检索结果-南通市图书馆

Chinese Journal of Polymer Science 2013年第4期31卷 574-582页

作者： yan-guo li Miao Hong Gui-bao Zhang 李悦生 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences

The ethylene/cyclopentadiene （CPD） copolymerization behavior by using fluoro-substituted bis（fl- enaminoketonato） titanium complexes [FC6H4NC（CH3）CHCO（CF3）]2TiC12 （la-lc） has been investigated in detail. Upon utilizing MMAO as a cocatalyst, complexes la-lc exhibit high catalytic activities, affording the copolymers with high molecular weight and unimodal molecular weight distribution. Compared with non-substituted complex [C6HsNC（CH3）CHCO（CF3）]2TiC12 （1）, complexes la-lc can produce the copolymers with CPD incorporation adjusted in a wide range due to the enhancement of electrophilicity of metal center caused by introducing electron-withdrawing groups. Especially complex lc bearing fluorine at the para-position of N-aryl moiety provides the highest CPD incorporation, which is nearly two times （18.5 mol%） higher than the non-substituted complex 1 （8.9 mol%） under the same conditions. The highest CPD incorporation up to 24.6 mol% can be easily achieved using this complex. 1H-and 13C-NMR spectra demonstrate that these fluoro-substituted complexes possess regioselective nature with exclusive 1,2-insertion fashion, and alternating ethylene-CPD sequence can be detected at high CPD incorporation.

关键词： Ziegler-Natta polymerization Titanium catalyst Cyclopentadiene copolymer.

Use of glycated albumin for the identification of diabetes in subjects from northeast China

在线全文

学校读者我要写书评

暂无评论

World Journal of Diabetes 2021年第2期12卷 149-157页

作者： guo-yan li Hao-Yu li Qiang li Department of Endocrinology and Metabolism The Second Affiliated Hospital of Harbin Medical UniversityHarbin 150080Heilongjiang ProvinceChina Faculty of Population Health Sciences University College LondonLondon WC1E 6BTUnited Kingdom

BACKGROUND Metabolic memory is important for the diagnosis and treatment of diabetes in the early stage,and in maintaining blood glucose concentrations within the normal *** clinical diagnosis of diabetes mellitus is currently made using fasting plasma glucose,2 h-plasma glucose(2h-PG)during a 75 g oral glucose tolerance test,and hemoglobin A1c(HbA1c)***,the fasting plasma glucose test requires fasting,which is a barrier to screening,and reproducibility of the 2h-PG level is ***1c is affected by a shortened red blood cell *** patients with anemia and hemoglobinopathies,the measured HbA1c levels may be *** with HbA1c,glycated albumin(GA)is characterized by more rapid and greater changes,and can be used to diagnose new-onset diabetes especially if urgent early treatment is required,for example in gestational *** this study,we provided cutoff values for GA and evaluated its utility as a screening and diagnostic tool for diabetes in a large high-risk group *** To evaluate the utility of GA in identifying subjects with diabetes in northeast China,and to assess the diagnostic accuracy of the proposed GA cutoff in the diagnosis of diabetes *** This cross-sectional study included 1935 subjects,with suspected diabetes or in high-risk groups,from 2014 to 2015 in the Second Affiliated Hospital of Harbin Medical University(Harbin,China).The use of GA to identify diabetes was investigated using the area under the receiver operating characteristic curve(AUC).The GA cutoffs were derived from different 2h-PG values with hemoglobin A1c cutoffs used as a calibration *** The GA cutoff for the diagnosis of diabetes mellitus was 15.15%from the receiver operating characteristic(ROC)*** analysis demonstrated that GA was an efficient marker for detecting diabetes,with an AUC of 90.3%.CONCLUSION Our study supports the use of GA as a biomarker for the diagnosis of diabetes.

关键词： Glycated albumin Receiver operating characteristic Cut-off Hemoglobin A1c Diagnosis Diabetes mellitus

ETHYLENE POLYMERIZATION AND ETHYLENE/HEXENE COPOLYMERIZAION WITH VANDIUM CATALYSTS BEARING THIOPHENOL-PHOSPHINE liGANDS

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 2013年第6期31卷 885-893页

作者： Sen-wang Zhang yan-guo li ling-pan Lu 李悦生 State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied Chemistry Chinese Academy of Sciences

Vanadium（III） complexes bearing thiophenol-phosphine ligands （2a-2b）（2-R-6-PPh2-C6H2S） VC12（THF）2 （2a： R = H; 2b： R = MeaSi） were prepared from VCla（THF）3 by treating with 1.0 equiv of the ligand in tetrahydrofuran in the presence of excess triethylamine. The two complexes were characterized by FTIR and mass spectra as well as elemental analyses. On activation with Et2AIC1, these complexes exhibited high catalytic activities （up to 22.1 kg PE/（***）） even at high temperature （70 ℃）, and produced high molecular weight polymers with unimodal molecular weight distributions, indicating the polymerization took place in a single-site nature. This result may be attributed to benefits of introduction of second-row donor atoms for adjusting charge density of the vanadium centers. In addition, these complexes also exhibited high catalytic activities for ethylene/1-hexene copolymerization. Catalytic activity, comonomer incorporation and polymer molecular weight can be controlled in a wide range by the variation of catalyst structure and the reaction parameters such as A1/V molar ratio, comonomer feed concentration and polymerization reaction temperature.

关键词： Ziegler-Natta polymerization Vanadium catalyst Polyethylene Copolymerization.

Introduction of Constrained Cyclic Skeleton into β-Enaminoketonato Vanadium Complexes： A Strategy for Stabilization of Active Centre of Vanadium Catalyst for Ethylene Polymerization

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Polymer Science 2017年第9期35卷 1110-1121页

作者： Kai-ti Wang Yong-xia Wang Bin Wang yan-guo li 李悦生 Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences Tianjin Key Lab of Composite & Functional Materials School of Materials Science and EngineeringTianjin University

Several novel mono（β-enaminoketonato） vanadium complexes bearing constrained [（C6Hs）C6H3C（O）=C（CH2）nCH=N-Ar]VCl2（THF）2 （V3a： n = 1, Ar = C6H5; V4a： n = 2, Ar cyclic skeleton, including C6H5; V4b： n = 2, Ar C6F5; V4c： n = 2, Ar = （C3H7）2C6H3; V5a： n = 3, Ar = C6H5）, were synthesized and their structure and properties were characterized. The structures of V4c and V5a in solid-state were further confirmed by X-ray crystallographic analysis. Density functional theory （DFT） results indicated that these complexes showed enhanced steric hindrance around the metal center as compared with the acyclic analogues. Upon activation with Et2AlCl and in the presence of ethyl trichloroacetate as a reactivator, all of the complexes exhibited high catalytic activities （107 gPE/（molv.h）） toward ethylene polymerization, and the obtained polymers exhibited unimodal distributions （Mw/Mn = 2.0-2.3） even produced at elevated temperatures （70-100 ℃） and prolonged reaction time. When MAO was employed as a cocatalyst, they only showed moderate catalytic activities （10^5 gPE/（molv·h））, but the resulting polymers had higher molecular weights （168-241 kg/mol）. These vanadium complexes with cyclic skeleton also showed high catalytic activities toward ethylene/norbornene copolymerization. The produced copolymers displayed approximate alternating structure at high in-feed concentration of norbornene. The catalytic capabilities of these complexes could be tuned conveniently by varying ligand structure. Furthermore, the cyclic voltammetry results also proved that these complexes exhibited better redox stabilities than the complexes bearing linear skeleton.

关键词： Vanadium catalysts Ethylene polymerization Cyclic skeleton Steric protection

Effect of dietary supplementation of pyrroloquinoline quinone disodium on growth performance, meat quality and antioxidative ability of broilers

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2020年第7期19卷 1850-1856页

作者： liU guo-qing SUN Guang-ming liAO Xiu-dong HUANG Jian-zhong guo Mei-jin ZHANG li-yang guo yan-li LU lin LUO Xu-gang Mineral Nutrition Research Division Institute of Animal ScienceChinese Academy of Agricultural SciencesBeiing 100193P.R.China Department of Animal Science Gansu Agricultural UniversityLanzhou 730070P.R.China Fujian Ubaifu Biotechnology Co.Ltd. Fuzhou 350108P.R.China Poultry Mineral Nutrition Laboratory College of Animal Science and TechnologyYangzhou UniversityYangzhou 225000P.R.China

This study was conducted to investigate the effect of dietary supplementation with pyrroloquinoline quinone(PQQ) in the form of PQQ disodium(PQQ·Na2) on the growth performance, carcass traits, meat quality and antioxidative ability of broilers. A total of 720 one-d-old Arbor Acres male broilers were randomly allocated to 1 of 6 treatments with 8 replicates of 15 birds per replicate in a completely randomized design. Birds were fed a PQQ·Na2-unsupplemented corn-soybean meal basal diet(control) or the basal diet supplemented with 0.1, 0.2, 0.3, 0.4 or 0.5 mg PQQ·Na2 kg-1 for 42 d. Compared with the control chicks, the chicks fed the diets supplemented with PQQ·Na2 had lower(Pliver T-AOC on d 21 and heart T-AOC on d 21 and 42 increased linearly(Pliver and heart on d 21 or 42 decreased linearly(Plity and meat quality of broilers, and in general, it is implied that the optimal supplemental PQQ·Na2 level is 0.1 mg kg-1 of diet for broilers from 1 to 42 d of age.

关键词： antioxidation broiler growth performance meat quality pyrroloquinoline quinone disodium

A NOVEL SUPER-RESOLUTION BEAMFORMING ALGORITHM

在线全文

学校读者我要写书评

暂无评论

Journal of Electronics(China) 2007年第3期24卷 406-411页

作者： guo li guo yan li Ning School of Information Engineering Beijing University of Posts and Telecommunications Beijing 100876 China Institute of Science PLA University of Science and Technology Nanjing 210007 China

A novel simply-structured hybrid smart antenna system suitable to be used in ad-hoc network terminals is proposed in this letter. The super-resolution beamforming algorithm is also pre-sented based on the system using DOA estimation results. The algorithm can switch the beamforming to the direction of the expected signal and get the best transmitting performance after the pre-beamforming of the Butler matrix. The shifting value formulas are presented to obtain the best SNR when there is no interfering signal and to acquire the highest Signal to Interference Ratio (SIR) as there is one interfering signal. When there are more than one interfering signals,the pre-beamforming feature of the Butler matrix can also suppress the interfering signals. Simulation results verified the algorithm.

关键词： Smart antennas Beamforming Direction-Of-Arrival (DOA) Iteration method

Comparison on wear resistance of nanostructured bainitic bearing steel with and without residual cementite

在线全文

学校读者我要写书评

暂无评论

Journal of Iron and Steel Research International 2022年第2期29卷 339-349页

作者： Yu-man Qin Chang-bo liu Chun-sheng Zhang Xu-biao Wang Xiao-yan Long yan-guo li Zhi-nan yang Fu-cheng Zhang State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao066004HebeiChina National Engineering Research Center for Equipment and Technology of Cold Rolled Strip Yanshan UniversityQinhuangdao066004HebeiChina

The sliding wear property of high-carbon nanostructured bainitic bearing steel with the equal initial hardness and different microstructures was investigated,and the reasons for the difference of wear resistance between the cementite-bearing(CB)and cementite-free(CF)specimens were *** results show that CF specimens have lower mass loss and surface roughness and shallower wear depth than CB specimens during wear *** with CB specimen,CF specimen presents superior wear *** is due to two reasons:(1)a lot of retained austenite in CF specimen is easy to produce TRIP effect and be transformed into martensite during wear process,which notably increased the surface hardness of worn specimen;(2)there is a nondestructive oxide layer in the surface of cementite-free worn specimen,which can protect the surface of worn specimen from *** the combined effect of retained austenite and oxide layer,the loss of matrix is ***,CF specimen exhibits high wear *** reveals that the wear mechanism of high-carbon nanostructured bainitic bearing steel with different microstructures can provide a reference for improving the wear resistance in high-carbon nanostructured bainitic bearing steel in future.

关键词： Cementite Nanostructured bainite Bearing steel Microstructure Wear resistance

Effects of 24-Epibrassinolide on Antioxidant System in Cucumber Seedling Roots Under Hypoxia Stress

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

Agricultural Sciences in China 2007年第3期6卷 281-289页

作者： KANG Yun-yan guo Shi-rong li Juan DUAN Jiu-ju College of Horticulture Nanjing Agricultural University Nanjing 210095 P.R.China

This article aims to study the effects of exogenous 24-epibrassinolide （EBR） on the changes in ROS, activities of antioxidative enzymes and antioxidants in cucumber （Cucumis sativus L.） seedling roots under hypoxia stress. Seedlings of a hypoxiaresistant cultivar, Lühachun 4, and a hypoxia-sensitive cultivar, Zhongnong 8, were hydroponically grown for 8 d in normoxic or hypoxic nutrient solutions that were added or not added with 10^-3 mg L^-1 EBR. Under hypoxia stress, the ROS levels and the lipid peroxidation were significantly increased in the roots upon exposure to hypoxia stress, which were inhibited by EBR application. The EBR treatment significantly increased the seedlings growth and SOD, APX, GR activities, and contents of AsA and GSH under hypoxia stress. From the results obtained in this study, it can be concluded that oxidative damage on seedling roots by hypoxia stress can be considerably alleviated and the tolerance of plants was elevated.

关键词： cucumber (Cucumis sativus L.) 24-epibrassinolide seedlings hypoxia stress antioxidative system lipid peroxidation

Manganese enhances the expression of the manganese superoxide dismutase in cultured primary chick embryonic myocardial cells

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Agriculture 2017年第9期16卷 2038-2046页

作者： QIN Shi-zhen liAO Xiu-dong LU lin ZHANG li-yang XI lin guo yan-li LUO Xu-gang Mineral Nutrition Research Division Institute of Animal SciencesChinese Academy of Agricultural Sciences College of Animal Science and Technology Gansu Agricultural University Department of Animal Science North Carolina State University

In the present study, the effect of manganese（Mn） on antioxidant status and the expression of the manganese superoxide dismutase（MnSOD） gene in cultured primary myocardial cells collected from the chick embryos was investigated. The hypothesis that Mn supplementation would enhance the expression of MnSOD in cultured primary myocardial cells of chick embryos was tested. Eggs collected from Mn-depleted Arbor Acres laying breeder hens were incubated for 10 days and then myocardial cells were isolated and cultivated for 8 days. The embryonic myocardial cells on day 6 were treated with Mn in the cell culture medium at different time points when the proportion of cells showing spontaneous contraction was over 95% after the 3-day primary culture. A completely randomized design involving a 3 Mn levels（0, 0.5 and 1.0 mmol L^（-1））×3 incubation time points（12, 24 and 48 h） factorial arrangement of treatments（n=6） was used in the current experiment. The results showed that MnSOD activity and m RNA expression level were induced by Mn and increased with incubation time, which supported the hypothesis that Mn would enhance the expression of the MnSOD gene, and thus might protect myocardial cells from oxidative stress during the chick embryonic development.

关键词： manganese MnSOD expressions cultured primary myocardial cells chick embryos

Recent Advances and Applications in Paper-Based Devices for Point-of-Care Testing

在线全文

学校读者我要写书评

暂无评论

Journal of Analysis and Testing 2022年第3期6卷 247-273页

作者： Yue Hou Cong-Cong Lv yan-li guo Xiao-Hu Ma Wei liu yan Jin Bao-Xin li Min yang Shi-Yin Yao Key Laboratory of Analytical Chemistry for life Science of Shaanxi Province School of Chemistry and Chemical EngineeringShaanxi Normal UniversityXi’an 710062China

Point-of-care testing(POCT),as a portable and user-friendly technology,can obtain accurate test results immediately at the sampling ***,microfluidic paper-based analysis devices(μPads)have attracted the eye of the public and accelerated the development of POCT.A variety of detection methods are combined withμPads to realize precise,rapid and sensitive *** article mainly introduced the development of electrochemistry and optical detection methods onμPads for POCT and their applications on disease analysis,environmental monitoring and food control in the past 5 ***,the challenges and future development prospects ofμPads for POCT were discussed.

关键词： Paper-based analysis device Point-of-care testing Detection methods Review