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排序方式: 共有174条查询结果,搜索用时 234 毫秒
171.
Brahmi Y Katir N Hameau A Essoumhi A Essassi el M Caminade AM Bousmina M Majoral JP El Kadib A 《Chemical communications (Cambridge, England)》2011,47(30):8626-8628
Controlled titanium alkoxide mineralization in the presence of phosphonated, dendrimeric nano-building blocks provides a new family of hierarchically porous dendrimer-bridged titanium dioxide materials. 相似文献
172.
Abdellatif El Kihel Mustapha Ahbala Abdelkrim Mouzdahir Naima Snader El Mokhtar Essassi Patrick Bauchat 《合成通讯》2013,43(2):200-204
Imidazobenzodiazepine derivatives were obtained by cyclization of the condensation products 7‐amino‐2,5,6‐trimethylbenzimidazole with acetylacetone and ethyl acetoacetate. By careful examination of spectroscopic data and the open‐chain intermediate isolation, we have identified the formed compound structure. 相似文献
173.
El Kadib A Primo A Molvinger K Bousmina M Brunel D 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7940-7946
The ability of chitosan biopolymer to coordinate vanadium, tungsten and molybdenum metallic species and to control their mineralisation growth provides a new family of surface-reactive organic-inorganic hybrid microspheres. Drying the resulting materials under supercritical conditions allowed the gel network dispersion to be retained, thereby leading to a macroporous catalyst with surface areas ranging from 253 to 278 m(2) g(-1). On account of the open framework structure of these microspheres, the redox species entangled within the fibrillar network of the polysaccharide aerogels were found to be active, selective and reusable catalysts for cinamylalcohol oxidations. 相似文献
174.
Adel Ehab Ibrahim Yasmine Ahmed Sharaf Sami El Deeb Rania Adel Sayed 《Molecules (Basel, Switzerland)》2022,27(12)
In 2018, the discovery of carcinogenic nitrosamine process related impurities (PRIs) in a group of widely used drugs led to the recall and complete withdrawal of several medications that were consumed for a long time, unaware of the presence of these genotoxic PRIs. Since then, PRIs that arise during the manufacturing process of the active pharmaceutical ingredients (APIs), together with their degradation impurities, have gained the attention of analytical chemistry researchers. In 2020, favipiravir (FVR) was found to have an effective antiviral activity against the SARS-COVID-19 virus. Therefore, it was included in the COVID-19 treatment protocols and was consequently globally manufactured at large-scales during the pandemic. There is information indigence about FVR impurity profiling, and until now, no method has been reported for the simultaneous determination of FVR together with its PRIs. In this study, five advanced multi-level design models were developed and validated for the simultaneous determination of FVR and two PRIs, namely; (6-chloro-3-hydroxypyrazine-2-carboxamide) and (3,6-dichloro-pyrazine-2-carbonitrile). The five developed models were classical least square (CLS), principal component regression (PCR), partial least squares (PLS), genetic algorithm-partial least squares (GA-PLS), and artificial neural networks (ANN). Five concentration levels of each compound, chosen according to the linearity range of the target analytes, were used to construct a five-level, three-factor chemometric design, giving rise to twenty-five mixtures. The models resolved the strong spectral overlap in the UV-spectra of the FVR and its PRIs. The PCR and PLS models exhibited the best performances, while PLS proved the highest sensitivity relative to the other models. 相似文献