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21.
A G 4.0 dendrimer-like poly (amido amine) (PAMAM) based on silica nanoparticles was fabricated via a divergent approach.It was built from γ-aminopropyi silica nanoparfides (APSN) core via repetitive addition of acrylate (MA) and hexylenediamine (HDA). FT-IR and EA were used to monitor the progress of dendrimer during each step. The amino group content of the resulting product increased from 0.49 to 3.72 mmol/g after the 4th generation. In addition, the percentage of grafting increased with increasing generation and reached to 65.9% after 4th generation. It was found that the resulting silica nanoparticles could be dispersed in methanol with a mean hydrodynamic particle diameter of 152.7 nm although the silica nanoparticles had agglomerated during the storage period.  相似文献   
22.
锥形光纤间耦合特性的分析与检测   总被引:2,自引:0,他引:2  
将通信光纤的末端拉制成锥形,利用光信号在光纤锥形区特有的传输和耦合特性,实现了光纤的耦合、连接和分束。用耦合模理论分析了锥形光纤间的传输和耦合性质,给出了光信号两锥形光纤间的耦合与两锥形光纤的距离和锥形区重叠长度等实验结果。  相似文献   
23.
The synthesized 1-aryliminomethylenylnaphthalen-2-ol derivatives reacted with nickel chloride to form bis(1-aryliminomethylenylnaphthalen-2-oxy)nickel complexes. All resultant compounds were structurally characterized by elemental analyses, IR and H NMR, and the structures of the formed complexes were elucidated by X-ray crystal structure analysis. The complexes show high catalytic activities for the vinyl polymerization of norbornene in the presence of methylaluminoxane. The catalytic activity variations have been followed by gas chromatography through monitoring the conversion of norbornene.  相似文献   
24.
Hybrid electrode combined coplanar waveguide (CPW) and microstrip lines in ultra-broadband electro-optic modulators. The characteristics of the modulators with hybrid electrode is like that of the modulator with the microstrip lines, in which the microstrip electrode is loaded above only one arm of Mach-Zehnder (M-Z) optical waveguide, besides the problem of microstrip line to coaxial transition and corona polarization in polymer modulators have been best solved at the same time. By using finite element method (FEM), the characteristic parameters such as half-wave voltage, modulation bandwidth characteristic impedance, effective microwave refractive index of polymer modulators with microstrip line and hybrid electrode are analysed and compared in this paper. The results present that velocity match, impendence match and lower microwave propagating loss is easily realized in modulators with hybrid electrode.  相似文献   
25.
使用结构简单的单温炉设备,通过三步升温热解二茂铁、三聚氰氨混合物方法,在二氧化硅、多晶陶瓷基底上分别合成了碳纳米管阵列、碳纳米管捆束.使用扫描电子显微镜、透射电子显微镜、电子能量损失谱和x射线光电子能谱对合成样品进行了结构和成分分析.结果显示:两种基底上合成的纳米管均为多壁纯碳管;生长于光滑二氧化硅表面的碳纳米管具有高度取向性和一致的外径,长度为10—40μm.碳纳米管采取催化剂顶端生长模式并展示出类杯状形貌;生长于粗糙多晶陶瓷表面的碳纳米管捆束随机取向,碳纳米管直径为15—80nm,长度在几百微米,展示 关键词: 碳纳米管 热解法 三步升温工艺  相似文献   
26.
Herein we report a new method to collect a qualified infrared spectrum of a solute in solution by two solvent cells with different thickness during background single-beam spectrum scanning. By collecting the background spectrum with two cells (two stages), we successfully achieved accurate solvent compensation between a sample and a reference, namely, the solvent amounts in the sample and background measurements could become congruent. Therefore, the solvent bands were thoroughly suppressed in the infrared spectrum and a qualified spectrum of the solute was obtained.  相似文献   
27.
网络股泡沫大小测度研究   总被引:1,自引:0,他引:1  
网络股泡沫是最能反映网络泡沫本质的表现形式,本文利用理性预期理论,构建了网络股泡沫大小的测度模型,说明网络股泡沫的存在,在此基础上确定了网络股泡沫大小的测度指标,并以雅虎公司股票为例对泡沫的大小进行了测度,结果符合网络泡沫的实际情况。  相似文献   
28.
一种有机电致发光共聚物的制备和性能   总被引:2,自引:1,他引:1  
杨坚  吴宏滨  侯琼  黄飞  阳仁强  杨伟  曹镛 《发光学报》2003,24(6):612-615
采用Suzuki方法合成了9,9-二辛基芴与萘并硒二唑的两种无规共聚物并研究了其紫外光谱、光致发光和电致发光性能。两种聚合物的电致发光波长为650~666nm,均为发饱和红光的LED材料,其电致发光外量子效率最高达到了1.05%。随着共聚物中萘并硒二唑含量的增加,共聚物的光致发光和电致发光的发射波长均有少量红移。证明了根据共轭高聚物链内能量转移原理,在聚芴链中引入不同含量的窄带隙杂环单元可实现对聚芴发光颜色的调节。  相似文献   
29.
S-naproxen imprinted polymer was prepared with acrylamide as a functional monomer, 1,4-butanediyl diacrylate as a new kind of crossliner, and 2,4,6-trimethylbenzoylphenyl-phosphinic acid ethyl ester as photoinitiator. Their UV and IR spectra were applied to study the interactions between the template and the monomer. Binding experiments showed that the S-naproxen imprinted polymer had better recognition capability for the template than that of a blank polymer. The adsorption distribution coefficient KD of S-naproxen on molecularly-imprinted polymer was 153.2 g/mL, and the separation factor was 1.95 when the initial concentration of substrate was 2.0 mmol/L. Scatchard curves suggested that there were two classes of binding sites in the imprinted polymer and only one class in the blank polymer. Computer simulation using Hyperchem showed the existence of the interactions between the template and the functional monomer as well as the models of the complexes formed by the template and the monomer.  相似文献   
30.
用形变的相对论平均场模型,Skyrme-Hartree-Fock模型及宏观-微观模型研究了新核素278113及其α衰变链的α衰变能和半衰期.计算的α衰变能同实验数据比较符合,相应的半衰期也在合理的范围内.计算进一步表明形变对超重核的基态性质有重要影响.  相似文献   
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