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101.
Functional magnetic resonance imaging (fMRI) is an effective tool for the measurement of brain neuronal activities. To date, several statistical methods have been proposed for analyzing fMRI datasets to select true active voxels among all the voxels appear to be positively activated. Finding a reliable and valid activation map is very important and becomes more crucial in clinical and neurosurgical investigations of single fMRI data, especially when pre-surgical planning requires accurate lateralization index as well as a precise localization of activation map.Defining a proper threshold to determine true activated regions, using common statistical processes, is a challenging task. This is due to a number of variation sources such as noise, artifacts, and physiological fluctuations in time series of fMRI data which affect spatial distribution of noise in an expected uniform activated region. Spatial smoothing methods are frequently used as a preprocessing step to reduce the effect of noise and artifacts. The smoothing may lead to a shift and enlargement of activation regions, and in some extend, unification of distinct regions.In this article, we propose a bootstrap resampling technique for analyzing single fMRI dataset with the aim of finding more accurate and reliable activated regions. This method can remove false positive voxels and present high localization accuracy in activation map without any spatial smoothing and statistical threshold setting. 相似文献
102.
Potassium iodide was used as a homogeneous electrocatalyst for the oxidation of captopril. Cyclic voltammetry and chronoamperometry were used in kinetic studies. The diffusion coefficient and catalytic rate constant were calculated to be 4.94?×?10?5?cm2?s?1 and 1.87?×?103?M?1?s?1, respectively. Linear sweep voltammetry was applied to quantitative determination of captopril; a linear calibration curve was obtained in the range of 4.0?C500???M of captopril with a limit of detection of 0.84???M and a sensitivity of 0.035 A?M?1. The method was applied to the determination of the drug in its tablets and validation methods showed that the results were quite satisfactory. 相似文献
103.
In order to experimentally study the catalyst loading method (dense and sock) influence on liquid distribution, a trickle-bed reactor (TBR) packed with extrudate trilobe catalysts was used. Furthermore, an artificial neural network (ANN) algorithm has been applied; the results show acceptable agreement between the ANN model prediction and experimental data. Due to the isotropic distribution of porosity in sock-loaded bed with trilobe catalysts, the results illustrate that with the same operating conditions the sock-packed beds spread liquid better than dense ones. The effects of bed height and variations of gas/liquid flow rate on liquid distribution in sock- and dense-loaded TBRs have been investigated. 相似文献
104.
Issa Yavari Mohammad J. Bayat Sanaz Souri Mehdi Sirouspour 《Helvetica chimica acta》2009,92(9):1903-1907
A one‐pot synthesis of 2‐(4‐oxo‐1,3‐thiazinan‐5‐yl)acetic acids is described via a three‐component reaction between primary alkylamines and ithaconic anhydride and phenyl isothiocyanate or benzoyl isothiocyanate. 相似文献
105.
A theoretical study on first protonation step of a series of triazacycloalkanes with general formula {([X]aneN3, X = 9–12)} (X = 9, L222; X = 10, L223; X = 11, L233; X = 12, L333) is reported. The geometry of all ligands and their monoprotonated forms were fully optimized at both the Hartree–Fock and DFT (B3LYP) levels of theory using 6-31+G* basis set. Then the first proton macroaffinities were calculated from the proton microaffinities according to defined equations. It is shown that there are good correlations between the calculated gas-phase first proton macroaffinities of these ligands with their protonation constants in solution. 相似文献
106.
Dispersive liquid-liquid microextraction based on solidification of floating organic droplet (DLLME-SFO) with simultaneous derivatization followed by high-performance liquid chromatography-diode array detection (HPLC-DAD) was applied for preconcentration and determination of primary and secondary aliphatic amines in environmental water samples. A ternary mixture consisting of a disperser, an extractant and a derivatization reagent was used for the simultaneous derivatization and extraction of aliphatic amines in different water samples. The effects of various experimental parameters on derivatization and extraction efficiency were studied simultaneously using experimental design. A Plackett-Burman design was performed for screening of variables in order to determine the significant variables affecting the extraction efficiency. Then, the significant factors were optimized by using a Box-Behnken design (BBD) and the response surface equations were derived. Under optimal conditions, the preconcentration factors were between 210 and 290. The limit of detections (LODs) ranged from 0.005 to 0.02 μg/L and dynamic linear ranges (DLRs) of 0.05-500 and 0.1-500 μg/L were obtained for most of analytes. The performance of the method was evaluated for extraction and determination of primary and secondary aliphatic amines in environmental water samples in micrograms per liter and satisfactory results were obtained (RSDs <12.5%). 相似文献
107.
Seyyed Javad Sabounchei Vida Jodaian Sadegh Salehzadeh Sepideh Samiee Alireza Dadrass Mehdi Bayat Hamid Reza Khavasi 《Helvetica chimica acta》2010,93(6):1105-1119
Reactions of phosphonium ylides (4‐MeC6H4)3PCHC(?O)(2‐C4H3S) (tptpy), Ph3PCHC(?O)(2‐C4H3O) (fppy), and (4‐MeC6H4)3PCHC(?O)(4‐BrC6H4) (bbtppy) with HgX2 (X=Cl, Br, and I) in equimolar ratios in MeOH as solvent leads to the binuclear products 1 – 3 (Scheme 1). The bridge‐splitting reaction of the binuclear complex [{HgI2(bbtppy)}2] ( 3c ) by DMSO yields the mononuclear complex [HgI2?(bbtppy) (DMSO)] ( 3d ) (Scheme 2). This bridge‐splitting reaction can also be a method for the synthesis of mononuclear products. C‐Coordination of the ylide and O‐coordination of DMSO are demonstrated by a single‐crystal X‐ray‐analysis of the mononuclear complex 3d . Characterization of the obtained compounds was also performed by means of elemental analysis and IR and 1H‐, 31P‐, and 13C‐NMR spectroscopy. A theoretical study of some HgII complexes with phosphonium ylides is also reported. 相似文献
108.
Highly functionalized 2-pyridones are obtained via a tandem reaction between primary amines and acetylenic esters in the presence of N-methylimidazole as an organocatalyst. 相似文献
109.
Hamid Reza Shaterian Fahimeh Khorami Razieh Doostmohammadi Azita Amirzadeh Majid Ghashang 《Phosphorus, sulfur, and silicon and the related elements》2013,188(9):2227-2237
Silica-supported zinc chloride (SiO2-ZnCl2) and novel alumina-supported sodium hydrogensulfate (NaHSO4-Al2O3) as recyclable heterogeneous catalysts have been used for the mild trimethylsilylation of hydroxyl groups under ambient conditions. This procedure also allows for the selective protection of primary and secondary alcohols in the presence of tertiary alcohols. 相似文献
110.
Zoghi Ali T. Shokouhi Mohammad Naderi Fahimeh Abbasghorbani Maryam Fatehi Azita Pouladi Babak Adhami Mohammad Amin 《Journal of solution chemistry》2022,51(1):84-96
Journal of Solution Chemistry - Hydrogen sulfide and carbonyl sulfide represent undesirable impurities in a variety of industrial gas streams such as natural gas, liquefied natural gas and... 相似文献