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排序方式: 共有121条查询结果,搜索用时 15 毫秒
51.
The modified titanium electrode with lead film (PbTiE) was used for determination of trace levels of cadmium using square wave anodic stripping voltammetry (SWASV). The measurement of cadmium on the PbTiE has the best reply under the following conditions of PbTiE preparation: 10–3 mol L–1 Pb2+ in HCl (pH 1.0), deposition potential of–1.40 V vs. Ag/AgCl/KClsat and deposition time of 300 s. The PbTiE reveals highly linear behavior in the concentration range 5 × 10–8 to 10–6 mol L–1, with a limit of detection of 2 × 10–9 mol L–1. Interference of nine ionic species was evaluated. The measurements were carried out without removing dissolved oxygen from the solution. 相似文献
52.
Fatiha Athman Mohamed Dahmane Soulimane Boudah Moulay-Hassane Guermouche Jean Pierre Bayle Saïd Sebih 《Chromatographia》2009,70(3-4):503-510
Comparative gas chromatographic applications of two new liquid crystals were investigated. The characterization of the two mesogenic compounds was performed with 1H NMR and mass spectrometry. The thermal properties were established by differential scanning calorimetry. The optical characterization of the liquid crystal was made by using polarizing optical microscopy. The chromatographic separation abilities of the mesogenic compounds were studied using fused silica capillary columns. Interesting analytical performances were obtained notably in the separation of volatile aroma compounds and derivatives phenols. 相似文献
53.
Effect of the chain length on the thermal and analytical properties of laterally biforked nematogens
Mohamed Dahmane Fatiha Athman Saïd Sebih Moulay-Hassane Guermouche Jean-Pierre Bayle Soulimane Boudah 《Journal of chromatography. A》2010,1217(42):6562-6568
Three laterally substituted liquid crystals were synthesized in order to investigate the effect of a lateral biforked chain on the thermal and analytical properties. The mesogenic molecules have the same core containing four aromatic rings connected by two ester and one diazo linkages, they differ by the length of one chain within the lateral biforked substituent. The phase transition temperatures were obtained by polarized light microscopy and differential scanning calorimetry (DSC). The clearing temperature and the nematic range decrease with increasing length of the lateral biforked chain. The stationary phases derived from these nematogens provide excellent resolution of various classes of compounds, including aromatic hydrocarbons (AH), substituted benzenes, polycyclic aromatic hydrocarbons (PAH), phenols and volatile organic compounds (VOC) present in the essential oils. The selectivities of the stationary phases were found to decrease according to the length of the side chain. 相似文献
54.
55.
M Menelaou F Ouharrou L Rodríguez O Roubeau SJ Teat N Aliaga-Alcalde 《Chemistry (Weinheim an der Bergstrasse, Germany)》2012,18(37):11545-11549
The multifunctional behavior of two mononuclear lanthanide compounds attached to a curcuminoid called 9?Accm has been investigated. The results show that [Dy(9?Accm)(2) (NO(3) )(dmf)(2) ] Yb(9?Accm)(3) (py)] behaves as a single-ion magnet and that both compounds display luminescent responses and exhibit affinity for graphite surfaces. 相似文献
56.
HA Alzahrani R Alsabehi L Boukraâ F Abdellah Y Bellik BA Bakhotmah 《Molecules (Basel, Switzerland)》2012,17(9):10540-10549
In order to assess their physicochemical and antioxidant properties as well as their antimicrobial potency, four varieties of honey from different botanical and geographical origins were used. The agar incorporation method was used to determine the antimicrobial potency of honeys. The total phenol content was determined by a modified Folin-Ciocalteu method and the free radical scavenging activity by the Fe3+ reducing power (FRAP) assay. Manuka honey was the most effective against Staphylococcus aureus Oxa R and S. aureus Oxa S with a Minimum Inhibitory Concentration (MIC) of 6% and 7%, respectively, whereas wild carrot honey was the most effective against Pseudomonas aeruginosa, with a MIC of 12%. Lavender honey was the least effective against all tested strains, even though was found to have the lowest pH and water content. Manuka honey had the highest content of polyphenols, with 899.09 ± 11.75 mg gallic acid/kg, whereas lavender honey had the lowest, with 111.42 ± 3.54 mg gallic acid/kg. A very significant correlation (r value was 0.9079 at P < 0.05) was observed between the total polyphenolic content and the Fe2+ content formed in the presence of the honey antioxidants. The differences between honey samples in terms of antibacterial and antioxidant activity could be attributed to the natural variations in floral sources of nectar and the different locations. 相似文献
57.
Reactions of aromatic amines with 3,3′-bithiophene-2,2′-dicarbaldehyde 1 and 3,3′-bithiophene-4,4′-dicarbaldehyde 2 gave the 2,2′-(N-(aryl)diimino)-3,3′-bithiophene 3 and 4,4′-(N-(aryl)diimino)-3,3′-bithiophene 4 in good yields. Orthophenylenediamine reacted with 1 and 2 to give dithieno[3,4-c;4′,3′-e]azepino[1,2-a]benzimidazole 5 and dithieno[2,3-c;3′,2′-e]azepino[1,2-a]benzimidazole 6. All these original products have been characterized by spectroscopic techniques and elemental analysis. 相似文献
58.
Djilani Imene Nouar Leila Madi Fatiha Haiahem Sakina Bouhadiba Abdelaziz Khatmi DjamelEddine 《Comptes Rendus Chimie》2013,16(8):696-703
The structural aspects for the complexation of ortho-anisidine (O-AN)/β-cyclodextrin were explored by using PM6, density function theory B3LYP/6-31G*, M05-2X/6-31G*, B3PW91/6-31G*, MPW1PW91/6-31G*, HF/6-31G* methods and several combinations of ONIOM2 hybrid calculations. Calculations were performed upon the inclusion complexation of β-cyclodextrin (β-CD) with neutral (O-AN1) and cationic (O-AN2) species of ortho-anisidine. The obtained results with PM6 method clearly indicate that the formed complexes are energetically favored, the complex of O-AN2/β-CD in B orientation is significantly more favorable than the others energetically. The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital (NBO) analysis, employed to quantify the donor–acceptor interactions between ortho-anisidine and β-CD. 相似文献
59.
Sahel Fatma Sebih Fatiha Bellahouel Salima Bengueddach Abdelkader Hamacha Rachida 《Research on Chemical Intermediates》2020,46(1):133-148
Research on Chemical Intermediates - Low-cost Al-MCM-41 and Al-SBA-15 mesoporous materials are successfully synthesized from bentonite as silicon and aluminum sources instead of laboratory reagents... 相似文献
60.
Bouhadiba Abdelaziz Nouar Leila Haiahem Sakina Djilani Imene Madi Fatiha Khatmi DjamelEddine 《Journal of inclusion phenomena and macrocyclic chemistry》2013,77(1-4):455-462
The inclusion complex of β-cyclodextrin (β-CD) and diphenylamine (DPA) was investigated by using PM3MM, DFT, HF and ONIOM2 methods. The most stable structure was obtained at the optimum position and angle. The results indicate that the inclusion complex formed by DPA entering into the cavity of β-CD from its wide side (the secondary hydroxyl group side) is more stable than that formed by DPA entering into the cavity of β-CD from its narrow side (the primary hydroxyl group side). The structures show the presence of several intermolecular hydrogen bond interactions that were studied on the basis of natural bonding orbital (NBO) analysis, employed to quantify the donor–acceptor interactions between diphenylamine and β-CD. A study of these complexes in solution was carried out using the CPCM model to examine the influence of solvation on the stability of the diphenylamine β-CD complex. 相似文献