Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and speci...Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.展开更多
Acenapththylene-imide(An I),similar to naphthalene diimide(NDI),is an outstanding building block for organic functional materials and has gained a lot of research attention.Herein,Sulphur and Selenium-embedded AnI-con...Acenapththylene-imide(An I),similar to naphthalene diimide(NDI),is an outstanding building block for organic functional materials and has gained a lot of research attention.Herein,Sulphur and Selenium-embedded AnI-containing polycyclic aromatic hydrocarbon molecules,AnI-SQ and AnI-SeQ,with[1,2,5]thiadiazolo[3,4-g]quinoxaline(SQ)and[1,2,5]selenadiazolo[3,4-g]quinoxaline(Se Q)are designed and synthesized with low-lying LUMO energy levels.The absorption and emission of AnI-SQ and An I-Se Q displayed a bathochromic shift upon protonation of the C=N bond.Besides,theoretical calculation indicates remarkable rigid planar backbones for both An I-SQ and An I-Se Q.Through self-assembly with polymeric Pluronic?F-127,corresponding hydrophilic nanoparticles(NPs)were prepared with low cytotoxicity.And AnI-SQ NPs could be applied for in vitro two-photon fluorescence imaging.展开更多
While the procurement of state enterprises is one of the most contentious issues for China＇s GPA accession negotiation, the regulation on such procurement is also of concerns under domestic law. From the Chinese dome...While the procurement of state enterprises is one of the most contentious issues for China＇s GPA accession negotiation, the regulation on such procurement is also of concerns under domestic law. From the Chinese domestic perspective, this Article first analyses the extent to which the procurement of state enterprises is regulated by national, ministerial, as well as firm-level procurement rules. On that basis, the incentives for adopting a principled approach to regulating such procurement are explored, such as value for money, preventing corruption, and fighting against local protectionism. A brief suggestion is made regarding the consolidation of the existing rules in the context of complicated underlying institutional framework.展开更多
基金supported by the National Natural Science Foundation of China(No.32060247)the Central Guidance on Local Science and Technology Development Fund of Gansu Province(No.22ZY2QG001).
文摘Research on the spatial patterns of tree populations is critical for understanding the structure and dynamic processes of forests.However,little is known about how the underlying drivers shape these patterns and species interactions in forest systems.In this study,spatial point pattern analysis investigated the combined eff ects of intraspecifi c interactions and environmental heterogeneity on the spatial structure and internal maintenance mechanisms of Picea crassifolia in the Qilian Mountain National Nature Reserve,China.Data were obtained from a 10.2-ha dynamic monitoring plot(DMP)and sixteen 0.04-ha elevation gradient plots(EGPs).Under complete spatial randomness,both mature trees and saplings in the DMP demonstratedlarge-scale aggregation with negative correlations.In EGPs,saplings were clustered in small mesoscales,mature trees were randomly distributed,and the interactions of saplingstrees at all elevations were not correlated.By eliminating the interference of environmental heterogeneity through the inhomogeneous Poisson process,saplings in the DMP and EGPs were clustered in small scales and trees randomly distributed.Intraspecifi c associations were negatively correlated,in the DMP and at low elevations,and no correlations in high elevations of EGPs.In the vertical scale,saplings showed a small-scale aggregation pattern with increase in elevation,and the aggregation degree fi rst decreased and then increased.The interactions of saplings-trees and saplings–saplings showed inhibitions at small scales,with the degree of inhibition gradually decreasing.Spatial patterns and associations of adults–adults did not change signifi-cantly.The results revealed that intraspecifi c interactions and environmental heterogeneity regulated the spatial patterns of P.crassifolia at small and large scales,respectively.Environmental heterogeneity might be the most decisive factor aff ecting the spatial patterns of saplings,while trees were more aff ected by intraspecifi c interactions.Moreover,competition between trees in this area could be more common than facilitation for the growth and development of individuals.
基金supported by the National Natural Science Foundation of China (61525402, 61775095 and 5161101159)Jiangsu Provincial Key Research and Development Plan (BE2017741)
基金supported by the National Natural Science Foundation of China (61604071, 61525402, 61604119, 61704131 and 61775095)Natural Science Foundation of Jiangsu Province (BK20161012)+1 种基金Postgraduate Research & Practice Innovation Program of Jiangsu Province (SJZZ16_0139)SICAM Scholarship (38600001)
基金supported by the Natural Science Foundation of Jiangsu Province(No.BK20200092)the National Natural Science Foundation of China(No.21972067)。
文摘Acenapththylene-imide(An I),similar to naphthalene diimide(NDI),is an outstanding building block for organic functional materials and has gained a lot of research attention.Herein,Sulphur and Selenium-embedded AnI-containing polycyclic aromatic hydrocarbon molecules,AnI-SQ and AnI-SeQ,with[1,2,5]thiadiazolo[3,4-g]quinoxaline(SQ)and[1,2,5]selenadiazolo[3,4-g]quinoxaline(Se Q)are designed and synthesized with low-lying LUMO energy levels.The absorption and emission of AnI-SQ and An I-Se Q displayed a bathochromic shift upon protonation of the C=N bond.Besides,theoretical calculation indicates remarkable rigid planar backbones for both An I-SQ and An I-Se Q.Through self-assembly with polymeric Pluronic?F-127,corresponding hydrophilic nanoparticles(NPs)were prepared with low cytotoxicity.And AnI-SQ NPs could be applied for in vitro two-photon fluorescence imaging.
文摘While the procurement of state enterprises is one of the most contentious issues for China＇s GPA accession negotiation, the regulation on such procurement is also of concerns under domestic law. From the Chinese domestic perspective, this Article first analyses the extent to which the procurement of state enterprises is regulated by national, ministerial, as well as firm-level procurement rules. On that basis, the incentives for adopting a principled approach to regulating such procurement are explored, such as value for money, preventing corruption, and fighting against local protectionism. A brief suggestion is made regarding the consolidation of the existing rules in the context of complicated underlying institutional framework.
