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排序方式: 共有1622条查询结果,搜索用时 31 毫秒
101.
A new and efficient synthetic method of a liquid crystalline epoxy resin with biphenol and aromatic ester group 总被引:1,自引:0,他引:1
Yin-Ling Liu Zhi-Qi Cai Xiufang Wen Pihui Pi Dafeng Zheng Jiang Cheng Zhuoru Yang 《Polymer Bulletin》2011,67(1):57-66
This article describes a high efficient and economical method to synthesize a liquid crystalline epoxy resin (LCER) containing
biphenol and aromatic ester group, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-(oxiran-2-ylmethoxy) benzoate) (4). First, 3,3′,5,5′-tetramethylbiphenyl-4,4′-diyl bis(4-hydroxybenzoate) (3) was prepared by direct esterification of 3,3′,5,5′-tetramethylbiphenyl-4,4′-diol (2) with p-hydroxybenzoic acid (1) in the presence of a certain amount of p-toluene sulfonic acid (p-TSA) as catalyst. And then (4) was synthesized by the reaction of (3) with epichlorohydrin. The chemical structure, melting range, and liquid crystalline phase transition behavior of (4) were characterized by FT-IR, 1H-NMR, 13C-NMR, mass spectroscopy, differential scanning calorimetry (DSC), and polarized optical microscopy (POM). 相似文献
102.
The flower-like tin disulphide (SnS2) microspheres have been synthesised by a facile solution-based route using polyethylene glycol 200 as the solvent and template. The products are characterised by X-ray diffraction, transmission electron microscopy and scanning electron microscopy. Experimental results show that the flower-like SnS2 microspheres with diameters around 2-5--m are made of many interleaving petal-like nanostructures. These nanopetals are 1-3--m in side length and less than 60-nm in thickness. The influences of solvent and sulphur source on the morphology of SnS2 nanostructures have also been investigated. The possible growth mechanism is discussed. Furthermore, the room-temperature Raman spectrum of the flower-like SnS2 microspheres is also studied. 相似文献
103.
Piérard-Franchimont C Goffin V Henry F Uhoda I Braham C Piérard GE 《International journal of cosmetic science》2002,24(5):249-256
Hair shedding and hair thinning have been reported to be affected by dandruff and seborrhoeic dermatitis. The present study was conducted in 150 men presenting with telogen effluvium related to androgenic alopecia associated with dandruff. They were randomly allocated to three groups receiving each one of the three shampoos in the market containing either 1% ketoconazole (KTZ), 1% piroctone olamine (PTO) or 1% zinc pyrithione (ZPT). Shampoos had to be used 2-3 times a week for 6 months. Hair shedding during shampoo was evaluated semiquantitatively. Hair density on the vertex was evaluated on photographs using a Dermaphot. Trichograms were used for determining the anagen hair percentage and the mean proximal hair shaft diameter using computerized image analysis. The sebum excretion rate (SER, mug cm(-2) h(-1)) was also measured using a Sebumeter. The three treatments cleared pruritus and dandruff rapidly. At end point, hair density was unchanged, although hair shedding was decreased (KTZ: -17.3%, PTO: -16.5%, ZPT: -10.1%) and the anagen hair percentage was increased (KTZ: 4.9%, PTO: 7.9%, ZPT: 6.8%). The effect on the mean hair shaft diameter was contrasted between the three groups of volunteers (KTZ: 5.4%, PTO: 7.7%, ZPT: -2.2%). In conclusion, telogen effluvium was controlled by KTZ, PTO and ZPT shampoos at 1% concentration. In addition, KTZ and PTO increased the mean hair shaft thickness while discretely decreasing the sebum output at the skin surface. 相似文献
104.
In this paper we propose a new variational model for image denoising and segmentation of both gray and color images. This
method is inspired by the complex Ginzburg–Landau model and the weighted bounded variation model. Compared with active contour
methods, our new algorithm can detect non-closed edges as well as quadruple junctions, and the initialization is completely
automatic. The existence of the minimizer for our energy functional is proved. Numerical results show the effectiveness of
our proposed model in image denoising and segmentation.
Fang Li received the MSc degree in Mathematics from the South West China Normal University in 2004 and from then on she works in
the South West University. Meanwhile, she studies mathematics at the East China Normal University as a doctoral student. Her
research interests include anisotropic diffusion filtering, the variational methods and PDEs in image processing.
Chaomin Shen received the MSc degree in Mathematics from the National University of Singapore (NUS) in 1998. He worked in the Centre for
Remote Imaging, Sensing and Processing (CRISP), NUS as an associate scientist during 1998 to 2004. Currently he is a lecturer
in Joint Laboratory for Imaging Science & Technology and Department of Computer Science, East China Normal University. His
research interests include remote sensing applications and variational methods in image processing.
Ling Pi received her MSc degree from the Department of Mathematics, East China Normal University in 2003. She is currently a lecturer
in the Department of Applied Mathematics, Shanghai Jiaotong University. Her work involves the application of geometric and
analytic methods to problems in image processing. 相似文献
105.
以柴油机 13工况排放试验结果为依据 ,研究了污染物中的碳氢化合物 (HC)与微粒 (PM )之间的关系 ,并考虑了影响因素 提出了通过每工况的HC来预测其微粒的新方法 ,计算结果和试验数据有较好的吻合 此预测模型对高压共轨柴油机ECU的设计是一个有力的工具 相似文献
106.
辽化医院检验科通用管理软件能够准确及时地利用Visual Basic 6.0采集检验科检测仪器的串口数据,存储到Microsoft Access数据库,能够对数据进行处理、查询、显示、打印,整个界面简洁、美观、功能完整. 相似文献
107.
A. Piñol-Juez A. Iza-Mendia I. Gutiérrez 《Metallurgical and Materials Transactions A》2000,31(6):1671-1677
In the present work, the mechanical properties and the microstructural evolution of a duplex stainless steel in the as-cast
and wrought conditions during deformation under hot-working conditions have been studied. Hot torsion tests, at strain rates
of
= 1 s−1, have been carried out using prepolished samples on which surface parallel scratches have been practiced. The observation
of the surface of the samples shows a large displacement of the scratches produced by two different mechanisms, sliding on
the δ/γ interface, and shearing of the ferrite. The displacements in the as-cast condition have been found to concentrate in a reduced
set of ferrite/austenite interfaces leading to the formation of cracks along them. In the wrought material, the distribution
of the sliding is more homogeneous over all the ferrite/austenite interfaces, and no damage has been produced. These behavioral
differences between both materials have been related in the present work, to the characteristics of the corresponding microstructures,
to the spatial phase distribution, and to the nature of the ferrite/austenite interface, among others. 相似文献
108.
Hermanns JF Piérard-Franchimont C Piérard GE 《International journal of cosmetic science》2000,22(1):67-71
Synopsis
Few subjects are as problematical to dermatologists, cosmetologists and related experimenters involved in safety testing as the clinical assessment of skin colour. At the core of the problem is the word erythema, which does not communicate a sense for the nuance of red. In addition, light shades of red are not visible in dark-skinned people. Human assays aiming at evaluating the irritancy and allergic potential of cosmetics take advantage to use instrumental assessments of skin colour. However, there are pitfalls related to the complex biological aspects of the cutaneous reactivity, to the design of the in vivo assay, and to technical aspects bound to the principle of the measuring methods. Sound information can only be reached when these concerns are solved.
Résumé
Peu de sujets sont aussi problématiques pour les dermatologues, cosmétologues et autres expérimentateurs impliqués dans les tests de sûreté que l'évaluation clinique des couleurs cutanées. Au centre du problème est le mot érythème qui ne communique pas la notion des nuances de rouge. De plus, un érythème discret peut ne pas être visible chez des individus à la peau foncée. Les tests humains visant àévaluer les potentialités d'irritation et d'allergie aux cosmétiques bénéficient des évaluations instrumentales de la couleur cutanée. Cependant, il existe des pièges liés aux aspects biologiques complexes de la réactivité cutanée, au choix du test in vivo et à des aspects techniques en relation avec le principe du système de mesure. Une information adéquate ne peut être obtenue qu'après avoir résolu ces problèmes. 相似文献
Few subjects are as problematical to dermatologists, cosmetologists and related experimenters involved in safety testing as the clinical assessment of skin colour. At the core of the problem is the word erythema, which does not communicate a sense for the nuance of red. In addition, light shades of red are not visible in dark-skinned people. Human assays aiming at evaluating the irritancy and allergic potential of cosmetics take advantage to use instrumental assessments of skin colour. However, there are pitfalls related to the complex biological aspects of the cutaneous reactivity, to the design of the in vivo assay, and to technical aspects bound to the principle of the measuring methods. Sound information can only be reached when these concerns are solved.
Résumé
Peu de sujets sont aussi problématiques pour les dermatologues, cosmétologues et autres expérimentateurs impliqués dans les tests de sûreté que l'évaluation clinique des couleurs cutanées. Au centre du problème est le mot érythème qui ne communique pas la notion des nuances de rouge. De plus, un érythème discret peut ne pas être visible chez des individus à la peau foncée. Les tests humains visant àévaluer les potentialités d'irritation et d'allergie aux cosmétiques bénéficient des évaluations instrumentales de la couleur cutanée. Cependant, il existe des pièges liés aux aspects biologiques complexes de la réactivité cutanée, au choix du test in vivo et à des aspects techniques en relation avec le principe du système de mesure. Une information adéquate ne peut être obtenue qu'après avoir résolu ces problèmes. 相似文献
109.
M. Barranco M. Guilleumas D. M. Jezek R. J. Lombard J. Navarro M. Pi 《Journal of Low Temperature Physics》1999,117(1-2):81-100
We present a study of phase separation from supersaturated
3
He-
4
He liquid mixtures at low temperatures addressing both the degree of critical supersaturation xcr
and the thermal-to-quantum crossover temperature T* for the nucleation process. Two different nucleation seeds are investigated, namely
3
He droplets and
4
He vortex lines with cores filled with
3
He. We have found that the experimental T* is reproduced when we consider that nucleation proceeds from
3
He droplets, whereas xcr
is reproduced when we consider
4
He vortex lines filled with
3
He. However, neither nucleation configuration is able to simultaneously reproduce the current experimental information on xcr
and T*. 相似文献
110.
GE Piérard 《Canadian Metallurgical Quarterly》1998,53(10):586-587
There exists two distinct types of patches aiming at increasing the pain threshold either systematically or locally. The first type of analgesic patch is a real transdermal delivery system releasing fentanyl. Such potent opioid drug exerts a systemic effect. The other type of patch associates lidocain and prilocain to induce a local anesthesia of the skin without inducing a systemic effect. 相似文献