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Chinese Geographical Science 2005年第3期15卷 212-218页

作者： wei Li-hua YAN Xiao-pei College of Architecture ＆ Civil Engineering South China University of Technology Guangzhou 510640 P. R. China Center for Urban ＆ Regional Studies Sun Yat-Sen University Guangzhou 510275 P. R. China

Many studies have been made concerning the problems, characteristics, formation, transformation measures, etc. of urban village from sociology, urban planning and geography, etc., which have made insightful analysis. However, most of these studies started mainly from the standpoint of the city govemment, drumming for the land- scape-oriented urbanization, namely pulling-down the urban village and constructing the splendid residence or business buildings. The article maintains that the most important thing the city government should do is to pay much attention to the sustainable living of urban villagers, who would lose their main income source, namely, the collective dividend and the family housing rent. The single method of compensation has been proved to be harmful to the villagers＇ community, in which some young villagers relying on rent were no longer to do anything but stay at home. On the other hand, considering the floating population has become the main stream of renters in urban villages, the emergence of urban villages was inevitable and would continue to exist in a long time under the socio-economic transition in urban China and globalization. Based on the analysis above, the transformation of urban village should take more concerns on the housing demands of floating population besides compensation for local villagers. Meanwhile, it is necessary to avoid the “landscape-oriented urbanization” without the “peasant-to-citizen” transformation.

关键词： urban-rural relation rapid urbanization areas Guangzhou urban village

Thermoluminescence of Al_2O_3 crystals grown by temperature gradient techniques

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Chinese Science Bulletin 2013年第16期58卷 1964-1968页

作者： CHEN wei SONG PingXin DONG YongJun ZHANG YingJiu hua wei College of Physical Science and Engineering Zhengzhou University State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences

Color center concentrations of the Al2O3 crystal grown by temperature gradient techniques were calculated from Gaussian fits to absorption spectra. The concentrations for F- and F + -centers at 204, 232, and 255 nm were determined to be 1.361×10 17 , 0.098×10 17 , and 0.325×10 17cm-3 , respectively. Studies have shown that the thermoluminescence (TL) glow curve exhibits a prominent 450 K peak that matches well the first-order fitting curve. The thermal activation energy E and frequency factor s of the trap were determined to be 0.94456±0.00545 eV and 5.8703×10 11 s-1 . With this theoretical analysis, a simple one-trap/one-center TL model is presented to provide a theoretical explanation of the TL process.

关键词：梯度技术晶体生长生长温度热释光色心浓度吸收光谱拟合曲线频率因子

Singularity analysis of Jeffcott rotor-magnetic bearing with time delays

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Applied Mathematics(A Journal of Chinese Universities) 2012年第4期27卷 419-427页

作者： XU Xiu-yan JIANG wei-hua Department of Mathematics Heilongjiang Institute of Science and TechnologyHarbin 150027China Department of Mathematics Harbin Institute of TechnologyHarbin 150001China

A Jeffcott rotor-magnetic bearing with time delays is investigated in this paper. Firstly, it is found that the characteristic equation of the system satisfies the conditions of the singularity. Secondly, the center manifold reduction and normal form are employed to study the bifurcation from simple zero and zero-purely imaginary singularities. The results of this paper will help to understand the influence of the time delays in feedback loop on the dynamics of rotor-magnetic bearing system.

关键词： Jeffcott rotor-magnetic bearing time delay singularity normal form.

Transverse Bending Characteristics in U-channel Forming of Tailor Rolled Blank

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Journal of Iron and Steel Research International 2016年第12期23卷 1249-1254页

作者： hua-wei ZHANG Ying-ping GUAN Jia-lu WU Xiang-hua LIU School of Control Engineering Northeastern University at Qinhuangdao College of Mechanical Engineering Yanshan University Research Institute of Science and Technology Northeastern University

Research on the formability of tailor rolled blank （TRB） is of good practical significance and application value because of the enormous potential of TRB in the aspect of automobile lightweight. However, the forming of TRB is problematic because of the varying properties; especially, springback is a main challenge. The transverse bending （bending axis is perpendicular to the rolling direction） of TRB U channel was studied through simulation and experiment. The forming characteristics of TRB U channel during transverse bending were analyzed. The mechanisms of forming defects, including bending springback and thickness transition zone （TTZ） movement, were revealed. On this basis, effects of blank geometric parameters on springbaek and TTZ movement were discussed. The results indicate that springback and TTZ movement happen during transverse bending of TRB U-channel. Nonuni form stress distribution is the most fundamental reason for the occurrence of springback of TRB during transverse bending. Annealing can eliminate nonuniform stress distribution, and thus diminish springbaek of TRB, especially springback on the thinner side. Therefore, springback of the whole TRB becomes more uniform. However, annealing can increase the TTZ movement. Blank thickness and TTZ position are the main factors affecting the formability of TRB U-channel during transverse bending.

关键词： tailor rolled blank transverse bending springback U-channel annealing thickness transition zone

Oscillatory and Asymptotic Behavior of Solutions for Nonlinear Impulsive Delay Differential Equations

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Acta Mathematicae Applicatae Sinica 2006年第3期22卷 387-396页

作者： wei-hua Mao An-hua Wan College of Science South China Agricultural University Guangzhou 510642 China Institute of Automation Chinese Academy of Sciences Beijing 100080 China

The oscillatory and asymptotic behavior of the solutions for third order nonlinear impulsive delay differential equations are investigated. Some novel criteria for all solutions to be oscillatory or be asymptotic are ... 详细信息

关键词： Impulse delay oscillation asymptotic property

Changes in fungal community and diversity in strawberry rhizosphere soil after 12 years in the greenhouse

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Journal of Integrative Agriculture 2019年第3期18卷 677-687页

作者： LI wei-hua LIU Qi-zhi College of Plant Protection China Agricultural University

Soil fungi play a very important role in the soil ecological environment. In agricultural production, long-term monoculture and continuous cropping lead to changes in fungal community diversity. However, the effects of long-term monoculture and continuous cropping on strawberry plant health and fungal community diversity have not been elucidated. In this study, using high-throughput sequencing(HTS), we compared the fungal community and diversity of strawberry rhizosphere soil after various durations of continuous cropping(0, 2, 4, 6, 8, 10 and 12 years). The results showed that soil fungal diversity increased with consecutive cropping years. Specifically, the soil-borne disease pathogens Fusarium and Guehomyces were significantly increased after strawberry continuous cropping, and the abundance of nematicidal(Arthrobotrys) fungi decreased from the fourth year of continuous cropping. The results of correlation analysis suggest that these three genera might be key fungi that contribute to the changes in soil properties that occur during continuous cropping. In addition, physicochemical property analysis showed that the soil nutrient content began to decline after the fourth year of continuous cropping. Spearman's correlation analysis showed that soil pH, available potassium(AK) and ammonium nitrogen(NH_4^+-N) were the most important edaphic factors leading to contrasting beneficial and pathogenic associations across consecutive strawberry cropping systems.

关键词： fungal community soil-borne disease replanted strawberry rhizosphere soil agricultural soil ecology

A Modified Residual-based Test for Serial Correlation in Linear Panel Data Models

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Acta Mathematicae Applicatae Sinica 2014年第2期30卷 401-410页

作者： Jian-hong WU wei-hua SU School of Statistics and Mathematics Zhejiang Gongshang University Zhejiang University of Finance and Economics Application of Statistical Science Research Center of Renmin University of China Key Research Institute

This paper suggests a modified serial correlation test for linear panel data models, which is based on the parameter estimates for an artificial autoregression modeled by differencing and centering residual vectors. Specifically, the differencing operator over the time index and the centering operator over the individual index are, respectively, used to eliminate the potential individual effects and time effects so that the resultant serial correlation test is robust to the two potential effects. Clearly, the test is also robust to the potential correlation between the covariates and the random effects. The test is asymptotically chi-squared distributed under the null hypothesis. Power study shows that the test can detect local alternatives distinct at the parametric rate from the null hypothesis. The finite sample properties of the test are investigated by means of Monte Carlo simulation experiments, and a real data example is analyzed for illustration.

关键词： panel data residual-based test serial correlation

Potassium Transporter KUP7 Is Involved in K^＋ Acquisition and Translocation in Arabidopsis Root under K^＋-Limited Conditions

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Molecular Plant 2016年第3期9卷 437-446页

作者： Min Han wei Wu wei-hua Wu Yi Wang State Key Laboratory of Plant Physiology and Biochemistry (SKLPPB) College of Biological Sciences National Plant Gene Research Centre (Beijing) China Agricultural University Beijing 100193 China

Potassium （K^＋） is one of the essential macronutrients for plant growth and development. K^＋ uptake from environment and K^＋ translocation in plants are conducted by K^＋ channels and transporters. In this study, we demonstrated that KT/HAK/KUP transporter KUP7 plays crucial roles in K^＋ uptake and translocation in Arabidopsis root. The kup7 mutant exhibited a sensitive phenotype on Iow-K^＋ medium, whose leaves showed chlorosis symptoms compared with wild-type plants. Loss of function of KUP7 led to a reduction of K^＋ uptake rate and K^＋ content in xylem sap under W-deficient conditions. Thus, the K^＋ content in kup7 shoot was significantly reduced under Iow-K^＋ conditions. Localization analysis revealed that KUP7 was predominantly targeted to the plasma membrane. The complementation assay in yeast suggested that KUP7 could mediate K^＋ transport. In addition, phosphorylation on S80, S719, and S721 was important for KUP7 activity. KUP7 was ubiquitously expressed in many organs/tissues, and showed a higher expression level inArabidopsis root. Together, our data demonstrated that KUP7 is crucial for K^＋ uptake inArabidopsis root and might be also involved in K^＋ transport into xylem sap, affecting K^＋ translocation from root toward shoot, especially under K^＋-Iimited conditions.

关键词： Arabidopsis thaliana K^+ uptake K^+ translocation KUP7 K^+ deficiency

Extremely metal-poor star candidates in the SDSS

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Research in Astronomy and Astrophysics 2013年第3期13卷 313-322页

作者： Si-Yao Xu hua-wei Zhang Xiao-wei Liu Department of Astronomy School of Physics Peking University Kavli Institute of Astronomy and Astrophysics Peking University

For a sample of metal-poor stars （-3.3 ≤ [Fe/H] ≤-2.2） that have highresolution spectroscopic abundance determinations, we have measured equivalent widths of the Ca II K, Mg I b and near-infrared Ca II triplet lines using low-resolution spectra from the Sloan Digital Sky Survey （SDSS）, calculated effective temperatures from （g - z）o color, deduced stellar surface gravities by fitting stellar isochrones, and determined metallicities based on the aforementioned quantities. Metallicities thus derived from the Ca II K line are in much better agreement with the results deter- mined from high-resolution spectra than the values given in the SDSS Data Release 7. The metallicities derived from the Mg I b lines have a large dispersion owing to the large measurement errors, whereas those deduced from the Ca II triplet lines are too high due to both non-local thermodynamical equilibrium （NLTE） effects and mea- surement errors. Abundances after correction for the NLTE effect for the Mg I b lines and Ca II triplet lines are also presented. Following this method, we have identified six candidates of ultra-metal-poor stars with [Fe/H] - -4.0 from a sample of 166 metal-poor star candidates. One of them, SDSS J102915＋172927, was recently con- firmed to be an ultra-metal-poor （[Fe/H] 〈 -4.0） star with the lowest metallicity ever measured. Follow-up high-resolution spectroscopy for the other five ultra-metal-poor stars in our sample will therefore be of great interest.

关键词： stars: abundances -- stars: Population -- techniques: spectroscopic

Utilization of Chinese Herbal Feed Additives in Animal Production

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Agricultural Sciences in China 2011年第8期10卷 1262-1272页

作者： LIU hua-wei TONG Jian-ming ZHOU Dao-wei Northeast Institute of Geography and Agroecology Chinese Academy of SciencesJilin 130012P.R.China State Key Laboratory of Animal Nutrition Institute of Animal ScienceChinese Academy of Agricultural SciencesBeijing 100193P.R.China

The experimental knowledge on efficacy,possible modes of action and aspects of application of Chinese herbs as feed additives for animal production are reviewed in this *** herbs commonly contain protein,carbohydrate,fat,vitamins,andmineral which are necessary nutrients to the growth of ***,organic acid,alkaloids,and essential oils involved in Chinese herbs can improve the immune function of ***,numerous studies have demonstrated anti-oxidative and anti-microbial efficacy and the assumption that Chinese herbs may improve the flavor of meat,which has been confirmed by some observations,but the mode of this action is still ***,several observations support the hypothesis that herbal feed additives may favorably affect gut functions （e.g.,enzyme activity,microbial eubiosis） in *** effects may explain a considerable number of practical studies with livestock reporting improved production performance after providing herbal feed *** summary,available evidence indicates that herbal feed additives may have the potential to add to the set of non-antibiotic growth promoters for use in livestock,such as organic acids and ***,a systematic approach toward the efficacy,mode of action and safety of herbal compounds used as feed additives for animal production seems to be required in the future.

关键词： anti-microbial anti-oxidative Chinese herbs animal production