检索结果-南通市图书馆

Phase-matched high-order harmonics by interaction of Ar atoms with high-repetition-rate low-energy femtosecond laser pulses

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Science China(Physics,Mechanics & Astronomy) 2004年第4期47卷 492-501页

作者： XIE Xinhua ZENG Zhinan LI Ruxin CHEN Shu LU Haihe YIN Dingjun XU Zhizhan Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China Key Laboratory for High Intensity Optics Shanghai Institute of Optics and Fine Mechanics Chinese Academy of Sciences Shanghai 201800 China

Phase-matched high-order harmonic generation in Ar gas-filled cell was investigated experimentally. We obtained phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1 kHz repetition rate. To our knowledge, this is the lowest driving laser energy used to obtain phase-matched 27th order harmonic in a static gas cell. High-order harmonic generation at different gas density was studied systematically. Spectral blueshift and broadening of high harmonics under different pressure were analyzed. We found that the source size and spatial distribution of high-order harmonics are quite different under the phase-matching condition from those of the phase-mismatching case.

关键词： high-order harmonic generation, phase matching, spectral characteristic, spatial distribution.

Differential retardation of organic matter maturation by overpressure

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Science China Earth Sciences 2004年第9期47卷 783-793页

作者： HAO Fang1,2, JIANG Jianqun1, ZOU Huayao1, FANG Yong1 & ZENG Zhiping2 1. Key Lab for Hydrocarbon Accumulation Mechanism in the Ministry of Education, Petroleum University, Beijing 102249, China 2. Department of Petroleum Geology, China University of Geosciences, Wuhan 430074, China Key Lab for Hydrocarbon Accumulation Mechanism in the Ministry of Education Petroleum University Beijing China Department of Petroleum Geology China University of Geosciences Wuhan China

The thermal evolution of organic matter (OM) is composed of a series of reactions that are paralell and successive with each other. Different reactions have different activation energy, different rates of product concentration variation, and different volume expansion effects, and therefore have different responses to overpressure, which determines the differential retardation of different OM maturation reactions and maturity parameters. Based upon comprehensive studies on the OM maturation in different pressure systems in the Yinggehai, Qiongdongnan and Bohai Bay basins, 4 hierarchies of overpressure retardation have been recognized. (1) OM maturation in all aspects has been retarded by overpressure. (2) The thermal evolution of hydrocarbons and thermal degradation of hydrogen-rich kerogens has been retarded, but the thermal evolution of hydrogen-poor kerogen components has not been affected by overpressure. As a result, vitrinite reflectance has not been retarded. (3) The thermal cracking of hydrocarbons has been retarded, yet overpressure has had little or no effect on thermal degradation of kerogens. (4) Overpressure has no detectable effect on all aspects of OM maturation. The hierarchy that overpressure has retarded all aspects of OM maturation is the combined result of early overpressure (overpressure began to develop when the source rock was still immature) and the protracted maintenances of closed fluid system. Any case that overpressure had developed too late, or overpressure was too small to reach the threshold values, or overpressured fluid had been frequently released, could give rise to the occurrence of state 4 that overpressure had no detectable effect on all aspects of OM maturation. It seems that in many basins, overpressure retardation of hierarchies 2 and 3 developed where the most commonly used maturity parameter, vitrinite reflectance, had not been affected. In theses cases, multiple parameters must be used to distinguish overpressure retardati

关键词： overpressure, organic matter maturation, hydrocarbon generation, differential retardation.

Sports video summarization and adaptation for application in mobile communication

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2006年第5期7卷 819-829页

作者： GAO Wen HUANG Qing-ming JIANG Shu-qiang ZHANG Peng Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Graduate School Chinese Academy of Sciences Beijing 100039 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China Institute of Computing Technology Chinese Academy of Sciences Beijing 100080 China

Sports video appeals to large audiences due to its high commercial potentials. Automatically extracting useful se- mantic information and generating highlight summary from sports video to facilitate users’ accessing requirements is an important problem, especially in the forthcoming broadband mobile communication and the need for users to access their multimedia in- formation of interest from anywhere at anytime with their most convenient digital equipments. In this paper, a system to generate highlight summaries oriented for mobile applications is introduced, which includes highlight extraction and video adaptation. In this system, several highlight extraction techniques are provided for field sports video and racket sports video by using multi-modal information. To enhance users’ viewing experience and save bandwidth, 3D animation from highlight segment is also generated. As an important procedure to make video analysis results universally applicable, video transcoding techniques are applied to adapt the video for mobile communication environment and user preference. Experimental results are encouraging and show the advantage and feasibility of the system for multimedia content personalization, enhancement and adaptation to meet different user preference and network/device requirements.

关键词： Video analysis, Video transcoding, Highlight summary, Animation generation, Mobile communication

Imaging theory of nonlinear second harmonic and third harmonic generations in confocal microscopy

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Science China(Physics,Mechanics & Astronomy) 2004年第1期47卷 8-16页

作者： TANG Zhilie1, XING Da2 & LIU Songhao2 1. Department of Physics, South China Normal University, Guangzhou 510631, China 2. School for Information and Optoelectronic Science and Engineering, South China Normal University, Guangzhou 510631, China Correspondence should be addressed to Tang Zhilie (email: tangzhl@***) Received April 23, 2003 Department of Physics South China Normal University Guangzhou China School for Information and Optoelectronic Science and Engineering South China Normal University Guangzhou China

The imaging theory of nonlinear second harmonic generation (SHG) and third harmonic generation (THG) in confocal microscopy is presented in this paper. The nonlinear effect of SHG and THG on the imaging properties of confocal microscopy has been analyzed in detail by the imaging theory. It is proved that the imaging process of SHG and THG in confocal microscopy, which is different from conventional coherent imaging or incoherent imaging, can be divided into two different processes of coherent imaging. The three-dimensional point spread functions (3D-PSF) of SHG and THG confocal microscopy are derived based on the nonlinear principles of SHG and THG. The imaging properties of SHG and THG confocal microscopy are discussed in detail according to its 3D-PSF. It is shown that the resolution of SHG and THG confocal microscopy is higher than that of single- and two-photon confocal microscopy.

关键词： second harmonic generation, third harmonic generation, confocal microscopy, three-dimensional point spread function.

Gas formation mechanism of marine carbonate source rocks in China

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Science China Earth Sciences 2005年第4期48卷 441-453页

作者： ZHAO Wenzhi1, WANG Zhaoyun1, HE Haiqing2, ZHANG Mingjie3, WANG Hongjun1, WANG Yunpeng4 & QIN Yong5 1. Research Institute of Petroleum Exploration & Development, PetroChina, Beijing 100083, China 2. PetroChina Exploration & Production, Beijing 100011, China 3. Department of Geology, Lanzhou University, Lanzhou 730000, China 4. Guangzhou Geochemical Institute, Chinese Academy of Sciences, Guangzhou 510640, China 5. China University of Mining and Technology, Xuzhou 221000, China Research Institute of Petroleum Exploration & Development PetroChinaBeijin China PetroChina Exploration & Production Beijing China Department of Geology Lanzhou University Lanzhou China Guangzhou Geochemical Institute Chinese Academy of Sciences Guangzhou China China University of Mining and Technology Xuzhou China

By breaking through the conventional ideology on the study of gas-formation mechanism of source rocks which focused on merely the characteristics of source rocks them- selves, and based on the development and distribution characteristics of marine carbonate source rocks in the medium-to-bottom parts of the Chinese superimposed sedimentary basins as well as various processes in the course of gas generation and reservoir forming, the complex hydrocarbon-generating model of carbonates is established. Such a model concerns not only the “three-stage” gas formation characteristics of carbonates, but also the gas generation process due to a thermal cracking of oil and the re-generation process of gas from heated secondary organic matters during the gas-generation and reservoir-forming course. The high-quality hy- drocarbon generating matter of marine carbonate source rocks determined a high gas-oil ratio and tended to form paleo-oil-reservoirs, representing an enrichment process of organic matters. The thermal cracking of oil in palaeo-oil-reservoirs is an important means for the effective forma- tion of gas reservoirs. The secondary organic matters in carbonate reservoirs may regenerate gas after a secondary deep burial, thus becoming an effective gas source.

关键词： carbonate, three-stage hydrocarbon generation, inhibitive effect of maturity, oil-cracking gas, second-ary asphalt gas.

Recent developments in study of the typical superimposed basins and petroleum accumulation in China: Exemplified by the Tarim Basin

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Science China Earth Sciences 2004年第Z2期47卷 1-15页

作者： JIN Zhijun1 & WANG Qingchen2 1. Academy of Petroleum Exploration and Exploitation, SinoPec Corp., Beijing 100083, China 2. Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 1000029, China Academy of Petroleum Exploration and Exploitation SinoPec Corp. Beijing 100083 China Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Most of petroliferous sedimentary basins in China have experienced multiple phases of tectonic evolution and deposition, and are characterized by tectonic and depositional superimposition. The term "superimposed basin" is suggested to describe those basins which consist of two or more simple prototype basins superimposing vertically and/or coalescing later-ally. The characteristics of petroliferous superimposed basins are "multiple stages of basin forming and reworking, multiple layers of source rocks, multiple periods of hydrocarbon genera-tion and expulsion, multiple periods of petroleum migration-accumulation-escape". Therefore, applying the wave process analysis method to studying the process of basin formation, hydro-carbon generation, and reservoir formation, and then establishing theory of "petroleum accumu-lation system" is helpful to enhancing petroleum exploration efficiency in superimposed basins. This paper will, based on case study in the Tarim basin, report the major developments in studying basin formation, hydrocarbon generation and petroleum accumulation. In study of basin formation, (1) geophysical comprehensive profiles reveal that the Tarim plate has been sub-ducted beneath the Tianshan orogenic belt with an interfinger structure and that the deep struc-ture in the eastern section of the Tianshan orogenic belt is different from that in the western sec-tion. (2) The vertical variation in debris and geochemical composition reveals the nature and Mesozoic-Cenozoic evolution history of the Kuqa Depression. (3) Field investigation and paleo-stress reconstruction show that the Kuqa Depression has undergone gravity-driven extension in sedimentary cover when the Tianshan uplifted vertically. In hydrocarbon generation study, new developments include (1) setting environmental index to judge high grade source rocks in marine carbonates, and (2) establishing the lower limit of the organic carbon content for effective car-bonate source rocks. In petroleum acc

关键词： superimposed basin, Tarim basin, basin formation, hydrocarbon generation, petroleum accumulation.

各种牙种植体软组织增量技术临床效果的系统评价

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中国口腔种植学杂志 2013年第2期18卷 81-82页

作者：吴庆庆王天璐杨阳向琳满毅四川大学华西口腔医院种植科

目的:评价各种软组织增量技术在牙种植体周软硬组织稳定度等方面随访半年以上的临床效果。方法:计算机检索MEDLINE(Pub-Med)和Cochrane Library(1980-2013),手动检索部分重要英文期刊(2000-2013),并辅以文章追溯,建立该系统评价的纳入...

目的:评价各种软组织增量技术在牙种植体周软硬组织稳定度等方面随访半年以上的临床效果。方法:计算机检索MEDLINE(Pub-Med)和Cochrane Library(1980-2013),手动检索部分重要英文期刊(2000-2013),并辅以文章追溯,建立该系统评价的纳入标准。由两位研究者主要进行文献筛选、数据提取和质量评价,并对合格文献进行综合描述或Meta分析。结果:初步筛选出文献325篇,纳入26篇。仅唇侧结缔组织移植恢复龈乳头外形、结缔组织移植恢复或保持KMW和腭侧带蒂瓣实现初期创口封闭的相关研究中测量方法和测量指标统一。对此三组数据分析的结果显示,该三种方法均有利软硬组织稳定。结论:现有各种手术方法均能不同程度扩增或维持软/硬组织水平。但是,由于手术方法、测量方法、测量指标不统一,同时受到纳入数量、研究质量的限制,本研究论证强度有待提高,其结果有待大量规范随机对照研究予以论证。讨论:纳入文献以手术目的分组,有利于各技术的比较,便于医生根据问题选择方案。然而,同一技术高质量文献极少,且测量方法多样,测量指标不全面,不利于统计。统一规范的软组织研究方法和测量标准是需要尽快解决的问题。

关键词： dental implant, connective tissue graft, papilla generation, KMW