Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups in...Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.展开更多
We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in s...We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in south China.We used a stratified cluster sampling method to recruit middle school students in a city experiencing population-emigration in Jiangxi Province in 2010.Participants included adolescents from families with:(1)one migrant parent,(2)both parents who migrated,or(3)non-left behind adolescents(i.e.,no migrant parent).To determine predictors of subjective well-being,we used structural equation models.Adolescents left behind by both parents(LBB)were less likely to express life satisfaction(P=0.038)in terms of their environments(P=0.011)compared with NLB.A parent or parents who migrated predicts lower subjective well-being of adolescents(P=0.051)and also lower academic performance.Being apart from their parents may affect family functioning negatively from an adolescent's viewpoint.Given the hundreds of millions of persons in China,many who are parents,migrating for work,there may be mental health challenges in some of the adolescents left behind.展开更多
Using data from the regional broadband dense temporary array deployed by the ChinArray project,we applied the three-dimensional(3D)Kirchhoff migration method of the teleseismic P-wave receiver function to investigate ...Using data from the regional broadband dense temporary array deployed by the ChinArray project,we applied the three-dimensional(3D)Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone(MTZ)in the central and western parts of the North China Craton(NCC)using a highresolution 3D velocity model of the East Asian region.The results show that the 410-km discontinuity beneath the Datong Volcano is depressed by~10 km,indicating the presence of a high-temperature anomaly near the depth of 410 km,which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the MTZ.The upwelling of hot material provides a heat source for surface magmatic activity.Beneath the Bohai Bay Basin,significant subsidence of the 660-km discontinuity is observed,and the transition zone here is extensively thickened.It’s suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the MTZ.Although the thickness of the transition zone west of the North-South Gravity Lineament appears normal,we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the NCC.In comparison,the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the MTZ.Furthermore,a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling Mountains.This is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate.展开更多
A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short perio...A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short period variations in the profile region was analyzed through geomagnetic transfer functions at measurement sites (Fan, et al, 1998). According to the theory of multi-scale analysis of wavelet transform, the components affected by regional origin in the region is extracted in this paper. The components of regional origin is used as original data in the inversion study for investigation of 2-D conductivity structure corresponding to the regional origin. The inversion method (Zhdanov, Traynin, 1997) which is based on the minimum of the total energy of the residual field between observational electro-magnetic field and the calculated theoretical field of conductivity model and the conception of migrated residual field is introduced into our inversion of the data of magneto-variation sounding. The result of the inversion gives the underground conductivity structure in depth range of 100 km beneath the profile, and shows that a high conductivity area is located under Wugong and Qianling. The main characteristics of the inversion method is briefly discussed, that is, it can reflect the depth and the distribution of anomalous conductivity area comparatively well, and large number of parameters of inversion model is allowed to be used in the Inversion.展开更多
With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sc...With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sciences demonstrate the in-situ atomic-scale electrically induced展开更多
A conceptually novel,trifunctional sulfoximine-mediatedγ-functionalization of unactivated C(sp^(3))–H bonds has been achieved.The reaction is initiated by the photo-induced homolytic cleavage of an N–S bond in the ...A conceptually novel,trifunctional sulfoximine-mediatedγ-functionalization of unactivated C(sp^(3))–H bonds has been achieved.The reaction is initiated by the photo-induced homolytic cleavage of an N–S bond in the absence of photosensitizer,and proceeds sequentially through a cascade of 1,5-hydrogen atom transfer,1,4-functional group migration,desulfoximination and a Minisci reaction.A major feature of this approach is the use of sulfoximine as a traceless directing group.Other positive properties include mild conditions,simple operation,exclusive site-selectivity,high product diversity and the avoidance of additional photosensitizers.The protocol provides a new reaction mode for HAT-induced C(sp^(3))–H functionalization,and allows a much broader chemical space for sulfoximine studies.展开更多
A novel photoinduced intermolecular 1,2-arylheteroarylation of alkenes and the efficient synthesis of valuable polyarylalkanes are reported.The reaction is operationally simple,proceeds under mild conditions and with ...A novel photoinduced intermolecular 1,2-arylheteroarylation of alkenes and the efficient synthesis of valuable polyarylalkanes are reported.The reaction is operationally simple,proceeds under mild conditions and with no additional catalyst and reagents.The strategically designed radical cascade reaction is enabled by electron transfer,and involves cleavage of an inert C–C bond.The process features broad functional group compatibility as well as high product transformability.展开更多
文摘Difunctionalization of unsaturated hydrocarbons is a pivotal synthetic strategy enabling the conversion of alkenes and alkynes into high value-added compounds.It allows for the introduction of two functional groups into the unsaturated bond in a single step,facilitating the efficient construction of complex molecular architectures,which has been widely utilized in material chemistry,pharmaceutical and fine chemical synthesis.Recently,significant progress has been made via free radical-mediated difunctionalization due to the extensive application of photocatalysis.However,highly selective difunc-tionalization reactions still remain challenging.The research progress of selective difunctionalization of unsaturated hydro-carbons using a free radical addition/functional group migration strategy over the past decade is summarized,and synthetic strategies and key reaction steps are systematically elaborated.
基金supported by Sub Four Programme of Public Health Welfare Research Special Funds[grants No.201202010]Natural Science Fund Commission of China[H2609/81673232]the Yale Center for Interdisciplinary Research on Acquired Immune Deficiency Syndrome supported by National Institutes of Health grant[P30MH062294]
文摘We sought to identify the differences between adolescents left behind in their home villages/towns(LBA)and non-left behind adolescents(NLB)on subjective well-being and family functioning due to parental migration in south China.We used a stratified cluster sampling method to recruit middle school students in a city experiencing population-emigration in Jiangxi Province in 2010.Participants included adolescents from families with:(1)one migrant parent,(2)both parents who migrated,or(3)non-left behind adolescents(i.e.,no migrant parent).To determine predictors of subjective well-being,we used structural equation models.Adolescents left behind by both parents(LBB)were less likely to express life satisfaction(P=0.038)in terms of their environments(P=0.011)compared with NLB.A parent or parents who migrated predicts lower subjective well-being of adolescents(P=0.051)and also lower academic performance.Being apart from their parents may affect family functioning negatively from an adolescent's viewpoint.Given the hundreds of millions of persons in China,many who are parents,migrating for work,there may be mental health challenges in some of the adolescents left behind.
基金supported by the National Key Research and Development Program of China(Grant No.42030310)the Special Fund of the Institute of Geophysics,China Earthquake Administration(Grant No.DQJB23K42)the National Key Research and Development Program of China(Grant No.41874073)。
文摘Using data from the regional broadband dense temporary array deployed by the ChinArray project,we applied the three-dimensional(3D)Kirchhoff migration method of the teleseismic P-wave receiver function to investigate discontinuity structures of the mantle transition zone(MTZ)in the central and western parts of the North China Craton(NCC)using a highresolution 3D velocity model of the East Asian region.The results show that the 410-km discontinuity beneath the Datong Volcano is depressed by~10 km,indicating the presence of a high-temperature anomaly near the depth of 410 km,which is likely related to small-scale mantle upwelling caused by the dehydration of the stagnant Pacific Plate in the MTZ.The upwelling of hot material provides a heat source for surface magmatic activity.Beneath the Bohai Bay Basin,significant subsidence of the 660-km discontinuity is observed,and the transition zone here is extensively thickened.It’s suggested that the anomalies in this region are related to the stagnation of the Pacific slab in the MTZ.Although the thickness of the transition zone west of the North-South Gravity Lineament appears normal,we propose that the subducting front of the Pacific slab did not cross the gravity lineament in the NCC.In comparison,the small-scale subsidence of the 660-km discontinuity and the thickening of the MTZ observed north of the Hannuoba Volcano likely indicate that the slab crossed the gravity lineament at its turning point and remained in the MTZ.Furthermore,a local thickening of the MTZ is observed in the Dabie orogenic belt of the Qinling Mountains.This is believed to be a combined effect of lithospheric delamination into the transition zone in the lower Yangtze region and the stagnation of the Pacific Plate.
文摘A temporary profile from Shiquan in the southern part of Shaanxi Province to Ningxian in Gansu Province for observation of geomagnetic short period variations was set up. The characteristics of geomagnetic short period variations in the profile region was analyzed through geomagnetic transfer functions at measurement sites (Fan, et al, 1998). According to the theory of multi-scale analysis of wavelet transform, the components affected by regional origin in the region is extracted in this paper. The components of regional origin is used as original data in the inversion study for investigation of 2-D conductivity structure corresponding to the regional origin. The inversion method (Zhdanov, Traynin, 1997) which is based on the minimum of the total energy of the residual field between observational electro-magnetic field and the calculated theoretical field of conductivity model and the conception of migrated residual field is introduced into our inversion of the data of magneto-variation sounding. The result of the inversion gives the underground conductivity structure in depth range of 100 km beneath the profile, and shows that a high conductivity area is located under Wugong and Qianling. The main characteristics of the inversion method is briefly discussed, that is, it can reflect the depth and the distribution of anomalous conductivity area comparatively well, and large number of parameters of inversion model is allowed to be used in the Inversion.
文摘With the support of the National Natural Science Foundation of China,two original studies by the research group led by Prof.Gu Lin(谷林)and Prof.Zhang Qinghua(张庆华)from the Institute of Physics,Chinese Academy of Sciences demonstrate the in-situ atomic-scale electrically induced
基金supported by the National Natural Science Foundation of China(21971173,22001185,22171201)the Natural Science Foundation of Jiangsu Province(BK20200852)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘A conceptually novel,trifunctional sulfoximine-mediatedγ-functionalization of unactivated C(sp^(3))–H bonds has been achieved.The reaction is initiated by the photo-induced homolytic cleavage of an N–S bond in the absence of photosensitizer,and proceeds sequentially through a cascade of 1,5-hydrogen atom transfer,1,4-functional group migration,desulfoximination and a Minisci reaction.A major feature of this approach is the use of sulfoximine as a traceless directing group.Other positive properties include mild conditions,simple operation,exclusive site-selectivity,high product diversity and the avoidance of additional photosensitizers.The protocol provides a new reaction mode for HAT-induced C(sp^(3))–H functionalization,and allows a much broader chemical space for sulfoximine studies.
基金the National Natural Science Foundation of China(21971173)the Project of Scientific and Technologic Infrastructure of Suzhou(SZS201905)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘A novel photoinduced intermolecular 1,2-arylheteroarylation of alkenes and the efficient synthesis of valuable polyarylalkanes are reported.The reaction is operationally simple,proceeds under mild conditions and with no additional catalyst and reagents.The strategically designed radical cascade reaction is enabled by electron transfer,and involves cleavage of an inert C–C bond.The process features broad functional group compatibility as well as high product transformability.
