检索结果-南通市图书馆

Land Use of the Three Gorges Reservoir Area and the Effect on Its Landscape Pattern in the Recent 50 Years

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 Academy of Sciences , chengdu 610041, sichuan, china 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, china 3. sichuan Institute of Land resource management, chengdu 610041, sichuan , china 4. Department of resources and Environment Science, sichuan Normal University , chengdu 610061, sichuan, china 5. College of Information Engineering, chengdu University of Technology, chengdu 610059, 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 50 years, but resumed in 2002; 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

Assessment of time-dependent seismic hazards on segments of active fault, and its problems

引用

Chinese Science Bulletin 1998年第23期43卷 1937-1950页

作者： WEN Xueze Seismological bureau of sichuan Province, chengdu 610041, {3. Seismological bureau of sichuan Province Chengdu China

Assessment of time dependent seismic hazards on segments of active fault is one of the important techniques of long term earthquake forecast for specific locations. It is based on the data from quantitatively seismo geologic investigation in active faults and expresses seismic hazards of a fault segment with both the earthquake occurrence probability, which increases as the elapsed time increases, and the magnitude predicted. Through summing up and analyzing main technical steps in research of the recent decade, some defects in the current theory and model of this technique are pointed out. For instance, the probabilistic models for recurrence interval are based solely on the quasi periodic behavior of earthquake recurrence, ignoring behavior’s diversity that possibly exists. Variability of repeated rupture dimensions in various cycles is considered inadequately in fault segmentation research, etc. It is most important for improving the reliability of the result of seismic hazard assessment to reveal actual earthquake recurrence behavior and its generalities, and to update relevant models for evaluating probabilistic earthquake hazard based on the behavior and generalities.

关键词： active fault rupture segmentation time dependent hazard probabilistic model long term forecast.

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 family net of giant pandas in the Tangjiahe Natural Reserve:Assessment of current individual migration

引用

Science Bulletin 2005年第17期 65-72页

作者： WAN Qiuhong1, FANG Shengguo1, LI Jianguo2, ZHANG Liming 3. OU Weifu4, XIAN Fanghai4 & CHEN Wanli4 1. College of Life Sciences, State conservation Center for Gene Re-sources of Endangered wildlife, and Key Laboratory of conservation Genetics and Reproductive Biology for Endangered Wild Animals of Ministry of Education, Zhejiang University, Hangzhou 3.0029, {3. 2. Forestry Department of sichuan Province, chengdu 610081, {3. 3. sichuan bureau for wildlife resource investigation, conservation and management, chengdu 610082. china 4. Tangjiahe Natural Reserve, Qingchuan 628109, {3.

In the present study, formalin-fixed feces, oli-gonucleotide fingerprinting and SRY-gene based sexing were used to construct a family net for giant pandas in the Tang-jiahe Natural Reserve and to assess contemporary gene flow (migration) in this population. A total of 124 fecal samples were attributed to 3. individuals (22 females and 15 males) that were then analyzed for family relationships. Based on DNA fingerprints, the deduced family net revealed the fol-lowing facts: (i) First-order relatives possessed similarities from 50% to 90%, and similarities between unrelated indi-viduals or distant relatives were as high as 77%, indicating that the Tangjiahe pandas are characterized by high genetic similarity; (ii) 15 matings were identified and 5 ones oc-curred between close relatives, implying that there is poten-tial for inbreeding to impact the pandas; (iii) four mating pairs and 5 offspring presented long distance migrations, demonstrating the intra-reserve habitat is continuous; (iv) four pairs of full sibs (also female-male dyads) dispersed short distance and all of them gave birth to highly inbred offspring, reflecting long distance migration is vital for in-breeding avoidance; (v) 17 adult individuals dispersed short or moderate distance and formed three clusters on the land-scape, indicating that it is necessary to find out whether there is a negative factor impacting the pandas.

关键词： multilocus DNA fingerprinting giant panda family rela-tionship close inbreeding dispersal pattern.

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Theoretical analysis and experiment of micromechanics and mechanics-optics coupling of distributed optic-fiber crack sensing

引用

中国科学：技术科学英文版 2011年第S1期54卷 185-191页

作者： LIU HaoWu 1,2,CHEN Jiang 2,SUN Man 3.& DING Rui 2 1 State Key Laboratory of Hydraulics and Mountain River Engineering,sichuan University,chengdu 610065,china 2 School of Water {3. Hydropower,sichuan University,chengdu 610065,china 3.School Electrical Engineering and Information,sichuan University,chengdu 610065,china sichuan Univ State Key Lab Hydraul & Mt River Engn Chengdu 610065 Peoples R China sichuan Univ Sch Water Resource Hydropower Chengdu 610065 Peoples R China sichuan Univ Sch Elect Engn & Informat Chengdu 610065 Peoples R China

The micromechanical behaviors and mechanics-optics coupling effects of optic-fiber-concrete complex in the distributed optic-fiber sensing concrete-crack technology,which was used in health monitoring of Wu Gorge Bridge on Yangtze River and a large dam successfully,have been investigated.A micromechanical theoretical analysis method and micromechanical frictional contact bi-interface model,as well as a modified optical theoretical analysis method of the mechanics-optics coupling effects are presented.A series of verification experiments,including mechanical experiments and mechanics-optics coupling experiments,have been *** results of micromechanical theoretical analysis and the analysis of the modified theory of mechanics-optics coupling along with mechanical and optical experimental data are shown to be in close *** the micromechanical theory and the modified theory of mechanics-optics coupling with their analysis methods can not only enhance credibility of this novel distributed sensing technology but also provide a way to understand its sensing mechanism and optimize its technical details and system.

关键词： optic-fiber sensing mechanics-optics coupling micromechanics health monitoring concrete structure crack detection

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 Biology, Chinese Academy of Sciences, chengdu 610041, sichuan,{3. 2. Graduate University of Chinese Academy of Sciences, Beijing 100049, {3. 3. Academy of Land Reconnaissance and Layout of sichuan Province , chengdu 61003., sichuan, {3. chengdu Institute of Biology 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 {3. of Lezhi County from 1990 to 2001. 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 {3. 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 2001. The value of obstacles degree of five indicators exceeded 5 in 1990, but in 2001, 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

Monitoring the Cultivated Slope Land in the Three Gorges Reservoir Area Based on Remote Sensing and GIS

引用

Wuhan University Journal of Natural Sciences 2006年第4期11卷 915-921页

作者： ZHOU Jieming1, ZHOU Qigang 2, 3.,HUANG Zhiqin 2, 3. 4 1. The Faculty of Geography and resources Science, sichuan Normal University, chengdu 610066, sichuan, china 2. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, chengdu 610041, sichuan, china 3. Graduate University of the Chinese Academy of Sciences, Beijing 100049, china 4. Information Center of Land and resources Department of sichuan Province, chengdu 610041, sichuan, china The Faculty of Geography resources Science Sichuan Normal University 610066 Chengdu Sichuan China Institute of Mountain Hazards Environment Chinese Academy of Sciences 610041 Chengdu Sichuan China Graduate University of the Chinese Academy of Sciences 100049 Beijing China Information Center of Land resources Department of sichuan Province 610041 Chengdu Sichuan China

By means of combining auto-extraction with manual interpretation, the current distribution information about cultivated land is obtained. The distribution information of 1992 is extracted from the dynamic polygons of 2002. The monitoring mini-system of the cultivated slope land is established. In the system, detailed surveys, focused on the resources of cultivated slope land, are carried out. The results indicate that the area of the cultivated slope land is very large. Meanwhile, there are lots of cultivated steep slopes with gradient above 3.°. The areas of steep land cultivated had been slowly reduced from 1992 to 2002. At the same time, the pressures of returning farm land to forestry are great in all counties. The conflicts between population growth, insufficient grain supply and stagnant economic development sharpen increasingly. It is inevitable to improve the agricultural structure.

关键词： slope land cultivated remote sensing geography information system (GIS) the pressure of returning farm land to forestry Three Gorges Reservoir Area

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 changes of water cycle and its impacts in the source region of the Yellow River

引用

Science china(Technological Sciences) 2004年第z1期47卷 142-151页

作者： ZHANG Shifeng1, JIA Shaofeng1, LIU Changming1, CAO Wenbing2, HAO Fanghua3. LIU Jiuyu4 & YAN Huayun5 1. Institute of Geographic Sciences and Natural resources Research, Chinese Academy of Sciences, Beijing 100101, china 2. china University of Geosciences, Beijing 100083. china 3. Beijing Normal University, Beijing 100875, china 4. bureau of Hydrology of Yellow River Conservancy Commission, Zhengzhou 450003. china 5. bureau of Hydrology and Water resource investigation of Qinghai Province, Xining 810001, china 1. Institute of Geographic Sciences and Natural resources Research Chinese Academy of Sciences 100101 Beijing China2. China University of Geosciences 100083 Beijing China3. Beijing Normal University 100875 Beijing China4. Bureau of Hydrology of Yellow River Conservancy Commission 450003 Zhengzhou China5. Bureau of Hydrology and Water Resource Investigation of Qinghai Province 810001 Xining China

The water cycle in the source region of the Yellow River underwent great changes in the 1990s. The major features of the changes are as follows: the gauged runoff declined significantly while the precipitation increased slightly, and the runoff process was more concentrated on the flood season. Water balance analyses indicate that the pondage was kept in the status of negative equilibrium, causing eco-environmental problems. The runoff decrement is due to evaporation increment in this region. Studies show that the runoff process in this region is closely related to that of the other hydrological stations in the upper reaches. When the runoff declines in the source regions, the amount of water also declines in the whole upper reaches of the Yellow River, affecting the balance between water demand and supply. Meanwhile changes will take place in the water cycle of the river course system when the eco-environment deteriorates. The trend of water cycle change in the source region is that the runoff will keep declining with the increment of evaporation caused by temperature rise in the northwest of china in the 21st century. But the hydraulic engineering in the source region will help to mitigate the deterioration of local eco-environment system, though the impacts to the lower reaches of this project may not be the case.

关键词： source region of the Yellow River, water cycle, evaporation, negative equilibrium.

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

On nulls of perturbed Fredholm operators and degenerate homoclinic bifurcations

引用

Science china Mathematics 2004年第4期47卷 617-627页

作者： ZHANG WeinianDepartment of Mathematics, sichuan University, chengdu 610064, china 1. Department of Mathematics Sichuan University 610064 Chengdu China

It is known that small perturbations of a Fredholm operatorL have nulls of dimension not larger than dimN(L). In this paper for any given positive integer κ ? dimN(L) we prove that there is a perturbation ofL which has an exactly κ-dimensional null. Actually, our proof gives a construction of the perturbation. We further apply our result to concrete examples of differential equations with degenerate homoclinic orbits, showing how many independent homoclinic orbits can be bifurcated from a perturbation.

关键词： Fredholm operator, perturbation, dimension, decomposition, degenerate homoclinic bifurcation.

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

EFFECT OF PAN-MILLING ON RHEOLOGICAL PROPERTIES OF HIGH DENSITY POLYETHYLENE

引用

Chinese Journal of Polymer Science 2000年第5期18卷 397-403页

作者： Hua Huang Polymer Research Institute, sichuan University, chengdu 610065, china sichuan Univ Polymer Res Inst Chengdu 610065 Peoples R China Shanghai Jiao Tong Univ Sch Chem & Chem Technol Shanghai 200240 Peoples R China

The effect of pan-milling on the rheological properties of high density polyethylene (HDPE) was studied. An innovative milling apparatus, viz. an inlaid pan-mill, was used. Melt indexer, capillary rheometer, Haake Rheocord 90 single-screw extruder and Brabender rheometer were used to evaluate the rheological properties of HDPE. HDPE with higher initial molecular weight and larger particle size was easier to degrade under pan-milling stress, as indicated by the melt index. Pressure oscillation in capillary flow occurred at significantly higher shear stress and shear rate for milled HDPE than for unmilled HDPE. The apparent shear viscosity of HDPE decreased with increasing times of milling. After milling, the flow activation energy decreased and thus the sensitivity of viscosity to temperature was reduced. Die pressure and torque during single screw extrusion were reduced significantly after milling. Plasticizing time as measured in a Brabander mixer decreased markedly with increasing milling times.

关键词： high density polyethylene rheological properties pan-milling

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

Effect of rare earths on phase transformation in as-cast ZA27 alloy dur-ing compressive creep

引用

Rare Metals 2003年第4期22卷 259-264页

作者： WEIXiaowei SHENBaoluo DepamnentofAppliedPhysics UniversityofElectronicScienceandTechnologyofChinaChengdu610045China DeparlanentofMetalScience SichuanUniversityChengdu610065China

The effect of the mixed rare earths of Ce on the phase transformation in ascast ZA 27 alloy during compressive was investigated under 3. MPa and at 160 deg C by X-raydiffraction technique and SEM. The results showed that the as cast microstructure of ZA 27-RE alloyconsisted of a dendritic Al-rich alpha' surrounded by Zn-rich beta' phase, interdendritic epsilonphase and Zn-rich eta phase together with a complex Z phase which was a complex constitute compound,(RE,Cu)Al_5Zn_(16), dispersed in crystal interfaces or branch crystal interfaces and stable duringcompressive creep test at 160 deg C. The phase transformations of ZA 27-RE alloy, decomposition ofbeta' phase arid four transformation, were delayed by the addition of rare earths, also the lamellarstructure and the spheroidized structure in ZA 27-RE alloy were finer than in ZA 27 alloy duringcompressive creep test at 160 deg C at the same creep time, and the compressive creep resistance ofZA 27-RE alloy was higher than that of ZA 27 alloy.

关键词： microstructure change compressive creep rare earths ZA 27 alloy

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：