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排序方式: 共有209条查询结果,搜索用时 15 毫秒
41.
42.
Yasir Khan Qingbiao Wu Naeem Faraz A. Yildirim M. Madani 《Applied Mathematics Letters》2012,25(10):1340-1346
This work suggests a new analytical technique called the fractional homotopy perturbation method (FHPM) for solving fractional differential equations of any fractional order. This method is based on He’s homotopy perturbation method and the modified Riemann–Liouville derivative. The fractional differential equations are described in Jumarie’s sense. The results from introducing a modified Riemann–Liouville derivative in the cases studied show the high accuracy, simplicity and efficiency of the approach. 相似文献
43.
Al-Subu Mohammad M. Jondi Waheed J. Dado Saida A. Hilal Hikmat S. 《Transition Metal Chemistry》2002,27(2):223-227
The kinetics of oxidation of 1-octene and heptanal by 18-crown-6-ether-solubilized KMnO4 in benzene and CH2Cl2 have been investigated. In benzene, the oxidation of 1-octene is first order with respect to the oxidant and zero order with respect to the substrate, whereas in CH2Cl2 the reaction is first order with respect to both substrate and oxidant. The reaction of heptanal followed different kinetics being first order with respect to both substrate and oxidant, regardless of whether benzene or CH2Cl2 was employed as the solvent. The values of activation energy E
a, standard enthalpy H
*, standard entropy change S
*, and standard free energy G
*, for the reaction, are reported. Mechanistic pathways for the studied reactions are also proposed. 相似文献
44.
S. Waheed J. H. Zaidi S. Ahmad M. Saleem 《Journal of Radioanalytical and Nuclear Chemistry》2002,254(3):597-605
Twenty-three individual food items commonly consumed in a high altitude region (Kashmir) have been investigated using instrumental neutron activation analysis. The concentration of Ca, Cl, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Se, Sn, and Zn is reported for these food articles. For quality assurance of our data, IAEA and NIST standard reference materials have also been studied. The dietary intake of these elements was calculated in accordance with the weekly food selection habits of the residents of this area. The dietary contribution of most of these elements was found to be in agreement to the RDA/ESadi levels. The purpose was to design a database of essential elements for this area and to study the adequacy levels of these elements in different dietary items. Fairly adequate intake of Ca, Co, Cr, Cu, Fe, Mg, Mn, Mo, Se, Sn, and Zn through these foodstuffs is reported, whereas, lower intakes through these items were found for Cl, K, and Na. 相似文献
45.
46.
Peng Liu Mohammad Yasir Dr. Albert Ruggi Prof. Dr. Andreas F. M. Kilbinger 《Angewandte Chemie (International ed. in English)》2018,57(4):914-917
Heterotelechelic polymers were synthesized by a kinetic telechelic ring‐opening metathesis polymerization method relying on the regioselective cross‐metathesis of the propagating Grubbs’ first‐generation catalyst with cinnamyl alcohol derivatives. This procedure allowed the synthesis of hetero‐bis‐end‐functional polymers in a one‐pot setup. The molecular weight of the polymers could be controlled by varying the ratio between cinnamyl alcohol derivatives and monomer. The end functional groups can be changed using different aromatically substituted cinnamyl alcohol derivatives. Different monomers were investigated and the presence of the functional groups was shown by NMR spectroscopy and MALDI‐ToF mass spectrometry. Labeling experiments with dyes were conducted to demonstrate the orthogonal addressability of both chain ends of the heterotelechelic polymers obtained. 相似文献
47.
Applicability Evaluation of Bright Green‐Emitting Carbon Dots in the Solid State for White Light‐Emitting Diodes 下载免费PDF全文
Self‐quenching‐resistant and bright green‐emitting carbon dots (CDs) in the solid state were synthesized via a facile hydrothermal method. Their structure, optical properties together with their thermal and photostabilities, as well as their applicability in white LEDs were investigated. The obtained CDs have nearly spherical shape with a size around 4–5 nm. The resulting powder CDs show excitation‐independent emission behavior, and can be excited over a broad range from 300–450 nm. Under optimal excitation at 400 nm, the resultant powder CDs yield bright and broad green emission around 505 nm with full width at half maximum (FWHM) of about 110 nm and under 360 nm excitation with lifetime of 15.8 ns. A potential application of the green‐emitting CDs was evaluated by constructing a white light‐emitting diode lamp. The fabricated white LED lamp emitted bright, warm white light with excellent color rendering properties (a color rendering index of 86.9 and a correlated color temperature of 3863 K). 相似文献
48.
A. Mannan S. Waheed S. Ahmad I. H. Qureshi 《Journal of Radioanalytical and Nuclear Chemistry》1992,162(1):111-123
Several potentially toxic trace elements, namely, Hg, Pb, Cd, As, Sb, Br and Se have been measured by INAA in combination with AAS techniques in the integrated diet representative of the inhabitants of Gujranwala, a highly industrialized city of Pakistan. The dietary intake values for these elements have been estimated from the prevailing concentration level in the summer and winter season diets, which reveals that present intake data are well within the reported WHO values and can be considered to be safe. Posslble sources of food contamination by the toxic elements and their adverse impacts on human heaith are briefly discussed. 相似文献
49.
Shahida Waheed Asma Rahman Naila Siddique Shujaat Ahmad Matthias Rossbach 《Accreditation and quality assurance》2007,12(6):311-316
The results from a proficiency test exercise for the determination of natural levels of radionuclides in mushroom reference
material carried out by laboratories in six different countries are discussed. These laboratories submitted data on seven
radionuclides, namely 134Cs, 137Cs, 40K, 90Sr, 241Am, 226Ra, and 210Po. However, only the data received for three of these radionuclides could be statistically evaluated to obtain consensus
mean values and confidence intervals (at a significance level of 0.05). The contents of 134Cs, 137Cs and 40K were quantified as 4.4, 2,899 and 1,136 Bq/kg, respectively. 相似文献
50.
Muhammad Faheem Arif-ullah Khan Muhammad Waqas Saleem Fawad Ali Shah Fawad Ali Abdul Waheed Khan Shupeng Li 《Molecules (Basel, Switzerland)》2022,27(15)
The current study explored the effects of natural compounds, berbamine, bergapten, and carveol on paclitaxel-associated neuroinflammatory pain. Berbamine, an alkaloid obtained from Berberis amurensisRuprhas been previously researched for anticancer and anti-inflammatory potential. Bergapten is 5-methoxsalenpsoralen previously investigated in cancer, vitiligo, and psoriasis. Carveol obtained from caraway is a component of essential oil. The neuropathic pain model was induced by administering 2 mg/kg of paclitaxel (PTX) every other day for a week. After the final PTX injection, a behavioral analysis was conducted, and subsequently, tissue was collected for molecular analysis. Berbamine, bergapten, and carveol treatment attenuated thermal hypersensitivity, improved latency of falling, normalized the changes in body weight, and increased the threshold for pain sensation. The drugs increased the protective glutathione (GSH) and glutathione S-transferase (GST) levels in the sciatic nerve and spinal cord while lowering inducible nitric oxide synthase (iNOS) and lipid peroxidase (LPO). Hematoxylin and eosin (H and E) and immunohistochemistry (IHC) examinations confirmed that the medication reversed the abnormal alterations. The aforementioned natural substances inhibited cyclooxygenase-2 (COX-2), tumor necrosis factor-alpha (TNF-α), and nuclear factor kappa B (NF-κb) overexpression, as evidenced by enzyme-linked immunosorbant assay (ELISA) and Western blot and hence provide neuroprotection in chronic constriction damage. 相似文献