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991.
Yu‐ting Lu Wen‐zhu Qi Yan‐fei Chen Min Song Tai‐jun Hang 《Journal of separation science》2019,42(16):2650-2659
Mycophenolate mofetil is an antiproliferative immunosuppressive agent. Since its clinical efficacy and safety highly depend on the quality, the stability, and impurity profiles of mycophenolate mofetil are paid ever‐increasing attention. However, there are few published studies reporting the complete characterization of both the process‐related substances and degradation products in mycophenolate mofetil. In the present study, a highly specific and efficient liquid chromatography coupled with quadrupole‐time of flight mass spectrometry method was developed for the separation and identification of all the potential impurities in mycophenolate mofetil. According to the ICH Q1A (R2) guideline, the forced degradation studies were conducted to elucidate the stability and degradation pathways of mycophenolate mofetil. A total of 15 related substances, including the process‐related substances and stress degradation products were characterized by the established hyphenated method, 11 of them have not been reported before. In view of the synthetic route and degradation pathways of mycophenolate mofetil, the origins and formation mechanisms of these related substances were discussed. Based on the obtained stability and impurity profiles, key points of the manufacturing process were proposed to deliver mycophenolate mofetil with high purity. 相似文献
992.
Aligned crystallites of 1,6‐di‐(N‐carbazolyl)‐2,4‐hexadiyne (DCHD) were prepared on the phenyltrichlorosilane‐modified SiO2/Si surface using the brush‐coating method. The length and width as well as the orientation of the crystallites depend on the coating speed. At a lower coating speed of 0.2 ~ 0.3 mm/s, well‐separated fibers with a width of 1–2 μm and a length of hundreds of μm were grown along the coating direction. Higher speeds resulted in shorter fibers together with randomly oriented tiny crystallites appearing in between. The diacetylene crystallites upon UV irradiation gave polydiacetylene fibers with deformations along the fiber axis. The poly(ene‐yne) backbones were shown to align along the fiber axes. With these poly‐DCHD fibers as a conducting channel for transistor fabrication, a highest field‐effect mobility of 0.039 cm2/Vs was obtained. 相似文献
993.
994.
A method is proposed to modulate phase using variant square holes in a metallic film based on a fundamental mode approximation model. Phase retardation through square holes in a subwavelength scale in a thin metal film has been analyzed and calculated. Based on the model, a structured lens with a numerical aperture of 0.583 and a focal length of 240 microm formed by a 2D square hole array in a metallic film is designed. Numerical simulation using the finite-difference time-domain method is carried out, and the results agree with the theoretical analysis. A focal spot close to the diffraction limit can be obtained. 相似文献
995.
Four explicit type time marching methods, including one proposed by the authors, are examined. The TVD conditions of this method are analyzed with the linear conservation law as the model equation. Performance of these methods when applied to the Euler equations are numerically tested. Seven examples are tested, the main concern is the performance of the methods when discontinuities with different strengths are encountered. When the discontinuity is getting stronger, spurious oscillation shows up for three existing methods, while the method proposed by the authors always gives the results with satisfaction. The effect of the limiter is also investigated. To put these methods in the same basis for the comparison the same spatial discretization is used. Roe's solver is used to evaluate the fluxes at the cell interface; spatially second-order accuracy is achieved by the MUSCL reconstruction. 相似文献
996.
Taxol@,ataxanediterpenoidisolatedfromthePacificyewtreebyWantetal.',hasattractedmuchattentionandiscurrentlyconsideredasoneofthemostimportantchemotherapeuticagents'forcancer.Inordertomeettherequirementsoftaxolforclinicalusageandtoprotectthenaturalresources,greatinterestisconcentratedontheisolationoftaxolanditsrelatedcompoundsfromrenewableresources,includingThousxmediaHicksii3.Inapreviouspaper,wereportedtheisolationofanewtaxoid,taxamedinA4,fromtheneedlesofthisplant.Oncontinuousinvestigationanot… 相似文献
997.
998.
Tai Chun Cheng A. F. Halasa D. P. Tate 《Journal of polymer science. Part A, Polymer chemistry》1973,11(1):253-259
A polybutadiene of high molecular weight was prepared in hydrocarbon solvent by using n-BuNa–tert-BuOM (M = Li, K) as a polymerization initiator. The microstructure of this polymer varied from 35 to 76% of 1,2 content, depending on the type of modifiers. The kinetics of polymerization was not studied, primarily due to the heterogeneous nature of the catalyst. However, other variables, such as the catalyst concentration and temperature, have been studied. The results and mechanistic implications are discussed. 相似文献
999.
1000.
Tai RZ Namikawa K Kishimoto M Tanaka M Sukegawa K Hasegawa N Kawachi T Kado M Lu P Nagashima K Daido H Maruyama H Sawada A Ando M Kato Y 《Physical review letters》2002,89(25):257602
A picosecond x-ray laser speckle has been conducted to study the dynamics of a disordered surface domain structure (BaTiO3 with 90 degrees c/a domains) as a function of temperature for the first time. The transient surface structures induced by ferroelectric domains decrease as temperature increases towards the Curie temperature T(c) and completely disappear above T(c). The dramatic change of the spatial configuration of the c/a domains was observed to occur from a temperature 2 degrees C below T(c), near which the average correlated domain size at equilibrium decreases as (T(c)-T)(0.37+/-0.02). 相似文献