检索结果-南通市图书馆

Depolymerization of Poly(bisphenol A carbonate) in Subcritical and Supercritical Toluene

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第4期17卷 545-548页

作者： Zhi Yan PAN Zhen BAO ying xu chen Department of Environmental Engineering Zhejiang University Hangzhou 310027 College of Biological and Environmental Engineering Zhejiang University of Technology Hangzhou 310032

The depolymerization of poly（bisphenol A carbonate）（PC） in subcritical and supercritical toluene was studied. The experimental parameters, which influence the depolymerization reaction such as temperature （570-633 K）, pressure （4.0-7.0 MPa）, reaction time （5-60 min）, and toluene to PC weight ratio （3.0-11.0）, were investigated, and the reaction products were determined by CrC, GC/MS and FT-IR spectrometer. It was found that the main product of the depolymerization reaction was bisphenol A（BPA）. BPA accounted for over 55.7% of the depolymerization products at reaction temperature 613 K, pressure 5.0-6.0 MPa, reaction time 15 min and toluene/PC weight ratio of around 7.0.

关键词： Depolymerization poly(bisphenol A carbonate) supercritical toluene.

Effects of 60-day NO_2 fumigation on growth,oxidative stress and antioxidative response in Cinnamomum camphora seedlings

在线全文

学校读者我要写书评

暂无评论

Journal of Zhejiang University-Science B(Biomedicine & Biotechnology) 2010年第3期11卷 190-199页

作者： Zhuo-mei chen ying-xu chen Guo-jian DU Xi-lin WU Feng LI College of Environmental and Resource Sciences Zhejiang University Hangzhou 310029 China Zhejiang Forestry Academy Hangzhou 310023 China Department of Geography Minjiang University Fuzhou 350108 China

Objective： To study the oxidative stress and antioxidative response of Cinnamomum camphora seedlings exposed to nitrogen dioxide （NO2） fumigation. Methods： Measurements were made up of the growth, chlorophyll content, chlorophyll fluorescence, antioxidant system and lipid peroxidation of one-year-old C. camphora seedlings exposed to NO2 （0.1, 0.5, and 4 μl/L） fumigation in open top chambers over a period of 60 d. Results： After the first 30 d, 0.5 and 4.0 μl/L NO2 showed insignificant effects on the growth of C. camphora seedlings. However, exposure to 0.5 and 4.0 pilL NO2 for 15 d significantly reduced their chlorophyll content （P〈0.05）, enhanced their malondialdehyde （MDA） content and superoxide dismutase （SOD） activity （P〈0.05）, and also significantly reduced the maximal quantum yield of PSII in the dark [the ratio of variable fluorescence to maximal fluorescence （Fv/Fm）] （P〈0.05）. In the latter 30 d, 0.5μl/L NO2 showed a positive effect on the vitality of the seedlings, which was reflected by a recovery in the ratio of Fv/Fm and chlorophyll content, and obviously enhanced growth, SOD activity, ascorbate （AsA） content and glutathione reductase （GR） activity （P〈0.05）; 4.0 pilL NO2 then showed a negative effect, indicated by significant reductions in chlorophyll content and the ratio of Fv/Fm, and inhibited growth （P〈0.05）. Conclusion： The results suggest adaptation of C. camphora seedlings to 60-d exposure to 0.1 and 0.5 μl/L NO2, but not to 60-d exposure to 4.0 pilL NO2 C. camphora seedlings may protect themselves from injury by strengthening their antioxidant system in response to NO2-induced oxidative stress.

关键词： Cinnamomum camphora Fumigation Growth Chlorophyll content Chlorophyll fluorescence Antioxidant Lipid peroxidation

Protein Changes in Response to Pyrene Stress in Maize （Zea mays L.） Leaves

在线全文

学校读者我要写书评

暂无评论

Journal of Integrative Plant Biology 2007年第2期49卷 187-195页

作者： Sheng-You xu ying-xu chen Wei-Xiang Wu Shao-Jian Zheng Sheng-Guo xue Shi-ying Yang Yi-Jin Peng Department of Environmental Engineering Zhejiang University Hangzhou 310029 China Department of Resource and Environment Huangshan University Huangshan 245000 China College of Environmental Science and Engineering Ocean University of China Qingdao 266003 China

Phytoremedlation is a relatively new approach to remove polycyclic aromatic hydrocarbons （PAHs） from the environment. When plants are grown under pyrene treatment, they respond by synthesizing a set of protective proteins. To learn more about protein changes in response to pyrene treatment, we extracted total proteins from the leaves of maize （Zea mays L.） 1 week after pyrene treatment. The proteins extracted were separated with twodimensional gel electrophoresis. In total, approximately 54 protein spots were found by comparing gels from treated and control groups. According to the Isoelectric point, molecular weight, and abundance of these protein spots, 20 pyrene-lnduced proteins were found to have changed abundance. Of these, 15 protein spots were Increased and five protein spots were newly appeared in pyrene-treated plant leaves. Six model upregulated protein spots of different molecular weights were excised from the gels and subjected to trypsin digestion followed by peptide separation using matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Peptlde masses were used to search the matrix-science database for protein Identification. Two of the proteins were Identified on the basis of the homology of their peptide profiles with existing protein sequences as pyruvate orthophosphate diklnase and the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunlt. These proteins are Involved in the regulation of carbohydrate and energy metabolism. The present study gives new Insights into the pyrene stress response In maize leaves and demonstrates the power of the proteomlc approach in phytoremedlation of PAHs.

关键词： maize mass spectrometry proteomic pyrene stress.

Interaction of Photoactive[Fe(CN)_6]^(4-) with TiO_2 Anatase(101) Surface:A Periodic Density Functional Theory Study

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 Structural Chemistry 2007年第3期26卷 361-366页

作者： xu ying chen Wen-Kai CAO Mei-Juan LIU Shu-Hong LI Jun-Qian Department of Chemistry Fuzhou University Fuzhou Fujian 350002 China

The plane-wave pseudopotential function method, based on density-functional theory, has been used to calculate the adsorption, electronic band structures, orbitals and optical absorption spectrum of [Fe（CN）6]^4- on TiOz anatase（101） surface. Our calculations reveal that the surface-modified anatase system has large adsorption energy and a much narrower band gap. [Fe（CN）6]^4- adsorption on the （101） surface could lead to a large red shift of the anatase optical absorption threshold, which extends into a visible region significantly. The calculated results are in agreement with the experiment and other theoretical studies reasonably. It is very important for the understanding and further development ofphotovoltaic materials that are active under visible light.

关键词： density functional theory (DFT) [Fe(CN)6]^4- anatase(101) surface adsorption absorption

Synthesis and Cytotoxic Activity of Novel Water-soluble Prodrugs of Combretastatin A-4

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2006年第1期17卷 23-26页

作者： Zhi Quart YONG Xiao Ping xu ying Chun chen xu BAO Ling Ling WENG Hu ZHENG Department of Medicinal Chemistry West China School of Pharmacy Sichuan University Chengdu 610041

Novel water-soluble prodrugs of combretastatin A-4 （5-8） were synthesized and evaluated for their in vitro cytotoxicity against lung carcinoma A549. Compound 5, bearing phosphoryl choline （PC） moiety, showed 90% inhibition at 32 ktg/mL concentration after 24 h. The findings showed the PC derivative would be a promising candidate for the development of new water-soluble prodrug of cytotoxic combretastatin A-4,

关键词： Combretastafin A-4 cytotoxicity phosphoryl choline water-soluble prodrug.

Timing and Spectral Analysis of the Black Hole X-Ray Binary MAXI J1803-298 with Insight-HXMT Data

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第6期24卷 209-224页

作者： ying-chen xu Jin-Lu Qu MMéndez Rui-Can Ma Long Ji Liang Zhang Yue Huang Qing-Cui Bu Li-Ming Song Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsChinese Academy of SciencesBeijing 100049China University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China Kapteyn Astronomical Institute University of GroningenP.O.BOX 8009700 AV GroningenThe Netherlands Dongguan Neutron Science Center Dongguan 523808China School of Physics and Astronomy Sun Yat-Sen UniversityZhuhai 519082China Institut für Astronomie und Astrophysik Kepler Center for Astro and Particle PhysicsEberhard Karls UniversitätSand 1D-72076 TübingenGermany

We present a comprehensive analysis of the 2021 outburst of MAXI J1803–298 utilizing observations of the Insight-Hard X-ray Modulation Telescope(Insight-HXMT)spanning from the low hard state to the high soft *** the Insight-HXMT data set,compared to the previous work,we identify a more prolonged presence of typeC quasi-periodic oscillations(QPOs)with centroid frequencies ranging from~0.16 to 6.3 Hz,which present correlations with the hardness ratio and the photon index of the Comptonized *** QPO frequencies less than~2 Hz,the QPO phase lags are hard(photons of 10–19 keV arrive later than those of 1–4 keV),while at higher frequencies,the lags become soft at and above~4 ***,the spectra in all Insight-HXMT observations consist of a multi-color blackbody component and a Comptonized component,as commonly observed in classical black hole X-ray *** analyze state transitions and the evolution of accretion geometry in this *** fitted inner disk radius increases abnormally during the low hard state,hypothesized to result from the corona condensing onto the inner ***,two significant drops in flux are observed during the soft intermediate state,maybe implying changes in the corona/jet and the disk,respectively.

关键词： X-rays:binaries accretion accretion disks stars:black holes

Observation of topological charge transformations in acoustic vortex using passive periodic systems

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & Astronomy) 2025年第1期Mechanics & Astronomy) .卷 140-147页

作者： Di-Chao chen Xie Liu Changqing xu Da-Jian Wu ying cheng Xiao-Jun Liu School of Physics and Technology Nanjing Normal University Key Laboratory of Modern Acoustics School of Physics Nanjing University

Vortex transmutation utilizes a periodic system, which not only enables the alteration of the topological charge(TC) of unstable input vortices but also facilitates their transformation into stable structures. This approach is crucial for investigating the characteristics of vortices in various wave systems. Here, we achieve acoustic vortex TC transmutation by employing a welldesigned dual-structured plate external system(DPES). The interactions between the acoustic vortex and the finite-order discrete rotational symmetry lead to the transformation of its topological charge when complete rotational symmetry is broken to Nthorder discrete symmetry. Our results experimentally demonstrate the acoustic vortex TC transmutation based on passive artificial structures, enabling numerous applications in particle manipulation and information multiplexing as well as advancing our understanding and control over free-space acoustic vortices.

关键词： acoustic vortex topological charge transformation artificial structure

Seismic Zonation of Central-Southern Hunan Province, China

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Earthquake Research in China 2007年第4期21卷 379-387页

作者： Li ying xu Guangyin chen Kun Gao Mengtan Institute of Geophysics China Earthquake Administration Beijing 100081 China

Based on basic data used in compiling the Zonation Map of Earthquake Ground Motion Parameters in China, recent research on seismic safety assessment for engineering sites in central-southern Hunan Province, the new attenuation relationships of moderate earthquakes and the background seismicity data obtained by modern instrumental earthquake records since 1970, a new result of seismic zonation of central-southern Hunan Province is provided. The result shows that the area with PGA=0.05g has obviously increased in the new map compared with the previous one and is relatively consistent with the seismic disaster characteristics of moderate earthquakes that took place in the central-southern part of Hunan in recent years. This result will benefit the research and compilation of a new-generation seismic zonation map of earthquake ground motion parameters and the seismic hazard assessment in the moderate earthquake active regions in the central and eastern part of China.

关键词： Background earthquake Moderate earthquake Attenuation relationship Seismiczonation

Temporal and Spectral Characteristics of Persistent Emission and Special Bursts of Magnetar SGR J1935+2154 Based on Insight-HXMT

在线全文

学校读者我要写书评

暂无评论

Research in Astronomy and Astrophysics 2024年第6期24卷 225-233页

作者： xue-Feng Lu Li-Ming Song Ming-Yu Ge Shuang-Nan Zhang Jin-Lu Qu Ce Cai Cong-Zhan Liu cheng-Kui Li Yu-Cong Fu ying-chen xu Key Laboratory of Particle Astrophysics Institute of High Energy PhysicsBeijing 100049China University of Chinese Academy of Sciences Chinese Academy of SciencesBeijing 100049China College of Physics and Hebei Key Laboratory of Photophysics Research and Application Hebei Normal UniversityShijiazhuang 050024China Department of Astronomy Beijing Normal UniversityBeijing 100875China

In October 2022,the magnetar SGR J1935+2154 entered the active outburst *** the episode,the InsightHXMT satellite carried out a long observation that lasted for 20 *** than 300 bursts were detected,and a certain amount of persistent radiation signals were also *** paper mainly introduces the results of persistent radiation profile folding and period search based on Insight-HXMT *** the same time,the burst phase distribution characteristics,spectral lag results of burst,the spectral characteristics of zero-lag bursts and the time-resolved spectral evolution characteristics of high-flux bursts are *** found that there is no significant delay feature during different energy bands for the bursts of SGR J1935+*** observed zero-lag burst does not have a unique *** time-resolved spectrum of the individual burst has consistent spectral types and spectral parameters at different time periods of the *** also find that the burst number phase distribution and the burst photon phase distribution have the same tendency to concentrate in specific regions of the persistent emission profile.

关键词： radiation mechanisms:general dense matter magnetic fields