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排序方式: 共有179条查询结果,搜索用时 343 毫秒
41.
Asma Akhtar Tasneem Gul Kazi Hassan Imran Afridi Jameel Ahmed Baig Mohammad Bilal Arain 《应用有机金属化学》2020,34(9):e5784
In the present study an innovative tandem ionic liquid-based dispersive microextraction method using an in-syringe air-assisted vesicle system was developed to determine the ultra-trace levels of lead (PbII) and cadmium (CdII) ions in synthetic sweat extract of branded and nonbranded facial cosmetic products. This method is based on injecting 2-amino-3-sulfhydrylpropanoic acid (l -cysteine) (as an eco-friendly chelating agent), hexafluorophosphate ion [PF6−] (as an ion pair agent) and 1-hexyl-3-methylimidazolium hexafluorophosphate [HMIM] [PF6] (as an acceptor phase) into the synthetic sweat extract of facial cosmetic products (branded and nonbranded). The acceleration of the dispersion process was carried out by rapid pressure in the syringe through the back-and-forth movement of plunger. The sediment phase was removed following centrifugation, and then hydrophobic complexes of analyte were back-extracted into HNO3 and finally injected into a flame atomic absorption spectrometer. Several factors were systematically optimized. The validity of the methodology was tested by analyzing spiked known standards of both metals in a real sample. The proposed method was applied to the artificial sweat extracts of face makeup products, indicating how much toxic metals from different cosmetics are directly absorbed into skin. 相似文献
42.
43.
A Study on Oscillatory and Asymptotic Nature of Impulsive Neutral Differential Equations of Order Three
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Abdur Raheem Asma Afreen Areefa Khatoon 《Journal of Nonlinear Modeling and Analysis》2022,4(3):475-487
In this paper, we consider a class of third-order neutral impulsive differential equations. An equivalent class of neutral differential equations is obtained by using a suitable substitution. Some new oscillation results are proved. Moreover, we discuss the asymptotic behavior of the solution. The results presented here are illustrated via examples. 相似文献
44.
Aïcha Arfaoui Fatma Saâdi Asma Bourafai Aziez Hammouda Chebbi Catherine Fressigné Julien Legros 《合成通讯》2018,48(6):705-713
An efficient coupling reaction of allyl bromides with various alcohols as nucleophiles activated by triethylamine, leading to functionalized vinyl ethers in good yields and with full stereoselectivity. 相似文献
45.
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
46.
Mahboba B. Naili Rabia O. Alghazeer Nabil A. Saleh Asma Y. Al-Najjar 《Arabian Journal of Chemistry》2010,3(2):79-84
The present work quantitatively evaluates the antimicrobial and antioxidant potentials of two Libyan folk medicinal plants [Artemisia campestris (Astraceae) and Ziziphus lotus (Rhamnacea)] that commonly grow in the south of Libya. The crude methanolic leaves extracts of both plants are appreciably active against Gram-positive species, associated with week anti-Gram-negative activity. These two plant extracts also showed reasonably high contents of polyphenolics and alkaloids, with minimal inhibitory concentrations between 12.5–25 and 250–1000 μg/ml for Gram-positive and Gram-negative species, respectively. Results collectively suggest that A. campestris and Z. lotus are not only reliable natural sources of antimicrobials but also potential sources of phenolic antioxidants and hence could be nominated for future intensive studies. 相似文献
47.
Hammami Asma Assaker Ibtissem Ben Chtourou Radhouane 《Journal of Solid State Electrochemistry》2022,26(1):211-218
Journal of Solid State Electrochemistry - In this work, we investigate the properties of manganese dioxide (MnO2) and graphene oxide (GO) to develop a new photoelectrochemical (PEC) sensor-based... 相似文献
48.
In this work, the photocatalytic activity of the synthesized graphene oxide (GO)‐Fe3O4/TiO2 mesoporous photocatalysts was evaluated using chlorpyrifos (CP) as a contaminant. The nano‐photocatalyst was characterized by X‐ray diffraction, field emission scanning electron microscopy with energy‐dispersive X‐ray spectroscopy, transmission electron microscopy, and specific surface area by the Brunauer–Emmett–Teller method. Using visible light, the GO‐Fe3O4/TiO2 mesoporous photocatalyst was investigated on the degradation of CP pesticide. The GO‐Fe3O4/TiO2 photocatalyst displayed a good photocatalytic activity, which was achieving 97% of CP degradation after 60 min. Finally, experiments were performed to evaluate GO‐Fe3O4/TiO2 mesoporous nanocatalyst activity on repeated applications; after several uses, its photocatalytic activity was retained, which indicated stability. 相似文献
49.
Dr. Honghong Fan Dr. Farzaneh Bahmani Dr. Yusuf Valentino Kaneti Dr. Yanna Guo Prof. Asma A. Alothman Prof. Xinglong Wu Prof. Yusuke Yamauchi Prof. Wenliang Li Prof. Jingping Zhang 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(60):13652-13658
Binary transition-metal oxides (BTMOs) with hierarchical micro–nano-structures have attracted great interest as potential anode materials for lithium-ion batteries (LIBs). Herein, we report the fabrication of hierarchical cauliflower-like CoFe2O4 (cl-CoFe2O4) via a facile room-temperature co-precipitation method followed by post-synthetic annealing. The obtained cauliflower structure is constructed by the assembly of microrods, which themselves are composed of small nanoparticles. Such hierarchical micro–nano-structure can promote fast ion transport and stable electrode–electrolyte interfaces. As a result, the cl-CoFe2O4 can deliver a high specific capacity (1019.9 mAh g−1 at 0.1 A g−1), excellent rate capability (626.0 mAh g−1 at 5 A g−1), and good cyclability (675.4 mAh g−1 at 4 A g−1 for over 400 cycles) as an anode material for LIBs. Even at low temperatures of 0 °C and −25 °C, the cl-CoFe2O4 anode can deliver high capacities of 907.5 and 664.5 mAh g−1 at 100 mA g−1, respectively, indicating its wide operating temperature. More importantly, the full-cell assembled with a commercial LiFePO4 cathode exhibits a high rate performance (214.2 mAh g−1 at 5000 mA g−1) and an impressive cycling performance (612.7 mAh g−1 over 140 cycles at 300 mA g−1) in the voltage range of 0.5–3.6 V. Kinetic analysis reveals that the electrochemical performance of cl-CoFe2O4 is dominated by pseudocapacitive behavior, leading to fast Li+ insertion/extraction and good cycling life. 相似文献
50.
Mosbah Habib Chahdoura Hassiba Mannai Asma Snoussi Mejdi Aouadi Kaïss Abreu Rui M. V. Bouslama Ali Achour Lotfi Selmi Boulbaba 《Applied biochemistry and biotechnology》2019,187(3):1113-1130
Applied Biochemistry and Biotechnology - A series of enantiopure isoxazolidines (3a–c) were synthesized by 1,3-dipolar cycloaddition between a (−)-menthone-derived nitrone and various... 相似文献