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Search Results: 1 - 10 of 161909 matches for " LI Zhi-Feng "
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Poly[diaqua-μ2-oxalato-di-μ4-terephthalato-diytterbium(III)]
Chun-Xiang Wang,Zhi-Feng Li
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810033052
Abstract: The crystal structure of the title complex, [Yb2(C8H4O4)2(C2O4)(H2O)2]n, features an extended three-dimensional framework made up of Yb3+ ions coordinated by terephthalate ligands, oxalate ligands and water molecules. The Yb3+ ion has a distorted square-antiprismatic coordination formed by one aqua ligand, two O atoms from an oxalate ligand and five O atoms belonging to four terephthalate anions. Two symmetry-independent terephthalate anions, as well as the oxalate anion, occupy special positions on inversion centers. The water molecule participates in O—H...O hydrogen bonding with both terephthalate anions.
Poly[μ6-adipato-diaquadi-μ2-oxalato-digadolinium(III)]
Zhi-Feng Li,Chun-Xiang Wang
Acta Crystallographica Section E , 2010, DOI: 10.1107/s1600536810036111
Abstract: In the centrosymmetric title compound, [Gd2(C6H8O4)(C2O4)2(H2O)2]n, the Gd3+ cations are each coordinated by nine O atoms, three from adipate anions, two from oxalate anions and one from an aqua ligand, completing a distorted tricapped trigonal-prismatic geometry. These tricapped trigonal prisms are bridged by the adipate ligands, generating layers lying parallel to (010). The coordination polymer layers are linked into a three-dimensional framework by the rigid oxalate ligands. The adipate and oxalate ions are all located on centers of inversion. A part of the adipate anion is disordered over two positions in a 0.75:0.25 ratio.
Poly[diaqua-μ2-oxalato-di-μ4-terephthalato-dilutetium(III)]
Zhi-Feng Li,Chun-Xiang Wang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809034370
Abstract: In the title compound, [Lu2(C8H4O4)2(C2O4)(H2O)2]n, the Lu3+ cations are each coordinated by eight O atoms of four terephthalate anions, one oxalate anion and one aqua ligand to complete a distorted square-antiprismatic geometry. They are bridged by the terephthalate ligands, generating a three-dimensional framework, which is further stabilized by the oxalate ligands. The terephthalate ions and oxalate ions are all located on centers of inversion.
Poly[diaqua-μ2-oxalato-di-μ4-succinato-diyttrium(III)]
Zhi-Feng Li,Chun-Xiang Wang,Ping Wang
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809032085
Abstract: In the title compound, [Y2(C4H4O4)2(C2O4)(H2O)2]n, the flexible succinate anion assumes a gauche conformation and bridges the eight-coordinated Y atoms, generating two-dimensional layers parallel to (010). The coordination polymer layers are linked into a three-dimensional framework by the rigid oxalate ligands. The oxalate ions are located on a center of inversion. Intermolecular O—H...O hydrogen bonds help to stabilize the crystal structure.
Parallel decline of CD8+CD38+ lymphocytes and viremia in treated hepatitis B patients
Wei Cao,Zhi-Feng Qiu,Tai-Sheng Li
World Journal of Gastroenterology , 2011, DOI: 10.3748/wjg.v17.i17.2191
Abstract: AIM: To assess the peripheral T lymphocyte subsets in chronic hepatitis B virus (HBV) infection, and their dynamics in response to adefovir dipivoxil monotherapy. METHODS: Proportions and absolute counts of peripheral natural killer cells, B cells, CD8+, CD4+, CD8+CD38+, CD8+CD28+ and CD4+CD28+ T cells were determined using three-color flow cytometry in chronic hepatitis B patients (n = 35), HBV carriers (n = 25) and healthy controls (n = 35). Adefovir dipivoxil was initiated in 17 chronic hepatitis B patients who were regularly followed for 72 wk, during which period the T cell subsets and serum viral load were measured at each follow-up point. RESULTS: The peripheral CD4+ T cell counts and CD8+ T cell counts decreased in chronic HBV infection. In chronic hepatitis B patients, proportions of CD8+CD38+ T cells were 62.0% ± 14.7%, much higher than those of HBV carriers and healthy controls. In the 13 hepatitis B patients who were treated and responded to adefovir dipivoxil, proportions of CD8+CD38+ T cells decreased from 53.9% ± 18.4% pre-therapy to 20.1% ± 11.3% by week 72 (P < 0.001), concomitant with viral load decline (HBV DNA fell from 7.31 to 3 log copies/mL). CD8+ T cell counts also underwent an average increase of 218 cells/μL by the end of 72-wk treatment. In those who failed the therapy, the CD8+CD38+ T cell population had more fluctuations. CONCLUSION: CD8+ T cells abnormally activated in chronic HBV infection can be partially reversed by antiviral therapy. HBV-associated immune activation may be a crucial part of the pathogenesis and a promising target of treatment.
Environmental impact of radionuclide migration in groundwater from a low-intermediate level radioactive waste repository
WANG Jin-sheng,YANG Zhi-feng,LI Shu-shen,WANG Zhi-ming
环境科学学报(英文版) , 2001,
Abstract: Thenearsurfacedisposalisthemainlydisposalmethodforlowintermediatelevelradioactivesolidwaste(LILW)inmanycountries.Usually,thedisposalwayinthedisposalunitistheconcretesolidificationisputandpiledinarray,andthebackfillandbuffermaterialisfilledbetweentheses…
Association between the Pro12Ala Polymorphism of Peroxisome Proliferator-Activated Receptor Gamma 2 and Inflammatory Bowel Disease: A Meta-Analysis
Zhi-Feng Zhang, Ning Yang, Gang Zhao, Lei Zhu, Li-Xia Wang
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030551
Abstract: Background Peroxisome proliferator-activated receptor gamma (PPARγ), a nuclear receptor, has been implicated playing a role in the development of inflammatory bowel disease (IBD). However, previous studies evaluating the association between the PPARγ2 Pro12Ala polymorphism and IBD are inconsistent. We performed a meta-analysis to determine whether the PPARγ2 Pro12Ala mutation was associated with the presence of IBD. Methods and Findings Electronic databases were searched for case-control studies evaluating the association between the Pro12Ala mutation and the presence of IBD. Effects were summarized with the methods recommended by the Cochrane Collaboration. A total of 7 studies including 1002 ulcerative colitis (UC) cases, 1090 Crohn`s disease (CD) cases and 1983 controls were involved in this meta-analysis. In the overall analysis, no significant association of this polymorphism with UC or CD was found. In the subgroup analyses in different populations, AlaAla genotype seemed to protect the European Caucasian population against the development of CD (Pro vs Ala: OR = 1.135, 95%CI = 0.951–1.354, P = 0.162, Bon = 1.000; ProPro vs ProAla: OR = 1.042, 95%CI = 0.852–1.273, P = 0.690, Bon = 1.000; ProPro vs AlaAla: OR = 2.379, 95%CI = 1.110–5.100, P = 0.026, Bon = 0.156; ProAla vs AlaAla: OR = 2.315, 95%CI = 1.064–5.037, P = 0.034, Bon = 0.204; Pro homozygotes vs Ala positives: OR = 1.094, 95%CI = 0.899–1.330, P = 0.371, Bon = 1.000; Pro positives vs Ala homozygotes: OR = 2.360, 95%CI = 1.103–5.053, P = 0.027, Bon = 0.162; heterozygotes vs all homozygotes: OR = 0.976, 95%CI = 0.799–1.192, P = 0.809, Bon = 1.000). There was no significant association of this polymorphism with UC or CD in the East Asian population and the Turkish population. Conclusion AlaAla genotype may be a protective factor in the European Caucasian population against the development of CD in a recessive way.
Revelation of Ecological Evaluation of the Farming-pastoral Transitional Zone to Land Arrangement--A Case Study on Zhenlai County
农牧交错地带的生态评估对土地整理的启示

ZHANG Yan,YANG Zhi-feng,LI Wei,
张妍
,杨志峰,李巍

自然资源学报 , 2005,
Abstract: The objective of this study is to provide a scientific enlightment for future ecological land use arrangement that can not only ensure the food supply,but also protect the eco-environ-mental quality,in the transition region of the farming-pastoral zone,through prohibiting from exploiting blindly wetlands and reclaiming farmlands from lakes.Although the concept of land arrangement is firstly provided in Land Management Law of the People's Republic of China enacted in 1998,the works of land arrangement (such as land development and renovation,land reclamation) have already been unfolded for a long time.Through the analysis of land use changes from 1986 to 2000,the traces of land arrangement are derived.At the same time,the ecological evaluation of land use changes will provide a scientific basis for future land arrangement work.Zhenlai County,the typical transitional belt of the farming-pastoral zone in the west of Jilin Province,is chosen as a case study area in this paper.Based on the interpretation of Landsat data,which are distilled from digital images taken in 1986,1996 and 2000 respectively,the land use and land cover changes are studied,the analysis of shape readjustment and the evaluation of the ecosystem services function of readjustment in Zhenlai County are unfolded applying the transitional matrix,landscape pattern method and ecosystem services function method.The preliminary results are as follows:1)Farmlands and pastoral land are the main land use categories in Zhenlai County;2)from 1986 to 1996,the work emphasis on land arrangement is the transformation between cultivated land and unused land,such as consolidating farm plots and developing unused land;3)and from 1996 to 2000,the work emphasis is the transformation of farmlands to grasslands.The land use arrangement will be bound to lead to the value changes of ecosystem services function,but with the degradation of eco-environment,the tiny changes of uncontrolled unit,such as wetland and water area,will induce the prodigious transformation.So the future focus and difficulty are to realize the ecological land arrangement from the point of view of cultivating ecosystem.
RAMAN SPECTROSCOPY STUDY ON LO PHONON-PLASMON COUPLED MODE IN GaN THIN FILMS
氮化镓薄膜中LO声子—等离子体激元耦合模拉曼光谱研究

LI Zhi-Feng,LU Wei,
李志锋
,陆卫

红外与毫米波学报 , 2003,
Abstract: A series of Si doped GaN thin films grown on sapphire substrate were measured by Raman spectroscopy. Both high-and low-frequency branches of the longitudinal-optical (LO) phonon and plasmon coupling modes (LPP modes) were resolved. With the increasing of doping level, the LPP mode shifts toward higher frequency. The two branches in each spectrum were independently lineshape-fitted based on scattering analysis, and plasmon frequency and damping constant were obtained, thus the free carrier concentration and mobility could be deduced. The carrier concentration derived from each branch of the single spectrum coincidences with each other, and it is also consistent with infrared (IR) reflection and Hall results. The mobility from the low branch fitting is in agreement with the IR values, and is about half values of the Hall mobility, which is close to the conduction drift mobility in the regime of ionized impurity scattering. The high branch mobility is even smaller, which implies some additional scattering effect.
Spatio-temporal changes of NDVI and their relations with precipitation and runoff in the Yellow River Basin
黄河流域NDVI时空变化及其与降水/径流关系

LI Chun-hui,YANG Zhi-feng,
李春晖
,杨志峰

地理研究 , 2004,
Abstract: NDVI is an important index denoting a region's vegetation cover. In this paper, the Yellow River Basin is divided into 16 sub-regions and their NDVI series of 1982-1998 are obtained from AVHRR-NDVI of Pathfinder. The spatio-temporal changes of NDVI in the Yellow River Basin are analyzed. The results show that:(1) In general, NDVI in all sub-regions reaches peak value in July or August within a year in the Yellow River Basin. In average in the 17 years, the NDVI values show the increasing trends in August and in annual average in other sub-regions except that they show the downward trends in the Sanhua and the above Longyang gorge sub-regions in August. These imply that the coverage percentage of the vegetation presents a rising trend and the ecological quality is being improved on the whole in the Yellow River Basin, but there is some deteriorating trend in some sub-regions in August. (2) With obvious differences in the 16 sub-regions, the higher annual values of NDVI occur in the Taohe, Yiluohe and Weihe sub-regions, while the lower in the indraft area and the Lanhe sub-regions. The spatial changes of NDVI are unanimous with precipitation in most part of the Yellow River Basin, and the average changing rates of NDVI in different sub-regions are different. Finally, the relations of NDVI between precipitation, runoff and runoff coefficient in every sub-region are researched. The results show that NDVI has some apparent positive correlations with precipitation and natural runoff within a year, and furthermore, NDVI has some time lags behind precipitation. From the perspective of inter-annual changes, NDVI has some positive correlations with precipitation, but has complex relations with natural runoff and runoff coefficient variability. There is no, if any, obscure correlations between them.
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