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131.
ZHENG Min WANG Dongmei JIAO Wenchang LI Haiming ZHAO Lianxu BAI Chixian WANG Yaping & PEI Xuetao . Lab of Stem Cell Biology Beijing Institute of Transfusion Medicine Beijing China . Institute of Basic Medical Sciences Chongqing University of Medical Sciences Chongqing China Correspondence should be addressed to Pei Xuetao 《科学通报(英文版)》2003,48(16):1759-1763
Recent progress in stem cell biology and recognition of the unique biological properties of stem cell have made it possible to treat the neurodegenerative diseases includ- ing Parkinson抯 disease (PD) by the approach of cell-re- placement and nutritional support with NSCs. Tissue re-construction based on the stem cells endowed us some unpredicted application and market opportunities. Studies in a variety of systems have highlighted perfect prospects for the application of stem cells in the t… 相似文献
132.
Luo Min Zhang Huan |guo Wang Li |na School of Computer Wuhan University Wuhan Hubei China 《武汉大学学报:自然科学英文版》2003,8(3):803-807
0 IntroductionWiththedevelopmentofthenetworktechnologyandnet workscale ,thenetworksecurityhasalreadybecomeaglobalimportantproblem .Howtofindvariousupdatedintrusionsrapidlyandeffectivelyiscriticalforguaranteeingthesecurityofthesystemandnetworkresources.Commonly ,therearetwocategoriesofintrusiondetectiontechniques,namely ,anomalydetectionandmisusedetection .Inanomalydetection ,normaluserbehaviorandsystemactivitiesarefirstsummarizedintonormalprofiles.Run timeactivitiesresultinginsignificantdevi… 相似文献
133.
Effects of space environment on biological characters of tissue cultured rose seedlings 总被引:3,自引:0,他引:3
Since 1987, many plant seeds have been carriedinto space by high altitude balloons, recoverable satel lites and spacecraft in China, and many studies onthese returned seeds have been reported[1—8]. Re cently we studied the effects of space environments onmorphology, cytology, physiology and molecular bi ology of the rose seedlings which were carried intospace by SHENZHOU 4 spacecraft, and this laid abasis for future studies on culturing and growingplants … 相似文献
134.
Starting from Maxwell's equations for inhomogeneous media, nonlinear integral equations of the inverse problem of the electromagnetic tomography (EMT) are derived, whose kernel is the dyadic Green's function for the EMT sensor with a homogeneous medium in the object space. Then in terms of ill-posedness of the inverse problem, a Tikhonov-type regularization model is established based on a linearization-approximation of the nonlinear inverse problem. Finally, an iterative algorithm of image reconstruction based on the inverse problem and reconstruction images of some object flows for simplified sensor are given. Initial results of the image reconstruction show that the algorithm based on the inverse problem is superior to those based on the linear back-projection in the quality of image reconstruction. 相似文献
135.
Structure and function of Rac genes in higher plants 总被引:3,自引:0,他引:3
As the sole ubiquitous signal GTP-binding protein in higher plants, Rac genes act as pivotal molecular switches and participate in regulations of many life activities, such as cell morphogenesis and polarity growth, programmed cell death, production of H2O2, cell differentiation, and hormone reaction. Based on our work on rice Rac genes, this paper summarizes the researches on Rac genes in higher plant of the last ten years. It will help us to understand the relation between the signal tranduction and the biological functions of plant Rac. 相似文献
136.
National 2000’ GPS control network of China 总被引:3,自引:0,他引:3
Yang Yuanxi Tang Yingzhe Chen Chuanlu Wang Min Zhang Peng Wang Xiaorui Song Lijie Zhang Zusheng 《自然科学进展(英文版)》2007,17(8):983-987
An accurately unified national GPS network with more than 2500 stations,named"National 2000' GPS Control Net- work",signed the epoch 2000.0,has been established by integrating the existing six nationwide GPS networks of China set up by differ- ent departments with different objectives.This paper presents the characteristics of the existing GPS networks,summarizes the strategies in the integrated adjustment of the GPS network,including functional model,stochastic model as well as the adjustment principle modifi- cation.By modifying the adjustment strategies according to the characteristics of the existing GPS networks and under the support of the IGS stations,the accuracy of the integrated national GPS network is greatly improved.The datum differences among the sub networks disappear,the systematic error influences are weakened,and the effects of the outliers on the estimated coordinates and their variances are controlled.It is shown that the average standard deviation for the horizontal component is smaller than 1.0 cm,the vertical component is smaller than 2.0 cm,and the three-dimensional (3-D) position of geocenter coordinates is smaller than 3.0 cm.The exterior checking ac- curacy for the 3-D position is averagely better than 1.0 cm. 相似文献
137.
Gas vesicles provide buoyancy to Microcystis and other common cyanobacterial bloom-forming species. gvpA and gvpC are structural genes encoding gas vesicle proteins. Phylogenetic analyses of 10 Microcystis strains/uncultured samples showed that gvpC and each intergenic segment of the gvpA-gvpC region can be divided into two types. The combination of different types of gvpC and intergenic segments is an important factor that diversifies this genomic region. Some Microcystis strains isolated in China possess a 172 to 176 bp sequence tag in the intergenic segment between gvpA and gvpC. The gvpA-gvpC region in Microcystis can be divided into at least 4 classes and more numbers of subclasses. Compared to rbcLX and other regions, the high variability of the gvpA-gvpC region should be more useful in identifying geographical isolates or ecotypes of Microcystis. 相似文献
138.
Exchange-coupling interaction, effective anisotropy and magnetic property of nano-magnetic materials
The theories and models of exchange-coupling interaction between grains in nanocrystalline magnetic materials are introduced here. Their insufficiencies and distinctions from the experimental results are pointed out, and some revisions are made. The effects of the phase component ratio, the grain size and microstructure on the effective anisotropy and magnetic properties in the nanocomposite permanent materials and the improved models are discussed in detail. 相似文献
139.
Coordinate registration algorithms for over-the-horizon radar 总被引:1,自引:0,他引:1
Kong Min Wang Guohong & Wang Yongcheng . Research Inst. of Information Fusion Naval Aeronautical Engineering Inst. Yantai P. R. China . The th Inst. of China Electronics & Technology Cooperation Nanjing P. R. China 《系统工程与电子技术(英文版)》2006,17(4):725-730
1. INTRODUCTION Over-the-horizon radar, which works in shortwave band,performs over-the-horizon wide area surveillance by reflecting via ionosphere. A significant problem is the phenomenon of multi-path propagation[1], which arises from the presence of layers or regions of relatively high electron density in the ionosphere. Radar signals scattered from the same target arrive at the receiver via different propagation paths. Presently, the common method in OTHR tracking system is multi-pat… 相似文献
140.
WANG Min ZHANG Peizhen SHEN Zhengkang LIU Jie SUN Hanrong GAN Weijun LI Peng 《科学通报(英文版)》2006,51(14):1771-1775
On December 26, 2004, a great earthquake along the northern Sumatra coast, with its consequent tsunami, caused about 300000 deaths (refer to the 2004 earth-quake hereafter). This great thrust faulting event oc-curred on the subduction zone between Indian … 相似文献