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排序方式: 共有133条查询结果,搜索用时 46 毫秒
41.
High performance liquid chromatography (HPLC) with a TSK-4000SW gel filtration column was used to compare envelope polypeptides from four strains of herpes simplex virus type 1 (HSV-1). The chromatographic profiles demonstrated polypeptide variability among three clinical strains and the wild-type F strain. Radioimmunoprecipitation of the HPLC fractions with polyclonal anti-HSV-1 followed by SDS-polyacrylamide gel electrophoresis (PAGE) of the immunoprecipitates revealed molecular weight differences of various polypeptides in fractions from the area containing major peaks. This HPLC method could prove useful for the analysis of polypeptide polymorphism in clinical isolates of HSV-1, as well as in other viruses. 相似文献
42.
X-ray reflectivity studies on Langmuir-Blodgett multilayer films of side-chain liquid crystal polymers are reported. The films have a high degree of lamellar order. The layer periodicity is independent of the type of monolayer deposition, implying a reorientation of the side group mesogens following the deposition process. X-ray reflectivity from thin films displays subsidiary maxima permitting a quantitative measure of the change in side-chain density between multilayer and monolayer. A unit cell density profile is calculated for thick films assuming a symmetric unit cell. 相似文献
43.
S.B. Qadri T.M. Keller C.A. Little P. Lubitz 《Applied Physics A: Materials Science & Processing》2005,81(3):587-590
Nanoparticles of FePd were synthesized using organo-metallic precursors. The crystallite sizes varied between 5 nm and 10 nm. Their magnetic and structural properties were investigated. Both cubic and tetragonal phases for FePd alloys were observed depending on the processing of the precursors. The magnetic moment per atom of the FePd alloy is about 1.5 μB. PACS 68.60.Wm; 68.55.-a; 78.66.-w; 61.46.+w; 81.10.Bk; 68.43.-h 相似文献
44.
Shahnaz Khan Farman Ali Nayab Ali Fahim Ullah Khan Sami Ullah Khan 《Natural product research》2016,30(11):1335-1338
Nelumbo nucifera seeds’ essential oil (EO), crude extract and subsequent fractions were evaluated for their DPPH, ABTS and superoxide anion-free radical scavenging and cholinesterase inhibitory activities. The ethyl acetate fraction and EO showed outstanding antioxidant activities with IC50 values of 191, 450 μg/mL (DPPH), 123, 221 μg/mL (ABTS) and 69, 370 μg/mL (superoxide anion). The ethyl acetate fraction and EO also caused significant inhibition of acetylcholinesterase and butyrylcholinesterase with IC50 values of 70 ± 0.6, 64 ± 0.8 and 75 ± 0.3, 58 ± 0.2, in dose-dependent manner. The first ever gas chromatography–mass spectrometry analysis of the EO obtained from N. nucifera seeds resulted in identification of 19 constituents, mainly comprised of oxygenated sesquiterpenes responsible for their promising bioactivity. The crude and fractions revealed the presence of saponins, flavonoids, steroids, alkaloids, terpenoids and cardiac glycosides in phytochemical investigation. 相似文献
45.
Johnson BJ Melde BJ Charles PT Cardona DC Dinderman MA Malanoski AP Qadri SB 《Langmuir : the ACS journal of surfaces and colloids》2008,24(16):9024-9029
Periodic mesoporous organosilicas incorporating diethylbenzene bridges in their pore walls were applied for the adsorption of nitroenegetic targets from aqueous solution. The materials were synthesized by co-condensing 1,4-bis(trimethoxysilylethyl)benzene (DEB) with 1,2-bis(trimethoxysilyl)ethane to improve structural characteristics. Molecular imprinting of the pore surfaces was employed through the use of a novel target-like surfactant to further enhance selectivity for targets of interest (tri- and dinitrotoluenes) over targets of similar structure ( p-cresol and p-nitrophenol). The headgroup of the commonly used alkylene oxide surfactant Brij76 was modified by esterification with 3,5-dinitrobenzoyl chloride. This provided a target analogue which was readily miscible with the Brij76 surfactant micelles used to direct material mesopore structures. The impact of variations in precursor ratios and amounts of imprint molecule was evaluated. The use of 12.5% of the modified Brij surfactant with a co-condensate employing 30% DEB was found to provide the best compromise between total capacity and selectivity for nitroenergetic targets. 相似文献
46.
An improved method for the synthesis of L-amino acids as their benzoxymethyl esters has been reported. All the synthesized compounds were characterized by (1)H NMR, EI-MS and IR spectroscopic methods. 相似文献
47.
Dr. M. Qadri E. Mubarak Dr. Hafiz Saqib Ali Jimei Zhou Prof. Chaoqun Li Prof. Jianliang Xiao Dr. Sam P. de Visser 《欧洲无机化学杂志》2023,26(5):e202200621
High-valent metal-oxo species are typical catalytic cycle intermediates in mono-oxygenases and dioxygenases and commonly react through oxygen atom transfer to substrates. In this work we study a biomimetic model complex with a 1,1’-bis((3,5-dimethylpyridin-2-yl)methyl)-2,2’-bipiperidine ligand system bound to a manganese(IV)-oxo(hydroxo) species and study its formation from manganese(II)-hydroxo and H2O2 as well as its reaction with (S)-1-phenylisochromane through dehydrogenative α-oxygenation. The work utilizes density functional theory methods to explore its catalytic cycle and its reactivity patterns. We show that the manganese(IV)-oxo(hydroxo) species is an active oxidant and preferentially the oxo group abstracts a hydrogen atom from substrate with barriers well lower in energy than those found for hydrogen atom abstraction by the hydroxo group. Interestingly, the rate-determining step is the OH rebound rather than the hydrogen atom abstraction, which would imply they would have limited kinetic isotope effect for the replacement of the transferring hydrogen atom by deuterium. 相似文献
48.
Shahnaz Sargazi Ramazan Mirzaei Mashaallah Rahmani Mahdi Mohammadi Abdolali Khammari Masoome Sheikh 《Journal of Analytical Chemistry》2017,72(5):557-561
Di(2-ethylhexyl) phthalate (DEHP) is used as plasticizer in polyvinylchloride (PVC) plastics. Its metabolites and the parent phthalates are considered toxic. As the DEHP plasticizers are not chemically bound to PVC, they can migrate, evaporate or be leached into indoor air and atmosphere, foodstuff, and other materials. We have reported a novel, easy and available analytical method for the determination of DEHP and its metabolite, mono(2-ethylhexyl) phthalate (MEHP) in human urine samples by the in-syringe dispersive liquid–liquid microextraction method coupled with gas chromatography with flame ionization detector. The limits of detection and precision (RSD) were 2.5 μg/L and 1.4% for DEHP and 1.1 μg/L and 3.0% for MEHP, respectively. This method could be utilized for routine monitoring of the trace DEHP and MEHP in urine of human exposure to plasticizers. 相似文献
49.
Mohammad Ali Karimi Abdolhamid Hatefi-Mehrjardi Mohammad Mazloum Ardakani Reza Behjatmanesh Ardakani Mohammad Hossein Mashhadizadeh Shahnaz Sargazi 《Russian Journal of Electrochemistry》2011,47(1):34-41
The anodic oxidation of chlorpromazine (CPZ) has been studied on a glassy carbon electrode by electrocatalytic effect of Alizarin
Red S (ARS) as a homogenous mediator in universal buffer (pH = 2). The linear sweep voltammetry (LSV) studies showed that
the catalytic current of this system depends on the concentration of CPZ. The magnitude of the peak current for ARS increased
severely in the presence of CPZ, and proportional to CPZ concentration. The catalytic peak current was linearly dependent
on CPZ concentration in the ranges of 10–500 μM and the detection limit was 5.16 μM by LSV. The diffusion coefficient of CPZ
was estimated using chronoamperometry. The method also was used for estimation of catalytic rate constant at catalytic reaction
between ARS and CPZ. The influences of potentially interfering substances on the current response of the system were examined.
The importance of technique is because of its ability to electrocatalytic determination of CPZ with ARS as homogenous electrocatalyst,
while it does not need to be prepared as for the modified electrode. The method was successfully applied for analysis of CPZ
in solid pharmaceutical formulations. 相似文献
50.
Ashraf SS Rao MV Kaneez FS Qadri S Al-Marzouqi AH Chandranath IS Adem A 《Journal of chromatographic science》2011,49(4):321-326
Various beneficial properties has been attributed to Nigella sativa, including its antioxidant potential. Previously, it was reported that supercritical fluid extraction (SFE) could be used to obtain N. sativa extract rich in antioxidants. In the present study, N. sativa extracts prepared using the previously optimized SFE as well as the traditional Soxhlet extraction approaches were analyzed for various known antioxidants. N. sativa extracts were found to prevent protein carbonyl formation as well as depletion of intracellular glutathione (GSH) in fibroblasts exposed to toluene. Furthermore, partially purified SFE and Soxhlet fractions could prevent loss of hepatic GSH in toluene-induced oxidative stressed Wistar rats as well as in L929 fibroblasts. The results showed that SFE-produced N. sativa extract is richer in antioxidants than the Soxhlet approach. It was also shown using preparative silica gel and reverse phase chromatography that different fractions of SFE-extracted or Soxhlet-extracted N. sativa had different levels of protective effects with regards to GSH depletion in vivo as well as in cell culture. Although fractions rich in thymoquinone were found to be most potent in terms of antioxidant capacity, the data indicates that the protective effects of N. sativa may not only be due to thymoquinone, but perhaps other antioxidants. 相似文献