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Search Results: 1 - 10 of 132794 matches for " Lan-Fen Li "
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Get Phases from Arsenic Anomalous Scattering: de novo SAD Phasing of Two Protein Structures Crystallized in Cacodylate Buffer
Xiang Liu, Heng Zhang, Xiao-Jun Wang, Lan-Fen Li, Xiao-Dong Su
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024227
Abstract: The crystal structures of two proteins, a putative pyrazinamidase/nicotinamidase from the dental pathogen Streptococcus mutans (SmPncA) and the human caspase-6 (Casp6), were solved by de novo arsenic single-wavelength anomalous diffraction (As-SAD) phasing method. Arsenic (As), an uncommonly used element in SAD phasing, was covalently introduced into proteins by cacodylic acid, the buffering agent in the crystallization reservoirs. In SmPncA, the only cysteine was bound to dimethylarsinoyl, which is a pentavalent arsenic group (As (V)). This arsenic atom and a protein-bound zinc atom both generated anomalous signals. The predominant contribution, however, was from the As anomalous signals, which were sufficient to phase the SmPncA structure alone. In Casp6, four cysteines were found to bind cacodyl, a trivalent arsenic group (As (III)), in the presence of the reducing agent, dithiothreitol (DTT), and arsenic atoms were the only anomalous scatterers for SAD phasing. Analyses and discussion of these two As-SAD phasing examples and comparison of As with other traditional heavy atoms that generate anomalous signals, together with a few arsenic-based de novo phasing cases reported previously strongly suggest that As is an ideal anomalous scatterer for SAD phasing in protein crystallography.

LI Lan-fen,NAN Jie,SU Xiao-dong,

生物物理学报 , 2007,
Abstract: It has taken more than 30 years for the development of methods and technology to enable the determination of the first protein structure in 1950s. Now, 50 years has past since the first protein crystal structure determination, protein crystallography has made such tremendous progress that over 35000 protein crystal structures have been obtained and deposited, and many complex mechanisms of large macromolecular machineries could be explained at atomic details. Structural data have been successfully applied to the studies of protein functions of many important biological processes, as well as to the studies of protein folding and design, structure-based drug design and many related fields. Meanwhile, the sequencing of hundreds of genomes of different species has provided much more targets for structural biology, and the so-called structural genomics appeared, aiming to determine all protein structures encoded by these genomes. The achievements of protein crystallography have always been accompanied by the breakthroughs in the fields of X-ray sources, sensitive detectors, fast computers and application programs, and in particular owing to the invention and applications of recombinant DNA technologies. We can thus expect that the further developments of novel methods, bioinformatics tools, particularly the technologies related to the automation and high-throughput will be the key points for the large-scale, high efficiency of protein crystallography. In this paper, the authors have reviewed the history of protein crystallography from the aspects of methods and technology, discussed the current status and future trends of protein crystallography.
Hyperspectral Image Processing and Analysis System: Integration and Applications

HU Xing-tang,ZHANG Bing,LI Jun-sheng,ZHENG Lan-fen,TONG Qing-xi,

遥感学报 , 2005,
Abstract: The architecture and integration of Hyperspectral Image Processing and Analysis System(HIPAS V1.0) are introduced in this paper. Under the modularized structure, HIPAS can offer customer more extensibility and convenience on huge image data processing and information extraction. We discuss the solutions for multi-source, multi-temporal and multi-thematic data processing, analysis and products distribution. Based on the airborne remote sensing data, we extracted and realized the typical operational model of hyperspectral remote sensing applications such as classfication, mapping,index inversion, identification etc. Under the integration of key technologies and special methodologies, such as Robust Pixel Unmixing, Auto Flat Field Transformation(AFFT), Self-Adaptive Filter(SAF), Univeral Gravitation Classification(UGC)etc,the application modules for environment monitoring in HIPAS were also introduced in this paper. As an example, some useful and valuable applications on pollution monitoring of water resource were given together with some constructive suggestions.
Thermal Evolution and Timing of Hydrogen Generation in the Huahai Basin: Evidence from Apatite Fission Track Data

WANG Shi-cheng,YUAN Wan-ming,WANG Lan-fen,REN Zhan-li,

地球学报 , 1999,
Abstract: 利用裂变径迹分析方法测量了取自花海拗陷的钻井磷灰石样品的裂变径迹年龄和长度。结果表明,随井深增加年龄减小,平均径迹长度亦变短。取自白垩纪地层的磷灰石样品的裂变径迹年龄都比地层年龄年轻得多,表明沉积后曾长时间处于磷灰石裂变径迹退火带中,沉积前的径迹记录已部分消失,古地温高于今地温。利用蒙特卡罗随机取样的热史模拟方法对裂变径迹数据进行了分析,结果表明白垩纪地层沉积后曾经历过超过110 ℃的加热,达到最高古地温的地质时代是早白垩世晚期—晚白垩世末,为主要生烃期。新生代以来盆地变冷,生油岩的成熟度主要受古地温控制
Cardiac autonomic nerve function in obese school-age children

易兰芬, 文红霞, 黄小力, 邱梅, 曹晓晓
YI Lan-Fen
, WEN Hong-Xia, HUANG Xiao-Li, QIU Mei, CAO Xiao-Xiao

- , 2017, DOI: 10.7499/j.issn.1008-8830.2017.05.009
Effect of vitamin D deficiency on cardiac autonomic nerve function in obese pre-school children

邱梅, 文红霞, 黄小力, 易兰芬, 曹晓晓, 王文娟
, WEN Hong-Xia, HUANG Xiao-Li, YI Lan-Fen, CAO Xiao-Xiao, WANG Wen-Juan

- , 2018, DOI: 10.7499/j.issn.1008-8830.2018.09.012


物理学报 , 1998,
Abstract: In this paper are discussed the time evolution and squeezed states of a time-depedent oscillator system. We obtain closed formulas for the time evolution of quantum states and the evolution operator of the system by selecting proper Hermitian invariant operator. We derive the condition generating squeezed states and obtain that the drive part does not influence the squeezed states of the system.
Effects of bone marrow mesenchymal stem cell transplantation on retinal neovascularization in neonatal rats with oxygen-induced retinopathy

牟青杰, 赵月华, 程丹丹, 王海宇, 陈岚芬, 赵岩松, 王晓莉
MU Qing-Jie
, ZHAO Yue-Hua, CHENG Dan-Dan, WANG Hai-Yu, CHEN Lan-Fen, ZHAO Yan-Song, WANG Xiao-Li

- , 2017, DOI: 10.7499/j.issn.1008-8830.2017.11.015
Study on Spectral Indices of MODIS for Wheat Growth Monitoring

ZHANG Xi,ZHANG Bing,WEI Zheng,CHEN Zheng-chao,ZHENG Lan-fen,ZHANG Xi,ZHANG Bing,WEI Zheng,CHEN Zheng-chao,ZHENG Lan-fen,ZHANG Xi,ZHANG Bing,WEI Zheng,CHEN Zheng-chao,ZHENG Lan-fen,ZHANG Xi,ZHANG Bing,WEI Zheng,CHEN Zheng-chao,ZHENG Lan-fen,ZHANG Xi,ZHANG Bing,WEI Zheng,CHEN Zheng-chao,ZHENG Lan-fen,

中国图象图形学报 , 2005,
Abstract: 利用多个时次的小麦地面光谱与相应的生理参量测量数据(140组),构建了常见宽波段植被指数形式的MODIS(中分辨率成像光谱仪)光谱指数。首先确定反映作物长势的因子为生物量和LAI(叶面积指数),以地面光谱模拟MODIS的波段1~19,穷尽所有波段两两组合,寻找同时与生物量和LAI关系显著且有物理意义的光谱指数NDSI和RDSI。综合分析得出了3个最佳的波段组合:(619,62),(619,617)和(619,616),这3种组合所对应的NDSI和RDSI与两个长势因子都达到99%显著相关,而且明显优于Mc)DIS自身的植被指数产品MODIS—NDVI和MODIS_EVI。与NDSI相比,RDSI对LAI更敏感。MODIS_EVI比MODIS_NDVI有显著改进,它与长势因子的相关性可达到95%置信度。对MODIS图像的初步分析表明,NDSI(619,617)能够增强云与其他地物的差异,有可能改进云的识别精度。
High-Rank Artificial Neural Network Algorithm for Classification of Hyperspectral Image Data
用于高光谱遥感图象分类的 一种高阶神经网络算法

XIONG Zhen,TONG Qing-xi,ZHENG Lan-fen,
熊 桢

中国图象图形学报 , 2000,
Abstract: The BP neural network is widely used for classification of remote sensing image data nowadays. But it has the usual shortcomings of multilayer sensor neural network too: the question about the number of crytic layer and the number of crytic layer node, the question about local minimum, the question about training speed, and so on. In order to solve the questions thoroughly, a sort of classification algorithm of high rank neural network is developed in this research. This algorithm has not crytic layer, so it hasn't the question about the number of crytic layer and the number of crytic layer node. It's interface of model classification is nonlenear, so the question about local minimum is solved thoroughly. It's training speed is faster and the precision of model classification is greater than that of the BP neural network algorithm. In this article, the structure, flow chart and course control of this algorithm is introduced detailedly. Using the hyperspectral data in the destrict of Shahe town, Beijing city, an experiment is done and a excellent result is gained. The classification precision of training sample and the classification precision of test sample are all 100 percent. It is proved that the algorithm of high rank neural network has great advantages than other algorithms of neural network in structure, speed and precision.
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