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Meccanica - In gear pair actual alternating meshing process, the comprehensive errors of the transmission system and the thermal elastic deformation of the teeth body cause the gears in the meshing... 相似文献
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Determination of nifedipine in dog plasma by high‐performance liquid chromatography with tandem mass spectrometric detection 下载免费PDF全文
Xigui Pan Shunchang Zhou Qinqin Fu Xianming Hu Jianhong Wu 《Biomedical chromatography : BMC》2014,28(7):1036-1040
Nifedipine is a dihydropyridine calcium channel blocker used widely in the management of hypertension and other cardiovascular disorders. In this work, a simple, rapid and sensitive liquid chromatography/tandem mass spectrometry method was developed and validated to determine nifedipine in dog plasma using nimodipine as the internal standard. Chromatographic separation was carried out on a C8 column. The mobile phase consisted of a mixture of acetonitrile, water and formic acid (60:40:0.2, v/v/v) at a flow rate of 0.5 mL/min. Detection was performed on a triple quadrupole tandem mass spectrometer in selected reaction monitoring mode via an atmospheric pressure chemical ionization source. The method has a lower limit of quantification of 0.20 ng/mL with consumption of plasma as low as 0.05 mL. The linear calibration curves were obtained in the concentration range of 0.20–50.0 ng/mL (r = 0.9948). The recoveries of the liquid extraction method were 74.5–84.1%. Intra‐day and inter‐day precisions were 4.1–8.8 and 6.7–7.4%, respectively. The quantification was not interfered with by other plasma components and the method was applied to determine nifedipine in plasma after a single oral administration of two controlled‐release nifedipine tablets to beagle dogs. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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A new monomer, (2,5‐dimethoxy)phenylhydroquinone (DMPH), was prepared in a two‐step synthetic procedure. One aromatic poly(ether ether ketone)s with 2,5‐dimethoxy phenyl side group (DMP‐PEEK) was synthesized via an aromatic nucleophilic substitution reaction with 4,4′‐difluorobenzophenone (DFB). Poly(ether ether ketone)s with 2,5‐dihydroxy phenyl side group (DHP‐PEEK) was obtained via hydrolysis of methoxy group on the DMP‐PEEK. Both of the high molecular weight polymers could be obtained despite the steric effect of the bulky pendant groups. The two polymers have good solubility at room temperature. 相似文献
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溶胶-凝胶法制备掺Sm3+的SiO2玻璃的结构及发光性能 总被引:1,自引:0,他引:1
利用溶胶-凝胶技术制备了掺不同量Sm3+和不同退火温度下的SiO2凝胶和玻璃,通过三维荧光光谱、激发光谱、发射光谱的测试,确定了Sm3+在SiO2凝胶玻璃中的最佳激发波长为360 nm,最强发射波长为610 nm,激发光谱的峰位置在360、393、464 nm处,发射光谱的峰位置在578、591、595、610、732nm处,分别归属于4G5/2-6H5/2、4G5/2-6H7/2、4G5/2-6H11/2跃迁,并证明当掺杂量达到1.15%时,Sm3+的发光最强,当Sm3+的掺杂量超过1.15%时,发生浓度猝灭效应. 相似文献
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内标-导数红外光谱法定量测定甲硫氨基酸的含量 总被引:1,自引:0,他引:1
本文利用内标-导数红外光谱法测定家禽营养限制性氨基酸--甲硫氨基酸的含量,选择了合适的内标物CaSO4,并采用峰高、峰面积、一阶导数、二阶导数等方法,所得的标准曲线方程的相关系数在0.994~0.998范围之间,结果比较满意。 相似文献
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化学课程结构的横向衔接性包括化学教科书内容的横向衔接性和化学课程设置类型的横向衔接性。从化学教科书内容的横向衔接性分析,化学学科在培养学生的创新思维、提高学生的实践能力上发挥着重要的作用;从化学课程类型的横向衔接性分析,化学学科有利于增强学生探索未知世界的兴趣和能力等。在义务教育阶段的理科综合不能普及的情况下,化学课程结构的横向衔接性对于培养学生的创新思维和实践能力具有独特的作用。 相似文献
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This study reported a method to prepare fully aromatic macrocycle‐terminated polyimides (MC‐PI). The macrocycle of aryl ether ketones was prepared from (4‐amino)phenylhydroquinone and a di‐fluoro monomer under pseudo high dilution condition. Novel aromatic fully MC‐PI oligomers were successfully prepared by the reaction of 2,3,3′,4′‐biphenyltetracarboxylic diandhydride with 2,5‐bis(4′‐aminophenoxy)‐biphenyl and sulfur‐containing macrocycle of aryl ether ketone. The MC‐PI oligomers were cross‐linkable in the heating, and the glass transition temperatures of the polyimides increased after thermally cured. The cross‐linking reaction of MC‐PI could form fully aromatic thermosetting polyimide by ring‐opening reaction. After cross‐linking, these polyimides showed higher glass transition temperatures and excellent thermal stability. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献