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81.
[reaction: see text] We describe a synthesis of a dendrimer-like amphiphile containing a flat rigid core and 12 hydrophobic and hydrophilic arms. We employ a modular approach based on stepwise protection chemistry starting from simple building blocks. The key feature of this approach is the absence of a polymerization step, which makes it applicable for linear monofunctionalized precursors of any kind. This strategy also allows for precise control of the number of arms and ensures their alternating arrangement. 相似文献
82.
Tahair Rasham Abdullah Shoaib Nawab Hussain Muhammad Arshad Sami Ullah Khan 《Journal of Fixed Point Theory and Applications》2018,20(1):45
In this article, common fixed point theorems for a pair of multivalued mappings satisfying a new Ciric-type rational F-contraction condition in complete dislocated metric spaces are established. An example is constructed to illustrate our results. An application to the system of integral equations is presented to support the usability of proved results. Our results combine, extend and infer several comparable results in the existing literature. 相似文献
83.
Angie R. Angeles Liping Yang Andrew Brunskill M. Arshad Siddiqui 《Tetrahedron letters》2010,51(48):6236-6239
A facile and highly convergent synthesis of biologically active spiro-fused thiadiazoline KSP inhibitors is reported. The highlights of the synthesis include the Michael reaction and cyclization of thiosemicarbazone to 1,3,4-thiadiazoline. This chemistry lends itself to the preparation of (+)-2, a potent and orally bioavailable anti-cancer agent, and to the development of a structure-activity relationship program. 相似文献
84.
Terbinafine, a widely used antifungal drug, is a challenging molecule for quantitative bioanalysis due to certain factors contributing assay variability. Despite previous attempts at human plasma determination of terbinafine, exhaustive stability of the drug or an internal standard was lacking. Internal standard stability with negligible variation throughout the analysis is an indicator of a reliable bioanalytical method as the majority of LC–MS/MS assays are based on analyte/IS response ratios for quantitation. A newly developed high‐throughput simple LC‐MS/MS method is described for human plasma determination of terbinafine using naftifine internal standard and eluting all compounds within 2 min. A solid‐phase extraction of terbinafine achieving mean recovery of 84.3% (CV < 4%) without compromising sensitivity (limit of quantitation 5.11 ng/mL) or linearity (5.11–3014.19 ng/mL) is delineated in this paper. A heated nebulizer in positive multiple reaction monitoring mode was employed with transitions m/z 292.2 →141.1 and 288.2 →117.0 for terbinafine and naftifine, respectively, resulting in excellent chromatographic separation on a Hypurity Advance (50 × 4.6 mm, 5 µm) column. The developed method was successfully applied to clinical samples and for the first time demonstrated marked improved extraction efficiency and reliable long‐term plasma stability results without any internal standard response variation during the entire course of study. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
85.
Syed Arshad Hussain 《Journal of Physics and Chemistry of Solids》2010,71(3):323-9718
In this paper we report the reaction kinetics of nanodimensional clay saponite and hectorite with an amphiphilic cation octadecyl rhodamine B (RhB) in hybrid Langmuir monolayer at the air-aqueous clay dispersion interface. The surface pressure-molecular area (π-A) isotherms were strongly influenced by the presence of clay and the lift-off area of the cationic amphiphile shifted to progressively larger area. In-situ fluorescence imaging microscopic (FIM) studies showed the formation of micro-order domains in the organo-clay hybrid monolayer films at the air-clay dispersion interface. In-situ infrared reflection-absorption spectroscopy (IRRAS) was used to demonstrate the reaction kinetics. The time taken to complete the reaction kinetics for RhB-hectorite hybrid films is larger than for RhB-saponite hybrid films. Atomic force microscopic images of hybrid Langmuir-Blodgett films gave compelling visual evidence of the incorporation of clay platelets into the hybrid films, whose density increased with the progress of reaction kinetics. 相似文献
86.
87.
S. Arshad Jamal Samina Qureshi Samina Noor Ali M. Iqbal Choudhary Atta-Ur-Rahman 《Chemistry of Heterocyclic Compounds》1995,31(9):1047-1059
Four bioactive withanolides withalactone (1), withaoxylactone (2), quresimine-A (4-hydroxy, 3-methoxy-5, 6-epoxy-(22R)-witha-24-enolide) (3) and quresindne-B (4, 27 dihydroxy-3-methoxy-5, 6-epoxy-(22R)-witha-24-enolide (4) have been isolated from the herbs of Withania somnifera, Dunal (Solanaceae). The elucidation of their structures is based on extensive spectroscopic studies, such as1H-NMR, COSY-45°, HMBC, HMQC HOHAHA, E.I., FAB (+ ve), and HR MS, etc.Published in Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1200–1213, September, 1995. 相似文献
88.
Akbar Azam Muhammad Arshad Ismat Beg 《Rendiconti del Circolo Matematico di Palermo》2008,57(3):433-441
We prove the existence of points of coincidence and common fixed points of a pair of self-mappings satisfying a generalized
contractive condition in cone metric spaces. Our results generalize several well-known recent and classical results.
相似文献
89.
We measure the geometry of a crumpled sheet of paper with laser-aided topography and discuss its statistical properties. The curvature of an elastoplastic fold scales linearly with applied force. The curvature distribution follows an exponential form with regions of high curvature localized along ridges. The measured ridge length distribution is consistent with a hierarchical model for ridge breaking during crumpling. A large fraction of the ridges are observed to terminate without bifurcating, and the ridge network connectedness is not as complete as anticipated. The self-affinity of the surface is characterized by a Hurst exponent of 0.71+/-0.01 in contrast with previous results. 相似文献
90.
Saeed‐ur‐Rehman Muhammad Arshad Masood Ahmad Khalid Masud Abdul Ghani Nasima Arshad Ammad Hussain Qureshi Sohail Akhtar Ghauri 《中国化学会会志》2000,47(3):501-508
Some of the bis‐complexes of a derivative of phenhomazine (dibenzo[b,f][1:5]diazocine‐6:12‐dione; PHZD) with Ni(II), Cu(II), Co(II), Cd(II), Zn(II) and Hg(II) of the general formula M(PHZD)2X2 [where X = C1, Br and I], were prepared and identified. These complexes have been characterised on the basis of elemental analysis, and spectroscopic, magnetic and conductance data. The thermal mode of decomposition and thermal stability of these complexes was investigated on the basis of the respective thermal curves in a static air atmosphere. The thermoanalytical investigations indicate that these complexes undergo two‐step changes as temperature is raised, except for Cd(II) and Hg(II) complexes, with the formation of metal oxides as end product. The degradation mechanism of the complexes has also been proposed. 相似文献