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A study on environmental aridity over northern and southern to Qinling Mountains under climate warming

Journal of Geographical Sciences 2001年第2期11卷 193-201页

作者： YAN Jun-ping~1, LIU Yan-sui~2 (1. college of tourism and environment, Shaanxi normal university, Xi’an 710062, china 2. Institute of Geographic Sciences and Natural resources Research, CAS, beijing 100101, china) college of tourism and environment Shaanxi Normal University Institute of Geographic Sciences and Natural resources Research CAS

Based on the data up to 1999 from hydroclimatological departments, this pape analyzes the climatic divide implications of the Qinling Mountains in regional response to the process of climate warming, due to which the grades of dryness/wetness (GDW) in 100 years show that the northern region has entered a drought period, while the southern is a humid period. In a course of ten years, the D-value of annual average air temperature over southern Shaanxi (the Hanjiang Valley) and the Central Shaanxi Plain (the Guanzhong Plain) has narrowed, i.e., the former with a slight change and the latter with rapid increase in temperature. Both regions were arid with the decrease in precipition D-value, namely the plain became warmer while the south was drier. The Qinling Mountains play a pronounced role in the climatic divide. The runoff coefficient (RC) of the Weihe River decreases synchronously with that of the Hanjiang due to climate warming. The RC of Weihe dropped from 0.2 in the 1950s to less than 0.1 in the 1990s. The Weihe Valley (the Guanzhong Plain) is practically an arid area due to shortage of water. The successive 0.5, 1.0°C temperature anomaly over china marks, perhaps, the improtant transition period in which the environment becomes more vulnerable than before. The study shows the obvious trend of environmental aridity, which is of help to the understanding of regional response to global climate change.

关键词： climate change aridity Qinling Mountains

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Predicting bioconcentration factor values of organic pollutants based on medv descriptors derived QSARs

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Science china Chemistry 2007年第5期50卷 587-592页

作者： CUI ShiHai1,2, YANG Jing1, LIU ShuShen2,3 & WANG LianSheng2 1 college of Chemistry and environment, Nanjing normal university, Nanjing 210097, china 2 State Key Laboratory of Pollution Control and resources Reuse, School of the environment, Nanjing university, Nanjing 210093, china 3 Key Laboratory of Yangtze Aquatic environment, Ministry of Education, college of environmental Science and Engineering, Tongji university, Shanghai 200092, china 1. college of Chemistry and environment Nanjing Normal University Nanjing 210097 China 2. State Key Laboratory of Pollution Control and resources Reuse School of the Environment Nanjing University Nanjing 210093 China 3. Key Laboratory of Yangtze Aquatic environment Ministry of Education College of Environmental Science and Engineering Tongji University Shanghai 200092 China

The molecular electronegativity-distance vector (MEDV) is employed todescribe the chemical structure of organic *** linear relationships between themolecular descriptors and BCF values are developed by best subset regression and partial leastsquare regression *** main structural factors influencing the bioactivities are -CH2,-X,-Cnot <,- C not <,-O-.The high values of r2 and q2_(LOO) present good estimation ability and stabilityof *** prediction power for external samples is validated by the model developed from thetraining set.

关键词： POPs, BCF, MEDV, QSAR

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Root Growth Potential and Energy Sources for New Root Growth of Three Conifer Species in Northern china

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北京林业大学学报 1993年第S3期 10-22页

作者： Liu Yong Forest resources college,beijing Forestry university

Seedlings of Pinus sylvestris var. mongolica, Larix principis—rupprechtii and Platycladus orientaliswere lifted from the nursery in March and transplanted to favorable growing conditions in a controlledenvironment chamber. The test of RGP showed that Platycladus orientalis seedlings had the greatest RGP amongthe three species, any one of the four parameters as TNR, TNR>1, TLR>1 and SAI could representthe RGP of Platycladus orientalis. However, at least two parameters (TNR and any one of TNR>1,TLR>1, SAI)must be used to represent the RGP of Larix principis—rupprechtii and Pinus sylvestris *** seedlings due to the weak correlation between root initiation and root elongation for the twospecies. The results of the RGP test and carbohydrate analysis for different treatments demonstrated thatcurrent photosynthate is needed for new root growth in Pinus sylvestris var. mongolica seedlings, whereasstored-carbohydrates provided the energy source for new root initiation. Current photosynthate is also neededfor root elongation in Larix principis — rupprechtii seedlings; New root growth of Platycladus orientalisseedlings is primarily caused by current photosynthate, but some reserve materials may be utilized at thesame time if photosynthesis is inadequate to meet growth demands.

关键词： root growth potential(RGP) current photosynthate stored carbohydrates

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Azomethine ylide-formation from N-phthaloylglycine by photoinduced decarboxylation:A theoretical study

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中国科学:化学 2012年第10期42卷 1499-1500页

作者： FANG Qiu,DING LiNa & FANG WeiHai* college of Chemistry,beijing normal university,beijing 100875,china college of Chemistry beijing normal university beijing 100875 china

In this work,we report the first CASPT2//CASSCF study of the mechanism of the photodecarboxylation of *** charge transfer excited state SCT(1ππ*) is initially populated upon irradiation at 266 *** a result of a fast internal conversion to the lowest excited singlet state SCT-N(1ππ*),this state becomes a favorable precursor state for proton transfer,which triggers ***,the excited state intramolecular proton transfer(ESIPT) and decarboxylation processes proceed in an asynchronous concerted *** ESIPT process is accomplished in the SCT-N(1ππ*) state,but the CO2 molecule is finally formed in the ground state via the SCT/S0 conical *** ylide is formed in the ground state as a complex with CO2.A barrier of ～15 kcal/mol indicates that azomethine ylide is stable in the ground state,which is consistent with the experimental *** work provides mechanistic details about the formation of azomethine ylide by photoreaction of N-phthaloylglycine.

关键词： N-phthaloylglycine photodecarboxylation excited state intramolecular proton transfer CASPT2//CASSCF method

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The ε-Complexity of the Approximate Solution of Integral Equations with Isotropic Kernels

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Acta Mathematica Sinica,English Series 2002年第4期18卷 679-686页

作者： Wan MA Gen Sun FANG college of Mathematics & Information Science of Wenzhou university, Wenzhou 325027, P. R. china Department of Mathematics, beijing normal university, beijing 100875, P. R. china college of Mathematics & Information Science of Wenzhou university Wenzhou 325027 P. R. China Department of Mathematics Beijing Normal University Beijing 100875 P. R. China

The exact order of s-complexity is determined in L_p (2≤p≤∞) spaces for the second kind of Fredholm integral equations with kernels belonging to an isotropic Sobolev class.

关键词： Fredholm equation ε-complexity Sobolev classes

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Theoretical study on thermal decomposition of azoisobutyronitrile in ground state

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Science china Chemistry 2004年第5期47卷 373-380页

作者： SUN Chengke1,2, ZHAO Hongmei1 & LI Zonghe1 1. Department of Chemistry, beijing normal university, beijing 100875, china 2. Department of Chemistry, Qujing normal college, Qujing 655000, china 1. Department of Chemistry Beijing Normal University 100875 Beijing China 2. Department of Chemistry Qujing Normal College 655000 Qujing China

The thermal decomposition mechanisms of azoisobutyronitrile (AIBN) in the ground state have been investigated systematically. Based on the potential energy surfaces (PES) of various possible dissociation paths obtained using the semiempirical AM1 method with partial optimization, the density function theory B3LYP/6-311G* method was employed to optimize the geometric parameters of the reactants, the intermediates, the products and the transition states, which were further confirmed by the vibrational analysis. The obtained results show that the re- action process of the two-bond (three-body) simultaneous cleavage Me2(CN)C─ N=N─ C(CN)Me2? 2Me2(CN)C?+N2 is much more favorable than the reaction process of the two one- bond asynchronous cleavage Me2(CN)CN=N─C(CN)Me2 ? Me2(CN)CN=N?+ Me2(CN)C?? Me2(CN)C?+ N2. It was suggested that the electron shrinking effect of double bond (─N=N─) in AIBN and the stabilities of the Me2(CN)C?radical as well as N2 molecule are main factors of leading to the reaction proceeding in the former pathway. The calculation results were consistent with all the experimental facts.

关键词： azoisobutyronitrile, radicals, thermal decomposition, density function theory (DFT).

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Constraints of authigenic carbonates on trace elements (Sr,Mg) of lacustrine ostracod shells in paleoenviron-ment reconstruction and its mechanism

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Science china Earth Sciences 2008年第5期51卷 654-664页

作者： HU Guang1,2, JIN ZhangDong1 & ZHANG Fei3 1 State Key Laboratory of Loess and Quaternary Geology, Institute of Earth environment, Chinese Academy of Sciences, Xi’an 710075, china 2 Graduate university of the Chinese Academy of Sciences, beijing 100049, china 3 college of resources and environmental Science, Nanjing Agricultural university, Nanjing 210095, china State Key Laboratory of Loess and Quaternary Geology Institute of Earth Environment Chinese Academy of Sciences Xi’an 710075 China Graduate university of the Chinese Academy of Sciences Beijing 100049 China college of resources and Env

Molar ratios of Mg/Ca and Sr/Ca were measured in two species of ostracod shells preserved in the upper core (15–55 m) of the Hequing Basin in Yunnan Province, southwest china. By correlating the molar ratios between Mg/Ca and Sr/Ca and comparing them with Sr concentrations of the sediments, we suggested that: (1) the molar Mg/Ca and Sr/Ca ratio variations in respective ostracod primo reflected the changes in its ambient water composition and ecology; (2) the molar Sr/Ca ratios responded better to the salinity change linearly than Mg/Ca without aragonite precipitation in the system, and otherwise there was no linear relation between them; and (3) the molar Sr/Ca ratios were mainly controlled by salinity and authigenic carbonate precipitation, whereas the molar Mg/Ca ratios were related to both salinity and temperature. In fact, the rate of ostracod growth owing to temperature controls the fluctuation of Mg/Ca in shells. Here, more attentions should be paid to the constraint of authigenic mineral precipitation processes on the trace elements in ostracod shells and to the correlation between these trace elements in biogenic carbonates and compositions of the sediments in systems and in future in vitro experiments.

关键词： ostracod shell molar Sr/Ca ratio molar Mg/Ca ratio environmental response Heqing Basin

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Sediment transport capacity of hyperconcentrated flow

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Science china(Physics,Mechanics & Astronomy) 2008年第8期51卷 961-975页

作者： SHU AnPing1,2 & FEI XiangJun2 1 School of environment & Key Laboratory of Water and Sediment Sciences,Ministry of Education,beijing normal university,beijing 100875,china 2 State Key Laboratory of Hydroscience and Engineering,Tsinghua university,beijing 100084,china School of environment & Key Laboratory of Water and Sediment Sciences Ministry of Education Beijing Normal University Beijing 100875 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

As one of the most important components of river mechanics,sediment transport capacity of sediment-laden flows has attracted much attention from many researchers working on river mechanics and hydraulic engineering. Based on the time-averaged equation for a turbulent energy equilibrium in solid and liquid two-phase flow,an expression for the efficiency coefficient of suspended load movement was derived for the two-dimensional,steady,uniform,fully-developed turbulent flow. A new structural expression of sediment transport capacity was achieved. Using 115 runs of flume experimental data,which were obtained through two kinds of sediment transport experiments in the state of equilibrium,in combination with the basic rheological and sediment transporting characteristics of hyperconcentrated flow,the main parameters in the structural expression of sediment transport capacity were calibrated,and a new formula of sediment transport capacity for hyperconcentrated flow was developed. A large amount of field data from the Yellow River,Wuding River,and Yangtze River,etc. were adopted to verify the new formula and good agreement was obtained. These results above contribute to an improved theoretical system of river mechanics and a reliable tool for management of rivers carrying high concentration of sediments.

关键词： hyperconcentrated flow turbulent energy equilibrium efficiency coefficient sediment transport capacity

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Mapping the Farming-pastoral Ecotones in china

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Journal of Mountain Science 2009年第1期6卷 78-87页

作者： ZHANG Jian WEI Jie CHEN Quangon Institute of Mountain Hazards and environment Chinese Academy of Sciences Chengdu 610041 China tourism college Chongqing Normal University Chongqing 400047 China School of PastoralAgricultural Science and Technology Lanzhou University Lanzhou 730020 China Graduate university of the Chinese Academy of Sciences Beijing 100049 China

Conventional farming-pastoral ecotones methods of delineating were not quantitative and could not fully show their spatial distribution. The present paper attempts to develop quantitative methods for mapping farming-pastoral ecotones in china. Nine indicators, related to temperature, precipitation and altitude aspects, were selected to quantify ecological susceptibility of vegetation （crops and forage）. Methods of analytic hierarchy process （AHP） and expert score ranking combined with fuzzy set theory were applied to assign the weight for each indicator and to define the membership functions. The geographic information system （GIS） was used to manage the spatial database and conduct the spatial analysis. According to the spatial calculation of evaluation model integrated with GIS, the ecological susceptibility of vegetation （crops and forage） was mapped. Three different zones, pastoral area, farming-pastoral ecotones and farming area, were classified by spatial cluster analysis and the maximum likelihood classification for the numeric map of vegetation ecological susceptibility by GIS. This map was validated by the economic statistical result based on the ratio of the output value from animal husbandry in total output value of agriculture by the National Bureau of Statistics in china, indicating that the mapping of the farming-pastoral ecotones may be accepted.

关键词： AHP Farming-pastoral ecotone Fuzzyset theory GIS

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A HIGH-ORDER FINITE DIFFERENCE METHOD FOR UNSTEADY CONVECTION-DIFFUSION PROBLEMS WITH SOURCE TERM

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Journal of Hydrodynamics 1999年第2期11卷 97-102页

作者： Yang Zhi-feng Wang Xuan(State Key Laboratory of environment Simulation and Pollution Control, Institute of environmental Sciences, beijing normal university, beijing 100875, P. R. china.) beijing normal Univ Beijing China

The convection and diffusion are the basic processes in fluid flow and heat& mass transfer. The upwind and evolution functions for the convection term are introduced to give a comprehensive transformation to one-dimensional unsteady convection-diffusion equation involving source term. The corresponding compact fourth-order finite difference methed is developed. With the trans formation, the authors overcome the difficultyin dealing with the convection term, and the high-order expression for the convection-diffusion term can be conveniently obtained. The proposed difference scheme with thefourth-order accuracy and unconditional stability can fully reflect the upwind and evolutioneffects of the convection. The calculated results show that the errors of the referencescheme are 600 or 6000 times those of the proposed scheme for the same computationalgrid. With the one time decrease of the space grid, the errors of the proposed scheme andthe reference scheme reduce about 20 times and 2 times respectively. It is evident that theaccuracy of the proposed scheme is remarkably higher than that of the reference scheme.

关键词： convection-diffusion compact difference method comprehensive transformation unsteady computational fluid dynamics

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