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排序方式: 共有163条查询结果,搜索用时 11 毫秒
91.
Abdulrahman Aljannahi Roudha Abdulla Alblooshi Rashed Humaid Alremeithi Ioannis Karamitsos Noora Abdulkarim Ahli Asma Mohammed Askar Ikhlass Mohammed Albastaki Mohamed Mahmood Ahli Sanjay Modak 《Molecules (Basel, Switzerland)》2022,27(13)
Synthetic fibers are one of the most valuable trace lines of evidence that can be found in crime scenes. When textile fibers are analyzed properly, they can help in finding a linkage between suspect, victim, and the scene of the crime. Various analytical techniques are used in the examination of samples to determine relationships between different fabric fragments. In this exploratory study, multivariate statistical methods were investigated in combination with machine learning classification models as a method for classifying 138 synthetic textile fibers using Fourier transform infrared spectroscopy, FT-IR. The data were first subjected to preprocessing techniques including the Savitzky–Golay first derivative method and Standard Normal Variate (SNV) method to smooth the spectra and minimize the scattering effects. Principal Component Analysis (PCA) was built to observe unique patterns and to cluster the samples. The classification model in this study, Soft Independent Modeling by Class Analogy (SIMCA), showed correct classification and separation distances between the analyzed synthetic fiber types. At a significance level of 5%, 97.1% of test samples were correctly classified. 相似文献
92.
Five groups of 4-substituted phenyl 4?-(2?- (or 3″-) substituted-4?-alkoxyphenylazo) benzoates (Ina-c to Vna-c) were investigated in which, within each group, the length of the terminal alkoxy group varies between 8 and 16 carbons, while the other terminal substituent, X, is a polar group that alternatively changed between the electron-donating CH3O and the electron-withdrawing Br group, in addition to the un-substituted analogue (X = H). The lateral substituent (Y) in the five groups I–V varies, respectively, between H, 3-CH3, 2-CH3, 3-F and 2-F. Their mesophase stabilities were determined by differential scanning calorimetry and phases identified by polarised light microscopy. The two newly prepared groups of compounds (IVna-c and Vna-c) are structurally characterised by infrared, 1H-NMR, mass spectroscopy, thermogravimetric and elemental analyses. Binary phase diagrams were constructed for each pair of isomers from groups IV and V bearing the same wing substituents but the lateral F is attached to different positions (2? or 3″). 相似文献
93.
Roshdi Rashed 《Comptes Rendus Mecanique》2019,347(4):357-364
The principle of least time was first conceived by mathematicians-physicists, such as Ibn al-Haytham (Alhazen), as the principle of the easiest way followed by the light ray. It was not until the invention of the maximum and minimum method by Pierre de Fermat that this principle, stated in the Book of Optics of Ibn al-Haytham, became the principle of least time. This article examines the history of this principle in ancient and classical optics. 相似文献
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96.
Ali Hussein Abu Almaaty Hadeer Abd El-hak Rashed Maha Farid Mohamed Soliman Eman Fayad Fayez Althobaiti Nahla Soliman El-Shenawy 《Molecules (Basel, Switzerland)》2021,26(15)
The active ingredients allicin and curcumin have a wide range of actions against fungi, bacteria, and helminths. Therefore, the study was aimed to evaluate the efficacy of allicin (AL) and curcumin (CU) as antischistosomal drugs and their biochemical effects in normal and Schistosoma mansoni-infected mice. Praziquantel (PZQ) was administrated for two successive days while AL or CU was given for two weeks from the week 7th postinfection (PI). The possible effect of different regimens on Schistosoma worms was evaluated by measuring the percentage of the recovered worms, tissue egg load, and oogram pattern. Serum alanine transaminase activity and levels of triglycerides, cholesterol, and uric acid were measured. Liver tissue malondialdehyde and reduced glutathione levels besides, the activities of glutathione-S-transferase, superoxide dismutase and catalase were assessed for the oxidative/antioxidant condition. DNA electrophoresis of liver tissue was used to indicate the degree of fragmentation. There was a significant reduction in the recovered worms and egg load, with a marked change of oogram pattern in all treated groups with PZQ, AL, and CU in comparison with infected-untreated mice. PZQ, AL, and CU prevented most of the hematological and biochemical disorders, as well as significantly improved the antioxidant capacity and enhanced DNA fragmentation in the liver tissue of schistosomiasis mice compared to the infected-untreated group. These promising results suggest that AL and CU are efficient as antischistosomal drugs, and it would be beneficial to test their combination to understand the mechanism of action and the proper period of treatment leading to the best result. 相似文献
97.
The 1H and 13C NMR spectra of sugar (5-methyl [1, 2, 4]-triazino [5, 6-b] indol-3-yl) hydrazones (1), per-0-acetyl aldehydo sugar 1-acetyl-1-(5-methyl [1, 2, 4] triazino [5, 6-b]-indol-3-yl) hydrazones (2), l- (penta-0-acetyl-pentitol-1-yl)-10-methyl [l, 2, 4] triazolo [3′, 4′:3, 4] [l, 2, 4] triazino [5, 6-b]-indoles (3) have been investigated. The 2 D NMR (H, C COSY) spectrum of 2a has been studied. 相似文献
98.
Phytochemical screening of air-dried leaves and fruit juice of certain Ficus and Morus spp. have been studied. In an in?vitro study, the ethanol and hexane extracts of the investigated plants were evaluated against hyperlipidaemia by estimating the rate limiting enzyme of cholesterol biothenysis; β-hydroxy-β-methylglutaryl coenzyme A reductase (HMG-CoA reductase). The antioxidant activity was evaluated by reduction of DPPH(-) free radical. Extra phytochemical screening of Ficus extracts was undertaken, which recorded potent hypolipidaemic and antioxidant activities. The more pronounced extract, Ficus mysorensis (hexane extract), was evaluated in?vivo by estimation of the lipid profile and certain antioxidant parameters in hypercholesterolemic rats. The hexane fraction was chromatographed and six isolated compounds were identified. Furthermore, its saponifiable fraction was identified by a MS/MS technique. In conclusion, F. mysorensis recorded hypolipidaemic and antioxidant effects. Detailed studies of the isolated compounds must be undertaken for an evaluation against hypercholesterolemia and free radical elevation. 相似文献
99.
Saponifiable and unsaponifiable fractions of Ficus microcarpa leaves hexane extract have been phytochemically studied and evaluated for its hypolipidaemic and antioxidant effects in hypercholesterolemic rats. The effect of the extract on the lipid profile was assessed by measuring the levels of total cholesterol, high-density lipoprotein cholesterol (HDL-C), low-density lipoprotein cholesterol (LDL-C), triglycerides, phospho and total lipids. Lipid peroxides, glutathione and superoxide dismutase were measured as antioxidants. The work was extended to evaluate liver function indices as well as the histopathological picture of the liver after treatment. Treatment with leaves extract (500 mg kg?1 body weight) 5 times/week for 9 weeks at the same time of cholesterol administration (30 mg/0.3 mL 0.7% tween/animal) recorded an improvement of lipid profile, antioxidants, liver function enzymes and the liver histopathological picture. The lipoidal matters of the unsaponifiable fraction of the hexane extract by GC/MS led to the identification of 22 compounds, while saponifiable fraction by (MS/MS) technique led to identification of 13 unsaturated and saturated fatty acid methyl ester derivatives. It can be concluded that the hexane extract of F. microcarpa L has been proved to have hypolipidaemic and antioxidant effects in hypercholesterolemic rats through its role in counteracting LDL oxidation, enhancement of HDL synthesis and inhibition of lipid peroxidation. 相似文献
100.
A series of 3,5-disubstituted pyrazole-1-carboxamides were obtained by treatment of chalcones with semicarbazide hydrochloride in dioxane containing sodium acetate/acetic acid as a buffer solution. N-acetyl derivatives of pyrazole-1-carboxamides were isolated in good yields either by treatment of the carboxamide derivatives with acetic anhydride or refluxing chalcones with semicarbazide in ethanol containing few drops of acetic acid to give the corresponding hydrazones. Subsequent treatment of hydrazones with acetic anhydride gave the desired N-acetyl pyrazole-1-carboxamides derivatives. When chalcones were refluxed with dioxane containing few drops of acetic acid, 4,5-dihydropyrazole-1-carboxamides were isolated, which were subsequently oxidized using 5% sodium hypochlorite in dioxane to afford pyrazole-1-carboxamides. The structures of isolated compounds were confirmed by elemental analyses and spectral methods. The isolated compounds were tested for their antimicrobial activities. 相似文献