glutamic acid on the magnetized silica followed by anchoring Cu (II) [nano Fe3O4‐SiO2@Glu‐Cu (II)]. The newly synthesized nanostructure is characterized through Fourier‐transform infrared (FT‐IR), field‐emission scanning electron microscopy (FESEM), energy dispersive X‐ray analysis (EDAX), transmission electron microscopy (TEM), X‐ray fluorescence (XRF), thermogravimetric analysis or derivative thermogravimetric (TGA/DTG), vibrating sample magnetometer (VSM), X‐ray photoelectron spectroscopy (XPS), and Brunauer–Emmett–Teller (BET) techniques. This protocol is a straightforward one‐step procedure to obtain thiazolidin‐2‐imines without requirement to propargylamines or imines as substrates. In addition, easy work‐up procedure, high yields of products, absence of organic solvents in the reaction media, recovery and reusability of nano Fe3O4‐SiO2@Glu‐Cu ( II) to promote the reaction at least for three runs without activity lost, simple separation of the catalyst from reaction mixture via an external magnet, and regioselectivity of the method are some highlighted aspects of the approach. 相似文献
63.
In this paper, we introduce a set of functions called fractional-order Legendre functions (FLFs) to obtain the numerical solution of optimal control problems subject to the linear and nonlinear fractional integro-differential equations. We consider the properties of these functions to construct the operational matrix of the fractional integration. Also, we achieved a general formulation for operational matrix of multiplication of these functions to solve the nonlinear problems for the first time. Then by using these matrices the mentioned fractional optimal control problem is reduced to a system of algebraic equations. In fact the functions of the problem are approximated by fractional-order Legendre functions with unknown coefficients in the constraint equations, performance index and conditions. Thus, a fractional optimal control problem converts to an optimization problem, which can then be solved numerically. The convergence of the method is discussed and finally, some numerical examples are presented to show the efficiency and accuracy of the method. 相似文献
64.
Kobra Pourabdollah Bahram Mokhtari 《Journal of Thermal Analysis and Calorimetry》2012,107(3):1353-1361
Traditional methods to measure and survey the productivity of oil wells mainly consisted of using test-separator units with
expensive instrumental, mechanical, electrical, piping, and safety devices along with technical and protective inspections,
repair and operation services, facilities, and infrastructures. Their inherent limitations are time and cost consuming, uncertainty
of well isolation in test separator, and need to close the co-line wells, which are diminished using multivariate thermal
well testing. In this study, an alternative method is presented using multivariate regression on thermal analysis data. The
objective of this study, which covered three distinctive major fields of statistics, thermal analysis, and well testing, is
predicting the accurate productivity of oil wells using a single sample point at the blend oil pipeline. This method is based
in performing multivariate regression of thermogravimetric data obtained from the samples of Iranian offshore oil wells. The
results revealed that the used model appropriate for crude oil blends, which thermal traces significantly differ from each
other. The calculated error function corrected the blend equation by considering the eutectic points and catalytic pyrolysis
in lower and higher temperatures, respectively. The model predicted the accurate productivity of oil wells in real samples
of blend oil pipeline. 相似文献
65.
Kobra Omidfar Solmaz Kia Soheila Kashanian Malihe Paknejad Afsaneh Besharatie Susan Kashanian Bagher Larijani 《Applied biochemistry and biotechnology》2010,160(3):843-855
Digoxin is widely used as a cardiac glycoside drug in the treatment of various heart conditions. Because it is a toxic drug, it should be regularly monitored in the serum of patients under treatment. In this study, colloidal nanogold is synthesized and the preparation of nanogold-labeled monoclonal antibody probe to digoxin is described under optimal conditions. In addition, an immunochromatographic (IC) method for digoxin analysis employing nanogold-labeled probe is developed. With this technique, it requires only 5 min to complete the quantitative detection of digoxin. The detection time is decreased 20–30 times in comparison to radioimmunoassay (RIA). The sensitivity to digoxin was about 2 ng/ml by naked eye, which is within the therapeutic and toxic ranges of digoxin. The results of serum samples obtained by IC strip were in agreement with those obtained by RIA. The IC strip was sufficiently sensitive and accurate to be used for the rapid detection of digoxin in serum samples. 相似文献
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67.
Bahram Mokhtari Kobra Pourabdollah 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):23-31
Calix[4]pyrrole is one such class which holds a great promise in the fields of sensors and their unique behavior as sensors owes to its structural flexibility. Anion binding ability of calix[4]pyrrole has been modified in a variety of ways. Introduction of electron releasing and electron withdrawing groups at the meso position or at β-pyrrolic positions leads to calix[4]pyrrole with deep cavities and fixed walls which shows increased selectivity and modified binding effects. Strapping of calix[4]pyrrole is another way to modify its structural behavior which is responsible for its binding behavior. Choice of strap could play a profound role not only in increasing the intrinsic anion binding affinity of calix[4] pyrrole, but also in modulating the receptor anion stoichiometry, thereby modifying potentially the inherent anion binding selectivity. Calix[n]pyrroles with extended cavities have also been synthesized. Such as calix[3]bipyrrole binds bromide substantially with high affinity than calix[4]pyrrole. Calix[4]pyrrole has also been used to produce anion sensors that can report the presence of anion by means of a color change. The medium effect on the complexation of calix[4]pyrrole and anion has been investigated in various solvents. Calix[4]pyrrole has also been used to increase the ionic conductivity of solid polymer electrolyte by anion complexation of the metal salt. Calix[4]pyrrole has been used to obtain optical sensors using surface plasmon resonance technique. Composite films of cellulose acetate containing calix[4]pyrrole has also been reported which has potential usage in packaging, storage and preservation. In nut shell, calix[4]pyrrole can be modified in a variety of ways to form versatile sensors which can be used in variety of ways in various areas. 相似文献
68.
Bahram Mokhtari Kobra Pourabdollah 《Journal of inclusion phenomena and macrocyclic chemistry》2013,76(3-4):403-413
Nano-assisted inclusion separation of alkali metals from basic solutions was reported by inclusion-facilitated emulsion liquid membrane process. The novelty and significance of this study is application of nano-baskets of calixarene in the selective and efficient separation of alkali metals, as both carrier and surfactant. For this aim, four derivatives of p-tert-calix[4]arene bearing different sulfonamide moieties were synthesized and their inclusion-extraction parameters were optimized. Maximum extraction was achieved using calixarene scaffold 03 (3.45 × 10?2 M) as carrier/demulsifier, commercial kerosene as diluent in membrane, sulphonic acid (0.2 M) and ammonium carbonate (0.4 M) as the strip and the feed phases, the phase and the treat ratios of 0.8 and 0.3, mixing speed (300 rpm), and initial solute concentration (100 mg/L). The selectivity of membrane over more than ten interfering cations was examined and the results reveled that under the optimized operating conditions, the extraction percent of alkali metals was 98–99 %. 相似文献
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70.
In this article we propose an efficient metal-free method for the mild oxidation of alcohols using dimethyl sulfoxide/tosyl chloride at ambient temperature. The procedure described here is an easy and practical method for the oxidation of primary, secondary, allylic, and benzylic alcohols into their corresponding aldehydes and ketones. The notable advantages of this protocol are mild reaction conditions, good yields and selectivity, and simple workup with minimal waste containing no metallic components. The mechanism of the transformation is also investigated. 相似文献