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| 1 | Growth–climate response and drought reconstruction from tree-ring of Mongolian pine in Hulunbuir,Northeast China显示文摘Aims Drought affected by atmosphere–ocean cycle is a dominant factor influencing tree radial growth of sandy Mongolian pine(Pinus sylvestris var.mongolica)and regional vegetation dynamics in Hulunbuir,China.However,historical droughts and its correlations with tree radial growth and atmosphere–ocean cycle in this area have been little tested.Methods We developed tree-ring chronologies of Mongolian pine from Hulunbuir,Inner Mongolia,China and analyzed the correlations between tree-ring width index,the normalized difference vegetation index and Palmer drought severity index(PDSI),then developed a linear model to reconstruct the drought variability from 1829 to 2009.Long-term trends and its linkages with atmosphere–ocean cycle were performed by the power spectral,wavelet and teleconnection analysis.Important Findings The local moisture variations affected largely the regional vegetation dynamics and tree-ring growth of Mongolia pine in the forest–grassland transition.Using tree-ring width chronology of Mongolian pine,the reconstruction explains 49.2%of PDSI variance during their common data period(1951–2005).The reconstruction gives a broad-scale regional representation of PDSI in the Hulunbuir area,with drought occurrences in the 1850s,1900s,1920s,mid-1930s and at the turn of the 21st century.Comparisons with other treering drought reconstructions and historical records reveal some common drought periods and drying trends in recent decades at the northern margin zones of the East Asian summer monsoon(EASM).The drying trends in these zones occurred earlier than weakening of the EASM.A REDFIT spectral analysis shows significant peaks at 7.2,3.9,2.7–2.8,2.4 and 2.2 years with a 0.05 significance level,and 36.9,18.1 and 5.0 years with 0.1 significance level.Wavelet analysis also shows similar cycles.Drought variations in the study area significantly correlated with sea surface temperatures in the western tropical Pacific Ocean and middle and northern Indian Ocean,and the Pacific Decadal Oscillation and North Atlantic Oscillation.This suggests a possible linkage with the El Niño-Southern Oscillation,the EASM and the Westerlies. | Zhongjie Shi Lihong Xu Linshui Dong Jixi Gao Xiaohui Yang Shihai Lü Chaoyang Feng Aiyun Song Hao Guo Xiao Zhang | 2016 | Journal of Plant Ecology2016，9，1： | 3 |
| 2 | Three novel photoisomeric compounds of the 4-acyl pyrazolone derivants: Crystal structures and substituent effects on photo-isomerism in solid state显示文摘Three new photoisomeric compounds: 1,3-diphenyl-4-benzal-5-pyrazolone 4-methylthiosemicarbazone (DPBP-MTSC), 1,3-diphenyl-4-(4′-methylbenzal)-5-pyrazolone 4-methylthiosemicarbazone (DP4MBP- MTSC), and 1,3-diphenyl-4-(4′-bromobenzal)-5-pyrazolone 4-methylthiosemicarbazone (DP4BrBP-MTSC) were synthesized by direct condensation of pyrazolones and 4-methylthiosemicarbazone. Their struc- tures were confirmed using 1H NMR, IR, elemental analyses, and X-ray crystallographic analyses. The photoisomeric properties in the solid state were studied under UV light irradiation and the photo- isomerization phenomena were interpreted by the double proton-transfer mechanism. Moreover, the effects of different substituent groups at the 4-position of the benzal in the three compounds on the photoisomeric properties were discussed. | WANG JunHua LIU Lang LIU GuangFei GUO JiXi JIA DianZeng | 2008 | Science China Chemistry2008，51，7： | 1 |
| 3 | Syntheses, crystal structures and thermal behaviors of three complexes with 4-acyl pyrazolone derivatives 显示文摘 | Yang Yun Zhang Li Liu Lang Liu Guangfei Guo Jixi Jia Dianzeng | 2007 | Inorganic Chimica Acta2007，360，： | 1 |
| 4 | Ultrathin oxygen-containing graphdiyne wrapping CoP for enhanced electrocatalytic hydrogen generation显示文摘Graphdiyne(GDY)is fascinating in the construction of efficient and stable catalysts,but their performance is still somewhat restricted due to GDY’s thicker layers,as well as hydrophobic and relatively chemically inert surfaces.Herein,via oxidationexfoliation-reduction strategy,the self-supported electrode material of CoP nanosheets with ultrathin oxygen-containing GDY wrapping(CoP@RGDYO)for effective HER is constructed.The wrapping of ultrathin oxygen-containing GDY promotes charge transfer,improves the surface property,and enhances the acid and alkali resistance as well as the structural stability of the catalyst.As a result,CoP@RGDYO shows enhanced activity and stability in both acidic and alkaline media.Especially,it exhibits a low overpotential of 86 mV and exceptional stability under a 14000-cycle cyclic voltammetry scanning in alkaline media.This work provides new ideas for the design of GDY hybrid materials and the preparation of high-efficiency catalysts. | Yan Lv Xueyan Wu Hao Li Hongbo Zhang Jiaxin Li Zhiyou Zhou Jixi Guo Dianzeng Jia | 2023 | Nano Research2023，16，4： | 0 |
| 5 | Heterometallic copper(Ⅱ) vanadates: synthesis, crystal structures and third-order nonlinear optical properties显示文摘Three polymeric heterometallic clusters with 1D, 2D, and 3D frameworks, constructed from a cyclic vanadate {V4O12}4-building block and three geometric constraint ligands, were synthesized by a one-pot self-assembly reaction. Z-scan experiments demonstrated that all the three cluster polymers have large hyperpolarizability γ values. TD-DFT calculations afforded insight into the electronic transitions and spectral characterization of these novel NLO molecular materials. | LIU FaQian WANG Lei GUO JiXi LI WeiHua LI ChaoQin JIN YanLing LI RongXun JIAN FangFang | 2014 | Science China Chemistry2014，57，9： | 0 |
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