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101.
A three-dimensional micromagnetic model with non-uniform grain size distribution has been built up to study the magnetization process in FePt L10 perpendicular media. A 3D model of a single FePt magnetic grain is also set up for comparison. The high magneto-crystalline anisotropy Ku results in a short exchange length lex in FePt nanograins. Therefore a magnetic grain is divided into smaller grids on the order of lex. The simulated perpendicular and longitudinal loops are consistent with experiments, and it is explained why the measured perpendicular Hc is relatively smaller compared with the saturation field of the longitudinal loop in the FePt perpendicular medium. 相似文献
102.
Accurate estimation of flow velocity requires measurement of Doppler angle, which is not available in general clinical applications. We describe a novel method of direct Doppler angle and flow velocity mapping that uses a conventional single-beam optical Doppler tomography system. The Doppler angle is estimated by combination of Doppler shift and Doppler bandwidth measurements, and flow velocity is calculated from the Doppler shift and the estimated Doppler angle. In vivo study of lip microvascularization demonstrates that this method is capable of providing both flow speed and flow direction information. 相似文献
103.
New method for preparation of coumarins and quinolinones via Pd-catalyzed intramolecular hydroarylation of C-C triple bonds 总被引:1,自引:0,他引:1
A new and general method has been developed for preparation of coumarins and quinolinones by intramolecular hydroarylation of alkynes. Various aryl alkynoates and alkynanilides undergo fast intramolecular reaction at room temperature in the presence of a catalytic amount of Pd(OAc)(2) in a mixed solvent containing trifluoroacetic acid (TFA), affording coumarins and quinolinones in moderate to excellent yields with more than 1000 turnover numbers (TON) to Pd. The methodology proved to tolerate a number of functional groups such as Br and CHO. On the basis of isotope experiments, a possible mechanism involving ethynyl chelation-assisted electrophilic metalation of aromatic C-H bonds by in-situ generated cationic Pd(II) species has been discussed. Also the involvement of vinylcationic species has been suggested. 相似文献
104.
Xu Feng-Lan Piao You-Zhi Zhang Yue-Qing Wu Sheng-Li Li Dian-Ying Du Shu-Qin 《Fiber and Integrated Optics》1990,9(3):225-230
GaAs/GaAlAs traveling wave type laser amplifiers with different tilted angle facets are defined by proton bombardment. Some characters are measured. Maximum single-pass gains of 27.8 dB are reached with an optical fiber coupling system. 相似文献
105.
Daxiong Piao 《中国科学 数学(英文版)》2001,44(9):1156-1161
In this paper, we investigate the existence and uniqueness of new almost periodic type solutions, so-called pseudo almost periodic solutions for the systems of differential equations with piecewise constant argument by means of introducing the notion of pseudo almost periodic vector sequences 相似文献
107.
设计合成了一系列2-(4-取代苄基-1,4-高哌嗪-1-基)-N-(5-溴喹喔啉-6-基)乙酰胺化合物,测定其对家兔离体左心房搏出量的影响,对化合物的正性肌力活性进行了初步评价.结果显示,一些衍生物在测试浓度下显示出比上市药物米力农更好的正性肌力活性,其中活性最好的化合物是3f,在浓度为3×10-5mol L-1时,增强左心房搏出量的强度达(6.18±0.06)%[米力农:(2.46±0.07)%].实验中所合成的化合物通过IR,1H NMR,MS和元素分析测试进行了确证. 相似文献
108.
Self‐assembled graphene oxide–gelatin nanocomposite hydrogels: Characterization,formation mechanisms,and pH‐sensitive drug release behavior 下载免费PDF全文
Novel physically crosslinked graphene oxide (GO)‐gelatin nanocomposite hydrogels were obtained by self‐assembly. The hydrogels with various ratios of GO to gelatin were prepared, and characterized by X‐ray diffraction, Fourier transform infrared spectroscopy, Raman spectroscopy, and scanning electron microscopy. The static and dynamic rheological properties of the hydrogels were investigated, along with the underlying hydrogel formation mechanisms. The storage modulus of the hydrogels (containing 98–98.5 wt % water) reached 114.5 kPa, owing to the relatively strong physical bonding (i.e., hydrogen bonding and electrostatic forces) between GO and gelatin. Drug release tests showed that the drug release from the hydrogel was pH‐dependent, with 96% of the model drug released in a neutral environment, compared to 28% released in an acidic medium. These hydrogels could have potential in pH‐sensitive drug delivery. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015 , 53, 356–367 相似文献
109.
110.
This article has been retracted: please see Elsevier Policy on Article Withdrawal (http://www.elsevier.com/locate/withdrawalpolicy).This article has been retracted at the request of the corresponding author. The corresponding author prepared a series of cinchonine derivatives and found that the structure of PCA, which was a major compound, was mistakenly assigned. The synthetic routes, physical and spectroscopic data for the products are valid. As a result the corresponding author withdraws this publication. 相似文献