检索结果-南通市图书馆

Land cover changes based on plant successions: Deforestation, rehabilitation and degeneration of forest in the upper Dadu River watershed

引用

Science china Earth sciences 2005年第12期48卷 2214-2230页

作者： YAN Jianzhong1,2.3, ZHANG Yili1, BAI Wanqi1, LIU Yanhua4, BAO Weikai5. LIU Linshan1, 2.& ZHENG Du1 1. institute of Geographic {2. and Natural Resources Research, Chinese academy of {2., Beijing 100101, china 2. Graduate School of the Chinese academy of {2., Beijing 100039, china 3. College of Resources and Environment, Southwest Agricultural University, Chongqing 400716, china 4. The Ministry of Science and Technology, P. C. china, Beijing 100862. china {12., Chinese academy of {2., chengdu 61004., china 1. institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences 100101 Beijing China 2. Graduate School of the Chinese academy of sciences 100039 Beijing China 3. College of Resources and Environment Southwest Agricultural University 400716 Chongqing China 4. The Ministry of Science and Technology P. C. China 100862 Beijing China 5. chengdu institute of biology Chinese Academy of Sciences 610041 Chengdu China

To link regional land use/cover changes with environmental effects, land cover changes are required to reflect vegetation successions, whereas the land cover classification systems commonly used nowadays cannot serve this purpose. In this paper, a new land cover classification system is established in which land covers are classified by the vegetation succes-sions, taking Zamtang County, Barkam County and Jinchuan County in the upper Dadu River watershed as a study area. Using multi-temporal remote sensing images, the land cover data of 1967, 1986 and 2.00 are obtained by means of integration of unsupervised classification and visual interpretation methods. The database facilitates the study of land use/cover changes, en-vironmental effects and ecological construction. Land cover changes reflect the main ecological processes in the upper Dadu River watershed. The landscape composed mainly of grasslands, wildwoods and alpine scrubs in 1967 was changed to that of grasslands, secondary forests, al-pine scrubs, fragmentary wildwoods, artificial forests, secondary scrubs in 2.00, meanwhile, the landscape got more fragmentized. The total area of the forests decreased by 9.43%. Study results have shown the process of restoration of logged areas in forest centers. From 1967 to 2.00, only 6.86 percents of logged areas were converted to shrubs, meadows or crop-lands, and the rest were converted into artificial forests or secondary forests. So the ecological shelter functions will be restored, stage by stage. Firewood collection, charcoal production and overgrazing are the three major triggers for the extensive degradation of alpine oak forests, Sa-bina tibetica forests and meadows. The arid valley grasslands expanded too. The degradation of vegetation in the southern slopes impairs ecological shelter functions and affects livelihood of local residents, so it is essential to find effective measures for ecological restoration and recon-struction. Field investigations have found

关键词： land use/cover classification, upper Dadu River watershed, vegetation successions, GIS, RS.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Evaluation of Sustainable Land Management and Diagnosis of Obstacle at County Scale in Sichuan Basin:Taking Lezhi County as Example

引用

Wuhan University Journal of Natural sciences 2006年第4期11卷 1046-1051页

作者： CHEN Guangjian 1, 2. 3 , LIU Qing 1 1. chengdu institute of {2., Chinese academy of sciences,{5., Sichuan,china 2. Graduate University of Chinese academy of sciences, Beijing 100049, china 3. academy of Land Reconnaissance and Layout of Sichuan Province , chengdu 610031, Sichuan, china chengdu institute of {2. Chinese Academy of Sciences Chengdu Sichuan China Graduate University of Chinese academy of sciences Beijing China academy of Land Reconnaissance and Layout of Sichuan Province Chengdu Sichuan China

This paper established sustainable land resources evaluating indicators fit for hilly area in Sichuan Basin, Southwest of china, and evaluated the case of sustainable land management of Lezhi County from 1990 to 2.01. The result showed that the land resource sustainable utilization ability in Lezhi County is belong to Second level （better sustainable）. Secondly, this paper diagnosed some years obstacles of sustainable land management of Lezhi County from base period to goal period and compared the obstacles factors in the indicators system. There were 16 indexes orderly become major affect factor to land sustainable utilization of Lezhi county in indicator system, of which there are 8 obstacles indexes exist both in 1990 and 2.01. The value of obstacles degree of five indicators exceeded 5.in 1990, but in 2.01, only two indicators＇ values were more than 5.

关键词： land resources sustainable land management assessment indicators diagnosis of obstacle

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Land Use of the Three Gorges Reservoir Area and the Effect on Its Landscape Pattern in the Recent 5. Years

引用

Wuhan University Journal of Natural sciences 2006年第4期11卷 910-914页

作者： HUANG Zhiqin 1,2.3 , ZHOU Wancun 1 ,ZHOU Jieming 4 , ZHU Mingcang 3,5.1. institute of Mountain Hazards and Environment, Chinese {2. of sciences , chengdu 61004., Sichuan, china 2. Graduate University of Chinese {2. of sciences, Beijing 100049, china 3. Sichuan institute of Land Resource Management, chengdu 61004., Sichuan , china 4. Department of Resources and Environment Science, Sichuan Normal University , {12. 610061, Sichuan, china 5. College of Information Engineering, {12. University of Technology, {12. 61005., Sichuan, china institute of Mountain Hazards and Environment Chinese Academy of Sciences Chengdu Sichuan China Graduate University of Chinese academy of sciences Beijing China Sichuan institute of Land Resource Management Chengdu Sichuan China Department of Resources and Environment Science Sichuan Normal University Chengdu Sichuan China College of Information Engineering Chengdu University of Technology Chengdu Sichuan China

The paper makes detailed analysis on the changing processes of the main types of land use in Three Gorges Reservoir Area through the techniques of RS （Remote Sense） and GIS （Geography Information System）. Based on the theory of landscape ecology, many types of landscape pattern indexes are calculated and made correlation analysis. The results indicate that： in 1995.the ecological environment of Three Gorges Reservoir Area was the most vulnerable in the recent 5. years, but resumed in 2.02. the landscape pattern diversity index, fractal dimension index and fragmentation index has close correlation with the area of land use/cover change （LUCC）. The research also releases that the increase of the cultivated land, grassland and construction land deteriorates the landscape ecological pattern, while the increase of forest land area will help restore the landscape ecological pattern to its original state. The rapid change of grassland is an important index of the change of landscape pattern, because it has the most effect on change of landscape pattern index.

关键词： the Three Gorges Reservoir Area land use/cover change landscape pattern.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Study on the coating of nano-scale SiO_2.film on the surface of nanocrystalline Mg-Al layered double hydroxides

引用

Science china Chemistry 2005年第2期48卷 107-114页

作者： ZHANG Zejiang1,2.3, MEI Xiujuan2. XU Chenghua1 & QIU Fali1 1. chengdu institute of Organic Chemistry, Chinese {2. of sciences, chengdu 61004.,{5. 2. Sichuan Fire Research institute of Public Security Ministry, chengdu 611830,{5. 3. Graduate School of the Chinese {2. of sciences, Beijing 100039,{5. Correspondence should be addressed to Zhang Zejiang (email: zzjzzjzz@***) 1. chengdu institute of Organic Chemistry Chinese Academy of Sciences 610041 Chengdu China 2. Sichuan Fire Research institute of Public Security Ministry 611830 Chengdu China 3. Graduate School of the Chinese academy of sciences 100039 Beijing China

The coating process of a nano-scale SiO2.film on the nanocrystalline Mg-Al layered double hydroxides via a sol-gel process was investigated. The uniform and dense SiO2.ilm with a thickness of about 5.nm on the nano-LDHs particles was characterized by the solubility test in the dilute HNO3 or HCl acid, TEM and FT-IR, XRD, TG and DSC. The chemical shifts of binding en- ergies of Al 2., Mg 2., Si 2. and O 1s on the coated particles indicate that the coating of the SiO2.nano-film on the surface of the nano-LDHs proceeds through the formation of Mg-O-Si and Al-O-Si bonds. The thermal analysis shows that both the SiO2.coated nano-LDHs and the nano-LDHs have a similar mass loss process, in which there are three obvious stages of mass loss in the temperature range of 40—700℃. Furthermore, the more the coatedamount of SiO2.n the surface of the nano-LDHs is, the less the mass loss of the samples is at 700℃.The nano- LDHs have two obvious endothermic peaks at 2.4.67℃ and 430.13℃, whose corresponding heat absorption capacities are 412.2. J/g and 336.30 J/g, respectively. In contrast, the coated nano-LDHs have only one endothermic peak at 2.3.60℃ with a heat absorption capacity of 2.1.2.0}J/g.

关键词： layered double hydroxides, nanocrystalline, silica, coating.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Kinetics and reaction mechanism of phenol hydroxylation catalyzed by La-Cu_4FeAlCO_3

引用

Science china Chemistry 2005年第6期48卷 530-537页

作者： CHEN Chunxia1,2. XU Chenghua1, FENG Liangrong1, SUO Jishuan1 & QIU Fali1 1. chengdu institute of Organic Chemistry, Chinese {2. of sciences, chengdu 61004.,{5. 2. Graduate School of the Chinese {2. of sciences, Beijing 100039,{5. 1. chengdu institute of Organic Chemistry Chinese Academy of Sciences 610041 Chengdu China 2. Graduate School of the Chinese academy of sciences 100039 Beijing China

The present work synthesizes La-Cu4FeAlCO3 catalyst under microwave irradiation and characterizes its structure using XRD and IR techniques. The results show that the obtained La-Cu4FeAlCO3 has a hydrotalcite structure. In the phenol hydroxylation with H2.2.catalyzed by La-Cu4FeAlCO3, the effects of reaction time and phenol/H2.2.molar ratio on the phenol hy-droxylation, and relationships between the initial hydroxylation rate with concentration of the catalyst, phenol, H2.2.and reaction temperature are also investigated in details. It is shown the phenol conversion can reach 5..09% (mol percent) in the phenol hydroxylation catalyzed by La-Cu4FeAlCO3, under the reaction conditions of the molar ratio of phenol/H2.2.1/2. the amount ratio of phenol/catalyst 2., reaction temperature 343 K, reaction time 12. min, 10 mL distilled water as solvent. Moreover, a kinetic equation of v = k[La ? Cu 4 FeAlCO 3 ][C 6 H 5.OH][H 2.O 2.. and the activation energy of Ea=5..37 kJ/mol are obtained according to the kinetic studies. Due to the fact that the HO-Cu+-OH species are detected in La-Cu4FeAlCO3/H2.2.system by XPS, the new mechanism about the generation of hydroxyl free radicals in the phenol hydroxylation is pro-posed, which is supposed that HO-Cu+-OH species are transition state in this reaction.

关键词： rare earth, hydrotalcite, microwave irradiation, phenol hydroxylation, kinetics, reaction mechanism.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

PREPARATION OF Fe_3O_4/PSt MAGNETIC PARTICLES IN THE PRESENCE OF MAGNETIC FLUID IN ETHANOL/WATER MIXTURE

引用

Chinese Journal of Polymer Science 1999年第2期17卷 129-134页

作者： Xiao-bin Ding Zong-hua Sun Guo-xiang Wan Ying-yan Jiang chengdu institute of Organic Chemistry, Chinesc {2. of sciences, chengdu 61004.,{5. institute of Chemistry, Chinese {2. of sciences, Beijing 100080,{5. Chinese Acad Sci Chengdu Inst Organ Chem Chengdu 610041 Peoples R China Chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

Fe_3O_4/Polystyrene(PSt) magnetic particles with core/shell structure have been prepared in thepresence of Fe_3O_4 magnetic fluid in ethanol/water medium by dispersion polymeriation of styrene. A Fe_3O_4particle formation mechanism was proposed. According to this mechanism, the size of particle nuclei isdetermined by the extent of aggregation of Fe_3O_4 /oligomer. Magnetic particles with diameter ranging from 5.o 2.0 μm were prepared under different reaction conditions. Some polymerization parameters such as theconcentration of monomer, stabilizer, initiator, and ethanol which affect particle size and size distribution arediscussed and their effect on particle formation are explained by the proposed mechanism.

关键词： Fe_3O_4 magnetic fluid Magnetic particle Polystyrene Polymerization Mechanism

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A New Triterpenoid Saponin from Anemone tomentosa

引用

Chinese Chemical Letters 1999年第12期10卷 0-0页

作者： Xun LIAO Shu Lin PENG Bo Gang LI Yao Zu CHEN Li Sheng DING(1. Department of Chemistry, Zhejiang University, Hangzhou 31002.||)(2. chengdu institute of {2., Chinese academy of sciences,{5.) Zhejiang Univ Dept Chem Hangzhou 310027 Peoples R China Chinese Acad Sci Chengdu Inst Biol Chengdu 610041 Peoples R China

A new triterpenoid saponin, tomentoside (5., together with prosapogenin CP 4 (1),huzhangoside B (2., C (3) and D (4) was isolated from the ethanolic extract of Anemone *** structure was established by spectroscopic an... 详细信息

关键词： Anemone tomentosa triterpenoid saponin tomentoside.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A Novel Pregnane Glycoside from Biondia chinensis

引用

Chinese Chemical Letters 2003年第10期14卷 1027-1028页

作者： Xing Gen TAN, Shu Lin PENG, Xun LIAO, Jian LIANG, Li Sheng DING chengdu institute of {2., Chinese academy of sciences,{5. chengdu institute of {2. Chinese Academy of Sciences Chengdu 610041

A novel pregnane glycoside, biondianoside E, was isolated from the roots of Biondia chinensis. By the spectroscopic and chemical methods, this structure was elucidated as 3B, 5., 14B, 2.5. 2.-pentahydroxypregnane 3-O-... 详细信息

关键词： Biondia chinensis pregnane glycoside biondianoside E.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

SYNTHESIS OF SOAP-FREE ACRYLIC HYDROSOLS

引用

Chinese Journal of Polymer Science 2002年第6期20卷 531-536页

作者： Li Jia Zong-hui Liu De-qing Wei Chengd institute of Organic Chemistry Chinese academy of {2., chengdu 61004., china Chinese Acad Sci Chengdu Inst Organ Chem Chengdu 610041 Peoples R China

Poly(methyl methacrylate/ethyl acrylate/acrylic acid) hydrosols were prepared by employing soap-free polymerization, and (acrylic acid/butyl acrylate) oligomer was used as the polymeric surfactant. The effect of reaction condition on the morphology and particle size of the hydrosols was investigated. The minimum amount of acrylic acid in the hydrosols is 2.. The maximum weight average molecular weight (M-w) of polymer that assures soap-free emulsion conversion into hydrosol is about 1.2.x 10(5.-1.3 x 10(5.. The particle transforming process was investigated, and an obvious change of particle diameter and morphology was observed.

关键词： hydrosol acrylic resin water-borne resin soap-free polymerization

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Synthesis,crystal structure and thermal behavior of Rb(NTO)·H_2.

引用

Chinese Science Bulletin 2001年第1期46卷 45-49页

作者： HU Mancheng, GAO Shiyang, LIU Zhihong, SONG Jirong, XIA Shuping & YU Kaibei1. institute of Applied Chemistry, Shaanxi Normal University, Xi’an 710062. china 2. Department of Chemical Engineering, Northwest University, Xi’an 710069, china 3. chengdu Branch of Chinese academy of {5., chengdu 61004., china institute of Applied Chemistry Shaanxi Normal University Xi’an China Department of Chemical Engineering Northwest University Xi’an China chengdu Branch of Chinese academy of {2. Chengdu China

The Rb(NTO) .H2. crystal has been synthesized by reaction of 3-nitro-l,2.4-triazole-5.one (NTO) with Rb2.O3 in aqueous solution. Its crystal structure has been determined. The crystal belongs to monoclinic system. Crystal structure data: space group P2./ n; a = 0.633 0(1), b = 0.82. 1(2., c =1.2.6 4(3) nm; β = 97.90(1)°; V = 0.669 9 (2. nm3, Z = 4, Dc= 2.306 g/cm3,μ = 7.365.nm-1, F(000) = 448. An eight coordinated compound is formed between Rb+ with oxygen atoms and nitrogen atoms. A layer structure is formed by coordination bonds and hydrogen bonds. The thermal decomposition mechanism of this coordination compound is discussed.

关键词： Rb-NTO coordination compound crystal structrue thermal decomposition.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：