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Science china Mathematics 2010年第1期53卷 105-114页

作者： fu BaoHua institute of Mathematics, academy of Mathematic and Systems Science, chinese academy of sciences, beijing 100190, china institute of Mathematics Academy of Mathematic and Systems Science Chinese Academy of Sciences Beijing China

We propose two conjectures of Hard Lefschetz type on Chow groups and prove them for some special cases. For abelian varieties, we show that they are equivalent to the well-known conjectures of Beauville and Murre.

关键词： Chow groups abelian varieties Bloch-Beilinson conjectures Beauville conjecture Murre conjecture

Observation of the Turbulent Burst near ASheared Air-Water Interface

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Communications in Nonlinear Science and Numerical Simulation 1999年第2期4卷 94-99页

作者： Shuangfeng WANG fu JIA Zhennan NIU Zhangzhi WU(institute of Mechanics, chinese academy of sciences, beijing 100080, china)(State Key Laboratory for Turbulence Research, Peking University, beijing 100871,china) institute of Mechanics Chinese Academy of Sciences Beijing 100080 China

The turbulent burst under a sheared air-water interface was experimentally investigated using hydrogen bubble visualization technique. The surface shear wasimposed by an airflow over the water flow which was kept free from surface waves. Resultsshow that the wind shear has the main influence on the bursting events. At relativelyhigh shear rates, the flow near the interface is dominated primarily by intermittent bursting events. The general features of bursting processes are described in some detail. Theobserved bursting events show qualitative similarities with those occurring in near-wallturbulence. However, a few distinctive phenomena were also observed, including the existence of vertical vortices and thickening process of the boundary layer, which appear tobe associated with the Characteristics of air-water interface.

关键词： air-water interface turbulent burst flow-visualization

Study on the Tautomerism of an Indoline Spiropyran in Compressed CO_2 and Ethanol Mixture

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chinese Chemical Letters 1999年第8期10卷 689-690页

作者： xi Feng ZHANG Qiang SUI Bu xing HAN Hai Ke YAN Yan Qiao WANG (institute of chemistry. chinese academy of sciences, beijing 100080) chinese Acad Sci Inst Chem Beijing 100080 Peoples R China

Thermodynamic and kinetic properties of the tautomerism of an indoline spiropyran in compressed CO2-ethanol mixture were studied by UV-Vis spectroscopy at 298.15 K, 303. 15 K, and 308.15 K. It was found that the compo... 详细信息

关键词： Compressed CO_2 ethanol indoline spiropyran tautomerism

Synthesis, complexation properties and crystal structure of 4',5'-dibromo-oxylyl-17-crown-5 ether

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chinese Journal of chemistry 1996年第5期14卷 447-453页

作者： xiONG,Guo-xiang ZHOU,Qing-fu XU,Hui-Juninstitute of Photographic chemistry,chinese academy of sciences,beijing 100101,china institute of Photographic chemistry Chinese Academy of Sciences Beijing 100101 China

4',5'-Dibromo-o-xylyl-17-crown-5 ether (2BrB17C5) was synthesized,starting from 1,2-dibromo-4,5-bis(bromomethyl)-benzene and tetraethylene glycol,and was characterized by 1H NMR,MS and elemental *** yellow prismatic single crystal obtained from anhydrous ethanol was investigated by X-ray structural *** complexation properties toward alkali metal ions were examined using the solvent extraction method and UV absorption *** crown ether was found to be conformationally deformed and oblate-like and is highly selective for lithium ion.

关键词： Crown ether complexation crystal structure

Fluorescence Spectra of the Poly (N-vinylcarbazole)Obtained with Asymmetric Polymerization

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chinese Chemical Letters 1999年第1期10卷 59-62页

作者： Chuan fu CHEN Quan SU Yong Ming CHEN fu xi(PCLCCinstitute of chemistry. chinese academy of sciences. BeUing 100080) chinese Acad Sci Inst Chem PCLCC Beijing 100080 Peoples R China

The fluorescence spectra of the poly (N-vinylcarbazole) in solution obtained with chirally organic salts or acid as catalyst or initiator [ (-)Sp: (-)-Sparteine, (+)CSA: D- (+)Camphor-10-sulfonic acid)], respectively, have been investigated. It is found that the two emission peaks at the longer wavelength (lambda max, ca, 415nm) and the shorter wavelength (lambda max, ca, 370nm) are assigned to the sandwich excimer and second excimer (partial overlap) fluorescence, respectively. The sandwich excimer and partially overlapped excimer are attributed to a fully overlapped structure of neighbouring carbazole chromophores in a totally elipsed conformation of the isotactic sequence, and partially overlapped structure of the syndiotactic sequence. The estimated values of I-415/I-370 and isotactic sequence content by using the fluorescence spectra are in the order: (-)Sp(+) (+)CSA(-)> (+)CSA(-)> (-)Sp(+)ClO(4)(-) (no peak at 415nm for AIBN).

关键词： fluorescence spectra poly (N-vinylcarbazole) asymmetric polymerization

A Calorimeter for Measuring the Enthalpy of Solution of Solid Solutes in Supercritical Fluids and Study on CO2-Naphthlene System

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chinese Chemical Letters 2001年第1期12卷 79-80页

作者： xiao Gang ZHANG, Guang Ying YANG , Bu xing HAN*, xi Feng ZHANG, Hai Ke YAN Center for Molecular sciences, institute of chemistry, the chinese academy of sciences, beijing 100080 chinese Acad Sci Inst Chem Ctr Mol Sci Beijing 100080 Peoples R China

An apparatus for measuring the enthalpy of solution of solids in supercritical fluids (SCFs) was constructed. The enthalpy of solution (ΔH) of naphthalene in supercritical (SC) CO2 was measured at 308.15 K in the pressure range from 8~11 MPa. It was found that ΔH was negative in the pressure range from 8 to 10 MPa, and the absolute value of ΔH decreases with increasing pressure. However, ΔH became positive at the pressures higher than 10 MPa. This unusual phenomenon can be explained by clustering between CO2 and naphthalene.

关键词： Solution enthalpy supercritical fluid molecular interaction

Structure Studies on Host-Guest Recognition Sensory Systems

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chinese Chemical Letters 1997年第8期8卷 707-710页

作者： Lin Jing YANG xi Zeng FENG Imshik LEE Chun Li BAI(institute of chemistry, the chinese academy of Science,beijing, 100080) chinese ACAD SCI INST CHEMBEIJING 100080PEOPLES R CHINA

Rhodamine B-ethylenediamine-beta-cyclodextrins (RhB-beta-CDen) and rhodamine B-beta-cyclodextrins (RhB-beta-CD) form inclusion complexes with many guest molecules, which can be used as nucleic acid probe. In this paper we determined the most stable conformations of RhB-beta-CDen and RhB-beta-CD by molecular mechanics and dynamics simulation. The interaction between RhB-beta-CDen and two guest molecules, 1-borneol and cyclohexanol, have been investigated both theoretically and experimentally. The results show that the interaction between borneol and RhB-beta-CDen is stronger than that between cyclohexanol and RhB-beta-CDen.

关键词： RhB Structure Studies on Host-Guest Recognition Sensory Systems

A USEfuL AND PRECISE EXPRESSION FOR ORIENTATION FACTOR OF POLED POLYMER FILMS

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chinese Chemical Letters 1993年第11期4卷 1007-1010页

作者： Cheng YE, Jia fu WANG institute of chemistry, chinese academy of sciences, beijing 100080

Based on ID ROGM, d_(33) of poled films can be estimated from orientation factor . In this letter, a direct expression

关键词： A USEfuL AND PRECISE EXPRESSION FOR ORIENTATION FACTOR OF POLED POLYMER FILMS COS~3

Stable carbon isotope composition and intrinsic water use efficiency in plants along an altitudinal gradient on the eastern slope of Yulong Snow Mountain, china

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Ecological Processes 2024年第2期13卷 218-230页

作者： Feng Jiang Tao Pu Zi-Jing Xue Yan-Wei Ma xiao-Yi Shi fu-xi Shi College of Geography and Environmental sciences Zhejiang Normal University Yulong Snow Mountain Glacier and Environment Observation and Research Station/State Key Laboratory of Cryospheric sciences Northwest Institute of Eco-Environment and ResourcesChinese Academy of Sciences Key Laboratory of National Forestry and Grassland Administration on Forest Ecosystem Protection and Restoration of Poyang Lake Watershed College of Forestry Jiangxi Agricultural University

Background Stable carbon isotope composition(δ13Cp) can be used to estimate the changes in intrinsic water use efficiency（iWUE） in plants,which helps us to better understand plants' response strategies to climate *** study focused on the variations in δ13Cpand iWUE for the different life-form plants（i.e.,herbs,shrubs,and trees）along an altitudinal gradient（3300,3600,3900,4100,4300,and 4500 m） on the eastern slope of Yulong Snow Mountain,southeastern margin of the Qinghai-Tibet *** response mechanisms of δ13Cpand iWUE for different life-form plants to altitude were thoroughly analyzed in this mountain *** The δ13Cpvalues of plants on the eastern slopes of Yulong Snow Mountain ranged from-30.4‰to-26.55‰,with a mean of-28.02‰,indicating a dominance of *** δ13Cpand iWUE values varied among different life-form plants in the order of herbs> shrubs> trees,particularly in 3600,3900,and 4300 ***δ13Cpand iWUE values for herbs and shrubs increased with altitude and were mainly controlled by air *** two parameters for trees exhibited a trend of initial decrease followed by an increase with *** 3900 m,the δ13Cpand iWUE values decreased with altitude,influenced by soil ***,above 3900 m,the two parameters increased with altitude,mainly regulated by air *** addition,iWUE was positively correlated with leaf P content but negatively correlated with leaf N:P ratio,especially for herbs and trees,suggesting that P plays a key role in modulating iWUE in this *** The diffe rentiated responses of water availability for different life-form plants to a higher altitudinal gradient are regulated by air temperature,soil moisture,and leaf P content in the Yulong Snow *** results provide valuable insights into understanding the wate r-carbon relationships in high-altitude ecosystems.

关键词： Stable carbon isotope Water use efficiency Altitude Life form Yulong Snow Mountain

Comparative study on the effect of integrin αvβ3 on secretion of matrix metalloproteinases in human normal and carcinoma trophoblasts

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Progress in Natural Science:Materials International 2005年第11期15卷 982-987页

作者： BAI Suxia, fu Yayuan, KONG Gang and WANG Yanling (State Key Laboratory of Reproductive Biology, institute of Zoology, chinese academy of sciences, beijing 100080, china The Second Hospital of chinese Medicine College, Shenyang 110003, china) State Key Laboratory of Reproductive Biology Institute of Zoology Chinese Academy of Sciences Beijing 100080 China. The Second Hospital of chinese Medicine College Shenyang 110003 China

The invasion of cytotrophoblast cells into the maternal endometrium during embryonic implantation is very similar to the metastasis of carcinoma cells. However, the significant difference is that the former is a highly controlled process. In this report, the effects of integnn αvβ3 on the secretion of matrix metalloproteinase (MMP) were compared between normal cytotrophoblast cells and chorio-carcinoma cells by RT-PCR, gelatin zymography and immunocytochemistry. The results reveal that both normal cytotrophobiast cells and choriocarcinoma cells can express integrin αvβ3. The secretion of MMPs in normal cytotrophoblast cells is up-regulated by anti-αvβ3 antibody, whereas, decreased in choriocarcmoma cells. It was suggested that αvβ3 can modulate the expression of MMPs in trophoblasts, and this action is carried out through distinct mechanisms in normal and carcinoma cytotrophoblast cells.

关键词： cytotrophoblast cells choriocarcinoma cells integrfn αvβ3 matrix metalloproteinase.