检索结果-南通市图书馆

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

固体核磁共振技术在高分子表征研究中的应用

高分子学报 2021年第7期52卷 840-856页

作者：王粉粉孙平川南开大学功能高分子材料教育部重点实验室化学学院

基于核自旋探针的核磁共振(NMR)波谱技术可以在非常宽广的时间和空间尺度上提供重要的微观结构和动力学信息.固体NMR已成为阐明高分子中化学键变化、链间相互作用、多尺度结构与动力学演化,及其与宏观物理化学性质关系的有力工具.本文... 详细信息

基于核自旋探针的核磁共振(NMR)波谱技术可以在非常宽广的时间和空间尺度上提供重要的微观结构和动力学信息.固体NMR已成为阐明高分子中化学键变化、链间相互作用、多尺度结构与动力学演化,及其与宏观物理化学性质关系的有力工具.本文从基础原理、实验方法与技巧、典型应用与研究进展等几方面进行简要综述.在基础原理部分介绍了化学位移各向异性和偶极相互作用等检测不同尺度信息的核自旋相互作用及其实验调控方法,魔角旋转、交叉极化和多脉冲去耦等高分辨技术,以及自旋扩散测定相区结构及复杂分子运动检测方法的原理等;在实验方法与技巧上,着重仪器精确校准、关键脉冲参数设置及仪器背景信号压制等;典型应用将聚焦于天然高分子及其复合材料的结构-性能关系、水与生物大分子间相互作用、多相高分子材料的微相分离结构、高分子中氢键相互作用和导电高分子材料等问题,介绍了固体NMR技术在上述领域的最新应用与进展.

关键词：固体核磁共振高分子微观结构动力学结构与性能

New monoterpene phenyl ethers from Illicium micranthum

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Natural Products and Bioprospecting 2013年第2期3卷 43-47页

作者： Zheng-Ye GUAN Chuan-Fu DONG a Li GAO Jia-Ping wang Shi-De LUO Yi-fen wang State Key Laboratory of Phytochemistry and Plant Resources in West China Kunming Institute of BotanyChinese Academy of SciencesKunming 650201China University of Chinese Academy of Sciences Beijing 100049China

Seven new monoterpene phenyl ethers,namely micranthumnins A-G(1-7),were isolated from the stem bark of Illicium micranthum(Illiciaceae).Their structures were elucidated by comprehensive spectroscopic analyses includin... 详细信息

关键词： Illicium micranthum monoterpene phenyl ethers micranthumnins anti-AChE activities

A method and results of color calibration for the Chang'e-3 terrain camera and panoramic camera

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2014年第12期14卷 1557-1566页

作者： Xin Ren Chun-Lai Li Jian-Jun Liu fen-Fei wang Jian-feng Yang En-Hai Liu Bin Xue Ru-Jin Zhao Key Laboratory of Lunar and Deep Space Exploration National Astronomical ObservatoriesChinese Academy of Sciences Xi’an Institute of Optics and Precision Mechanics Chinese Academy of Sciences Institute of Optics and Electronics Chinese Academy of Sciences

The terrain camera （TCAM） and panoramic camera （PCAM） are two of the major scientific payloads installed on the lander and rover of the Chang＇e 3 mission re- spectively. They both use a Bayer color filter array covering CMOS sensor to capture color images of the Moon＇s surface. RGB values of the original images are related to these two kinds of cameras. There is an obvious color difference compared with human visual perception. This paper follows standards published by the International Commission on Illumination to establish a color correction model, designs the ground calibration experiment and obtains the color correction coefficient. The image qual- ity has been significantly improved and there is no obvious color difference in the corrected images. Ground experimental results show that：（1） Compared with uncor- rected images, the average color difference of TCAM is 4.30, which has been reduced by 62.1%. （2） The average color differences of the left and right cameras in PCAM are 4.14 and 4.16, which have been reduced by 68.3% and 67.6% respectively.

关键词： Moon -- methods: data analysis -- techniques: image processing

Al-Ti-TiO_2-Nb_2O_5系的热扩散法合成及热力学计算

在线全文

学校读者我要写书评

暂无评论

特种铸造及有色合金 2006年第12期26卷 822-823,824页

作者：艾桃桃王芬陕西科技大学

对Al-Ti-TiO2-Nb2O5系用热扩散反应法合成了钛铝基复合材料，利用差热分析（DTA）与热力学计算表征了体系的反应过程。结果表明，铝熔化后在721℃发生了Al-Ti及Al-TiO2间的反应，后者反应速度快。在721-810℃之间发生了Al-Nb2O5间的复... 详细信息

对Al-Ti-TiO2-Nb2O5系用热扩散反应法合成了钛铝基复合材料，利用差热分析（DTA）与热力学计算表征了体系的反应过程。结果表明，铝熔化后在721℃发生了Al-Ti及Al-TiO2间的反应，后者反应速度快。在721-810℃之间发生了Al-Nb2O5间的复杂分步反应。在810℃发生了由固相原子扩散控制的TiAl3→TiAl→Ti3Al的渐进反应过程。基于体系的放热反应，大量热能促进了整个系统的反应进程。热力学计算验证了TiAl3作为初生相先于TiAl和Ti3Al相生成。Nb2O5与Al的反应以生成NbAl3相。获得了γ＋α2双相片层组织，处于稳定状态的增强相Al2O3分布于基体界面。

关键词：差热分析热力学计算复合材料

106 New Emission-line Galaxies and 29 New Galactic HⅡ Regions are Identified with Spectra in the Unknown Data Set of LAMOST DR7

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2022年第6期22卷 170-182页

作者： Yan Lu A-Li Luo Li-Li wang You-fen wang Yin-Bi Li Jin-Shu Han Li Qin Yan-Ke Tang Bo Qiu Shuo Zhang Jian-Nan Zhang Yong-Heng Zhao CAS Key Laboratory of Optical Astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China College of Computer and Information Engineering&Institute for Astronomical Science Dezhou UniversityDezhou 253023China University of Chinese Academy of Science Beijing 100049China College of Physics and Electronic Information Dezhou UniversityDezhou 253023China School of Electronic Information Engineering Hebei University of TechnologyTianjin 300401China Department of Astronomy School of PhysicsPeking UniversityBeijing 100871China Kavli institute of Astronomy and Astrophysics Peking UniversityBeijing 100871China

This work is to retrieve emission-line spectra from the“Unknown”data set in LAMOST DR7 V1.2,most of which are low signal-to-noise ratios *** the work,we perform emission line search and redshift calculations on the Unknown data set to get possible emission line galaxy *** the galaxy spectra released by LAMOST as templates,the Product Quantization(PQ)based approximate nearest neighbor(ANN)search is used to retrieve the nearest neighbors of each *** keep the spectra for which the calculated redshift and the published redshift of the template meet the threshold,and 16,188 spectra with emission lines are obtained from the LAMOST DR7 Unknown data *** visual inspection of spectra 10,266 spectra are left,in which 5828 spectra are identified as emission-line galaxies,1782 spectra show ionization nebula features,and other 2656 are not clearly *** 5828 spectra,5720 can be found in Strasbourg astronomical Data Center catalog,Sloan Digital Sky Survey catalog,or NASA/IPAC Extragalactic Database *** 108 spectra(corresponding to 106unique coordinates of *** decl.)which have no record in these three databases are new discoveries;for the1782 spectra showing ionization nebula features,most of them have radial velocities less than 150 kilometers per *** check them with the latest version of WISE HⅡcatalog V2.0(short for HIICat V2)and 985 out of the1782 spectra belong to 72 HⅡ*** these HⅡregions,43 were previously identified while the other 29 are newly identified in this work including 797 newly observed ***,there are still 2656 spectra that cannot be clearly classified although they have obvious emission lines and with small ***,106 new emissionline galaxies and 29 new Galactic HⅡregions are identified,and we conclude that the ANN method sped up by the PQ algorithm is efficient in solving the problem of pairing spectra with massive data set to figure out their *** present our result

关键词： techniques spectroscopic-Galaxies-(ISM:)HⅡregions

Survival and prognostic factors in hepatitis B virus-related acute-on-chronic liver failure

在线全文

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2011年第29期17卷 3448-3452页

作者： Kun Huang Jin-Hua Hu Hui-fen wang Wei-Ping He Jing Chen XueZhang Duan Ai-Min Zhang Xiao-Yan Liu Liver Failure Treatment and Research Center 302 Military HospitalPeking University Health Science CenterBeijing 100191China Liver Failure Treatment and Research Center 302 Military HospitalBeijing 100039China

AIM:To investigate the survival rates and prognostic factors in patients with hepatitis B virus-related acuteon-chronic liver failure(HBV-ACLF).METHODS:Clinical data in hospitalized patients with HBV-ACLF admitted from 2006 to 2009 were retrospectively *** general conditions and survival were analyzed by survival analysis and Cox regression ***:A total of 190 patients were included in this *** overall 1-year survival rate was 57.6%.Patients not treated with antiviral drugs had a significantly higher mortality[relative risk(RR)=0.609,P=0.014].The highest risk of death in patients with ACLF was associated with hepatorenal syndrome(HRS)(RR=2.084,P=0.026),while other significant factors were electrolyte disturbances(RR=2.062,P=0.010),and hepatic encephalopathy(HE)(RR=1.879,P<0.001).CONCLUSION:Antiviral therapy has a strong effect on the prognosis of the patients with HBV-ACLF by improving their 1-year survival ***,electrolyte disturbances,and HE also affect patient survival.

关键词： Hepatitis B virus Acute-on-chronic liver failure Antiviral therapy Nucleosides Survival analysis

Comparative genomic study of gastric epithelial cells co-cultured with Helicobacter pylori

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

World Journal of Gastroenterology 2012年第48期18卷 7212-7224页

作者： fen wang Li-Dan Luo Jian-Hua Pan Li-Hua Huang Hong-Wei Lv Qin Guo Can-Xia Xu Shou-Rong Shen Department of Gastroenterology The Third Xiangya HospitalCentral South University Department of Gastroenterology Hunan Provincial Hospital

AIM:To identify genes potentially involved in Helicobacter pylori(***)-induced gastric ***:GES-1 cells were co-cultured with *** strains isolated from patients with gastric carcinoma(GC,n = 10) or chronic gastritis(CG,n = 10) for in vitro proliferation and apoptosis assays to identify the most and least virulent *** two strains were cagA-genotyped and used for further in vivo carcinogenic virulence assays by infecting Mongolian gerbils for 52 wk,respectively;a broth free of *** was lavaged as *** profiles of GES-1 cells cocultured with the most and least virulent strains were determined by microarray *** most differentially expressed genes were further verified using quantitative real-time polymerase chain reaction in GES-1cells infected with the most and least virulent strains,and by immunohistochemistry in *** positive CG,precancerous diseases,and GC biopsy specimens in an independent ***:GC-derived *** strains induced a potent proliferative effect in GES-1 cells in co-culture,whereas CG-derived strains did *** most(from a GC patient) and least(from a CG patient) virulent strains were cagA-positive and negative,*** week 52,CG,atrophy,metaplasia,dysplasia,and GC were observed in 90.0%,80.0%,80.0%,90%,and 60.0%,respectively,of the animals lavaged with the most virulent ***,only mild CG was observed in 90% of the animals lavaged with the least virulent *** microarray analysis,800 differentially expressed genes(49 up-and 751 down-regulated),involving those associated with cell cycle regulation,cell apoptosis,cytoskeleton,immune response,and substance and energy metabolisms,were identified in cells co-cultured with the most virulent strain as compared with those co-cultured with the least virulent *** six most differentially expressed genes(with a betweenness centrality of 0.1-0.2) were identified among the significant differential gene prof

关键词： Helicobacter pylori Gastric carcinoma Proliferation Genomic profiles

稀释剂对Al_2O_(3(f))/Ti-Al原位复合材料纤维相的影响

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

粉末冶金技术 2007年第6期25卷 407-411页

作者：王芬李萌陕西科技大学材料科学与工程学院西安710021

以Ti、Al、TiO2及Al2O3为原料,制成预制体,通过石墨与Al2O3混合粉对预制体的覆埋实现气氛保护并进行热处理,使其原位合成Al2O3纤维增强Ti-Al金属间化合物复合材料。考察了Al2O3对材料断口形貌组织、物相成分的影响,并结合DTA进行了热力... 详细信息

以Ti、Al、TiO2及Al2O3为原料,制成预制体,通过石墨与Al2O3混合粉对预制体的覆埋实现气氛保护并进行热处理,使其原位合成Al2O3纤维增强Ti-Al金属间化合物复合材料。考察了Al2O3对材料断口形貌组织、物相成分的影响,并结合DTA进行了热力学分析。XRD表明,外加Al2O3后材料氮化严重,主晶相由Al3Ti变为AlN。SEM表明,材料基体周围分布大量纤维,稀释剂Al2O3的加入有利于纤维的生长及分布。

关键词： Al2O3纤维 Ti—Al金属间化合物稀释剂

在线全文

学校读者我要写书评

暂无评论

污泥超声破解预处理的影响因素分析

天津大学学报（自然科学与工程技术版） 2005年第7期38卷 649-653页

作者：王芬季民天津大学环境科学与工程学院天津300072

通过投加自由基消除剂NaHCO3屏蔽自由基氧化作用的方法,研究了超声破解污泥的主要途径以及各途径对超声破解污泥的贡献.根据超声破解污泥的动力学模型,得出了各因素对超声破解污泥的影响程度.结果发现,声能密度为0.096W/mL时,超声破解... 详细信息

通过投加自由基消除剂NaHCO3屏蔽自由基氧化作用的方法,研究了超声破解污泥的主要途径以及各途径对超声破解污泥的贡献.根据超声破解污泥的动力学模型,得出了各因素对超声破解污泥的影响程度.结果发现,声能密度为0.096W/mL时,超声破解污泥的主要作用力是水力剪切力,羟基氧化几乎不起作用;声能密度为0.384W/mL时,水力剪切力与自由基氧化在超声破解污泥反应中所占的比例分别为80.850/0与19.150/0;声能密度为0.72W/mL时,水力剪切力与自由基氧化在超声破解污泥反应中所占的比例分别为74.140/0与25.860/0.所以,超声破解污泥的主要作用途径是水力剪切力的机械作用.由溶解性化学需氧量(SCOD)增加值为因变量的动力学模型可知,在各影响因素中,pH值对超声破解污泥的效果影响最大.

关键词：超声波剩余污泥碳酸氢钠动力学模型