检索结果-南通市图书馆

PTC/NTC Behavior of PVDF Composites Filled with GF and CF

在线全文

学校读者我要写书评

暂无评论

Chemical Research in Chinese Universities 2008年第5期24卷 648-652页

作者： WANG xin-lei ZHANG Guo li Ji-xin li Zhuo-shi liu Zhan-fang liu Xiu-qi Key Laboratory of Automobile Materials Ministry of Education College of Materials Science and Engineering Jilin University. Changehun 130012 P. R. China

Conductive polyvinylidene fluoride（PVDF）matrix composites filled with graphited fiber（GF）or carbon fiber（CF）were prepared by the melt-mixing *** breakage and length distribution of the fibers in the polymer matrix were studied by scanning electron microscope（SEM）and optical microscope（OM）observations,respectively. The differences in the positive temperature coefficient（PTC）effects of the composites were mainly attributed to inter-fiber contact *** elimination of the negative temperature coefficient（NTC）effect for CF/PVDF composite was because of an increase in the viscosity of the polymer *** the same filler content,CF could be more effective,to eliminate the NTC effect when compared with *** of 2%CF（mass fraction）in the PVDF composite with 7%GF（mass fraction）could effectively eliminate the NTC phenomenon of the composite.

关键词： Polyvinylidene fluoride Graphited fiber Carbon fiber Positive temperature coefficient effect Negative temperature coefficient effect

Phenols/Al(C_(6)F_(5))_(3) Initiation Systems for Cationic Polymerizations of Isobutylene

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2023年第5期41卷 713-719,I0008页

作者： ling Cai Qi-Yuan Wang xin-li liu Dong-Mei Cui State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Department of Polymer Science and Engineering University of Science and Technology of ChinaHefei 230026China

We report herein the cationic polymerization of isobutylene(IB)under mild conditions is realized with a new binary initiation system generated by simply mixing a Lewis super acid Al(C_(6)F_(5))_(3) and a substituted phenol(RPhOH).Polymers with medium and/or high molecular weights(M_(W)=4.9×10^(4)-27.7×10^(4) g·mol^(-1))can be obtained in toluene and temperatures from-20℃to 0℃.NMR spectrum analysis and DFT sim ulation reveals the in situ generated acidic coordinating complex Ak(C_(6)F_(5))_(3)·RPhOH is the initiating active species,which fu rther tran sformed into the ion-pair[Al(C_(6)F_(5))_(3)ORPh]^(-)[PIB]^(+)of the active intermediates upon growing IB monomers where the counter anion[Al(C_(6)F_(5))_(3)R^(O)Ph]-coordinates to the macrocation via the phenoxy *** catalyst performances are the concert effects of the steric bulkiness and electronics of the counter anion on the coordinating strength to the macrocation,which is significant to the stability of the active species.

关键词： Cationic polymerization Phenols Lewis super acid Polyisobutylene

Research on the preparation of amorphous diamond nanorod arrays and their excellent field emitting properties

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2006年第2期49卷 156-163页

作者： YAN Pengxun li Xiaochun XU Jianwei li xin li Chun liu Yang Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China Institute for Plasma & Metal Materials Lanzhou University Lanzhou 730000 China

Amorphous diamond nanorod arrays with excellent field emitting have been fabricated firstly on the AAO template by the filtered cathodic arc plasma technique. Microscopic analysis has displayed that the nanorods are very uniformly distributed, and the density is very high up to ～109 cm-2. The nanorod arrays are found to have an extremely low turn-on field of 0.16 V/μm, which is lower than other reported materials, and a high- emission current density of 180 mA/cm2 under an applied field of 2 V/μm can also be obtained. Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and filed emitting tester are employed to characterize the nanorod arrays. The field emission mechanism of the nanorod arrays is also discussed.

关键词： amorphous diamond nanorod arrays, magnetic filtered plasma, AAO, field electron emitting.

Effect of Low-temperature Imidization on Properties and Aggregation Structures of Polyimide Films with Different Rigidity

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2024年第8期42卷 1134-1146页

作者： Yan Jia Lei Zhai Song Mo Yi liu li-xin liu xin-Yu Du Min-Hui He lin Fan Key Laboratory of Science and Technology on High-tech Polymer Materials Institute of ChemistryChinese Academy of SciencesBeijing 100190China School of Chemical Sciences University of Chinese Academy of SciencesBeijing 100049China

The traditional high-temperature preparation process of polyimide can cause many problems and limits the wider application in extreme *** important challenge to be solved urgently is the reduction of imidization *** this work,twelve kinds of polyimide films with different chain rigidity were prepared at low temperature of 200℃,in the absence or presence of imidazole used as the *** molecular rigidity and free volume were theoretically calculated,and relationship between structure and properties were systematically *** results show that imidization reaction under low temperatures is significantly affected by the rigidity of molecula r *** rigid structure of polyimide is not conducive to the low-temperature imidization,but this adverse effect can be eliminated by adding catalyst,resulting the notably increased imidization *** optical and thermal properties can be improved to a certain extent for the chemically catalyzed system,resulting in relatively higher heat resistance and thermal *** the mechanical performance could be determined by com plicating factors,greatly different from polyimide films prepa red by high temperature *** investigate aggregation structures of film s,the effect of chain rigidity and catalyst on the stacking or orientation of molecular chains was further *** wo rk can contribute to the understanding of chemically catalyzed imidization that is rarely reported in the existing research,and will provide guidance for the low-temperature preparation of high-performance polyimides.

关键词： Polyimide Imidization Catalyst Structure and properties Aggregation structures

Improved Region Energy Based Image Fusion Rule for Multi-focus Image Fusion

在线全文

学校读者我要写书评

暂无评论

Journal of Harbin Institute of Technology(New Series) 2013年第4期20卷 109-115页

作者： Chun-Hui Zhao li-Juan Ma Guo-Feng Shao li-xin liu College of Information and Communication Engineering Harbin Engineering University College of Underwater Acoustic Engineering Harbin Engineering University

In this paper,we propose a novel improved region energy based image fusion *** original images are firstly decomposed by using the lifting scheme of wavelet transform into four sub-bands:LL,LH,HL,HH,by studying principles and characteristics of the wavelet subbands,and we put emphasis on the high frequency *** HH,HL,LH sub-bands,which represent three direction of high frequency details,are weighted by different size of three direction Gaussian kernel,then the energy based image fusion rule is applied with a optional size of window,thus the activity level of high frequency subbands are obtained,followed by a local region matching degree in the corresponding direction and resolution,an activity level of low frequency subband is calculated,then perform consistency verification on the selected wavelet coefficients,by doing the inverse wavelet transform the fused image is *** performance of the proposed novel image fusion scheme is conducted and compared with a few existing image fusion algorithm,the experimental results show that the proposed method is an effective multi-focus image fusion algorithm.

关键词： lifting scheme weighted energy region matching degree consistency verification

Cistanche deserticola decoction alleviates the testicular toxicity induced by hydroxyurea in male mice

在线全文

学校读者我要写书评

暂无评论

Asian Journal of Andrology 2013年第6期15卷 838-840,I0011页

作者： li Gu Wen-Ting Xiong Chao Wang Hong-Xia Sun Guo-Fu li xin liu Food and Health Engineering Research Center of State Education Ministry Sun Yat-Sen University Guangzhou 510275 China

This study aimed to evaluate testicular toxicity induced by hydroxyurea （HU） and the possible counteracting effect of an aqueous extract of Cistanche deserticola （CD）. HU is an antineoplastic drug that has potential reproductive toxicity, and Herba Cistanche has been used as a tonic for the reproductive system for thousands of years. Sixty mice were randomly divided into five groups. Except mice in normal group, the rest received HU （400 mg kg^-1 body weight） intragastrically. Meanwhile, mice in normal and HU control groups received purified water, and the rest received intragastrically three doses of CD decoctions （1.5, 3.0 and 6.0 g crude drug kg^-1 body weight, respectively） daily for 4 weeks. Severe testes lesions were observed, testes weight （P〈0.01） and serum luteinising hormone levels （P〈0.0 1） were also decreased significantly, in the HU groups. Three doses of CD decoctions alleviated the spermatogenetic cell degeneration induced by HU and modulated the serum sex hormones levels to some extent.

关键词： Cistanche deserticola hormones hydroxyurea semin iferous tubule

Interaction between insulin-like growth factor binding protein-related protein 1 and transforming growth factor beta 1 in primary hepatic stellate cells

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Hepatobiliary & Pancreatic Diseases International 2017年第4期16卷 395-404页

作者： Xiu-Qing li Qian-Qian Zhang Hai-Yan Zhang Xiao-Hong Guo Hui-Qin Fan li-xin liu Department of Gastroenterology and Hepatology The First Clinical Hospital of Shanxi Medical University Experimental Center of Science and Research The First Clinical Hospital of Shanxi Medical University Key Laboratory of Cell Physiology Provincial Department of the Ministry of EducationShanxi Medical UniversityTaiyuan 030001China

BACKGROUND: We previously showed that insulin-like growth factor binding protein-related protein 1 (IGFBPrP1) is a novel mediator in liver fibrosis. Transforming growth factor beta 1 (TGF beta 1) is known as the strongest effector of liver fibrosis. Therefore, we aimed to investigate the detailed interaction between IGFBPrP1 and TGF beta 1 in primary hepatic stellate cells (HSCs). METHODS: We overexpressed TGF beta 1 or IGFBPrP1 and inhibited TGF beta 1 expression in primary HSCs for 6, 12, 24, 48, 72, and 96 hours to investigate their interaction and observe the accompanying expressions of a-smooth muscle actin (alpha-SMA), collagen I, fibronectin, and phosphorylated-mothers against decapentaplegic homolog 2/3 (p-Smad2/3). RESULTS: We found that the adenovirus vector encoding the TGF beta 1 gene (AdTGF beta 1) induced IGFBPrP1 expression while that of alpha-SMA, collagen I, fibronectin, and TGF beta 1 increased gradually. Concomitantly, AdIGFBPrP1 upregulated TGF beta 1, alpha-SMA, collagen I, fibronectin, and p-Smad2/3 in a time-dependent manner while IGFBPrP1 expression was decreased at 96 hours. Inhibition of TGF beta 1 expression reduced the IGFBPrP1-stimulated expression of alpha-SMA, collagen I, fibronectin, and p-Smad2/3. CONCLUSIONS: These findings for the first time suggest the existence of a possible mutually regulation between IGFBPrP1 and TGF beta 1, which likely accelerates liver fibrosis progression. Furthermore, IGFBPrP1 likely participates in liver fibrosis in a TGF beta 1-depedent manner, and may act as an upstream regulatory factor of TGF beta 1 in the Smad pathway.

关键词： insulin-like growth factor binding protein related protein 1 transforming growth factor in primary hepatic stellate cells alpha-smooth muscle actin extracellular matrix Smad pathway

Insulin-like growth factor binding protein-7 induces activation and transdifferentiation of hepatic stellate cells in vitro

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2009年第26期15卷 3246-3253页

作者： li-xin liu Shuai Huang Qian-Qian Zhang Yi liu Dong-Mei Zhang Xiao-Hong Guo De-Wu Han Experimental Center of Science and Research of The First Teaching Hospital of Shanxi Medical University Taiyuan 030001 Shanxi Province China Institute of liver Disease of Shanxi Medical University Taiyuan 030001 Shanxi Province China The First Teaching Hospital of Shanxi Medical University Taiyuan 030001 Shanxi Province China Key Laboratory of Cell Physiology Provincial Department of the Ministry of Education Taiyuan 030001 Shanxi ProvinceChina

AIM:To investigate the role of insulin-like growth factor binding protein-7 (IGFBP-7) in the activation and transdifferentiation of hepatic stellate cells (HSC) in ***:Rat HSC-T6 cells were cultured in separate dishes and treated with various concentration of transforming growth factor (TGF)-β1,IGFBP-7 or antiIGFBP-7 antibody for 24 *** supernatant or a cytoplasm suspension was obtained from cultured HSC,followed by transfer of cells to form cell-coated *** and Western blotting were used to analyze the expression of IGFBP-7 induced by TGF-β1 and the level of fibronectin,collagen and α-smooth muscle actin (SMA).The pro-apoptotic effect of antiIGFBP-7 antibody was determined by flow ***:Immunocytochemistry and Western blotting revealed that the expression of IGFBP-7 in TGF-β1 treated HSC was significantly up-regulated compared to that in the control *** addition,fibronectin,collagen and α-SMA also showed enhanced expression in accordance with the transdifferentiation process in a dose-dependent manner to some ***,flow cytometry suggested that anti-IGFBP-7 antibody induced apoptosis of activated HSC,which is responsible for the development of liver fibrosis,and may represent a novel pathway and target for therapeutic ***:IGFBP-7 showed increased expression in activated HSC and played an important role in the activation and transdifferentiation process of ***-7 antibody may ameliorate liver fibrogenesis.

关键词： Insulin-like growth factor-binding protein-7,Smooth muscle actin Fibronectins Collagen type Ⅰ Hepatic stellate cells

Synthesis of Ultraviolet Absorption Polylactide via Immortal Polymerization of rac-Lactide Initiated by a Salan-yttrium Catalyst

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2018年第2期36卷 202-206页

作者： Wei Zhao Chuan-Yang li Chun-Ji Wu xin-li liu Ze-Huai Mou Chang-Guang Yao Dong-Mei Cui State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Chinese Academy of Sciences Changchun BranchChangchun 130022China College of Bioresources Chemical and Materials Engineering Shaanxi University of Science and TechnologyXi'an 710021China

A highly efficient strategy for the synthesis of polylactide with the UV absorption ability was established by employing a Salan-yttrium complex（acting as a fast runing catalyst） combined with large excess hydroxyl functionalized benzophenone, BP′-OH. During polymerization, BP′-OH, acting as the chain transfer agent, attached to the active rare-earth metal catalyst via a rapid-reversible exchange reaction to initiate the polymerization. Thus, more polyester chains appeared to grow from one active metal species, and the UV absorption fragments were incorporated into the polymer chains at specific sites, in situ. A high productivity up to 1000 mol LA/mol（Salan-Y） was successfully achieved and 100 BP′-labeled PLA chains grew from each active metal center.

关键词： Yttrium catalyst Ring-opening polymerization Polylactide Ultraviolet absorption