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排序方式: 共有1729条查询结果,搜索用时 62 毫秒
61.
采用二环己基碳二亚胺缩合法由去氢胆酸和苯并三唑合成了去氢胆酰苯并三唑,产率60%,并利用FT-IR和1H NMR对产物进行了表征.通过考察去氢胆酰苯并三唑对胰岛素的化学修饰作用,进一步证实该酰化苯并三唑的合成是成功的,并且对胰岛素的侧链氨基具较高的修饰反应活性. 相似文献
62.
利用对称分步傅立叶方法(SSFM)求解非线性薛定谔方程(NLS),探讨了光纤损耗、三阶色散和五阶非线性极化效应对啁啾高斯光脉冲传输的影响.数值研究结果指出:在一定条件下,初始啁啾、三阶色散和五阶非线性效应都会对脉冲的波形、宽度和峰值功率产生影响,脉冲的振荡波形主要由三阶色散决定,五阶非线性和啁啾会对它起到调制作用,存在一定的三阶色散和五阶非线性能减弱初始啁啾对脉冲的影响. 相似文献
63.
Tao Wan Fei Feng Yuechuan Wang 《北京科技大学学报(英文版)》2006,13(4):372-379
The effects of postthermal treatment and irradiation time on the structure and thermal stability of TiO2/polyacrylate nanocomposites by a sol-gel process in reverse micelles and subsequent rapid photopolymerization were investigated, and the hybrid films were characterized by thermal gravimetry analysis (TGA), X-ray photoelectron spectrum (XPS), and atomic force microscopy (AFM). XPS data suggested that the prolongation of irradiation time and the postthermal treatment promoted titania formation, with the former affecting more remarkably. TGA data showed that TiO2-hybrid films could upgrade the decomposition onset temperature (Tonset) as well as the temperature at which there is a maximum mass loss rate (Tmax). AFM data demonstrated that the inorganic titania particles with a mean diameter of 25.26-28.84 nm were homogeneously distributed in the organic matrix. 相似文献
64.
ZHANG Junfeng XU Yongjun QI Tao & LI Zhengguo Institute of Mechanics Chinese Academy of Sciences Beijing China 《中国科学E辑(英文版)》2005,48(Z1)
1 Introduction The damage or failure of faulted rock slope is a quite difficult problem in geotechni- cal engineering, and attention has been drawn from researchers for a long time. Apart from the toppling damage of steep slopes, most of the failure pattern of faulted rockslopes is shear-typed. The failure process of such a slope includes: initiation and devel- opment of a single micro-crack, breakthrough of two or more cracks, formation of fail- ure zones, and even shear damage in large scale… 相似文献
65.
QIU Kai WANG Fengming WAN Changxiu HU Tao TANG Changwei 《武汉理工大学学报(材料科学英文版)》2005,20(B12):111-113
Fabrication, in vitro degradation and cytotoxic assay of different crystalline phases calcium polyphosphate(CPP) were reported. The CPP ceramics were fabricated by crystallizing the amorptous frits, and sintered at 550℃ ,875℃, 1000℃ for 1 h to obtain the 7-CPP, β-CPP and α-CPP respectively. The efffects of the different crystalline phases on their weight loss and released PO4^3- were investigated during the degradation. And the surface change was observed by the SEM, The osteoblastic ROS17/2.8 cell line was used to estimate the cytotoxicity of CPP. The effects of CPP on cells ' proliferation were evaluated by using MTT assay. The experimental restdts showed that γ-CPP, β-CPP and α-CPP did not exert cytotoxic effect on the cells. In addition, the proliferation of the growth of ROS17/2.8 cells on β-CPP was optimal. 相似文献
66.
WAN Tao AOKI Hideki KATOH Ayako 《武汉理工大学学报(材料科学英文版)》2005,20(B12):260-262
Radiofrequeut magnetron sputtering technique was used to produce calcium phosphate coated on the titurdum substrates, and the sputtered coating films were crystallized in an autoclave at 110℃ using a low temperature hydrothermal technique. The crystallization of as-sputtered coating film on the titanium substrates were amorphous calcium phosphate film. However, after the hydrothermal technique, calcium phosphate crystals grew and these were cohumnar crystal. The Ca/P ratio of sputtered coating films in 1.6 to 2.0. 相似文献
67.
68.
NiCr合金在KCl-ZnCl2盐膜下含氯氧化性气氛中的腐蚀 总被引:1,自引:0,他引:1
研究了纯Ni、纯Cr以及3种不同Cr含量的NiCr合金在600℃KCl-ZnCl2盐膜下含氯氧化性气氛中的腐蚀行为.结果表明,5种材料均发生了严重的加速腐蚀.在材料表面形成了多孔的氧化膜,并发生了开裂,在氧化膜与基体金属的界面处有金属氯化物生成.NiCr合金的腐蚀增质比纯Ni和纯Cr的小.Ni50Cr和纯Cr有较高的腐蚀速度,前者与其具有的双相组织有关,后者是其氧化膜易脱落所致.材料的加速腐蚀机制是氯化物蒸汽的气相输运加速了金属离子向外扩散速度的‘活化氧化'. 相似文献
69.
Induction melting was used as a routine method to synthesize Mg_(23)Ni_(10), Mg_(22)LaNi_(10) and Mg_(21)La_2Ni_(10) alloys, and followed by a detailed microstructural characterization which included X-ray diffraction(XRD), scanning electron microscopy(SEM) with energy dispersive spectrometer(EDS), high resolution transmission electron microscope(HRTEM) and hydrogen absorption/desorption measurements. XRD analysis results showed that Mg_2Ni and Mg phases were detected in the XRD pattern of the Mg_(23)Ni_(10) alloy, however, the La addition results in conversion from Mg to LaMg_3 and La_2Mg_(17) phases and appearance of crystal defects included dislocations, twin grain boundary and vacancy in the Mg_(22)LaNi_(10) and Mg_(21)La_2Ni_(10) alloy textures. The total maximum hydrogen absorption capacity was 4.45 wt% for the Mg_(23)Ni_(10) alloy, however, the Mg_(22)LaNi_(10) and Mg_(21)La_2Ni_(10) alloys with vacancy, dislocations and twin grain boundary, absorbed 3.66 wt% and 3.60 wt%, respectively, indicating that the La addition led to decreasing of the maximum hydrogen absorption capacity. Besides, hydrogen absorption/desorption of 90% of saturated state expended for about 456 and 990 s for pristine Mg_(23)Ni_(10) alloy, by contrast, the time decreased owing to improvement of hydrogen absorption and desorption kinetics in the alloy with La element, with which the uptake time for hydrogen content to 90% of saturated state was 150 and 78 s, and 90% hydrogen can be released in 930 and 804 s for Mg_(22)LaNi_(10) and Mg_(21)La_2Ni_(10) alloys in the experimental condition. 相似文献
70.
A facile approach to prepare a thin film vapor sensor is demonstrated through droplet interfacial reaction on an IDA microelectrode.Scanning electron microscopy,atomic force microscopy and transmission electron microscopy analyses show that the film of the vapor sensor is composed of self-assembled gold nanocrystals in an average diameter of about 4.3 nm.The as-prepared sensor was examined by potential step method and impedance measurement,which exhibited significant A/?//?,responses and excellent cycle performance to the volatile organic compound(VOC) vapors of acetone,methanol,styrene,benzene,toluene and ethanol.The selectivity to the VOCs with benzene ring or organic solvents suggests that the sensor is probably in line with the swelling and dielectric sensing mechanisms. 相似文献