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Role of gallium wetting layer in high-quality ZnO growth on sapphire (0001) substrates

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Science China(Physics,Mechanics & Astronomy) 2004年第5期47卷 612-620页

作者： ZENG Zhaoquan1,3, WANG Yong2, DU Xiaolong1, MEI Zengxia1, KONG Xianghe3, JIA Jinfeng1, XUE Qikun1 & ZHANG Ze2, 4.1. State Key laboratory for Surface Physics, Institute of Physics, Chinese Academy of Sciences, beijing 100080, China 2. laboratory of Electron Microscopy, Institute of Physics, Chinese Academy of Sciences, beijing 100080, China 3. College of Physics and Engineering, Qufu Normal University, Qufu 273165, China 4. {4. University of Technology, {4. 100022, China State Key laboratory for Surface Physics Institute of Physics Chinese Academy of Sciences Beijing China College of Physics and Engineering Qufu Normal University Qufu China laboratory of Electron Microscopy Institute of Physics Chinese Academy of Sciences Beijing China beijing University of Technology Beijing China

A Ga wetting layer was used to modify the surface structure of sapphire (0001) substrate to prepare high-quality ZnO film by radio frequency plasma-assisted molecule beam epitaxy. We found that this Ga layer plays a crucial role in eliminating 30 rotation domains, controlling polarity and decreasing defect density in ZnO epilayers, as demonstrated by in situ reflection high energy electron diffraction, ex situ high resolution X-ray diffraction and high resolution cross-sectional transmission electron microscopy. Zn-polar film of ZnO was determined by convergent beam electron diffraction. A Ga bilayer model is proposed to understand the effects of the Ga wetting layer on high-quality ZnO growth.

关键词： Ga wetting layer, sapphire, polarity, defect density, zinc oxide, rf-MBE, RHEED, HRXRD, TEM, CBED.

Modeling and verifying Web services driven by requirements:An ontology-based approach

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Science in China(Series F) 2006年第6期49卷 792-820页

Automatic discovery and composition of Web services is an important research area in Web service technology, in which the specification of Web services is a key issue. This paper presents a Web service capability description framework based on the environment ontology. This framework depicts Web services capability in two aspects： the operable environment and the environment changes resulting from behaviors of the Web service. On the basis of the framework, a requirement-driven Web service composition model has been constructed. This paper brings forward the formalization of Web service interactions with π calculus. And an automatic mechanism converting conceptual capability description to the formal process expression has been built. This kind of formal specification assists in verifying whether the composite Web service model matches the requirement.

关键词： Web service environment ontology automatic composition π calculus formal verification.

Fluorescence dynamics of interactions between polyamide PyPyPyβDp and DNA

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Science China Chemistry 2006年第1期49卷 75-80页

作者： ZHANG Huijuan1,2, WANG Jin3, WU Yishi1, YUAN Gu3, AI Xicheng1, WANG Li4.& ZHANG Jianping1 1. State Key laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, beijing 100080, China 2. School of Life Science and Technology, beijing Institute of Technology, beijing 100081, China 3. College of Chemistry and Molecular Engineering, Peking University, beijing 100080, China 4. Center for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, beijing 100080, China Correspondence should be addressed to Ai Xicheng and Zhang Jianping State Key laboratory for Structural Chemistry of Unstable and Stable Species Institute of Chemistry Chinese Academy of Sciences Beijing China School of Life Science and Technology Beijing Institute of Technology Beijing China College of Chemistry and Molecular Engineering Peking University Beijing China Center for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing China

The photophysical properties of the polyamide PyPyPyβDp (PPP) were investigated by means of steady-state absorption and fluorescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. It was found that the excited-state properties of PPP are very sensitive to solvents. In TKMC buffer PPP exhibited weak fluorescence with a decay time constant of 16 ps, while with the decrease of the solvent polarity PPP showed the blue-shifted peak position, increased inten-sity and lengthened life-time for its fluorescence behavior. In the presence of calf thymus DNA, it was observed that the fluorescence intensity was enhanced and the fluorescence lifetime increased from 16 to 32 ps for PPP, which verified that PPP bound into the minor groove of DNA duplex.

关键词： polyamide (PPP), calf thymus DNA (ctDNA), time-resolved fluorescence spectroscopy, recognition dynamics.

国家发展改革委国家数据局财政部自然资源部关于深化智慧城市发展推进城市全域数字化转型的指导意见

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中国产经 2024年第10期 12-17页

作者： 1.国家发展改革委 2.国家数据局 3.财政部 4.自然资源部国家发展改革委国家数据局财政部自然资源部

各省列、市、自新治疆区、生直产辖建市设及兵计团发划展单改革委、数据管理部门、财政厅（局）、自然资源主管部门：城市是推进数字中国建设的综合载体，推进城市数字化转型、智慧化发展，是面向未来构筑城市竞争新优势的关键之举，也...

各省列、市、自新治疆区、生直产辖建市设及兵计团发划展单改革委、数据管理部门、财政厅（局）、自然资源主管部门：城市是推进数字中国建设的综合载体，推进城市数字化转型、智慧化发展，是面向未来构筑城市竞争新优势的关键之举，也是推动城市治理体系和治理能力现代化的必然要求。为深入贯彻落实党中央、国务院关于数字中国建设的决策部署，以数据融通、开发利用贯穿城市全域数字化转型建设始终，更好服务城市高质量发展、高效能治理、高品质生活，支撑发展新质生产力，推进中国式现代化城市建设，特制定本意见。

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关于深化智慧城市发展推进城市全域数字化转型的指导意见

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安装 2024年第6期 1-3页

作者： 1.国家发展改革委 2.国家数据局 3.财政部 4.自然资源部国家发展改革委国家数据局财政部自然资源部

城市是推进数字中国建设的综合载体,推进城市数字化转型、智慧化发展,是面向未来构筑城市竞争新优势的关键之举,也是推动城市治理体系和治理能力现代化的必然要求。为深入贯彻落实党中央、国务院关于数字中国建设的决策部署,以数据融通... 详细信息

城市是推进数字中国建设的综合载体,推进城市数字化转型、智慧化发展,是面向未来构筑城市竞争新优势的关键之举,也是推动城市治理体系和治理能力现代化的必然要求。为深入贯彻落实党中央、国务院关于数字中国建设的决策部署,以数据融通、开发利用贯穿城市全域数字化转型建设始终,更好服务城市高质量发展、高效能治理、高品质生活,支撑发展新质生产力,推进中国式现代化城市建设,特制定本意见。一、总体要求以习近平新时代中国特色社会主义思想为指导,完整、准确、全面贯彻新发展理念,统筹发展和安全,充分发挥数据的基础资源和创新引擎作用,整体性重塑智慧城市技术架构、系统性变革城市管理流程、一体化推动产城深度融合,全面提升城市全域数字化转型的整体性、系统性、协同性,不断满足人民日益增长的美好生活需要,为全面建设社会主义现代化国家提供强大动力。

关键词：习近平新时代中国特色社会主义思想数字化转型全域高品质生活智慧化综合载体深度融合智慧城市

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Progress and review of the studies on the end-Triassic mass extinction event

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Science China Earth Sciences 2005年第12期48卷 2049-2060页

作者： DENG Shenghui1,2, LU Yuanzheng1,2,3 & XU Daoyi4.1. Research Institute of Petroleum Exploration and Development, beijing 100083, China 2. Key laboratory of Oil and Gas Reservoir of PetroChina, beijing 100083, China 3. China University of Geosciences, beijing 100083, China 4. Institute of Geology, China Earthquake Administration, beijing 100029, China Research Institute of Petroleum Exploration and Development Beijing China Key laboratory of Oil and Gas Reservoir of PetroChina Beijing China China University of Geosciences Beijing China Institute of Geology China Earthquake Administration Beijing China

The mass extinction at the end-Triassic is one of the five biggest in the Phanerozoic. However,it is the least well understood among these five events, and only till last decade it became a great academic interesting subject to geologists. The evidences for this event come obviously from bivalves, brachiopods, ammonites, corals, radiolaria, ostracods and foraminifera of marine habitats, and plants and tetrapods of terrestrial realm. By contrast, for some of other groups, such as marine gastropods and marine vertebrates, no mass extinction has been recog-nized yet. The extinction event is strongly marked at specific level but shown a complicated situa-tion at generic and family levels. Dramatic changing of the environment, such as the temperature raise due to the greenhouse effect, the marine anoxic habitats caused by a sudden transgression after the regression at the end of Triassic, has been claimed to be the main cause of the extinction. Many hypotheses have been suggested to demonstrate the mechanisms of the environment changing, among which two popular ones are the bolide impact and volcanic eruption. The Triassic-Jurassic (Tr-J) boundary mass extinction event is still poorly understood because no enough data have been obtained from the Tr-J boundary successional sections of both marine and terrestrial sediments, and most of these studies were regionally restricted. The basic aspects of the event and its associated environmental conditions remain poorly characterized and the causal mechanism or mechanisms are equivocal. Some authors even doubt its occurrence. China has many successionally developed terrestrial and marine Tr-J sections. Detailed studies of these sections may be important and significant for well understanding of the event.

关键词： progress, review, end-Triassic, mass extinction, mechanism, Tr-J boundary.

BRST quantization and canonical Ward identity of the supersymmetric electromagnetic interaction system

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Science China(Physics,Mechanics & Astronomy) 2007年第3期50卷 339-347页

作者： HUANG YongChang1,3,4. JIANG YunGuo1 & LI XinGuo2,3 1 Institute of Theoretical Physics, College of Applied Sciences, beijing University of Technology, beijing 100022, China 2 Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou 730000, China 3 Center of Theoretical Nuclear Physics, National laboratory of Heavy Ion Collisions, Chinese Academy of Sciences, Lanzhou 730000, China 4.China Center of Advanced Science and Technology (world laboratory), {4., China Institute of Theoretical Physics College of Applied Sciences Beijing University of Technology Beijing China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Collisions Chinese Academy of Sciences Lanzhou China China Center of Advanced Science and Technology (world laboratory) Beijing China Institute of Modern Physics Chinese Academy of Sciences Lanzhou China

According to the method of path integral quantization for the canonical constrained system in Becchi-Rouet-Stora-Tyutin scheme, the supersymmetric electromagnetic interaction system was quantized. Both the Hamiltonian of the supersymmetric electromagnetic interaction system in phase space and the quantization procedure were simplified. The BRST generator was constructed, and the BRST transforma- tions of supersymmetric fields were gotten; the effective action was calculated, and the generating functional for the Green function was achieved; also, the gauge generator was constructed, and the gauge transformation of the system was ob- tained. Finally, the Ward-Takahashi identities based on the canonical Noether theorem were calculated, and two relations between proper vertices and propaga- tors were obtained.

关键词： supersymmetric electromagnetic interaction BRST quantization Ward identity

Studies of low-lying states of even-even Xe isotopes within the nucleon pair approximation

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Science China(Physics,Mechanics & Astronomy) 2011年第S1期54卷 103-108页

作者： ZHANG LiHua1, JIANG Hui1,2 & ZHAO YuMin1,3,4.1Institute of Nuclear, Particle, Astrophysics and Cosmology, Department of Physics, Shanghai Jiao Tong University, Shanghai 20024., China 2School of Arts and Sciences, Shanghai Maritime University, Shanghai 200135, China 3Center of Theoretical Nuclear Physics, National laboratory of Heavy Ion Accelerator, Lanzhou 730000, China 4.1}, world laboratory, P.O. Box 8730, beijing 100080, China Institute of Nuclear Particle Astrophysics and Cosmology Department of Physics Shanghai Jiao Tong University Shanghai China School of Arts and Sciences Shanghai Maritime University Shanghai China Center of Theoretical Nuclear Physics National Laboratory of Heavy Ion Accelerator Lanzhou China ccast World Laboratory Beijing China

We study the relevance of nucleon pairs with higher spins, in addition to spin-zero and spin-two pairs (i.e., S D pairs), in low-lying states of even-even Xe nuclei. By including those higher-spin pairs in our configuration, we recalculate energy level schemes, elec trical quadrupole moments, magnetic moments and electric quadrupole transition rates, for low-lying states of even-even 128-14.Xe nuclei. The agreement between our calculated results and the experimental data is substantially improved in comparison with previous studies.

关键词： nucleon pair approximation shell model configuration space low-lying states

Theoretical study on the reaction mechanism of(CH_3)_3CO+CO

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Science China Chemistry 2005年第1期48卷 18-24页

作者： ZHAO Hongmei1,2,3, SUN Chengke1,4. ZHANG Rongchang3, XI Hongmin3 & LI Zonghe1 1. Department of Chemistry, beijing Normal University, beijing 100875, China 2. The laboratory of Molecular Reaction Dynamics, Institute of Chemistry, Chinese Academy of Sciences, beijing 100080, China 3. Department of Chemistry, Beihua University, Jilin 132013, China 4. Department of Chemistry, Qujing Normal University, Yunnan 655000, China Department of Chemistry Beijing Normal University Beijing China The laboratory of Molecular Reaction Dynamics Institute of Chemistry Chinese Academy of Sciences Beijing China Department of Chemistry Beihua University Jilin China Department of Chemistry Qujing Normal University Yunnan China

The reaction mechanism of (CH3)3CO with CO has been theoretically investigated using density-functional theory (DFT) calculations at B3LYP/6-31G* level. In order to get more reliable energy values the single-point energy is evaluated at CCSD (T)/6-31++G** level. The results show that the reaction is multi-channel and the reaction of (CH3)3CO radical with CO mostly produces (CH3)3C + CO2. The reaction could play a role in eliminating air pollution.

关键词： DFT, B3LYP, (CH3)3CO, radical.