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Search Results: 1 - 10 of 42794 matches for " Lifang Xu "
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Magnetotactic Bacteria Algorithm for Function Optimization  [PDF]
Hongwei Mo, Lifang Xu
Journal of Software Engineering and Applications (JSEA) , 2012, DOI: 10.4236/jsea.2012.512B014
Abstract: Magnetotactic bacteria is a kind of polyphyletic group of prokaryotes with the characteristics of magnetotaxis that make them orient and swim along geomagnetic field lines. A magnetotactic bacteria optimization algorithm(MBOA) inspired by the characteristics of magnetotactic bacteria is researched in the paper. Experiment results show that the MBOA is effective in function optimization problems and has good and competitive performance compared with the other classical optimization algorithms.
中國大陸非國有書業發展歷程研究 A Brief History of Non-state-owned Book Industry on the Mainland of P. R. China
Qing Fang,Lifang Xu
Journal of Educational Media & Library Sciences , 2005,
Abstract: 文章對中華人民共和國成立以來,中國大陸非國有書業發展歷程進行了系統回顧與分析。作者將1949年以來大陸書業的發展以1980年為界劃分為前後兩個階 段,前一階段為非國有書業的限制發展時期;後一階段為鼓勵發展時期。文章重點分析了1980年以來大陸非國有書業發展的三個步驟,即1980年非國有經濟 開始進入圖書零售領域;1988年非國有經濟得以進入圖書二級批發環節;2003年圖書的總發行權和全國連鎖經營權的大門開始向非國有經濟敞開。 This article reviews and analyzes the brief history of the Non-state-owned Book Industry on the Mainland of P. R. China since 1949, which is divided into two stages by the year of 1980. The first phase is a restriction period and the second one is an encouragement period. The article focuses especially on the 3 steps of the second stage, namely: firstly, Non-state-owned enterprises was permitted to enter the book retailing sector in 1980; secondly, Second level wholesale right could he delegated to privately-owned enterprises in 1988; thirdly, general distribution right and the chain bookstores operation right were opened tip to the Non-state-owned enterprises.
Outlier Detection Based on Robust Mahalanobis Distance and Its Application  [PDF]
Xu Li, Songren Deng, Lifang Li, Yunchuan Jiang
Open Journal of Statistics (OJS) , 2019, DOI: 10.4236/ojs.2019.91002
Abstract: Classical Mahalanobis distance is used as a method of detecting outliers, and is affected by outliers. Some robust Mahalanobis distance is proposed via the fast MCD estimator. However, the bias of the MCD estimator increases significantly as the dimension increases. In this paper, we propose the improved Mahalanobis distance based on a more robust Rocke estimator under high-dimensional data. The results of numerical simulation and empirical analysis show that our proposed method can better detect the outliers in the data than the above two methods when there are outliers in the data and the dimensions of data are very high.
Self-Assembly of Glycine on Cu (001): the Tales of Polarity and Temperature
Jing Xu,Zheshuai Lin,Sheng Meng,Lifang Xu,Enge Wang
Physics , 2012,
Abstract: Glycine on Cu(001) is used as an example to illustrate the critical role of molecular polarity and finite temperature effect in self-assembly of biomolecules at a metal surface. A unified picture for glycine self-assembly on Cu(001) is derived based on full polarity compensation considerations, implemented as a generic rule. Temperature plays a non-trivial role: the ground-state structure at 0 K is absent at room temperature, where intermolecular hydrogen bonding overweighs competing molecule-substrate interactions. The unique p(2X4) structure from the rule is proved as the most stable one by ab initio molecular dynamics at room temperature, and its STM images and anisotropic free-electron-like dispersion are in excellent agreement with experiments. Moreover, the rich self-assembling patterns including the heterochiral and homochiral phases, and their interrelationships are entirely governed by the same mechanism.
Influence of the cobalt concentration on optical and magnetic properties of zinc oxide
LiWei Wang,FuJun Zhang,Zheng Xu,SuLing Zhao,LiFang Lu
Chinese Science Bulletin , 2010, DOI: 10.1007/s11434-009-0732-z
Abstract: A series of Co-doped ZnO thin films have been prepared by direct current reactive magnetron sputtering on glass substrates. The structural characterization by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM) gave no evidence of second phase formation. The qualitative composition and chemical state were characterized by energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectronic spectrometry (XPS), respectively. The results confirmed that Co was incorporated as Co3+, occupying the Zn2+ sites in ZnO’s wurtzite structure. The luminescence properties of the films were investigated by room temperature photoluminescence, and the optical properties were studied by optical transmittance. The magnetic analysis was carried out at room temperature and at 50 K by Quantum Design MPMS (SQUID) XL. The results showed that all the Co-doped ZnO thin films prepared by direct current magnetron sputtering were not ferromagnetic above 50 K.
Use of DNAzymes for cancer research and therapy
ZhiJie Xu,LiFang Yang,LunQuan Sun,Ya Cao
Chinese Science Bulletin , 2012, DOI: 10.1007/s11434-012-5380-z
Abstract: DNAzymes (Dzs) are single-stranded DNA catalysts that specifically cleave the mRNA of targeted genes. Compared with other gene-silencing technologies, such as ribozymes, antisense oligonucleotide and small interference RNA (siRNA), DNAzymes have several advantages, including small molecular weight, diversity, low cost and relative stability in serum. With the evolution of molecular technology, the first DNAzyme was generated in vitro in 1994. From then on, DNAzymes have been studied in order to understand their structures, chemistry and biological applications. Particularly, DNAzymes have been widely applied as a new interference strategy in the treatment of many conditions, including cancer, viral diseases, and cardiovascular diseases. This review mainly summarizes the use of DNAzymes in the areas of cancer research and therapy.
The Effect of Autophagy on the Radioresistance of Human Adenocarcinoma A549 Cell in Hypoxia Condition
Yong LI,Liyao XU,Aqiao CAI,Lifang LI
Chinese Journal of Lung Cancer , 2012, DOI: 10.3779/j.issn.1009-3419.2012.11.06
Abstract: Background and objective It has been proven that cancer cell autophagy can be induced by hypoxia. In addition, autophagy was correlated with radiosensitivity. Thus, regulating the autophagy signaling pathway is a potential treatment strategy. The aim of this study is to investigate the effects of combined autophagy inhibitor 3-methyladenine (3-MA) on the radiosensitivity of human adenocarcinoma A549 cells in hypoxia condition. Methods A549 cells were cultured in hypoxia condition, and then divided into two groups: hypoxia group and 3-MA plus hypoxia group. Electronic microscopy was used to detect autophagosome levels at different time points. The expression of LC3 was examined by Western blot. The proliferation activity of A549 cells after radiotherapy (0 Gy, 2 Gy, 4 Gy, 6 Gy, 8 Gy, and 10 Gy) was determined with an MTT assay. Results Autophagosome formation and the LC3II/LC3I ratio increased under hypoxic conditions. After treatment with the autophagy inhibitor 3-MA, the quantity of autophagosomes and the LC3II/LC3I ratio decreased. The proliferative activity of the cells in the 3-MA plus hypoxia group was remarkably lower than that in the hypoxia group after treatment with radiotherapy. Conclusion The level of protective autophagy of A549 cells increased in hypoxia condition; thus, inhibiting autophagy improves the radiosensitivity of A549 cells.
Application of GDAHP on Quality Evaluation of Urban Lake Landscape  [PDF]
Lifang QIAO, Yichuan ZHANG
Journal of Water Resource and Protection (JWARP) , 2009, DOI: 10.4236/jwarp.2009.16051
Abstract: The quality evaluation of urban lake landscape (QEULL) is extremely important for the healthy development of lake landscape. In this research, the evaluation model was established with the group decision analytic hierarchy process (GDAHP) method, which consisted of four layers including the target layer, the factor layer, the index layer and the criterion layer, thus forming a model tree based on their subordinate relation-ships. The GDAHP method was employed to determine the weights of constituting factors of each layer in the evaluation model, and the fuzzy method was used to establish the factors remark sets of the criterion layer, thus the single-layer evaluation and comprehensive evaluation of urban lake landscape quality was carried out. Quality evaluation model of urban lake landscape established based on the GDAHP method can provide grounds for planning, design, and renewal of urban lake landscape. This model has been used to evaluate and analyze the artificial lake in People’s Park of Xinxiang City, Henan Province. The results proved that the overall landscape quality of the artificial lake of Peoples Park in Xinxiang city was good.
Comparison of chiral separations of felodipine by high performance liquid chromatography using two cellulose tris(4-methyl benzoate) stationary phases
高效液相色谱使用两种类型的纤维素-三(对甲基苯甲酸酯)固定相手性拆分非洛地平的比较

XU Lifang,LU Yao,LI Yi,XU Xu,
徐丽芳
,鲁耀,李奕,许旭

色谱 , 2010,
Abstract: 以高效液相色谱手性固定相法对非洛地平(FEL)进行手性拆分。分别采用两种类型的纤维素-三(对甲基苯甲酸酯)手性柱Chiralcel OJ-R和Chiralcel OJ-H进行比较实验,以正己烷-异丙醇(90:10, v/v)为流动相,考察了流动相、柱温对保留及手性拆分的影响。实验显示,两柱拆分FEL的van’t Hoff图均发生了转折,在高温区域为焓驱动,在低温区域为熵驱动。两柱在温度升高时拆分FEL的分离度均提高,其中OJ-H的分离度优于OJ-R。两种手性柱对FEL具有相似的拆分机理。
Cloning and high-level expression of plasminogen activator inhibitor-1 cDNA derived from human glomerular mesangial cells
Yibin Deng,Xiangmei Chen,Hongjun Liao,Yizhou Ye,Qihe Xu,Lifang Yu
Science China Life Sciences , 1998, DOI: 10.1007/BF02895108
Abstract: Translation reading frame of human plasminogen activator inhibitor-1 (PAI-1) cDNA was amplified from total RNA extracted from glomerular mesangial cells by using reverse-transcription polymerase chain reaction (RT-PCR) and inserted into plasmid pUC19 in a sense orientation. Sequencing results revealed that PAI-1 cDNA had new initial codon ATG, but no signal peptide sequences, and translation reading frame was in agreement with PAI-1 cDNA derived from human endothelial cells. PAI-1 cDNA determined by sequencing was inserted into prokaryotic expression plasmid pBV220, and recombinant plasmid pBV220-PAI-l which had high-level expression inEscherichia coli was obtained. Recombinant PAI-1 protein attained to approximately 45 % of total bacterial proteins. Western blotting showed that there was a specific band in the region of 43.0 ku. Latent recombinant PAI-1 with 97 % purity was obtained from inclusion bodies after denaturation, renaturation and purification by FPLC. Recombinant PAI-1 activated by treatment with 4.0 mol/L guanidinium-hydrochloride had significant inhibition activity to u-PA and shared bioactivity in common with natural PAI-1.
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