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101.
Distinguishing and quantification of the human visual pathways using high-spatial-resolution diffusion tensor tractography 总被引:1,自引:0,他引:1
Arash Kamali Khader M. Hasan Pavani Adapa Azadeh Razmandi Zafer Keser John Lincoln Larry A. Kramer 《Magnetic resonance imaging》2014
Quantification of the living human visual system using MRI methods has been challenging, but several applications demand a reliable and time-efficient data acquisition protocol. In this study, we demonstrate the utility of high-spatial-resolution diffusion tensor fiber tractography (DTT) in reconstructing and quantifying the human visual pathways. Five healthy males, age range 24–37 years, were studied after approval of the institutional review board (IRB) at The University of Texas Health Science Center at Houston. We acquired diffusion tensor imaging (DTI) data with 1-mm slice thickness on a 3.0-Tesla clinical MRI scanner and analyzed the data using DTT with the fiber assignment by continuous tractography (FACT) algorithm. By utilizing the high-spatial-resolution DTI protocol with FACT algorithm, we were able to reconstruct and quantify bilateral optic pathways including the optic chiasm, optic tract, optic radiations free of contamination from neighboring white matter tracts. 相似文献
102.
103.
104.
《Electrophoresis》2018,39(17):2202-2209
The synergistic effect of two acidic amino acids, aspartic and glutamic acid, on the electrophoretic enantioseparation of four basic drugs was evaluated in the BGE containing a CD and at different pHs. Chlorpheniramine, hydroxyzine, propranolol and tramadol were used as the basic model drugs. However, no enantioseparations were achieved with a BGE containing sole amino acid, but the combined use of an acidic amino acid and a CD showed improved enantioseparations (synergistic effect) compared with the single CD system. The results demonstrated that at optimized pH, the electrostatic interactions of the anionic amino acids with the positively charged basic drugs could result in a decrease of the analyte migration velocity and it consequently improved the enantioseparation. The effective parameters such as the amino acid and chiral selector type and concentration, buffer pH, applied voltage, and capillary temperature were optimized. Favorable enantiomeric resolution and migration times of the model drugs were achieved with a 100 mM phosphate buffer solution (pH 3.0) containing 5.0 mM HP‐α‐CD/HP‐β‐CD and 20 mM aspartic acid with an 18 kV applied voltage at 25°C. 1H NMR experiments were also carried out in a mixture of an analyte and CD in the absence and presence of aspartic acid. The NMR results were consistent with the results obtained by CE which showed the synergistic effect of amino acid. 相似文献
105.
106.
Jian-Ping Fang 《Journal of Mathematical Analysis and Applications》2007,332(2):1393-1407
In this paper, we construct a new q-exponential operator and obtain some operator identities. Using these operator identities, we give a formal extension of Jackson's transformation formula. A formal extension of Bailey's summation and an extension of the Sears terminating balanced transformation formula are also derived by our operator method. In addition, we also derive several interesting a formal extensions involving multiple sum about three terms of Sears transformation formula and Heine's transformation formula. 相似文献
107.
在阴离子交换树脂催化剂上合成二丙酮醇的动力学研究 总被引:1,自引:0,他引:1
动力学研究表明,在碱性树脂催化剂上丙酮缩合制二丙酮醇是一个1-1级可逆反应,本文对此多相催化的反应机理进行了探讨。 相似文献
108.
The hydrolysis kinetics of spread insoluble monolayers of poly(α-hydroxy acid)s with various molecular weights and lactic
acid–glycolic acid molar ratios was followed by measuring simultaneously the decrease in the surface area at constant surface
pressure and the evolution of the surface potential. The interfacial hydrolysis at alkaline pH leads to the progressive fragmentation
of the polymer molecules and the appearance of charged insoluble products (detected by measuring the surface potential) and
small soluble fragments (detected by measuring the decrease in the surface area). The data obtained by both approaches were
interpreted in the framework of the random scission model. The rates of hydrolysis are larger for polymers with smaller initial
polymerization numbers and increase with the decrease in the molar ratio of lactic acid units.
Received: 7 December 1998 Accepted in revised form: 8 March 1999 相似文献
109.
A. Bakkali A. Barranco R. M. Alonso-Salces E. Corta L. A. Berrueta B. Gallo F. Vicente J. I. Márquez 《Chromatographia》1999,49(3-4):202-207
Summary A solid-phase extraction (SPE) method for sample clean-up followed by a reversed-phase HPLC procedure is reported for the
assay of papaverine, diltiazem, desipramine and nicardipine in urine. Disposable extraction cartridges (DECs) filled with
C18, C8, C2, CH and PH silica-bonded phases were used. The effect on recovery of sample pH, composition of washing and elution
solvents and nature of SPE cartridge were evaluated. The selectivity of SPE was examined using spiked urine samples and the
PH cartridge gave rise to the cleanest extracts. Phenyl cartridges were conditioned with methanol and acetic acid-sodium acetate
buffer. Urine sample was buffered and then applied to the DEC. The washing step was with acetone-water and subsequently with
methanol-acetate buffer. The analytes were eluted with methanol-acetate buffer. The extract was evaporated to dryness, reconstituted
in mobile phase, and chromatographed on a reversed-phase C18 column with UV detection at 212 nm. Recoveries of the tested
compounds from spiked urine samples using the PH cartridge were in all cases>80%. The within-day and between-day repeatabilities
were<5% and 9%, respectively. 相似文献
110.
线性方程组的不带负分量的非零解向量称为半正解.本文给出非齐次线性方程组AX= b (b≠0)的半正解结构,进而得到该类线性方程组有半正解的充分条件和必要条件以及唯一半正解的充要条件. 相似文献