检索结果-南通市图书馆

Comparison of eastern paleo-Tethyan ophiolites and its geodynamic significance--Evidence from Dur'ngoi ophiolite

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2004年第4期47卷 378-384页

作者： CHEN Liang1,2. SUN Yong1,2. PEI Xianzhi2. Feng Tao2.& Zhang Guowei2.1. Open Laboratory of Continental Dynamics, Ministry of Education, Northwest University, Xi抋n 710069, china 2. institute of Geology and Geophysics, Chinese Academy of {2., beijing 10002., china Open Laboratory of Continental Dynamics Ministry of Education Northwest University Xi’an 710069 China institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Nd-Pb isotopic geochemistry of metabasalt from Dur抧goi ophiolite, Qinghai Prov-ince, NW china reveals the presence of DMM mixing with EMII components in its upper mantle source, which is comparable with present Indian MORB. Comparisons indicate that the geo-chemistry, chronology and source characteristics of Dur抧goi ophiolite coincide with Pa-leo-tethyan ophiolites from 揝anjiang?area. Together with evidences from regional geology in adjacent areas, this study proves that independent paleo-tethyan basins evolved contemporarily, the dynamics of which is attributed to the interaction of mantle plume with over-riding lithosphere.

关键词： ophiolite, Paleo-Tethys, DUPAL anomaly, Indosinian movement.

The upper mantle structure of the Tibetan Plateau and its implication for the continent-continent collision

在线全文

学校读者我要写书评

暂无评论

Science china Earth sciences 2005年第8期48卷 1158-1164页

作者： WU Qingju1, ZENG Rongsheng1 & ZHAO Wenjin2.1. institute of Geophysics, china Earthquake Administration, {2. 100081, china 2. institute of Geology, china Academy of Geological sciences, {2. 100037, china 1. institute of Geophysics China Earthquake Administration 100081 Beijing China 2. institute of Geology China Academy of Geological Sciences 100037 Beijing China

The upper mantle structures of Himalayas-Tibet have been obtained from the mi-gration of receiver functions of the teleseismic events recorded by INDEPTH-III. The result of migration imaging shows a dipping interface subducting northward from the depth of 100 km to the 4.0-km discontinuity underneath southern Tibet. It indicates that the lithospheric mantle of the Indian continent had been detached from the crust and deeply subducted to the upper mantle of Eurasia during the Indo-Eurasian collision. This kind of continent-continent collision process is fundamentally different from the oceanic collision.

关键词： Tibetan Plateau, receiver function, upper mantle structures, Indo-Eurasian collision, dipping interface.

Characteristics and geological significance of olivine xenocrysts in Cenozoic volcanic rocks from western Qinling

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第12期16卷 1300-1306页

作者： SU Benxun~ 1,2.**, ZHANG Hongfu~1, XIAO Yan~ 1,2.and ZHAO Xinmiao~ 1,2.(1. State Key Laboratory of Lithospheric Evolution, institute of Geology and Geophysics, Chinese Academy of {4., {2. 10002., china 2. Graduate School of Chinese Academy of {4., {2. 100039, china) [a]State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China [b]Graduate School of Chinese Academy of sciences Beijing China

Cenozoic volcanic rocks from the Haoti, Dangchang County of the western Qinling Mountains, contain a few clearly-zoned olivines. These olivines are relatively big in grain sizes and usually have cracks or broken features. Their cores have similar compositions （Mg#=90.4.91.0） to those for the peridotitic xenoliths entrained in host volcanic rocks and their rims are close to the compositions of olivine phenocrysts （Mg#=85.5-81.9）. The CaO contents in these zoned olivines are lower than 0.1%. These features demonstrate that the clearly-zoned olivines are xenocrysts and disaggregated from mantle peridotites. The zoned texture was the result of the interaction between the olivine and host magma. Available data show that the volcanic rocks would have been derived from the mantle source metasomatized by subducted hydrathermally-altered oceanic crust. The formation of these Cenozoic volcanic rocks was perhaps related to the rapid uplift of the Tibetan Plateau.

关键词： Western Qinling Dangchang Haoti Cenozoic volcanic rocks olivine xenocrysts zoned texture.

Application of the moist vorticity vector in the analysis of a heavy rainfall event in North china

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第12期17卷 1457-1465页

作者： Zhao Yu1,2.3, Wang Jianguo4.and Xue Deqiang2.1. Laboratory of Cloud-Precipitation Physics and Severe Storms, institute of Atmospheric Physics, Chinese Academy of sciences, {2. 10002., china 2. Shandong Provincial Meteorological Observatory, Jinan 2.0031, china 3. Graduate University of Chinese Academy of sciences, {2. 100039, china 4. Shandong Provincial Meteorological Bureau, Jinan 2.0031, china) Laboratory of Cloud-Precipitation Physics and Severe Storms Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China Shandong Provincial Meteorological Observatory Jinan 250031 China Graduate University of Chinese Academy of sciences Beijing 100039 China Shandong Provincial Meteorological Bureau Jinan 250031 China

The moist vorticity vector (MVV), defined as (ζa×▽qv)/ρ introduced by Gao et al. is used to study a heavy rainfall event in North china. The MVV has zonal, meridional and vertical components in a three-dimensional framework. Analysis of domain-mean and mass-integrated quantities shows that the variation of the vertical component of the MVV closely follows the variation of the cloud hydrometeors, with a linear correlation coefficient of 0.95, indicating that the vertical component of the MVV is strongly associated with midlatitude convection. Further analysis shows that the vertical component of the MVV reflects the interaction between the horizontal vorticity and the horizontal specific humidity gradient, which can associate dynamic and thermodynamic processes with cloud microphysical processes. Thus, this study can help to understand how the interaction between circulations and clouds aids the development of convection, and the MVV can be used to trace the development and evolution of heavy rainfall.

关键词： moist vorticity vector heavy rainfall modeling study.

Experimental study of composite medium with simultaneously negative permeability and permittivity

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2004年第1期47卷 64-78页

作者： SUI Qiang1, 2.& LI Fang1 1. institute of Electronics, Chinese Academy of sciences,{2.,{4. 2. School of Information, beijing Broadcasting institute, beijing 10002.,{4. Correspondence should be addressed to Sui Qiang (email: suiqiang@***) Received July 2., 2.03 1. institute of Electronics Chinese Academy of Sciences 100080 Beijing China 2. School of Information Beijing Broadcasting Institute 100024 Beijing China

This paper focuses on a composite medium structure that exhibits simultan- eously negative values of effective permeability and permittivity, and our experimental study in an anechoic chamber. The experiment results show that the artificial medium, based on a periodic array of interspaced conducting nonmagnetic split ring resonators and continuous metallic wires, can have a simultaneously negative effective permeability and permittivity within a frequency region in the microwave regime under certain linearly polarized waves.

关键词： permittivity, permeability, negative index of refraction, split ring resonator, LHM, RHM.

Isotopic feature and uranium dating of the volcanic rocks in the Okinawa Trough

在线全文

学校读者我要写书评

暂无评论

中国科学：地球科学英文版 2006年第4期49卷 375-383页

作者： HUANG Peng1,2. LI Anchun1, HU Ningjing2.3, FU Yongtao1& MA Zhibang4.1. institute of Oceanology, Chinese Academy of sciences, Qingdao 2.6071,{2. 2. Graduate School of the Chinese Academy of sciences, beijing 100039,{2. 3. institute of Soil Science, Chinese Academy of sciences, Nanjing 2.0008,{2. 4. institute of Geology and Geophysics, Chinese Academy of sciences, beijing 10002.,{2. 1. institute of Oceanology Chinese Academy of Sciences Qingdao 266071 China 2. Graduate School of the Chinese Academy of sciences Beijing 100039 China 3. institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China 4. institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China

Volcanic rocks from the northern and middle Okinawa Trough were dated by ura- nium-series dating method. Differential fractions using magnetic procedure were designed to separate samples. New report on the ages and isotopic data of rocks in the northern trough (especially black pumice) was discussed. Based on the uranium dates and Sr-Nd isotopic ratio, magmatic evolution process of the Okinawa Trough was noted. Firstly, there have been wide silicic volcanic activities in the Okinawa Trough from late Pleistocene to present, and the volcanic rocks can be divided into three subgroups. Secondly, magma generally came from PREMA source area under the Okinawa Trough. Magmatic evolution in the northern trough was similar to the middle, but different to the south. Finally, volcanic activities indicated that opening of the southern Okinawa Trough did not happen due to the collision between Luson Arc and Eurasian Plate until the early Pleistocene.

关键词： Okinawa Trough, black pumice, uranium-series dating, Sr-Nd isotopic ratio, magmatic evolution.

Calculating soil moisture by remote sensing and analyzing hydrologic cycle process in the Yellow River basin

在线全文

学校读者我要写书评

暂无评论

Science china(Technological sciences) 2004年第z1期47卷 1-13页

作者： YANG Shengtian1 & LIU Changming1, 2.1. School of Environmental sciences, beijing Normal University, beijing 100875,{4. 2. institute of Geographic Science and Natural Resources Research, beijing 100101,{4. beijing Normal Univ Sch Environm Sci Beijing 100875 Peoples R China Inst Geog Sci & Nat Resources Beijing 100101 Peoples R China

Based on the AVHRR pathfinder remote sensing data, soil moisture, precipitation and evaporation during the period of 1982.1998, soil moisture of all layers of soil-profile (0—1 m) in the Yellow River basin over the 17 years are calculated by the remote sensing model of calculating soil water. The Yellow River basin is divided into seven subcatchments as control sections at the location of six hydrologic stations (Lanzhou, Toudaoguai, Longmen, Sanmenxia, Huayuankou and Lijin). After calculating soil moisture and obtaining runoff data and precipitation data, the dynamical features of hydrological cycle in the Yellow River basin are analyzed for the period from 1982.to 1988 using water balance method. The conclusions are as follows: It is feasible to calculate the soil water on the macro-scale, in the soil profile with temporal continuity by means of remote sensing and survey in land. Some values of the key water cycle factors in the Yellow River are obtained, which include the annual precipitation of 4.00 km3, the evapotranspiration of 3000-3500 km3, and the soil moisture transformation of ?500- 500 km3. Consequently, we analyzed the process of the water cycle in the Yellow River over the 17 years, and the results show that the segment upstream of Lanzhou city is a relatively humid region, and the area of internal waters and the reaches of Shanshan is the most desiccated region. Therefore, the runoff in the depth process is intensive and the runoff-generating process is weak in more arid regions.

关键词： the Yellow River, soil moisture, remote sensing, hydrologic cycle.

A formal model of fair exchange protocols

在线全文

学校读者我要写书评

暂无评论

Science in china(Series F) 2005年第4期48卷 499-512页

作者： QING Sihan1,2.3 & LI Gaicheng1,2.3 1. Engineering Research Center for Information Security Technology, institute of Software, Chinese Aca- demy of sciences,{2., china 2. beijing Zhongke Ansheng Corporation of Information Technology,{2., china 3. Graduate School of the Chinese Academy of sciences, beijing 100039, china 1. Engineering Research Center for Information Security Technology Institute of Software Chinese Academy of Sciences 100080 Beijing China 2. beijing Zhongke Ansheng Corporation of Information Technology 100080 Beijing China 3. Graduate School of the Chinese Academy of sciences 100039 Beijing China

Based on the study of existing fair exchange protocols, this paper sets up an accurate formal model by stepwise refinement. In the process of refinement an unreliable channel is employed to simulate an attack behavior. The model provides a novel formal definition of exchanged items, and presents the formal goals for fairness, accountability, etc., reflecting the inherent requirements for fair exchange protocols across-the-board. In order to check, prove, and design fair exchange protocols effectively and efficiently, the model puts forward a novel property of abuse-freeness which applies to all fair exchange protocols, gives a formal definition for trust strand of the third party, and presents general criteria of designing a secure and effective fair exchange protocol. Taking a typical fair exchange protocol as an example, this paper presents the analysis steps of fair exchange protocols appealing to our model. An unknown attack is uncovered. The analysis reveals the process of a complete attack, discovering deeper reasons for causing an attack. Finally, we modify the flawed protocol and the revised protocol ensures the desirable properties.

关键词： events local causal relation local temporal relation global relation exchanged item security goals.

Photogeneration of the free radicals and singlet oxygen by chrysophanol from rheum

在线全文

学校读者我要写书评

暂无评论

Science china Chemistry 2004年第5期47卷 381-387页

作者： RAO Jing1,2. XIE Jie1, ZHAO Jingquan1 & ZHU Teng2.1. Key Laboratory of Photochemistry, Center for Molecular Science, institute of Chemistry, The Chinese Academy of sciences,{2., china 2. University of Science and Technology beijing, beijing 10083, china 1. Key Laboratory of Photochemistry Center for Molecular Science Institute of Chemistry The Chinese Academy of Sciences 100080 Beijing China 2. University of Science and Technology beijing 10083 Beijing China

In the current work, chryosphanol (MHAQ) was isolated and purified from rheum, and the photosensitization activities were studied. In nitrogen-saturated DMSO solution, irradia- tion of chryosphanol (MHAQ) with visible light (>4.0 nm) produced the semiquinone radical anions (MHAQ??), which was intensified significantly by an electron donor NADH, suggesting electron transfer between the excited and ground state photosensitizer molecules. In an air-saturated DMSO solution, superoxide radical anions (O2.), trapped by DMPO, were detected. ?? It was proved that O2.was not originated from the singlet oxygen (1O2. but dependent on DMPO, ?? chrysophanol, oxygen and the irradiation time. The singlet oxygen and OH could also be pro- ? duced by the photosensitization of the photosensitizer. These suggest that chrysophanol pos- sesses the photosensitization activity via Type I mechanism and Type II mechanism. To evaluate the photosensitization activities of MHAQ, emodin and mixed anthraquinone derivatives ex- tracted from rheum, the relative productivities of O2.were estimated to be 1.8, 1.1 and 1.0 re- ?? spectively and the quantum yields for singlet oxygen to be 0.36, 0.53 and 0.14.respectively. Therefore, these low-cost pigments may be potentially used as phototherapeutic medicine for some kind of vascular diseases or photo-activated pesticides.

关键词： chrysophanol, ESR, semiquinone radical anions, superoxide radical anions, hydroxyl radical, singlet oxygen.