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Oligosaccharide Synthesis by Pre-Activation Strategy

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Oligosaccharide Synthesis by Pre-Activation Strategy

Latest progress on interactions between VLF/ELF waves and energetic electrons in the inner magnetosphere

第五届全国化学生物学学术会议

作者： Xin-Shan Ye The state key laboratory of natural and biomimetic drugs,School of Pharmaceutical Sciences,Peking University,Xue Yuan Rd#38,beijing 100083,china

＜正＞Saccharide synthesis is a formidable task to synthetic *** recent years many advances have been made in this area,development of more convenient and efficient strategies for oligosaccharide synthesis is still in great *** recent years,“pre-activation”as a new glycosylation approach has received increasing ***-activation strategy has some advantages over the routine glycosylation operations,since it does not require the tuning of the building blocks in an armed-disarmed *** have established the concept of iterative one-pot synthesis of oligosaccharides based on pre-activation *** concept refers to that glycosyl donors can be pre-activated,which generates a reactive intermediate in the absence of the acceptor. After addition of the second building block to the pre-activated donor,a disaccharide will be formed with an identical activatable aglycon at the reducing ***,by repeating this process in the same reaction flask,rapid construction of oligosaccharides can be *** also found that

关键词： carbohydrates pre-activation synthetic methods

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Science china Earth Sciences 2010年第3期53卷 317-326页

作者： XIAO FuLiang1,2, ZONG QiuGang3, SU ZhenPeng4, TIAN Tian3 & ZHENG HuiNan4 1 School of Physics and Electronic Sciences, Changsha University of Science and Technology, Changsha 410004, china 2 state key laboratory of Space Weather, Chinese Academy of Sciences, beijing 100190, china 3 Institute of Space Physics and Applied Technology, Peking University, beijing 100871, china 4 CAS key lab for Basic Plasma Science, School of Earth and Space Sciences, University of Science and Technology of china, Hefei 230026, china 1. School of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410004 China2. State Key Laboratory of Space Weather Chinese Academy of Sciences Beijing 100190 China3. Institute of Space Physics and Applied Technology Peking University Beijing 100871 China4. CAS Key Lab for Basic Plasma Science School of Earth and Space Sciences University of Science and Technology of China Hefei 230026 China

Interactions between very/extremely low frequency (VLF/ELF) waves and energetic electrons play a fundamental role in dynamics occurring in the inner magnetosphere. Here, we briefly discuss global properties of VLF/ELF waves, along with the variability of the electron radiation belts associated with wave-particle interactions and radial diffusion. We provide cases of electron loss and acceleration as a result of wave-particle interactions primarily due to such waves, and particularly some preliminary results of 3D evolution of phase space density from our currently developing 3D code. We comment on the existing mechanisms responsible for acceleration and loss, and identify several critical issues that need to be addressed. We review latest progress and suggest open questions for future investigation.

关键词： wave-particle interaction VLF/ELF waves energetic electrons acceleration and loss inner magnetosphere

The roles of a decision support system in applying forest ecosystem management in Northeast china

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Science china(Technological Sciences) 2006年第z1期49卷 9-18页

作者： DAI Limin, ZHENG Bofu, Guofan Shao & ZHOU Li state key lab.of Systems Ecology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, beijing 100085, china Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, china Department of Forestry and natural Resources, Purdue University, West Lafayette, IN 47907, USA Graduate University of Chinese Academy of Sciences, beijing 100101, china 1. state key lab.of Systems Ecology Research Center for Eco-Environmental Sciences Chinese Academy of Sciences Beijing 100085 China2. Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China3. Department of Forestry and Natural Resources Purdue University West Lafayette IN 47907 USA4. Graduate University of Chinese Academy of Sciences Beijing 100101 China

Forest ecosystems provide a variety of services and forest ecosystem management (FEM) is an effective approach to maximize the services. Because of the complexity of forest ecosystems, the applications of FEM can be facilitated with decision support systems (DSS) that recognize and incorporate ecological and socio-economic variables. With the rapid development of computation and information technologies, DSS have been advanced in many ways. Traditional forest management within a forestry unit in china is planned on a yearly basis. The planning itself remains primarily a verbal concept as there are no quantitative decision-support tools available to translate the concept into forest management actions. For the purposes of FEM at the management level, a forest management DFF, FORESTAR, has been developed under a framework of geographic information system (GIS) and forest models. The paper explained the intelligent modeling mechanisms and demonstrated how the applications of FEM can be strengthened with the applications of FORESTAR.

关键词： forest functions, forested landscapes, forest services, forest models, geographic information systems.

Synthesis and Properties of siRNA Incorporated with Isonucleosides

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Synthesis and Properties of siRNA Incorporated with Isonucle...

Influence of Aluminum Content in γ-TiAl with L1_0 Structure during Ordering Processes

第六届全国化学生物学学术会议

作者： Zhen-jun Yang state key laboratory of natural and biomimetic drugs School of Pharmaceutical Sciences,Peking University,beijing 100191,china

＜正＞RNA interference（RNAi） represents a powerful molecular strategy for inhibition of gene *** process can be induced by 21-23 nt double-stranded RNAs（dsRNAs）,known as small interfering RNAs（siRNAs）.These olig...

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Rare Metals 2001年第4期20卷 230-235页

作者： Timothée Nsongot1,2 Xiaodong Ni1,3 Guoliang Chen1, Keh-Minn Chang4 1) state key laboratory for Advanced Metals and Materials, University of Science and Technology beijing, beijing 100083, china 2) Faculty of Science, P. 0. Box 69, Brazzaville, Congo Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Fac Sci Brazzaville Rep Congo Univ Sci & Technol beijing Dept Phys Beijing 100083 Peoples R China W Virginia Univ Dept Mech & Aerosp Engn Morgantown WV 26506 USA

Based on EAM (embedded atom method) interatomic potential, the effect of aluminum content on the type of order-disorder transformation (ODT) and the structure properties (lattice constants, volume, c/a ratio and configu- ration energy) during ordering processes was investigated for γ-TiAI based alloys. Results show that for the alloys with lower than 50%Al (all composition is in atom number fraction), the ODT is the first order transition, and the second order transition for the alloys with equal or higher than 50% Al. The increase of aluminum content results in the critical temperature increasing. The aluminum content has a very little effect on the lattice constants, the volume and the c/a ratio, but has a significant effect on the configuration energy. A metastable disordered state was found for the alloys with less than 50%Al.

关键词： TiA1 order-disorder transformation long-range order

Ginsenoside-Rg_6, a Novel Triterpenoid Saponin from the Stem-Leaves of Panax ginseng C. A. Mey.

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Chinese Chemical Letters 2000年第10期11卷 909-912页

作者： Xiu Wei YANG, Long Yun LI, Jian Ming TIAN, Zhi Wei ZHANG, Jin Mei YE, Wei Fang Gu (National Research laboratory of natural & biomimetic drugs, Peking University, beijing 100083) (Academy of Chinese Traditional Medicine and Materia Medica of Jilin Provinc Peking Univ Natl Res Lab Nat & Biomimet Drugs Beijing 100083 Peoples R China Acad Chinese Tradit Med & Mat Med Jilin Province Changchun 130021 Peoples R China

A novel dammarane-type triterpene oligoglycoside, named ginsenoside-Rg6 3, was isolated from the stem-leaves of Panax ginseng C. A. Mey., together with two known ones, 20(S)-ginsenoside-Rg2 1 and 20(R)-ginsenoside-Rg2 2. On the basis of chemical and physicochemical evidence , the structure of ginsenoside-Rg6 have been elucidated as 6-O-(-L-rhamnosyl-(1?2)-(-D-glucopyranosyl-dammarane-(E)-20(22), 24-diene-3(, 6(, 12(-triol.

关键词： Panax ginseng C. A. Mey. stem-leaves triterpenoid ginsenoside-Rg_6.

SILICA-SUPPORTED NICKEL AND ZIRCONIUM CATALYSTS FOR BRANCHED POLYETHYLENE

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Chinese Journal of Polymer Science 2003年第4期21卷 453-458页

作者：孙文华 state key laboratory of Engineering Plastics The Center for Molecular Sciences Institute of Chemistry Chinese Academy of Sciences beijing 100080 china Chinese Acad Sci Inst Chem Ctr Mol Sci State Key Lab Engn Plast Beijing 100080 Peoples R China

8-Aminoquinoline nickel dichloride and bis(cyclopentadienyl)zirconium dichloride (Cp_2ZrCl_2) were supportedsimultaneously on silica to produce branched polyethylene successfully by combined polymerization. The supportedpolymerization results showed that the molecular weight of polyethylene increased while the molecular weight distributionbecame wider and the molecular chains of oligomers remaning in the final solution became shorter as compared to theoligomers obtained in polymerization processes with pure 8-aminoquinoline nickel dichloride catalysis, as well as theCp_2ZrCl_2 and nickel combination system. With decreasing amount of Ni catalyst in the supported catalyst, the molecular chains of oligomers in the resulting solution became shorter, while α-olefin selectivity increased.

关键词： 8-Aminoquinoline nickel dichloride, Cp_2ZrCl_2 Silica supported catalysts Branched polyethylene

EAM Analysis of the Lattice Parameter Effect in Order-Disorder Transformation

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Journal of University of Science and Technology beijing 2001年第3期8卷 189-194页

作者： Timoth■e Nsongo, Xiaodong Ni, Guoliang Chen state key laboratory for Advanced Metals and Materials, University of Science and Technology beijing, beijing 100083, china Faculty of Science, Physics Department, P. O. Box 69, Brazzaville (CONGO) Applied Scie Univ Sci & Technol beijing State Key Lab Adv Met & Mat Beijing 100083 Peoples R China Fac Sci Dept Phys Brazzaville Rep Congo Univ Sci & Technol beijing Appl Sci Sch Beijing 100083 Peoples R China

The embedded atom method (EAM) was used to theoretically analyze the effect of the lattice parameter variation on the order-disorder transformation in binary alloys. Based on EAM, it is found that only one kind of order-disorder transition (second-order transition) exists for AB alloy. Three groups of order-disorder transformation can be observed for the A(3)B or AB(3) compounds. For group I, the order-disorder is a completely first-order transition. For group II, the order-disorder transformation is a classical first-order transition. For group III, the order-disorder transformation is found to be a second-order transition. The lattice parameter variations have a significant effect on E-2 coefficient, which is related to the ordering energy. These results are in good agreement with experiments.

关键词： order-disorder transformation embedded atom method (EAM) phase transformation binary alloy

Quantitative studies of hydrocarbon loss of the Silurian bitumen sandstone in the Tarim Basin

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Science china Earth Sciences 2008年第S2期51卷 101-107页

作者： JIANG ZhenXue1,2,PANG XiongQi1,2,LIU LuoFu1,2,WANG XianDong3,ZHANG Jun4 & LI HongYi1,2 1 Basin and Reservoir Research Center,china University of Petroleum,beijing 102249,china 2 state key laboratory of Petroleum Resource and Prospecting,china University of Petroleum,beijing 102249,china 3 Research Institute of Exploration and Development,Daqing Oilfield Company Ltd,Daqing 163712,china 4 Petroleum Exploration and Production Institute of SINOPEC,beijing 100083,china china Univ Petr Basin & Reservoir Res Ctr Beijing 102249 Peoples R China china Univ Petr State Key Lab Petr Resource & Prospecting Beijing 102249 Peoples R China Daqing Oilfield Co Ltd Res Inst Explorat & Dev Daqing 163712 Peoples R China SINOPEC Petr Explorat & Prod Inst Beijing 100083 Peoples R China

The evolution of Tarim Basin experienced several tectonic movements,of which Caledonian movement caused a serious damage to reservoirs of Silurian. The earlier reservoirs size and the later hydrocarbon loss are two key factors to exploration prospect of Silurian. On the basis of net thickness of bituminous sandstone and recovery coefficient of crude oil converting to bitumen,the scale of the hydrocarbon loss of palaeo-accumulation in bitumen sandstone of Silurian was calculated (86.30×108t). The deter-mination of net thickness of bitumen sandstone was completed mainly by several methods,such as physical property demarcation,observing lithology,grains with oil inclusion (GOI) technology,and quantitative grains fluorescence (QGF) technology. The samples of black sandstone and white sand-stone were collected and compared by means of the methods mentioned above. The results showed that there was little hydrocarbon,or none,in the white sandstone. The recovery coefficient was ob-tained by the analyses of plentiful physical parameters of crude oil and bitumen sandstone,based on the hypothesis that nonhydrocarbon compounds and bitumen were invariable in the process of bitu-men forming. The calculated result,which is more scientific and actual,indicates the exploration pros-pect is more promising in Silurian of the Tarim Basin.

关键词： Tarim Basin Silurian bitumen sandstone hydrocarbon loss quantitative research recovery coefficient