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排序方式: 共有410条查询结果,搜索用时 15 毫秒
1.
Naoto Takase Junpei Kuwabara Seong Jib Choi Takeshi Yasuda Liyuan Han Takaki Kanbara 《Journal of polymer science. Part A, Polymer chemistry》2015,53(4):536-542
The Pd‐catalyzed polycondensation of 4‐octylaniline with various dibromoarylenes was carried out under microwave heating. Microwave heating led to a decrease in the reaction time and an increase in the molecular weight of the polymers as compared to conventional heating. Microwave heating also allowed the catalyst loading to be reduced to 1 mol %, yielding polymerization results that were comparable to those under conventional heating and 5 mol % catalyst. Investigations regarding field‐effect transistors and organic photovoltaic cells using the obtained poly(arylamine) with azobenzene units revealed that increasing the molecular weight of the polymer led to improved device performance, including hole mobility and power conversion efficiency. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2015 , 53, 536–542 相似文献
2.
基于混沌映射密钥空间拓展的DES算法 总被引:1,自引:0,他引:1
提出一种基于混沌映射产生一种伪随机密钥流发生器,并结合shanon的“一次一密”思想,建立一种基于混沌映射的“分组密码密钥空间拓展”理论,很好地解决DES加密算法密钥空间小的问题,实现了一种混沌的DES变形密码算法。 相似文献
3.
2003年的诺贝尔物理奖授予了低温物理领域的三位物理学家,他们是Alexei A、Abrikosov(阿布里柯索夫),Vitaly L.Ginzburg(京茨堡)以及Anthony J.Leggett(莱格特),此奖用以表彰前两者在超导电性方面的贡献,后者为在超流方面作出的贡献.大家知道,自然界中的微观粒子服从量子力学规律; 相似文献
4.
基于高相干点进行相位分析,才能有效保证地基SAR(Synthetic Aperture Radar,合成孔径雷达)形变测量的准确性。在差分干涉测量领域中,广泛使用幅度离差法,可以有效地选择出岩石、建筑物等PS(Permanent Scatterer,永久散射体)点作为高相干点,但对于植被边坡,采用该方法选择出高相干点数量较少,不利于差分干涉处理。在星载SAR领域,普遍采用StaMPS方法解决植被边坡的高相干点选择问题。本文探索了StaMPS方法在地基SAR领域的适用性,提出采用非PS点来计算相干系数门限,并引入DS(Distributed Scatterer,分布式散射体)选择技术,进一步提高了高相干点的数量。对一处植被边坡的实验结果表明,相比于幅度离差法和StaMPS方法,改进方法在提高高相干点数量的同时,有效保证了其相位质量。 相似文献
5.
Powell KD Ghaemmaghami S Wang MZ Ma L Oas TG Fitzgerald MC 《Journal of the American Chemical Society》2002,124(35):10256-10257
A new method that utilizes matrix-assisted laser desorption/ionization (MALDI) mass spectrometry and exploits the hydrogen/deuterium (H/D) exchange properties of proteins was developed for measuring the thermodynamic properties of protein-ligand complexes in solution. Dissociation constants (Kd values) determined by the method for five model protein-ligand complexes that included those with small molecules, nucleic acids, peptides, and other proteins were generally in good agreement with Kd values measured by conventional methods. Important experimental advantages of the described method over existing methods include: the ability to make measurements in a high-throughput and automated fashion, the ability to make measurements using only picomole quantitities of protein, and the ability to analyze either purified or unpurified protein-ligand complexes. 相似文献
6.
Chen Lai Liyuan Sheng Shibo Liao Tingfei Xi Zhixiong Zhang 《Surface and interface analysis : SIA》2013,45(11-12):1673-1679
In this study, we focused on the surface character of bacterial cellulose (BC) before and after oxidation mediated by 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO).Solid‐state 13C NMR, XPS, SEM, contact angle and surface free energy analyses were performed to investigate the effects of various parameters (reaction time and oxidant and catalyst concentrations) on the surface composition, morphology and polarity of the BC. The results provided by the combined use of these techniques showed that hydrogen bonds were disrupted on the BC surface after carboxylation occurred; therefore, the surface of oxidized BC was rougher than that of the original BC, and the surface free energy, especially the polar components, increased after oxidation. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
7.
Yuta Nohara Junpei Kuwabara Takeshi Yasuda Liyuan Han Takaki Kanbara 《Journal of polymer science. Part A, Polymer chemistry》2014,52(10):1401-1407
A naphthalenediimide (NDI)‐based conjugated polymer was synthesized by a two‐step direct C‐H arylation sequence. In the first step, two ethylenedioxythiophene units were coupled to NDI by direct arylation. In the second step, the direct arylation polycondensation of the monomer, formed in the first step, with 2,7‐dibromo‐9,9‐dioctylfluorene afforded the corresponding NDI‐based conjugated polymer ( PEDOTNDIF ) with molecular weight of 21,500 in 91% yield. The optical and electrochemical properties of the polymer were evaluated. The polymer showed ambipolar behavior in organic field‐effect transistors (OFETs). The electron mobility of PEDOTNDIF was estimated to be 2.3 × 10?6 cm2 V?1 s?1 using an OFET device with source‐drain (S‐D) Au electrodes. A modified OFET device with S‐D MgAg electrodes increased the electron mobility for PEDOTNDIF to 1.0 × 10?5 cm2 V?1 s?1 due to the more suitable work function of these electrodes, which reduced the injection barrier to the semiconducting polymer. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 1401–1407 相似文献
8.
9.
Zhaorui Li Dr. Kristin Werner Lu Chen Aiping Jia Dr. Kun Qian Dr. Jian-Qiang Zhong Dr. Rui You Dr. Lihui Wu Liyuan Zhang Dr. Haibin Pan Prof. Dr. Xin-Ping Wu Prof. Dr. Xue-Qing Gong Dr. Shamil Shaikhutdinov Prof. Weixin Huang Prof. Dr. Hans-Joachim Freund 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(16):5268-5276
The study reports the first attempt to address the interplay between surface and bulk in hydride formation in ceria (CeO2) by combining experiment, using surface sensitive and bulk sensitive spectroscopic techniques on the two sample systems, i.e., CeO2(111) thin films and CeO2 powders, and theoretical calculations of CeO2(111) surfaces with oxygen vacancies (Ov) at the surface and in the bulk. We show that, on a stoichiometric CeO2(111) surface, H2 dissociates and forms surface hydroxyls (OH). On the pre-reduced CeO2−x samples, both films and powders, hydroxyls and hydrides (Ce−H) are formed on the surface as well as in the bulk, accompanied by the Ce3+ ↔ Ce4+ redox reaction. As the Ov concentration increases, hydroxyl is destabilized and hydride becomes more stable. Surface hydroxyl is more stable than bulk hydroxyl, whereas bulk hydride is more stable than surface hydride. The surface hydride formation is the kinetically favorable process at relatively low temperatures, and the resulting surface hydride may diffuse into the bulk region and be stabilized therein. At higher temperatures, surface hydroxyls can react to produce water and create additional oxygen vacancies, increasing its concentration, which controls the H2/CeO2 interaction. The results demonstrate a large diversity of reaction pathways, which have to be taken into account for better understanding of reactivity of ceria-based catalysts in a hydrogen-rich atmosphere. 相似文献
10.
Chen Huang Lihong Han Liyuan Wu Rui Su Jun Chen Pengfei Lu 《The European Physical Journal B - Condensed Matter and Complex Systems》2015,88(6):147
The electronic structure and optical properties of boron-doped, sulfur-doped, andboron-sulfur-codoped graphene systems have been studied by using first-principlescalculations. Energy band structure and density of states are presented to describe theelectronic properties. The doping can open the band gap and change the optical propertiesof graphene. For all optical properties of doped graphene systems, parallel(E ∥) polarization and perpendicular(E ⊥) polarization are presented. Theoptical properties under two kinds of polarizations are reflected in the range of peakheight and the change of some extraordinary features. 相似文献