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81.
82.
B. Pignataro L. Chi S. Gao B. Anczykowski C. Niemeyer M. Adler H. Fuchs 《Applied Physics A: Materials Science & Processing》2002,74(3):447-452
Self-assembled oligomeric nanostructures consisting of bisbiotinylated DNA fragments connected by the protein streptavidin
(STV) are studied by dynamic scanning force microscopy (SFM) operating in air. A comparison of the images taken in repulsive
and attractive regimes is systematically made on DNA and STV structures. Stable and reproducible SFM images are obtained in
the attractive regime by using a special feedback circuit, called Q-control. On the other hand, when SFM is operating in the
repulsive regime, deformation of the structures that reduce the resolution and the image quality are clearly observable. The
heights of both DNA and STV have been measured as a function of the tip/molecule interaction forces. This study offers the
possibility to suggest a different mechanical behavior of DNA with respect to STV.
Received: 24 July 2001 / Accepted: 3 December 2001 / Published online: 4 March 2002 相似文献
83.
本文通过对大量的黄酮类化合物13C NMR图谱的分析和研究,总结了不同类型的黄酮类化合物的13C NMR图谱特征及化学位移规律.对影响黄酮类化合物结构骨架上不同位置碳原子化学位移的因素进行了分析,建立了用于黄酮类天然产物13C NMR图谱智能解析的知识库. 相似文献
84.
高智民 《纯粹数学与应用数学》1994,10(2):1-5
本文证明了:若X是K-半分层空间,f是闭映射,则f(X)是K-半分层空间,这一结果推广改进了Lutzer与高国士的有关结果。 相似文献
85.
在e-A深度非弹性散射过程中, 喷注穿过冷核介质时, 多重散射诱导胶子辐射会导致对碎裂函数的修正及喷注的能量损失.前期研究中关于计算e-A深度非弹性散射中胶子辐射振幅的两种方法: 螺旋振幅近似和微扰QCD严格计算都异常繁杂.
本文发展了一种新的方法, 可以方便计算出多重散射导致胶子辐射的振幅, 得到的碎裂函数的修正以及能量损失与严格计算的结果一致. 相似文献
86.
Observation of spontaneous pattern with six-fold symmetry in disk-shaped ZnO complex microstructures
L.W. Yang Y.J. Gao X.L. Wu Y.M. Yang G.S. Huang Z.Y. Zhang P.K. Chu 《Applied Physics A: Materials Science & Processing》2007,89(1):173-176
Using a simple vapor phase transport technique, we have fabricated unique complex disk-shaped ZnO microstructures comprising
a small disk coaxially grown on a large one and observed spatially perfect six-fold symmetric patterns. The observed results
can be explained based on the spontaneous nanoindentation (NI) effect under the geometric constraints and the explanation
can be extended to fathom the growth mechanism of other highly symmetrical ZnO nanostructures. Our results indicate that NI
not only can elucidate the mechanical properties of surfaces and thin films but also is an effective approach to fabricate
ordered nanostructures with high precision on the location of the building blocks.
PACS 81.16.Rf; 81.07.-b; 81.05.Dz 相似文献
87.
Zhihui Zhao Hui Dai Xiangmei Wu Haitao Chang Xiaoming Gao Mengjun Liu Pengfei Tu 《Chemistry of Natural Compounds》2007,43(4):374-376
A pectic polysaccharide was isolated from the fruits of Ziziphus jujuba Mill. cv. jinsixiaozao Hort. and its structure was characterized by acid hydrolysis, methylation, and NMR spectroscopies.
The purified fraction Ju-B-7 had a molecular mass of over 2000 kDa. Chemical and spectroscopic analyses indicated that Ju-B-7
is composed mainly of α-1,4-linked D-galactopyranosyluronic acid and 1,2-linked L-rhamnose with a molar ratio of 8.1:1. It can significantly stimulate
spleen cell proliferation in vitro (P<0.01, 10 μmg/mL).
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 311–312, July–August, 2007. 相似文献
88.
89.
CHEN Hongjia GAO Yun & SHANG Shikui Department of Mathematics University of Science Technology of China Hefei China Department of Mathematics Statistics York University Toronto Ontario Canada MJ P 《中国科学A辑(英文版)》2006,(11)
We use a fermionic extension of the bosonic module to obtain a class of B(0, A)graded Lie superalgebras with nontrivial central extensions. 相似文献
90.
Baowei Qiao Jie Feng Yun Ling Ting’ao Tang Bomy Chen 《Applied Surface Science》2006,252(24):8404-8409
The effects of Si doping on the structural and electrical properties of Ge2Sb2Te5 film are studied in detail. Electrical properties and thermal stability can be improved by doping small amount of Si in the Ge2Sb2Te5 film. The addition of Si in the Ge2Sb2Te5 film results in the increase of both crystallization temperature and phase-transition temperature from face-centered cubic (fcc) phase to hexagonal (hex) phase, however, decreases the melting point slightly. The crystallization activation energy reaches a maximum at 4.1 at.% and then decreases with increasing dopant concentration. The electrical conduction activation energy increases with the dopant concentration, which may be attributed to the increase of strong covalent bonds in the film. The resistivity of Ge2Sb2Te5 film shows a significant increase with Si doping. When doping 11.8 at.% of Si in the film, the resistivity after 460 °C annealing increases from 1 to 11 mΩ cm compared to the undoped Ge2Sb2Te5 film. Current-voltage (I-V) characteristics show Si doping may increase the dynamic resistance, which is helpful to writing current reduction of phase-change random access memory. 相似文献