Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 colu...Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 columns. The structures were elucidated by spectral analysis. Results Thirteen compounds were isolated and their structures were identified as （-）-syringaresinol （1）, syringaresinol-4-O-β-D-glucopyranoside （2）, syringaresinol-4,4′-bis-O-β-D-glucopyranoside （3）, （±）-catechin （4）, catechin-3-O- β-D-glucopyranoside （5）, catechin-5-O-β-D-glucopyranoside （6）, 1,3-bis-（4-hydroxy-3,5-dimethoxyphenyl）-1,3-propanediol （7）, （R）-（＋）-chaulmoogric acid （8）, friedelin （9）, uracile （10）, benzoic acid （11）, vaniUic acid （12）, and 4-hydroxybenzoic acid （13）. Conclusion All the compounds described above were isolated from this genus for the first time.展开更多
The atmospheric corrosion behavior of pure copper exposed for three years in Turpan, China, which is a typical hot and dry atmosphere environment, was investigated using mass-loss tests, morphology observations, com...The atmospheric corrosion behavior of pure copper exposed for three years in Turpan, China, which is a typical hot and dry atmosphere environment, was investigated using mass-loss tests, morphology observations, composition analyses, and electrochemical techniques. The results indicated that the annual corrosion rate of pure copper was approximately 2.90 μm/a. An uneven distribution of corrosion products was observed by scanning electron microscopy; this uneven distribution was attributed to the dehydration process during wet–dry and cold–hot cycles, and the compositions mainly consisted of cuprite （Cu2O） and atacamite （Cu2Cl（OH）3）. Electrochemical measurements showed that deposits on copper improved its resistance to corrosion and the protectiveness decreased with increasing temperature. On the other hand, results obtained using the scanning vibrating electrode technique showed that the porous and uneven structure of the deposit layer generated a spatial separation of cathodic and anodic reaction sites, which accelerated the corrosion process in wet and rainy weather.展开更多
Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that gr...Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that group seperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solvents. The results show that CS2 was effective for extracting arenes from the coal sample, n-Hexane extractable fraction from Datong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in the components of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes with long-chain alkyl-substitutes are detected in acetone-soluble fraction. Dicyclic aramatic hydrocarbons are identified in benzene-soluble fraction and 4-6 cyclic condensed aramatic hydrocarbons are identified in THF-soluble fraction. The molecular structures detection of 1,2-dichlorobenzene, 2,4-dibromophnol, 2,4,6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coal.展开更多
[Objective] The aim was to study the chemical constituents of Euphorbia hirta. [Method] The constituents were isolated and purified by various chromatography methods including normal phase and reverse phase silica gel...[Objective] The aim was to study the chemical constituents of Euphorbia hirta. [Method] The constituents were isolated and purified by various chromatography methods including normal phase and reverse phase silica gel as well as Sephadex LH-20 gel column, and then elucidated by spectroscopic analysis such as MS and NMR etc. Compounds 1, 4, 5 and 6 were evaluated for their immunostimulatory activity against splenic cell of mouse by FCM. [Result] Six compounds were isolated from Euphorbia hirt, and identified as diisobutyl-O-phthalate （compond 1）, diethylhexyl phthalate （compond 2）, hispidulin （compond 3）, acetyl peroxide （compond 4）, quercetein （compond 5） and gallic acid （compond 6）. All compounds were inactive against splenic cell of mouse. [Conclusion] Compounds 1, 2 and 3 were isolated from this plant for the first time, and compound 4 was the first naturally occurring compound. This study provided reference for isolating bioactive substances from Euphorbia hirta.展开更多
In this study six Pinus L. taxa from Canada （P. strobus L., P. parviflora Siebold ＆ Zucc., P. mugo Turra subsp, mugo, P. resinosa Sol. ex Alton, P. flexilis E. James and P. nigra J. F. Arnold） were studied to deter...In this study six Pinus L. taxa from Canada （P. strobus L., P. parviflora Siebold ＆ Zucc., P. mugo Turra subsp, mugo, P. resinosa Sol. ex Alton, P. flexilis E. James and P. nigra J. F. Arnold） were studied to determine on chemical characters of studied taxa. For this purpose, essential oil from needles of the six Pinus taxa were investigated by HS-SPME/GC-MS. 38, 33, 39, 28, 31 and 46 compounds were respectively identified from each species representing 95.90%, 95.07%, 95.79%, 96.20%, 93.05% and 96.25% of the oil. The results have given some clues on the chemotaxonomy of this genus and are of usable potentials of the plants as renewable resources. Although the essential oil composition of studied taxa showed chemical divergences because of climatical, seasonal, geographical and geological factors, but the major compounds of plant derivatives are generally similar and the major compounds are chemotaxonomical markers for studied taxa.展开更多
The debate on the marketization of discourse in higher education has sparked and sustained interest among researchers in discourse and education studies across a diversity of contexts.While most research in this line ...The debate on the marketization of discourse in higher education has sparked and sustained interest among researchers in discourse and education studies across a diversity of contexts.While most research in this line has focused on marketized discourses such as advertisements,little attention has been paid to promotional discourse in public institutions such as the About us texts on Chinese university websites.The goal of the present study is twofold:first,to describe the generic features of the university About us texts in China;and second,to analyze how promotional discourse is interdiscursively incorporated in the discourse by referring to the broader sociopolitical context.Findings have indicated five main moves:giving an overview,stressing historical status,displaying strengths,pledging political and ideological allegiance,and communicating goals and visions.Move 3,displaying strengths,has the greatest amount of information and can be further divided into six sub-moves which presents information on campus facilities,faculty team,talent cultivation,disciplinary fields construction,academic research,and international exchange.The main linguistic and rhetorical strategies used in these moves are analyzed and discussed.展开更多
the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the pract...the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the practice process of shaping the political people. Our country is in the period of social transition, this period of transformation of political, economic and cultural construction of the China different from traditional political culture atmosphere, in the impact of the global political factors, college students＇ political psychology, political attitude and political behavior has undergone a series of changes. These changes impact on the existing college students＇ political socialization outcomes, so that students show the political and social highlights issues in the process of social transformation. In this case,we should only study the college students＇ optimization approach of political socialization carefully, improve the level of Chinese college students＇ political socialization, to ensure China＇ s social transition in a stable order smoothly, develop socialist political requirements of qualified university students, so as to make the socialism prosperous.展开更多
Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in...Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence （WD-XRF）. Source appointment was implemented by the principal component analysis/absolute principal component analysis （PCA/APCA） to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from （85.6±43.7） μg/m3 in July 2008 to （107.6±35.7） μg/m^3 in October 2008, the concentrations of the anthropogenic elements （P, S, C1, K, Mn, Ni, Cu, Zn, and Pb） are basically increased but concentrations of the natural elements （Na, Mg, Al, Si, Ca, Ti, and Fe） are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China： soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants.展开更多
Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging...Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.展开更多
Cultural construction plays an important part in the university construction. As a soft power, campus culture shows the features of tmiversities However, there are still problems in the process of cultural constructio...Cultural construction plays an important part in the university construction. As a soft power, campus culture shows the features of tmiversities However, there are still problems in the process of cultural construction in universities such as the lack of the spirit of being diligent, rigorous, realistic and creative in studies. So it is necessary to find out solutions to solve these problems. And this paper is trying to help improve the cultural construction in universities.展开更多
基金Program for Changjiang Scholar and InnovativeTeam in Peking University (Grant number: 985-2-063-112).
文摘Aim To study the chemical constituents from the stems of Xylosma controversum Clos. Methods The constituents were isolated by solvent extraction, repeated chromatography with silica gel, Sephadex LH-20, and RP-18 columns. The structures were elucidated by spectral analysis. Results Thirteen compounds were isolated and their structures were identified as （-）-syringaresinol （1）, syringaresinol-4-O-β-D-glucopyranoside （2）, syringaresinol-4,4′-bis-O-β-D-glucopyranoside （3）, （±）-catechin （4）, catechin-3-O- β-D-glucopyranoside （5）, catechin-5-O-β-D-glucopyranoside （6）, 1,3-bis-（4-hydroxy-3,5-dimethoxyphenyl）-1,3-propanediol （7）, （R）-（＋）-chaulmoogric acid （8）, friedelin （9）, uracile （10）, benzoic acid （11）, vaniUic acid （12）, and 4-hydroxybenzoic acid （13）. Conclusion All the compounds described above were isolated from this genus for the first time.
基金Project(51222106)supported by the National Natural Science Foundation of ChinaProject(FRF-TP-14-011C1)supported by the Fundamental Research Funds for the Central Universities,ChinaProject(2014CB643300)supported by the National Basic Research Program of China
文摘The atmospheric corrosion behavior of pure copper exposed for three years in Turpan, China, which is a typical hot and dry atmosphere environment, was investigated using mass-loss tests, morphology observations, composition analyses, and electrochemical techniques. The results indicated that the annual corrosion rate of pure copper was approximately 2.90 μm/a. An uneven distribution of corrosion products was observed by scanning electron microscopy; this uneven distribution was attributed to the dehydration process during wet–dry and cold–hot cycles, and the compositions mainly consisted of cuprite （Cu2O） and atacamite （Cu2Cl（OH）3）. Electrochemical measurements showed that deposits on copper improved its resistance to corrosion and the protectiveness decreased with increasing temperature. On the other hand, results obtained using the scanning vibrating electrode technique showed that the porous and uneven structure of the deposit layer generated a spatial separation of cathodic and anodic reaction sites, which accelerated the corrosion process in wet and rainy weather.
基金Projects 20076051, G1999022101, and 98029016 supported by National Natural Science Foundation of China, the Special Found for Major State BasicResearch Project, and Research Found for the Doctoral Program of Higher Education
文摘Datong coal was extracted with CS2, n-hexane, benzene, methanol, acetone, tetrahydro-furan（THF） and THF/methanol（1：3,v/v） mixed solvent sequentially. The extracts were analyzed with GC/MS. It is presented that group seperation of soluble organic compounds in the coal can be achieved by fractionated extraction using different solvents. The results show that CS2 was effective for extracting arenes from the coal sample, n-Hexane extractable fraction from Datong coal mainly consists of n-alkanes. A great variety of oxygen-containing compounds are dominant in the components of methanol-soluble fraction. Acyclic isoprenoids, pentecyclic triterpanes and a series of cyclohexanes with long-chain alkyl-substitutes are detected in acetone-soluble fraction. Dicyclic aramatic hydrocarbons are identified in benzene-soluble fraction and 4-6 cyclic condensed aramatic hydrocarbons are identified in THF-soluble fraction. The molecular structures detection of 1,2-dichlorobenzene, 2,4-dibromophnol, 2,4,6-tribromophenol and 4-chlorobenzophenone firstly provide information for existence form of bromine and chlorine in coal.
基金Supported by the National Natural Science Foundation of China(21162044)Yunnan Natural Science Foundation(2009CD051)Middle-aged and Young Talents Program of Yunnan Province(2010CI040)~~
文摘[Objective] The aim was to study the chemical constituents of Euphorbia hirta. [Method] The constituents were isolated and purified by various chromatography methods including normal phase and reverse phase silica gel as well as Sephadex LH-20 gel column, and then elucidated by spectroscopic analysis such as MS and NMR etc. Compounds 1, 4, 5 and 6 were evaluated for their immunostimulatory activity against splenic cell of mouse by FCM. [Result] Six compounds were isolated from Euphorbia hirt, and identified as diisobutyl-O-phthalate （compond 1）, diethylhexyl phthalate （compond 2）, hispidulin （compond 3）, acetyl peroxide （compond 4）, quercetein （compond 5） and gallic acid （compond 6）. All compounds were inactive against splenic cell of mouse. [Conclusion] Compounds 1, 2 and 3 were isolated from this plant for the first time, and compound 4 was the first naturally occurring compound. This study provided reference for isolating bioactive substances from Euphorbia hirta.
文摘In this study six Pinus L. taxa from Canada （P. strobus L., P. parviflora Siebold ＆ Zucc., P. mugo Turra subsp, mugo, P. resinosa Sol. ex Alton, P. flexilis E. James and P. nigra J. F. Arnold） were studied to determine on chemical characters of studied taxa. For this purpose, essential oil from needles of the six Pinus taxa were investigated by HS-SPME/GC-MS. 38, 33, 39, 28, 31 and 46 compounds were respectively identified from each species representing 95.90%, 95.07%, 95.79%, 96.20%, 93.05% and 96.25% of the oil. The results have given some clues on the chemotaxonomy of this genus and are of usable potentials of the plants as renewable resources. Although the essential oil composition of studied taxa showed chemical divergences because of climatical, seasonal, geographical and geological factors, but the major compounds of plant derivatives are generally similar and the major compounds are chemotaxonomical markers for studied taxa.
基金This study is supported by the Chinese Ministry of Education(MOE)Humanities and Social Science Research Funding(20YJA740050)the MOE Key Research Project of Humanities and Social Science(16JJD740006)conducted by the Center for Linguistics and Applied Linguistics(CLAL),Guangdong University of Foreign Studies(GDUFS).We would like to thank the reviewers for their comments and suggestions on earlier versions of this manuscript.
文摘The debate on the marketization of discourse in higher education has sparked and sustained interest among researchers in discourse and education studies across a diversity of contexts.While most research in this line has focused on marketized discourses such as advertisements,little attention has been paid to promotional discourse in public institutions such as the About us texts on Chinese university websites.The goal of the present study is twofold:first,to describe the generic features of the university About us texts in China;and second,to analyze how promotional discourse is interdiscursively incorporated in the discourse by referring to the broader sociopolitical context.Findings have indicated five main moves:giving an overview,stressing historical status,displaying strengths,pledging political and ideological allegiance,and communicating goals and visions.Move 3,displaying strengths,has the greatest amount of information and can be further divided into six sub-moves which presents information on campus facilities,faculty team,talent cultivation,disciplinary fields construction,academic research,and international exchange.The main linguistic and rhetorical strategies used in these moves are analyzed and discussed.
文摘the political socialization of college students is the purpose of the individual to accept political culture in the historical, social, cultural and the specific interaction, formation of political attitude, the practice process of shaping the political people. Our country is in the period of social transition, this period of transformation of political, economic and cultural construction of the China different from traditional political culture atmosphere, in the impact of the global political factors, college students＇ political psychology, political attitude and political behavior has undergone a series of changes. These changes impact on the existing college students＇ political socialization outcomes, so that students show the political and social highlights issues in the process of social transformation. In this case,we should only study the college students＇ optimization approach of political socialization carefully, improve the level of Chinese college students＇ political socialization, to ensure China＇ s social transition in a stable order smoothly, develop socialist political requirements of qualified university students, so as to make the socialism prosperous.
基金Project (FANEDD 200545) supported by the Foundation for the Author of National Excellent Doctoral Dissertation of China Project (50408019) supported by the National Natural Science Foundation of China Project (2008BAJ12B03) supported by National Key Project of Scientific and Technical Supporting Programs of China
文摘Source apportionment of particulate matters with aerodynamic diameter less than 10 μm （PM10） was conducted in the suburban area of Changsha, China. PM10 samples for 24 h collected with TEOM 1400a and ACCU system in July and October 2008 were chemically analyzed by the wavelength dispersive X-ray fluorescence （WD-XRF）. Source appointment was implemented by the principal component analysis/absolute principal component analysis （PCA/APCA） to identify the possible sources and to quantify the contributions of the sources to PM10. Results show that as the PM10 concentration is increased from （85.6±43.7） μg/m3 in July 2008 to （107.6±35.7） μg/m^3 in October 2008, the concentrations of the anthropogenic elements （P, S, C1, K, Mn, Ni, Cu, Zn, and Pb） are basically increased but concentrations of the natural elements （Na, Mg, Al, Si, Ca, Ti, and Fe） are essentially decreased. Six main sources of PM10 are identified in the suburban of Changsha, China： soil dust, secondary aerosols, domestic oil combustion, waste incineration, traffic emission, and industrial emission contribute 57.7%, 24.0%, 9.8%, 5.0%, 2.0%, and 1.5%, respectively. Soil dust and secondary aerosols are the two major sources of particulate air pollution in suburban area of Changsha, China, so effective measures should be taken to control these two particulate pollutants.
基金Under the auspices of National Natural Science Foundation of China(No.41471026,31171451)Strategic Science and Technology Program in the Thirteenth Five-Year Plan of Institute of Geographical Sciences and Natural Resources Research,Chinese Academy of Sciences(No.2012ZD003)
文摘Examining the direct and indirect effects of climatic factors on vegetation growth is critical to understand the complex linkage between climate change and vegetation dynamics. Based on the Moderate Resolution Imaging Spectroradiometer(MODIS) Normalized Difference Vegetation Index(NDVI) data and meteorological data(temperature and precipitation) from 2001 to 2012, the trend of vegetation dynamics were examined in the Ziya-Daqing basins, China. The path analysis was used to obtain the information on the relationships among climatic factors and their effects on vegetation growth. It was found that the trends of growing season NDVI were insignificant in most plain dry land, while the upward trends were significant in forest, grass and dry land in Taihang Mountains. According to the path analysis, in 23% of the basins the inter-annual NDVI variation was dominated by the direct effect of precipitation, in 5% by the direct effects of precipitation and temperature, and in less than 1% by the direct effect of temperature or indirect effects of these two climatic factors. It indicated that precipitation significantly affected the vegetation growth in the whole basins, and this effect was not regulated by temperature. Precipitation increase(especially in July, August and September) was favorable to greenness enhancement. Summer temperature rising showed negative effect on plant productivity enhancement, but temperature rise in April was beneficial for the vegetation growth. When April temperature increases by 1℃, the onset date of greenness for natural vegetation will be 2 days in advance. There was a lag-time effect of precipitation or temperature on monthly NDVI for all land use types except grass.
文摘Cultural construction plays an important part in the university construction. As a soft power, campus culture shows the features of tmiversities However, there are still problems in the process of cultural construction in universities such as the lack of the spirit of being diligent, rigorous, realistic and creative in studies. So it is necessary to find out solutions to solve these problems. And this paper is trying to help improve the cultural construction in universities.
