The careers of three Chinese physicists,Hu Ning,Ma Shijun,and Peng Huanwu at the Dublin Institute for Advance Studies in the 1940s,and later,are described.A brief history of the foundation and operations of the instit...The careers of three Chinese physicists,Hu Ning,Ma Shijun,and Peng Huanwu at the Dublin Institute for Advance Studies in the 1940s,and later,are described.A brief history of the foundation and operations of the institute,as well as the roles in it of Erwin Schrodinger,Walter Heitler,Max Born,and others are included.Some details are given of the works carried out there.The three men's post-institute careers are described,Ma eventually in Australia,and Hu and Peng in the People's Republic of China where they became distinguished leaders of theoretical physics research.展开更多
The study area lies in the Dadu River drainage area in upstream Yangtze River.The spatial distribution of subalpine coniferous forests in 1989 and 2009 was extracted by means of a combined method of object orientation...The study area lies in the Dadu River drainage area in upstream Yangtze River.The spatial distribution of subalpine coniferous forests in 1989 and 2009 was extracted by means of a combined method of object orientation and visual interpretation,and then the overlaying analysis of these data was conducted.The type and spatial location of succession were discovered and served as the sample of dependant variable.Meanwhile,supported by GIS technology and based on DEM and thematic data,the eight variables including altitude,slope,sin and cosin of aspect,curvity of land surface,and distance to residential area,cultivated land and road were extracted served as the sample of spatial succession of subalpine coniferous forests to fit Logistic Regression,and then the contribution of each independent variable as well as the spatial property of the occurrence probability of succession was calculated.The results suggested that,during the succession of subalpine coniferous forests to meadow,the closer to the residential area and cultivated land,the greater the contribution to succession is.In particular,when the distance to the residential area decreases by one unit,the probability for its conversion to meadow will be increased by 1.15 times.During the succession of subalpine coniferous forests to deciduous-broadleaved shrubs,the sin of aspect and distance to residential area contribute more,and the probability of succession increases with increasing degree of northwardness,i.e.when the degree of northwardness increases by one unit,the probability will be increased by 1.2 times.The quantitative analysis of spatial succession property of subalpine coniferous forests will supply scientific basis to the protection and restoration of subalpine coniferous forests.展开更多
[Objective]The paper was to study the effect of continuous cropping on leaf nutrient and growth of different species of poplar plantation.[Method] The tree height,diameter at breast height（DBH）,volume of different g...[Objective]The paper was to study the effect of continuous cropping on leaf nutrient and growth of different species of poplar plantation.[Method] The tree height,diameter at breast height（DBH）,volume of different generations and species of poplar plantation in poplar production area in northern Jiangsu Province,as well as TN,TP and TK content in their leaves were determined through field investigation and indoor experiment.[Result] With the increasing generation,the changes of TN,TP and TK content in the leaves of different ages of two varieties of forest stand were also different.However,with the increasing tree ages,TN,TP and TK contents in leaves showed decrease trend.With the increasing generation,the changes of tree height of I-69 and I-72 poplar showed the similar trend.The effect of increasing generation on tree height of 7-year-old and 10-year-old poplar was relatively stable,showing decrease trend from generation to generation.The tree height of 4-year-old poplar first increased and then decreased with the increasing generation.The changes of DBH along with different generations were basically consistent with the changes of tree height.With the increasing cultivation generations,the volume of 7-year-old and 10-year-old poplar decreased with significant difference.[Conclusion ] The result provided basis for rational fertilization and management of poplar plantation,improvement of productivity of poplar plantation,and achievement of sustainable management of plantation.展开更多
We examined the competitive ability of larval toads （Bufo gargarizans ） and frogs （Rana kukunoris ） which co-occur in natural pools in the Jiuzhaigou Nature Reserve. We measured the activity level, growth rate, ma...We examined the competitive ability of larval toads （Bufo gargarizans ） and frogs （Rana kukunoris ） which co-occur in natural pools in the Jiuzhaigou Nature Reserve. We measured the activity level, growth rate, mass at metamorphosis and larval period in a laboratory experiment. Tadpoles of B. gargarizans were significantly more active when food was abundant than scarce, while there was no significant difference in the activity of R. kukunoris tadpoles at different food levels. At low food availability, mass at metamorphosis and growth rate of R. kukunoris were significantly increased in the presence of B. gargarizans, whereas the presence of R. kukunoris had no significant effect on the mass and growth rate of B. gargarizans. In all treatments, the larval period of B. gargarizans at low food availability was the shortest. These results suggest that B. gargarizans can adapt to different food levels by changing their activity rate. At high food level, B. gargarizans increased activity to gain more food. At low food level, B. gargarizans decreased activity and achieved early metamorphosis. However, when food resources were limited, R. kukunoris could gain more food than B.gargarizans .展开更多
Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. Th...Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. The results showed that the main tree species were Picea and Abies in this region, and there were more than 90 forest types. Abies forests mainly dis-tributed in the middle and upper reaches of rivers and their branches, and Picea forests mainly distributed in wide valleys and on half-shaded and half-sunny slopes. The natural regeneration was poor under primitive spruce and fir forest canopy, but was good in the spruce and fire forest gap. The relationship between forest succession and vertical gradient was closely related to the relationship between forest succession procession and plant synusia under primary forests. Human activities could promote and postpone succession process. The results of expanding regeneration were often influenced by topography, vegetation and wind direction.展开更多
Structural properties of forest soils have important hydro-ecological function and can influence the soil water-physical characters and soil erosion. The experimental soil samples were obtained in surface horizon (0-1...Structural properties of forest soils have important hydro-ecological function and can influence the soil water-physical characters and soil erosion. The experimental soil samples were obtained in surface horizon (0-10 cm) from different subalpine forest types on east slope of Gongga Mountain in the upriver area of Yangtze River China in May 2002. The soil bulk density, porosity, stable infiltration rate, aggregate distribution and particle-size distribution were analyzed by the routine methods in room, and the features and effects on eco-environment of soil aggregation were studied. The results showed that the structure of soil under mixed mature forest is in the best condition and can clearly enhance the eco-environmental function of soil, and the soil structure under the clear-cutting forest is the worst, the others are ranked between them. The study results can offer a basic guidance for the eco-environmental construction in the upper reaches of Yangtze River.展开更多
The traditional calculation method of frequency-domain Green function mainly utilizes series or asymptotic expansion to carry out numerical approximation, however, this method requires very careful zoning, thus the co...The traditional calculation method of frequency-domain Green function mainly utilizes series or asymptotic expansion to carry out numerical approximation, however, this method requires very careful zoning, thus the computing process is complex with many cycles, which has greatly affected the computing efficiency. To improve the computing efficiency, this paper introduces Gaussian integral to the numerical calculation of the frequency-domain Green function and its partial derivatives. It then compares the calculation result with that in existing references. The comparison results demonstrate that, on the basis of its sufficient accuracy, the method has greatly simplified the computing process, reduced the zoning and improved the computing efficiency.展开更多
文摘The careers of three Chinese physicists,Hu Ning,Ma Shijun,and Peng Huanwu at the Dublin Institute for Advance Studies in the 1940s,and later,are described.A brief history of the foundation and operations of the institute,as well as the roles in it of Erwin Schrodinger,Walter Heitler,Max Born,and others are included.Some details are given of the works carried out there.The three men's post-institute careers are described,Ma eventually in Australia,and Hu and Peng in the People's Republic of China where they became distinguished leaders of theoretical physics research.
基金Supported by National Natural Science Foundation of China(40901057)Key Project of Chinese National Programs for Fundamental Research and Development(2010CB951704)~~
文摘The study area lies in the Dadu River drainage area in upstream Yangtze River.The spatial distribution of subalpine coniferous forests in 1989 and 2009 was extracted by means of a combined method of object orientation and visual interpretation,and then the overlaying analysis of these data was conducted.The type and spatial location of succession were discovered and served as the sample of dependant variable.Meanwhile,supported by GIS technology and based on DEM and thematic data,the eight variables including altitude,slope,sin and cosin of aspect,curvity of land surface,and distance to residential area,cultivated land and road were extracted served as the sample of spatial succession of subalpine coniferous forests to fit Logistic Regression,and then the contribution of each independent variable as well as the spatial property of the occurrence probability of succession was calculated.The results suggested that,during the succession of subalpine coniferous forests to meadow,the closer to the residential area and cultivated land,the greater the contribution to succession is.In particular,when the distance to the residential area decreases by one unit,the probability for its conversion to meadow will be increased by 1.15 times.During the succession of subalpine coniferous forests to deciduous-broadleaved shrubs,the sin of aspect and distance to residential area contribute more,and the probability of succession increases with increasing degree of northwardness,i.e.when the degree of northwardness increases by one unit,the probability will be increased by 1.2 times.The quantitative analysis of spatial succession property of subalpine coniferous forests will supply scientific basis to the protection and restoration of subalpine coniferous forests.
基金Supported by National 948 Project(2011-4-63)Special Research Fund for Welfare Act of State Forestry(200904001-3)Youth Fund of Anhui Normal University(2009xqn73)~~
文摘[Objective]The paper was to study the effect of continuous cropping on leaf nutrient and growth of different species of poplar plantation.[Method] The tree height,diameter at breast height（DBH）,volume of different generations and species of poplar plantation in poplar production area in northern Jiangsu Province,as well as TN,TP and TK content in their leaves were determined through field investigation and indoor experiment.[Result] With the increasing generation,the changes of TN,TP and TK content in the leaves of different ages of two varieties of forest stand were also different.However,with the increasing tree ages,TN,TP and TK contents in leaves showed decrease trend.With the increasing generation,the changes of tree height of I-69 and I-72 poplar showed the similar trend.The effect of increasing generation on tree height of 7-year-old and 10-year-old poplar was relatively stable,showing decrease trend from generation to generation.The tree height of 4-year-old poplar first increased and then decreased with the increasing generation.The changes of DBH along with different generations were basically consistent with the changes of tree height.With the increasing cultivation generations,the volume of 7-year-old and 10-year-old poplar decreased with significant difference.[Conclusion ] The result provided basis for rational fertilization and management of poplar plantation,improvement of productivity of poplar plantation,and achievement of sustainable management of plantation.
文摘We examined the competitive ability of larval toads （Bufo gargarizans ） and frogs （Rana kukunoris ） which co-occur in natural pools in the Jiuzhaigou Nature Reserve. We measured the activity level, growth rate, mass at metamorphosis and larval period in a laboratory experiment. Tadpoles of B. gargarizans were significantly more active when food was abundant than scarce, while there was no significant difference in the activity of R. kukunoris tadpoles at different food levels. At low food availability, mass at metamorphosis and growth rate of R. kukunoris were significantly increased in the presence of B. gargarizans, whereas the presence of R. kukunoris had no significant effect on the mass and growth rate of B. gargarizans. In all treatments, the larval period of B. gargarizans at low food availability was the shortest. These results suggest that B. gargarizans can adapt to different food levels by changing their activity rate. At high food level, B. gargarizans increased activity to gain more food. At low food level, B. gargarizans decreased activity and achieved early metamorphosis. However, when food resources were limited, R. kukunoris could gain more food than B.gargarizans .
基金This article was supported by State Tenth Five-Year Plan Project (2001BA510B0105) and the Project for Pioneering New Knowledge from Chinese Academy of Sciences (KZCX2-SW-319).
文摘Since 1950, 700 plots were established in the alpine and canyon region of western Sichuan. The distribution charac-teristics and the relationships between forest succession and environmental gradients were studied. The results showed that the main tree species were Picea and Abies in this region, and there were more than 90 forest types. Abies forests mainly dis-tributed in the middle and upper reaches of rivers and their branches, and Picea forests mainly distributed in wide valleys and on half-shaded and half-sunny slopes. The natural regeneration was poor under primitive spruce and fir forest canopy, but was good in the spruce and fire forest gap. The relationship between forest succession and vertical gradient was closely related to the relationship between forest succession procession and plant synusia under primary forests. Human activities could promote and postpone succession process. The results of expanding regeneration were often influenced by topography, vegetation and wind direction.
基金This study was supported by the Knowledge innovation project of Chinese Academy of Sciences (KZCX2-Sw-319)
文摘Structural properties of forest soils have important hydro-ecological function and can influence the soil water-physical characters and soil erosion. The experimental soil samples were obtained in surface horizon (0-10 cm) from different subalpine forest types on east slope of Gongga Mountain in the upriver area of Yangtze River China in May 2002. The soil bulk density, porosity, stable infiltration rate, aggregate distribution and particle-size distribution were analyzed by the routine methods in room, and the features and effects on eco-environment of soil aggregation were studied. The results showed that the structure of soil under mixed mature forest is in the best condition and can clearly enhance the eco-environmental function of soil, and the soil structure under the clear-cutting forest is the worst, the others are ranked between them. The study results can offer a basic guidance for the eco-environmental construction in the upper reaches of Yangtze River.
基金Supported by the National Natural Science Foundation of China under Grant No.50779007the National Science Foundation for Young Scientists of China under Grant No.50809018+2 种基金the Specialized Research Fund for the Doctoral Program of Higher Education of China under Grant No.20070217074the Defence Advance Research Program of Science and Technology of Ship Industry under Grant No.07J1.1.6Harbin Engineering University Foundation under Grant No.HEUFT07069
文摘The traditional calculation method of frequency-domain Green function mainly utilizes series or asymptotic expansion to carry out numerical approximation, however, this method requires very careful zoning, thus the computing process is complex with many cycles, which has greatly affected the computing efficiency. To improve the computing efficiency, this paper introduces Gaussian integral to the numerical calculation of the frequency-domain Green function and its partial derivatives. It then compares the calculation result with that in existing references. The comparison results demonstrate that, on the basis of its sufficient accuracy, the method has greatly simplified the computing process, reduced the zoning and improved the computing efficiency.
