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621.
Leonetti Paolo Miller Harry I. Wieren Leila Miller-Van 《Periodica Mathematica Hungarica》2019,78(2):152-156
Periodica Mathematica Hungarica - Let S be the set of subsequences $$(x_{n_k})$$ of a given real sequence $$(x_n)$$ which preserve the set of statistical cluster points. It has been recently shown... 相似文献
622.
Chia-Yen Wu Dosh Whye Lisa Glazewski Leila Choe Douglas Kerr Kelvin H Lee Robert W Mason Wenlan Wang 《BMC neuroscience》2011,12(1):25
Background
Deletion or mutation(s) of the survival motor neuron 1 (SMN1) gene causes spinal muscular atrophy (SMA), a neuromuscular disease characterized by spinal motor neuron death and muscle paralysis. Complete loss of the SMN protein is embryonically lethal, yet reduced levels of this protein result in selective death of motor neurons. Why motor neurons are specifically targeted by SMN deficiency remains to be determined. In this study, embryonic stem (ES) cells derived from a severe SMA mouse model were differentiated into motor neurons in vitro by addition of retinoic acid and sonic hedgehog agonist. Proteomic and western blot analyses were used to probe protein expression alterations in this cell-culture model of SMA that could be relevant to the disease. 相似文献623.
A simple and appropriate procedure for the synthesis of 4,5‐dihydro‐5‐hydroxy‐3H‐pyrrole‐3,3‐dicarbonitrile derivatives is reported. The advantages of this method are one‐pot conditions, high yield of products, short reaction times, and no need of metal catalyst. The structures are confirmed spectroscopically (IR, 1H‐ and 13C‐NMR, and EI‐MS) and by elemental analyses. A plausible mechanism for this reaction is proposed (Scheme 2). 相似文献
624.
Partial last square regression (PLS) and artificial neural network (ANN) combined to FTIR-ATR and FTNIR spectroscopies have been used to design calibration models for the determination of methyl ester content (%, w/w) in biodiesel blends (methyl ester + diesel). Methyl esters were obtained by the methanolysis of soybean, babassu, dende, and soybean fried oils. Two sets of samples have been used: Group I, binary mixtures (diesel + one kind of methyl ester), corresponding to 96 biodiesel blends (0–100%, w/w), and Group II, quaternary mixtures (diesel + three types of methyl esters), corresponding to 60 biodiesel blends (0–100%, w/w). The PLS results have shown that the FTNIR model for Group I is more precise and accurate (±0.02 and ±0.06%, w/w). In the case of Group II the PLS models (FTIR-ATR and FTNIR) have shown the same accuracies, while the ANN/FTNIR models has presented better performance than the ANN/FTIR-ATR models. The best accuracy was achieved by the ANN/FTNIR model for diesel determination (0.14%, w/w) while the worthiest was that of dende ANN/FTIR-ATR model (0.6%, w/w). Precisions in Group II analysis ranged from 0.06 to 0.53% (w/w) and coefficients of variation were better than 3% indicating that these models are suitable for the determination of diesel–biodiesel blends composed of methyl esters derived from different vegetable oils. 相似文献
625.
Issa Yavari Samereh Seyfi Manijeh Nematpour Zinatossadat Hossaini 《Helvetica chimica acta》2010,93(7):1413-1417
A one‐pot synthesis of dialkyl 1,3a,4,8b‐tetrahydro‐3a,8b‐dihydroxy‐1‐alkyl‐4‐oxoindeno[1,2‐b]pyrrole‐2,3‐dicarboxylates via three‐component reaction from indan‐1,2,3‐trione hydrate (ninhydrin), primary amines, and dialkyl acetylenedicarboxylates is described. 相似文献
626.
BiBi Fatemeh Mirjalili Abdolhamid Bamoniri Leila Rahmati 《Arabian Journal of Chemistry》2019,12(8):2216-2223
1-Amidoalkyl-2-naphthols were prepared via one-pot multi-component reaction of 2-naphthol, aldehydes, and amides in the presence of nano-silica supported boron trifluoride (nano-BF3·SiO2) in ethyl acetate at 80 °C. Short reaction times, high yields, scaleup and easy work-up are the advantages of this protocol. 相似文献
627.
Design, synthesis and characterization of nano Fe3O4@meglumine sulfonic acid as a new solid acid catalyst for the simple and green one pot multicomponent synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones was studied. New solid acid catalyst was prepared through a clean and simple protocol and characterized using FTIR, VSM, TGA, SEM, elemental analysis (CHN) and XRD techniques. Heterogenization of homogeneous catalyst as a green approach is a useful method for enhancing the efficiency of catalyst. Presented study was a new method for attachment of homogeneous highly soluble catalyst (meglumine sulfate) to the magnetite nanoparticle surfaces for preparing a heterogeneous and effective catalyst. Obtained heterogeneous and reusable solid acid catalyst has high performance in the synthesis of Biginelli compounds. The reaction was performed under microwave irradiation as a rapid and green condition. Easy work up as well as excellent yield (90–98%) of products in short reaction times (40–200 s) and reusable catalyst are the main advantages of presented procedure. Reaction products were characterized in details using physical and chemical techniques such as melting point, 1H NMR, 13C NMR and FTIR. 相似文献
628.
A series of mono- and heterodinuclear complexes of type MLnH2 and MLnM′ where M = CoIII, CrIII, ZnII and M′ = CuII, ZnII have been synthesized and characterized. The non-macrocyclic ligands LnH4 contain two geometrically distinct compartments, hexa- (N4O2) and tetradentate (O4) compartments which are bridged by phenolic oxygen atoms. The dinuclear complexes were prepared in stepwise reactions. The non-macrocyclic ligand showed a site specificity of metal ions upon the synthetic procedure. The results obtained reveals that in case of using ligand L2H4 only an isomer (trans-pyridines and cis-phenolates) among three possible geometrical isomers is formed. The metal site scrambling in the prepared complexes were not also observed in the reaction conditions used. The crystal structure of [CrIIIL2H2]ClO4 was determined and discussed. 相似文献
629.
Jamlet Monaselidze Marina Abuladze Eugene Kiziria George Majagaladze Leila Tabatadze Nelly Sapojnikova 《Thermochimica Acta》2006,441(1):8-15
The present study examined the cytotoxic effect of increasing Cr(VI) concentrations on cultured cells by a combination of biochemical methods and DSC, a novel use of DSC in the study of cell death. The characteristics of apoptotic cells are compared with normal cells. Chromatin in human epithelial-like L-41 cells has two thermal transitions at 100 and 105 °C. The heat from these endotherms is 90.5 ± 11.0 J/g DNA. The total heat of denaturation (Qd) is 27.5 ± 3.5 J/g dry biomass. The heat evolved (−Q) is 15.6 ± 3.0 J/g dry biomass. The treatment of cells with 20 μM Cr(VI) for 2 and 4 h has not revealed any changes in heat of denaturation and heat evolution (−Q). However increased treatment time with Cr(VI) at 20 μM resulted in significant changes to the thermal profile and a sharp linear decrease of (−Q) and Qd values. The Qd and (−Q) values of cells treated with 20 μM Cr(VI) for 48 h are equal to 15.5 ± 2.0 and 2.1 ± 0.4 J/g dry biomass, respectively. The changes in chromatin conformation, Bax expression and the collapse of the mitochondrial membrane permeability coincide with the time point from which the action of chromium is irreversible. 相似文献
630.
In this paper, dispersive solid phase extraction with following back-extraction and HPLC/UV determination of Rosmarinic acid have been investigated. Multi-walled carbon nanotubes were used as sorbent in the suggested method. The effectiveness of some parameters such as extraction time, sorbent dosage, pH and ionic strength of the aqueous solution on Rosmarinic acid adsorption were studied. The extraction time of 5.0 min, adsorbent weight of 5.0 mg, and pH of 2.5 were obtained as the optimum experimental parameters. Adsorption of Rosmarinic acid molecules was almost independent from ionic strength. For back-extraction purpose a basic solution containing methanol was brought into contact with sorbent to desorb Rosmarinic acid molecules from sorbent containing adsorbed Rosmarinic acid molecules. Linear range of HPLC method for Rosmarinic acid quantification was 1.80–21.62 mg/L (R2 = 0.998). The relative standard deviation, limit of detection, and limit of quantification for the suggested method were 0.81%, 0.68 mg/L, and 2.86 mg/L, respectively. The proposed method was applied for extraction and HPLC/UV determination of Rosmarinic acid in Lemon balm and Rosemary plant samples. Comparison between obtained chromatograms before adsorption and after desorption processes showed that suggested extraction/back-extraction process has good selectivity and efficiency for separation of Rosmarinic acid molecules from interfering molecules existing in the plant extracts. The proposed method is efficient, low cost, fast, and simple for separation, extraction, and determination of Rosmarinic acid. 相似文献