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排序方式: 共有105条查询结果,搜索用时 46 毫秒
31.
Dr. Joyram Guin Dr. Qinggang Wang Manuel van Gemmeren Prof. Dr. Benjamin List 《Angewandte Chemie (International ed. in English)》2015,54(1):355-358
The first catalytic enantioselective Abramov reaction is described. The process is based on the utilization of a chiral disulfonimide catalyst, which efficiently avoids the difficulties encountered with metal‐based catalysts. Several functionalized α‐hydroxy phosphonates were synthesized in good yields and with excellent enantiomeric ratios of up to >99:1. The process was shown to be scalable and up to 1 g of starting material could be employed under mild reaction conditions. 相似文献
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现有B超成像可以提供基于声阻抗差异的组织解剖结构信息,而近年来研究发现,光声成像可以提供标记组织成分的分布和功能信息。本文基于商用B超仪和脉冲激光系统建立了光声超声双模态成像系统,实现了超声组织结构成像和光声生物功能的同时成像。首先基于血红蛋白在某些波段的较强吸光性,实现了肿瘤内部组织血管灌注图像;其次用链接有靶向抗体的纳米颗粒作为靶向光声造影剂,对恶性肿瘤边缘和内部的血管以及血管附近的肿瘤组织进行了成像。最终,通过超声和光声的融合图像提供的肿瘤结构信息与光声图像提供的肿瘤功能信息,可以准确识别肿瘤组织。 相似文献
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35.
LIU Xinguo BAI Lihua & ZHANG Qinggang Department of Physics Shandong Normal University Jinan China Correspondence should be addressed to Liu Xinguo 《中国科学G辑(英文版)》2004,(2)
There are some statistical model codes[1—4] as the evaluation tool that have been long and widely used to set up neutron data library below 20 MeV, which is the most important energy region in the application of nuclear engineering. The emitted particles considered in these codes mentioned above are neutrons, protons, as well as the compos-ite particles, such as deuterons, tritons, 3He and alpha particles. These emitted particles and nuclei can be treated as the nucleon or stable clusters. H… 相似文献
36.
Multilayer films consisting of polyethylenimine (PEI) and albumin were successffully prepared on plasma treated poly(vinyl chloride) (PVC) via electrostatic self‐assembly of the PEI and albumin. The layer‐by‐layer assembly of the PEI/albumin on plasma treated PVC was monitored by contact angle and 125I radiolabeled method. The stability of the mutilayer coating was determined by 125I radiolabeled method. The results revealed that less than 10% albumin was eluted by a phosphate buffered saline (PBS) solution in 45 days. The static platelet adhesion indicated that the PEI/albumin deposited PVC could resist the platelet adhesion effectively. Such an easy processing and shape‐independent method may have good potential for surface modification of cardiovascular device. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
37.
A time-dependent quantum wave packet method was used to study the dynamics of dissociative adsorption of H2 and D2 on a flat and static surface. The molecule-surface interaction is described using a modified London-Eyring-Polanyi-Sato (LEPS)
type potential for the H2/Ni(100) system. The three-dimensional (3-D) dissociation probabilities were calculated for different initial rovibrational
states as a function of initial incident energies. Our results show that the dissociation of the diatomic rotational states
whose quantum numbers satisfyj+m = odd is forbidden at low energies for the homonuclear Hz and D2 due to the selection rule. The effect of the rotational orientation of diatoms on adsorption predicts that the in-plane rotation
(m = j) is more favorable for dissociation than the out-of-plane rotation (m = 0). Enhanced dissociation for vibrationally excited molecules and the significant enhancement of the dissociation probability
of H2 when compared to D2 were explained reasonably in terms of quantum mechanical zero-point energies, the tunneling effect and the reflection from
an activation barrier.
Project supported by the National Natural Science Foundation of China (Grant No. 19694033) and partially by the Science Foundation
for Overseas Chinese Scholars and Students, administered by the State Education Commission of China (Grant No. 1992), by the
State Key Laboratory of Theoretical and Computational Chemistry of Jilin University at Changchun (Grant No. 98011, and by
the Natural Science Foundation of Shandong Province (Grant No. Y96B03022) 相似文献
38.
Electromobility focusing (EMF) is a relatively new protein separation technique that utilizes an electric field gradient and a hydrodynamic flow. Proteins are focused in order of electrophoretic mobility at points where their electrophoretic migration velocities balance the hydrodynamic flow velocity. Steady state bands are formed along the separation channel when equilibrium is reached. Further separation and detection can be easily achieved by changing the electric field profile. In this paper. we describe an EMF system with on-line UV absorption detection in which the electric field gradient was formed using a dialysis hollow fiber. Protein focusing and preconcentration were performed with this system. Voltage-controlled separation was demonstrated using bovine serum albumin and myoglobin as model proteins. The limitations of the current method are discussed, and possible solutions are proposed. 相似文献
39.
A Two‐Dimensional Ruddlesden–Popper Perovskite Nanowire Laser Array based on Ultrafast Light‐Harvesting Quantum Wells
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Haihua Zhang Dr. Yishi Wu Prof. Qing Liao Zhaoyi Zhang Yanping Liu Qinggang Gao Peng Liu Meili Li Prof. Jiannian Yao Prof. Hongbing Fu 《Angewandte Chemie (International ed. in English)》2018,57(26):7748-7752
Miniaturized nanowire nanolasers of 3D perovskites feature a high gain coefficient; however, room-temperature optical gain and nanowire lasers from 2D layered perovskites have not been reported to date. A biomimetic approach is presented to construct an artificial ligh-harvesting system in mixed multiple quantum wells (QWs) of 2D-RPPs of (BA)2(FA)n−1PbnBr3n+1, achieving room-temperature ASE and nanowire (NW) lasing. Owing to the improvement of flexible and deformable characteristics provided by organic BA cation layers, high-density large-area NW laser arrays were fabricated with high photostability. Well-controlled dimensions and uniform geometries enabled 2D-RPPs NWs functioning as high-quality Fabry–Perot (FP) lasers with almost identical optical modes, high quality (Q) factor (ca. 1800), and similarly low lasing thresholds. 相似文献