The planning site was divided into a spatial structure of"one center,one corridor,two axes,two belts and three communities"and traffic system designed to a 3-grade road system of"artery,secondary artery...The planning site was divided into a spatial structure of"one center,one corridor,two axes,two belts and three communities"and traffic system designed to a 3-grade road system of"artery,secondary artery and by-pass".Meanwhile,a 3-ring structure of the planning site was constructed:diffusion waterfront landscape belt,waterfront pathway and core eco-green island.Finally,the planning concepts for major ecological constructions were given.This study tried to explore the group eco-landscape pattern in urban core areas so as to provide a strategic instruction for the regional sustainable development.展开更多
The research purpose is to accurately reveal the temporal and spatial law of the urban expansion of Changsha-Zhuzhou-Xiangtan, one of the seven major urban agglomeration areas in China, and provide decision-making bas...The research purpose is to accurately reveal the temporal and spatial law of the urban expansion of Changsha-Zhuzhou-Xiangtan, one of the seven major urban agglomeration areas in China, and provide decision-making basis for the future urban construction land layout and regional development policy-making. Based on the night lighting data (DMSP/OLS), this paper extracts the boundary of the urban construction land of Changsha-Zhuzhou-Xiangtan urban agglomeration from 1993 to 2017, and quantitatively studies the spatial and temporal characteristics of the expansion of the metropolitan area in the past 25 years according to the methods of spatial expansion analysis, center of gravity migration measurement, landscape pattern index, spatial autocorrelation, etc. The results show that: 1) it is scientific and feasible to extract urban agglomeration construction land by the method of auxiliary data comparison for the study of urban expansion;2) the expansion of regional space in Changsha-Zhuzhou-Xiangtan metropolitan area shows a trend of “weakening first and strengthening later”. The construction land keeps increasing, and the expansion form gradually changes from extensive type to intensive type;3) the center of gravity of the metropolitan area fluctuated and repeated in part during the past 25 years, but it was always located in the municipal district of Changsha city. The eastern region, mainly Changsha city, was still the core area of urban agglomeration expansion;4) strengthening the territorial space protection and control of ecological green core in the metropolitan area is a key measure for the high-quality development of urban agglomeration.展开更多
Grain production core area is key region of modern agricultural development in China. Through summarizing related literature about grain production area and modern agricultural development researches both at home and ...Grain production core area is key region of modern agricultural development in China. Through summarizing related literature about grain production area and modern agricultural development researches both at home and abroad,it obtained characteristics and existing problems in the modern agricultural development of the grain production core area. It is found that there are many research perspectives in modern agricultural development of the grain production core area. On the basis of analyzing the grain production core area and connotation,mode and evaluation of the modern agricultural development,it is concluded that further study should be carried out for adopting which development mode and how to make evaluation,so as to provide theoretical guidance for balanced development of modern agriculture in grain production core area of different regions.展开更多
The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.U...The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.展开更多
Objective:To study the changes of nitric oxide synthase(NOS)activity in penumbral and core area during focal cerebral ischemia and reperfusion,and to explore the therapeutic window of focal cerebral ischemia. Methods...Objective:To study the changes of nitric oxide synthase(NOS)activity in penumbral and core area during focal cerebral ischemia and reperfusion,and to explore the therapeutic window of focal cerebral ischemia. Methods:The middle cerebral artery of rats was occluded for 15,30,60,90 and 120 min by an intraluminal filament respectively,and recirculation was instituted for 24 h.The changes of NOS activity in ischemic core area(parietal cortex and caudoputamen)and penumbral area (frontal cortex)were examined after focal cerebral ischemia and reperfusion using NADPH-d histochemistry technique.Results:The NOS activity of the ischemic penumbral area peaked at 60 min while the ischemic core area peaked at 30 min then declined at 90-120 min sharply.Conclusion:NOS takes part in cerebral ischemic damage during focal cerebral ischemia and reperfusion.The NOS activity of the ischemic penumbral area is different from the ischemic core area.The peak time of the penumbral area is delayed comparing with the core area.The data suggest that the best time to apply NOS inhibitor is within 30 min in ischemic core area, and 60 min in penumbral area.展开更多
Studying tiie urban landscape pattern plays a crucial role in scientific land use and management and in improving the urban ecological environment In this paper, AutoCAD, ArcGIS, Fragstats, and other software were u...Studying tiie urban landscape pattern plays a crucial role in scientific land use and management and in improving the urban ecological environment In this paper, AutoCAD, ArcGIS, Fragstats, and other software were used to analyse the data of the fourth phase of land use in the core atea of Yangling Demonstration Zone. The results showed that: ① in the core area, the percentage of construction land incteased from 18.22% to 61.72%, and the percentage of agricultufal land decreased from 58.36% to 11.14%. And the fafm land was fragmented, and traffic connectivily was strengthened. The afea of garden land was reduced from 251.89 hm2 to 50.38 hm^2, and the landscape metric of forest land showed an inverted V-shaped curve. ②The year 2009 in four phases witnessed the greatest landscape fragmentation, both Edge Density (ED) and Ingest Patch Index (LPI) increased, and human interference enhanced the overall landscape complexity. Measures were fotmulated in terms of deaf development goals, optimized allocation of land resoutces, effective protection of ecological ted lines, and definite ecological responsibility, so as to optimize the urban landscape pattern.展开更多
Urban planning is a process of government as planner to purposefully manage and intervene in the urban development. In this paper,five major tasks for the construction of an international language environment in the c...Urban planning is a process of government as planner to purposefully manage and intervene in the urban development. In this paper,five major tasks for the construction of an international language environment in the core urban areas are proposed from the perspective of urban planning:to explore an effective working mechanism for the construction of the international language environment;to improve the ability of citizens in foreign language communication;to standardize public bilingual notices and signs marking system;to innovate the internationalized operational models of the key industries;to create a multi-functional foreign language consulting service system. Thereby,the objective to improve the international language environment and competitiveness of the urban areas can be accomplished.展开更多
Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples ...Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals.These samples included gneisses rocks,monzogranite,and metavolcano-sedimentary rocks for both the Thalbah and Bayda groups.Using the Rf/j and Fry methods,the axial ratios(XZ)range about 2.20 to 7.10 and 1.90 to 9.10,respectively.For various rock units,the strain measurements show moderate to highly deformation.Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X).The short axes(Z)based to be subvertical foliation related with a subhorizontal foliation.The results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units.It concluded that nappe generation in orogens results from pure shear deformation.展开更多
The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to...The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.展开更多
Shenhu Area is located in the Baiyun Sag of Pearl River Mouth Basin,which is on the northern continental slope of the South China Sea.Gas hydrates in this area have been intensively investigated,achieving a wide cover...Shenhu Area is located in the Baiyun Sag of Pearl River Mouth Basin,which is on the northern continental slope of the South China Sea.Gas hydrates in this area have been intensively investigated,achieving a wide coverage of the three-dimensional seismic survey,a large number of boreholes,and detailed data of the seismic survey,logging,and core analysis.In the beginning of 2020,China has successfully conducted the second offshore production test of gas hydrates in this area.In this paper,studies were made on the structure of the hydrate system for the production test,based on detailed logging data and core analysis of this area.As to the results of nuclear magnetic resonance(NMR)logging and sonic logging of Well GMGS6-SH02 drilled during the GMGS6 Expedition,the hydrate system on which the production well located can be divided into three layers:(1)207.8–253.4 mbsf,45.6 m thick,gas hydrate layer,with gas hydrate saturation of 0–54.5%(31%av.);(2)253.4–278 mbsf,24.6 m thick,mixing layer consisting of gas hydrates,free gas,and water,with gas hydrate saturation of 0–22%(10%av.)and free gas saturation of 0–32%(13%av.);(3)278–297 mbsf,19 m thick,with free gas saturation of less than 7%.Moreover,the pore water freshening identified in the sediment cores,taken from the depth below the theoretically calculated base of methane hydrate stability zone,indicates the occurrence of gas hydrate.All these data reveal that gas hydrates,free gas,and water coexist in the mixing layer from different aspects.展开更多
Kinds of photonic crystal fibers with chalcogenide core tellurite cladding composite microstructure are proposed. The multi-core photonic crystal fiber can reach the higher nonlinearity coefficient and the larger effe...Kinds of photonic crystal fibers with chalcogenide core tellurite cladding composite microstructure are proposed. The multi-core photonic crystal fiber can reach the higher nonlinearity coefficient and the larger effective mode area. The small single-core photonic crystal fiber has a very high nonlinearity coefficient. At the wavelength λ=0.8μm, the nonlinearity coefficient can reach 31.37053 W-1·m-1, at the wavelength λ=1.55μm, the nonlinearity coefficient is 11.19686W-1·m-1.展开更多
文摘The planning site was divided into a spatial structure of"one center,one corridor,two axes,two belts and three communities"and traffic system designed to a 3-grade road system of"artery,secondary artery and by-pass".Meanwhile,a 3-ring structure of the planning site was constructed:diffusion waterfront landscape belt,waterfront pathway and core eco-green island.Finally,the planning concepts for major ecological constructions were given.This study tried to explore the group eco-landscape pattern in urban core areas so as to provide a strategic instruction for the regional sustainable development.
文摘The research purpose is to accurately reveal the temporal and spatial law of the urban expansion of Changsha-Zhuzhou-Xiangtan, one of the seven major urban agglomeration areas in China, and provide decision-making basis for the future urban construction land layout and regional development policy-making. Based on the night lighting data (DMSP/OLS), this paper extracts the boundary of the urban construction land of Changsha-Zhuzhou-Xiangtan urban agglomeration from 1993 to 2017, and quantitatively studies the spatial and temporal characteristics of the expansion of the metropolitan area in the past 25 years according to the methods of spatial expansion analysis, center of gravity migration measurement, landscape pattern index, spatial autocorrelation, etc. The results show that: 1) it is scientific and feasible to extract urban agglomeration construction land by the method of auxiliary data comparison for the study of urban expansion;2) the expansion of regional space in Changsha-Zhuzhou-Xiangtan metropolitan area shows a trend of “weakening first and strengthening later”. The construction land keeps increasing, and the expansion form gradually changes from extensive type to intensive type;3) the center of gravity of the metropolitan area fluctuated and repeated in part during the past 25 years, but it was always located in the municipal district of Changsha city. The eastern region, mainly Changsha city, was still the core area of urban agglomeration expansion;4) strengthening the territorial space protection and control of ecological green core in the metropolitan area is a key measure for the high-quality development of urban agglomeration.
文摘Grain production core area is key region of modern agricultural development in China. Through summarizing related literature about grain production area and modern agricultural development researches both at home and abroad,it obtained characteristics and existing problems in the modern agricultural development of the grain production core area. It is found that there are many research perspectives in modern agricultural development of the grain production core area. On the basis of analyzing the grain production core area and connotation,mode and evaluation of the modern agricultural development,it is concluded that further study should be carried out for adopting which development mode and how to make evaluation,so as to provide theoretical guidance for balanced development of modern agriculture in grain production core area of different regions.
基金the financial support of the National Natural Science Foundation of China(42176212,41976074 and 41302034)the Marine S&T Fund of Shandong Province for Laoshan Laboratory(2021QNLM020002)the Marine Geological Survey Program(DD20221704)。
文摘The Qilian Mountain permafrost area located in the northern of Qinghai-Tibet Plateau is a favorable place for natural gas hydrate formation and enrichment,due to its well-developed fractures and abundant gas sources.Understanding the formation and distribution of multi-component gas hydrates in fractures is crucial in accurately evaluating the hydrate reservoir resources in this area.The hydrate formation experiments were carried out using the core samples drilled from hydrate-bearing sediments in Qilian Mountain permafrost area and the multi-component gas with similar composition to natural gas hydrates in Qilian Mountain permafrost area.The formation and distribution characteristics of multi-component gas hydrates in core samples were observed in situ by X-ray Computed Tomography(X-CT)under high pressure and low temperature conditions.Results show that hydrates are mainly formed and distributed in the fractures with good connectivity.The ratios of volume of hydrates formed in fractures to the volume of fractures are about 96.8%and 60.67%in two different core samples.This indicates that the fracture surface may act as a favorable reaction site for hydrate formation in core samples.Based on the field geological data and the experimental results,it is preliminarily estimated that the inventory of methane stored in the fractured gas hydrate in Qilian Mountain permafrost area is about 8.67×1013 m3,with a resource abundance of 8.67×108 m3/km2.This study demonstrates the great resource potential of fractured gas hydrate and also provides a new way to further understand the prospect of natural gas hydrate and other oil and gas resources in Qilian Mountain permafrost area.
文摘Objective:To study the changes of nitric oxide synthase(NOS)activity in penumbral and core area during focal cerebral ischemia and reperfusion,and to explore the therapeutic window of focal cerebral ischemia. Methods:The middle cerebral artery of rats was occluded for 15,30,60,90 and 120 min by an intraluminal filament respectively,and recirculation was instituted for 24 h.The changes of NOS activity in ischemic core area(parietal cortex and caudoputamen)and penumbral area (frontal cortex)were examined after focal cerebral ischemia and reperfusion using NADPH-d histochemistry technique.Results:The NOS activity of the ischemic penumbral area peaked at 60 min while the ischemic core area peaked at 30 min then declined at 90-120 min sharply.Conclusion:NOS takes part in cerebral ischemic damage during focal cerebral ischemia and reperfusion.The NOS activity of the ischemic penumbral area is different from the ischemic core area.The peak time of the penumbral area is delayed comparing with the core area.The data suggest that the best time to apply NOS inhibitor is within 30 min in ischemic core area, and 60 min in penumbral area.
基金Sponsored by Humanities and Social Sciences Project in Northwest A&F University(2015RWYB38)
文摘Studying tiie urban landscape pattern plays a crucial role in scientific land use and management and in improving the urban ecological environment In this paper, AutoCAD, ArcGIS, Fragstats, and other software were used to analyse the data of the fourth phase of land use in the core atea of Yangling Demonstration Zone. The results showed that: ① in the core area, the percentage of construction land incteased from 18.22% to 61.72%, and the percentage of agricultufal land decreased from 58.36% to 11.14%. And the fafm land was fragmented, and traffic connectivily was strengthened. The afea of garden land was reduced from 251.89 hm2 to 50.38 hm^2, and the landscape metric of forest land showed an inverted V-shaped curve. ②The year 2009 in four phases witnessed the greatest landscape fragmentation, both Edge Density (ED) and Ingest Patch Index (LPI) increased, and human interference enhanced the overall landscape complexity. Measures were fotmulated in terms of deaf development goals, optimized allocation of land resoutces, effective protection of ecological ted lines, and definite ecological responsibility, so as to optimize the urban landscape pattern.
基金The Philosophy and Social Science Planning Project of Henan Province(No.2013BYY013)the Key Humanities and Social Science Project of the Educational Department of Henan Province(No.2010-ZD 021)
文摘Urban planning is a process of government as planner to purposefully manage and intervene in the urban development. In this paper,five major tasks for the construction of an international language environment in the core urban areas are proposed from the perspective of urban planning:to explore an effective working mechanism for the construction of the international language environment;to improve the ability of citizens in foreign language communication;to standardize public bilingual notices and signs marking system;to innovate the internationalized operational models of the key industries;to create a multi-functional foreign language consulting service system. Thereby,the objective to improve the international language environment and competitiveness of the urban areas can be accomplished.
基金supported and funded by the Researchers Supporting Project(Project No.RSPD2024R781),King Saud University,Riyadh,Saudi Arabia。
文摘Identifying deformational mechanisms and associated structures at various scales,ranging from regional-scale structures to microscopic fabric,is crucial for the assessment of tectonic development.Thirty-three samples were taken from the Qazzaz metamorphic core complex to estimate the finite strain for felsic and mafic minerals.These samples included gneisses rocks,monzogranite,and metavolcano-sedimentary rocks for both the Thalbah and Bayda groups.Using the Rf/j and Fry methods,the axial ratios(XZ)range about 2.20 to 7.10 and 1.90 to 9.10,respectively.For various rock units,the strain measurements show moderate to highly deformation.Most of the observed samples show shallow WNW dipping along a N to WNW trend of finite strain(X).The short axes(Z)based to be subvertical foliation related with a subhorizontal foliation.The results demonstrate that contacts generated at semi-brittle to ductile deformation and that the strain of magnitude has the same value for different lithologic units.It concluded that nappe generation in orogens results from pure shear deformation.
文摘The selected area electron diffraction (SAED) pattern of magnetic iron oxide core/gold shell nanoparticles has been studied. For the composite particles with mean size less than 10 nm, their SAED pattern is found to be different from either the pattern of pure Fe oxide nanoparticles or that of pure Au particles. Based on the fact that the ring diameters of these composite particles fit the characteristic relation for the fcc structure, the Au atoms on surfaces of the concerned particles are supposed to pack in a way more tightly than they usually do in pure Au nanoparticles. The driving force for this is the coherency strain which enables the shell material at the heterostructured interface to adapt the lattice parameters of the core.
基金Jointly funded by a major research plan of National Natural Science Foundation of China(51991365)titled“Multi-Field Spatial-Temporal Evolution Laws of Phase Transition and Seepage of Natural Gas Hydrate in Reservoirs”and a geological survey project initiated by China Geological Survey(DD20190226)titled“Implementation of Natural Gas Hydrate Production Test in Pilot Test Area in Shenhu Area”.
文摘Shenhu Area is located in the Baiyun Sag of Pearl River Mouth Basin,which is on the northern continental slope of the South China Sea.Gas hydrates in this area have been intensively investigated,achieving a wide coverage of the three-dimensional seismic survey,a large number of boreholes,and detailed data of the seismic survey,logging,and core analysis.In the beginning of 2020,China has successfully conducted the second offshore production test of gas hydrates in this area.In this paper,studies were made on the structure of the hydrate system for the production test,based on detailed logging data and core analysis of this area.As to the results of nuclear magnetic resonance(NMR)logging and sonic logging of Well GMGS6-SH02 drilled during the GMGS6 Expedition,the hydrate system on which the production well located can be divided into three layers:(1)207.8–253.4 mbsf,45.6 m thick,gas hydrate layer,with gas hydrate saturation of 0–54.5%(31%av.);(2)253.4–278 mbsf,24.6 m thick,mixing layer consisting of gas hydrates,free gas,and water,with gas hydrate saturation of 0–22%(10%av.)and free gas saturation of 0–32%(13%av.);(3)278–297 mbsf,19 m thick,with free gas saturation of less than 7%.Moreover,the pore water freshening identified in the sediment cores,taken from the depth below the theoretically calculated base of methane hydrate stability zone,indicates the occurrence of gas hydrate.All these data reveal that gas hydrates,free gas,and water coexist in the mixing layer from different aspects.
基金the National Natural Science Foundation of China(Grant Nos.61178026 and 60978028)the Specialized Research Fund for the Doctoral Program of Higher Education of China(Grant No.20091333110010)the Natural Science Foundation of Hebei Province,China(Grant No.E2012203035)
文摘Kinds of photonic crystal fibers with chalcogenide core tellurite cladding composite microstructure are proposed. The multi-core photonic crystal fiber can reach the higher nonlinearity coefficient and the larger effective mode area. The small single-core photonic crystal fiber has a very high nonlinearity coefficient. At the wavelength λ=0.8μm, the nonlinearity coefficient can reach 31.37053 W-1·m-1, at the wavelength λ=1.55μm, the nonlinearity coefficient is 11.19686W-1·m-1.