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Seasonal dynamics of CO_2 fluxes from subtropical plantation coniferous ecosystem

Science china Earth sciences 2006年第S2期49卷 99-109页

作者： liU Yunfen, YU Guirui, WEN Xuefa, WANG Yinghong, SONG Xia, li Ju, SUN Xiaomin, yang Fengting, CHEN Yongrui & liU Qijing Institute of Geographic sciences and Natural Resources Research, Chinese Academy of sciences, beijing 100101, china Institute of Atmospheric Physics, Chinese Academy of sciences, beijing 100029, china college of Resources and Environmental Science, china Agricultural university, beijing 100094, china Institute of Geographic sciences and Natural Resources Research Chinese Academy of Sciences Beijing China Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China college of Resources and Environmental Science China Agricultural University Beijing China

As one component of chinaFLUX, the measurement of CO2 flux using eddy covariance over subtropical planted coniferous ecosystem in Qianyanzhou was conducted for a long term. This paper discusses the seasonal dynamics of net ecosystem exchange (NEE), ecosystem respiration (RE) and gross ecosystem exchange (GEE) between the coniferous ecosystem and atmosphere along 2003 and 2004. The variations of NEE, RE and GEE show obvious seasonal variabilities and correlate to each other, i.e. lower in winter and drought season, but higher in summer; light, temperature and soil water content are the main factors determining NEE; air temperature and water vapor pressure deficit (VPD) influence NEE with stronger influence from VPD. Under the proper light condition, drought stress could decrease the temperature range for carbon capture in planted coniferous, air temperature and precipitation controlled RE; The NEE, RE, and GEE for planted coniferous in Qianyanzhou are -387.2 gC·m-2 a-1,1223.3 g C·m-2 a-1, -1610.4 g C·m-2 a-1 in 2003 and -423.8 g C·m-2 a-1, 1442.0 g C·m-2 a-1, -1865.8 g C·m-2 a-1 in 2004, respectively, which suggest the intensive ability of plantation coniferous forest on carbon absorbing in Qianyanzhou.

关键词： plantation eddy covariance photosynthesis respiration drought stress.

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Effect of Caffeic acid on the Tumor Cells U937 Evaluated by an Electrochemical Voltammetric Method

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Chinese Chemical Letters 1999年第9期10卷 781-782页

作者： Hong Yan JIAN Cheng Cat AN Jun FENG Yun Xiang CI Yi li Ayako SUGISAWA Maremitsu IZUMITANI Zhang liang CHEN (1NLPGE.college of life sciences. peking university, beijing 1008712Departmcnt of Chemistry,peking university,beijing 1008713Laborutory of F NLPGE College of Life Sciences Peking University Beijing 100871 China Department of Chemistry Peking University Beijing 100871 China Laboratory of Food and Nutrition Kyoritsu Women's University Tokyo 101-0003 Japan

Electrochemical voltammetric method can;be used to monitor cell health state during its growth. Here we studied the effect of caffeic acid on leukemia cells U937 by the voltammetric behavior of the cells. The result showed that this drug had a negative influence on cell health. which suggests that caffeic acid may be used in inhibition of tumor cells.

关键词： voltammetric behavior U937 cells caffeic acid

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Carbon isotope ratios of C_(4) plants in loess areas of North china

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Science china Earth sciences 2006年第1期49卷 97-102页

作者： WANG Guoan1,2,3, HAN Jiamao 2, ZHOU liping3, xiong Xiaogang4, TAN Ming2, WU Zhenhai5 & PENG Jun6 1. Department of Plant Nutrition, china Agricultural university, beijing 100094, china 2. Institute of Geology and Geophysics, Chinese Academy of sciences, beijing 100029, china 3. college of Environmental sciences, MOE Laboratory for Earth Surface Processes, peking university, beijing 100871, china 4. Institute of Botany, Chinese Academy of sciences, beijing 100093, china 5. Northwest Sci-Tech university of Agriculture and Forestry, yangling 712100, china 6. Network Center, china Agricultural university, beijing 100094, china Department of Plant Nutrition China Agricultural University Beijing China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China college of Environmental sciences MOE Laboratory for Earth Surface Processes Peking University Beijing China Institute of Botany Chinese Academy of Sciences Beijing China Northwest Sci-Tech university of Agriculture and Forestry Yangling China Network Center China Agricultural University Beijing China

Carbon isotope ratios (δ^(13)C) of 89 C_4 plant samples were determined fromthe loess area in North china. δ^(13)C values vary between -10.5per thousand and -14.6per thousandwith a mean of -12.6per thousand. Along a precipitation gradient from the semi-moist area to thesemiarid area, then to the arid area, the δ^(13)C values of C_4 plants show a slight decreasingtrend. The δ^(13)C values of C_4 plants in the dry season are found lower than those in the wetseason. These trends are opposite to those observed for C_3 species.

关键词： C4 plants, carbon isotope ratios, loess area.

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Development of rabbit monoclonal and polyclonal antibodies for detection of site-specific histone modifications and their application in analyzing overall modification levels

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Cell Research 2006年第5期16卷 519-527页

作者： Lan Guo~(1,2,*) Benliang Yin~(1,*) Junli Zhou~(1,3) Xueyong li~3 Xing Wang Deng~(1,2,3) ~1National Institute of Biological Science,Zhongguancun life Science Park,beijing 102206,china ~2peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology,college of life sciences,peking university,beijing 100871,china ~3Department of Molecular,Cellular,and Developmental Biology,Yale university,New Haven,Connecticut 06520-8104,USA National Institute of Biological Science Zhongguancun Life Science Park Beijing China peking-Yale Joint Center of Plant Molecular Genetics and Agrobiotechnology College of Life Sciences Peking University Beijing China Department of Molecular Cellular and Developmental Biology Yale University New Haven USA

In addition to DNA sequence information,site-specific histone modifications are another important determinant ofgene expression in a eukaryotic *** selected four modification sites in common histones that are known tosignificantly impact chromatin function and generated monoclonal or polyclonal antibodies that recognize each of thosesite-specific *** used these antibodies to demonstrate that the site-specific histone modification levelsremain relatively constant in different organs of the same *** also compared the levels of selected histonemodifications among several representative organisms and found that site-specific modifications are highly variable amongdifferent organisms,providing new insight into the evolutionary divergence of specific histone modifications.

关键词： histone modification site-specific antibody chromatin

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Pointwise estimates for the maximal multilinear singular integral operators

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Science china Mathematics 2005年第12期48卷 1696-1706页

作者： HU Guo’en, li Dengfeng & LU Shanzhen Department of Applied Mathematics, university of Information Engineering, P. O. Box 1001 -747, Zhengzhou 450002, china college of Mathematical and Information sciences, Henan university, Kaifeng 475001, china Department of Mathematics, beijing Normal university, beijing 100875, china Department of Applied Mathematics University of Information Engineering Zhengzhou China college of Mathematical and Information sciences Henan University Kaifeng China Department of Mathematics Beijing Normal University Beijing China

Two pointwise estimates relating the maximal multilinear singular integral operators and some classical maximal operators are established. These pointwise estimates imply the rearrangement estimate and the BLO(Rn) est... 详细信息

关键词： multilinear singular integral,maximal operator,BMO (Rn),BLO (Rn).

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Changes of decay rates of radioactive ^(111)In and ^(32)P induced by mechanic motion

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Science china Chemistry 2007年第2期50卷 170-174页

作者： HE YuJian1,QI Fei2 & QI ShengChu3 1 college of Chemistry and Chemical Engineering,Graduate university of Chinese Academy of sciences,beijing 100049,china 2 No. 1,Gravenhurst Court,Gaithersburg,Md 20878,USA 3 Department of Applied Chemistry,peking university,beijing 100871,china college of Chemistry and Chemical Engineering Graduate University of Chinese Academy of Sciences Beijing China No. 1 Gravenhurst Court Gaithersburg USA Department of Applied Chemistry Peking University Beijing China

The changes of decay rates of radionuclide 111In(electron capture) and 32P(β decay) induced by exter-nal mechanic motion are studied. The results indicate that,in the external circular rotation in clockwise and anticlockwise centrifuge on Northern Hemisphere(radius 8 cm,2000 r/min) ,the half life of 111In compared with the referred(2.83 d) is decreased at 2.83% and increased at 1.77%,respectively;the half life of 32P compared with the referred(14.29 d) is decreased at 3.78% and increased at 1.75%,respec-tively. When the clockwise and anticlockwise rotations increase to 4000 r/min,the half life of 111In is decreased at 11.31% and increased at 6.36%,respectively;the half life of 32P is decreased at 10.08% and increased at 4.34%,respectively. When the circular rotation is removed,the decay rates of 111In and 32P return back to the referred,respectively. It is found that the external circular rotations in clockwise and anticlockwise centrifuge selectively increased and decreased the decay rates of 111In and 32P,respec-tively,and the effects are strongly dependent on the strength of circular rotation. It is suggested that these effects may be caused by the chiral interaction.

关键词： circular rotation helical motion 111In 32P decay rate chirality

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Oxidative Methylation of Toluene with Methane over Basic Zeolite Catalysts Promoted with Alkali Metal Bromides and Alkali Metal Oxides

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Chinese Chemical Letters 2000年第9期11卷 827-830页

作者： ling Ping ZHOU Wei li Ke Yi TAO Xuan Wen li He Xuan li college of Chemistry and Molecular Engineering, peking university, beijing 100871 Department of Chemistry, Nankai university, Tianjin 300071 Coll. of Chem. and Molec. Eng. Peking University Beijing 100871 China Department of Chemistry Nankai University Tianjin 300071 China

The catalytic effects for the oxidative methylation of toluene with methane over the basic zeolite catalysts prepared by promoting KY, KX, KM, KZSM-5 or KP with alkali-metal bromides and alkali-metal oxides have been investigated comparatively. The alkali-metal bromides promoted substrates are more effective than the alkali-metal oxides promoted systems. Moreover, the NaBr promoted systems are more active than KBr promoted systems. The most effective catalytic system (8wt%NaBr)/KZSM-5 gave a toluene conversion as high as 76.3% and a total C-8 selectivity of 76.4% (styrene/ethylbenzene=9.76) resulting in a total C-8 yield of 58.3%.

关键词： styrene methane oxidative methylation alkali-metal oxides alkali-metal bromides

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Phylogenetics and biogeography of eastern Asian–North American disjunct genus Pachysandra (Buxaceae) inferred from nucleotide sequences

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Journal of Systematics and Evolution 2009年第3期47卷 191-201页

作者： 1Zhihua JIAO 2,3Jianhua li 1(School of Chemical and Environmental Engineering, china university of Mining and Technology, beijing 100083, china) 2(The Arnold Arboretum of Harvard university, Cambridge, MA 02138, USA) 3(Adjunct Faculty of college of life sciences, Zhejiang university, Hangzhou 310029, china) (School of Chemical and Environmental Engineering China University of Mining and Technology Beijing 100083 China) (The Arnold Arboretum of Harvard university Cambridge MA 02138 USA) (Adjunct Faculty of college of life sciences Zhejiang University Hangzhou 310029 China)

Pachysandra is an eastern Asian-North American disjunct genus with three species, two in eastern Asia (Pachysandra axillaris and Pachysandra terminalis) and one in eastern North America (Pachysandra procumbens). Although morphological and cytological studies suggest a close affinity of P. procumbens with P. axillaris, molecular data from nuclear and chloroplast DNA regions have provided conflicting signals. In this study, we tested previous phylogenetic hypotheses using sequences of nuclear ribosomal DNA internal transcribed spacers and chloroplast ndhF gene from multiple individuals of each of the three species. We also estimated the time of divergence between eastern Asia and eastern North America. Our results support the morphological and cytological conclusion that P. procumbens is more closely related to P. axillaris than to P. terminalis. The estimated time of divergence of P. axillaris and P. procumbens was 14.6±5.5 mya, consistent with estimates from many other eastern Asian-North American disjunct genera. The migration of Pachysandra populations from eastern Asia to North America might have occurred by way of the North Atlantic land bridge.

关键词： Buxaceae divergence time ndhF nrDNA ITS Pachysandra.

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Computational stability of the forced dissipative nonlinear atmospheric equations

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Chinese Science Bulletin 1999年第10期44卷 949-952页

作者： li Jianping and CHOU Jifan LASG , Institute of Atmospheric Physics , Chinese Academy of sciences , beijing 100080, china Department of Atmospheric sciences , Lanzhou university , Lanzhou 730000, china beijing Meteorological college, beijing 100081, china LASG Institute of Atmospheric Physics Chinese Academy of Sciences Beijing China Department of Atmospheric sciences Lanzhou University Lanzhou China beijing Meteorological college Beijing China

A new concept of computational quasi-stability (CQS) is introduced to study the computational stability (CS) of the forced dissipative nonlinear (FDN) evolution equations. Based on the concept, the CQS criterion of difference scheme of FDN atmospheric equations is obtained. So it provides the theoretical basis for designing the computational stable difference scheme of FDN atmospheric equations.

关键词： computational stability (CS) computational quasi-stability (CQS) operator equation difference scheme forced dissipative nonlinear (FDN) equations.

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A NEW METHOD FOR NUMERICAL SIMULATION OF TWO TRAINS PASSING BY EACH OTHER AT THE SAME SPEED

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Journal of Hydrodynamics 2010年第5期22卷 697-702页

作者： ZHAO Xiao-li SUN Zhen-xu School of Aerospace Tsinghua University Beijing China State Key Laboratory for Turbulence and Complex Systems College of Engineering Peking University Beijing China

A new method is proposed to numerically simulate problems of trains passing by each other at the same speed, and is implemented in UDF language of commercial software Fluent. Because only a half of the computational domain is required and the dynamic mesh technique is avoided, the computational efficiency is greatly improved. A two-dimensional test case is used for validation, which shows that the flow field and the pressure wave during the train-passing events can be correctly calculated by this new method. This method can be easily extended to three-dimensional simulations, to deal with practical problems.

关键词： trains passing by each other rotational symmetry dynamic mesh pressure wave

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