检索结果-南通市图书馆

Isotopic compositions of small shelly fossil Anabarites from Lower Cambrian in Yangtze Platform of South china: Implications for palaeocean temperature

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第10期17卷 1185-1191页

作者： Chen Yongquan1,2, Jiang Shaoyong1, Ling Hongfei1, Yang Jinghong1 and Wan Defan3(1. State Key Laboatory for mineral Deposits Research and Center for Marine Geochemistry Research, Department of Earth Sciences, nanjing University, nanjing 210093, china 2. Tarim Oilfield Company Exploration & Development Research institute, Ku’erle 841000, china 3. institute of mineral resources, Chinese Academy of Geological Sciences, Beijing 100037, china) State Key Laboratory for mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing 210093 China Exploration and Development Research institute Tarim Oilfield Company Ku'erle 841000 China institute of mineral resources Chinese Academy of Geological Sciences Beijing 100037 China

Anabarites belong to small shelly fossils (SSF), which occur widely in the Lower Cambrian strata of Yangtze Platform in South china. They are phosphate shell in composition and represent the earliest stage of the Cambrian bioradiation of Bilateria, the so-called "Cambrian Explosion". In this study, we attempted to separate Anabarites fossils from Lower Cambrian dolostones, and we obtained samples of both the fossils (SSF) and the granular phosphates (GP). Isotopic analyses were performed on samples of SSF, GP, and matrix dolostone (DH-23). The results showed that the δ30Si values of the quartz filling in fossils celoms, and the siliceous materials in granular phosphates are -0.6‰ and -0.7‰, which is different from normal sedimentary siliceous rocks from the Lower Cambrian strata (0—0.7‰) as reported by Li et al., but is consistent with the data for siliceous rocks and cherts of submarine hydrothermal origin. It is likely that a later hydrothermal replacement could have taken place in the SSF-bearing sedimentary rocks. The oxygen isotope values of the phosphate of SSF and GP are 16.8‰ and 17.0‰, respectively. These are significantly higher than the Neoproterozoic phosphate ores (10.9‰—13.9‰) as reported by Ling et al., hence, late diagenesis and hydrothermal replacement may not have caused a significant change in the oxygen isotope compositions of the small shelly fossils, and the calculated temperatures (25.4—26.3℃) for palaeo-seawater using a SSF phosphate oxygen isotope thermometer are therefore considered here as the upper limit of seawater temperature in the Early Cambrian ocean of the Yangtze Platform.

关键词： Anabarites oxygen isotope silicon isotope paleo-temperature.

Holocene grassland vegetation, climate and human impact in central eastern Inner Mongolia

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 Earth Sciences 2005年第7期48卷 1025-1039页

作者： HUANG Fei1, Kealhofer Lisa2, XIONG Shangfa3 & HUANG Fengbao1 1. nanjing institute of geology and Paleontology,Chinese Academy of Sciences,nanjing 210008,china 2. Anthropology and Sociology Department,Santa Clara University,CA 95053,USA 3. institute of geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,china nanjing institute of geology and Paleontology Chinese Academy of Sciences Nanjing 210008 China Anthropology and Sociology Department Santa Clara University CA 95053 United States institute of geology and Geoohysics Chinese Academy of Sciences Beijina 100029 China

Phytolith and pollen preserved in the Taipusi Banner paleosol profile, central eastern Inner Mongolia, provide evidence of Holocene grassland vegetation, climate and human impact. The combined phytolith and pollen records reveal a major change in vegetation composition about 5000 a BP. Before 5000 a BP, the vegetation was dominated by Aneurolepidium Chinese-Stipa grandis grassland of C4 grasses. After 5000 a BP, C4 grasses rapidly retreated, indicating a shift to colder and more arid conditions. The gradual invasion of Stipa krylovii, Ag-ropyron desertorum, Ephedra, Chenopodiaceae and Caragana reveal the onset of grassland degeneration. Between 10000 and 8720 a BP, the Aneurolepidium Chinese-Stipa grandis grassland included a small proportion of Artemisia shrub and Echionopos type plants, implying a strong winter monsoon and very weak summer monsoon. From 8720 to 7000 a BP, C4 grasses were common, indicating a strengthening of the summer monsoon. Between 7000 and 5000 a BP, the Holocene thermal maximum was evident, with a significant expansion of C4 grasses and the presence of some trees (such as Pinus and Betula, and so on) in or near the study site. From 4200?000 a BP, a sandy grassland of Artemisia and Agropyron desertorum together with Aster-type taxa occurred. Precipitation amelioration took place between 3000 and 2170 a BP, with a rapid development of Echinops type plants and a small expansion of C4 grasses. From 2170 a BP to present, human activities accelerated the process of grassland degeneration.

关键词： phytolith and pollen records grassland environment change human impact Holocene central eastern Inner Mongolia.

SOME ROTORDYNAMIC PROBLEMS IN SMALL TURBO—ENGINES

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 1992年第1期 52-58页

作者： Huang Tai-ping (nanjing Aeronautical institute, nanjing, 210016)

Rotordynamics in small turbo-engines is a very important topic owing to their highrotating speeds and small sizes. In this paper, some rotordynamic problems in smallturbo-engines have been discussed and the approaches to solving these problems have beenanalyzed briefly. Numerical and experimental results show that the analysis is valuableand reliable.

关键词： mode ENGINES SOME ROTORDYNAMIC PROBLEMS IN SMALL TURBO

Ore-forming fluid and mineralization of Caijiaying and Dajing polymetallic ore deposits

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 Earth Sciences 2004年第2期47卷 97-107页

作者： WANG Lijuan,WANG Jingbin, WANG Yuwang & ZHU Heping1. Key Laboratory of mineral resources, institute of geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, china 2. Beijing institute of geology for mineral resources, Beijing 100012, china Correspondence should be addressed to Wang Lijuan (email: wlj@***) Key Laboratory of mineral resources Institute of Geology and Geophysics Chinese Academy of Sciences Beijing China Beijing institute of geology for mineral resources Beijing China

Fluid inclusions from the Dajing and Caijiaying deposits have nearly the same homogenization temperature. Correlation between temperature and salinity shows that both Sn- and Cu-bearing fluids Sn and Cu were present in the Dajing deposit but only one kind of fluids continuously evolved in the Caijiaying deposit. Study on rare earth elements (REE) in ancient fluid from the inclusions indicates that the fluid of Sn mineralizing stage in Dajing was derived from remelting magma of the continental crust, and the fluid of Cu-Pb-Zn mineralizing stage in the Dajing deposit and the fluid of Cu-Pb-Zn mineralization in the Caijiaying deposit were derived from the mantle. It is concluded that the Cu-Pb-Zn mineralizations in the Dajing and Caijiaying deposits resulted from the identical tectono-thermal event of magma-fluids induced by Mesozoic tectonic transition and extension in the eastern part of North china Craton.

关键词： Caijiaying, Dajing, Mesozoic tectonic transition, ore-forming fluid, REE.

在线全文

学校读者我要写书评

暂无评论

NOTICE

NOTICE

OPTIMIZATION DESIGN OF HELICOPTER FOR PRELIMINARY PARAMETERS

作者： nanjing institute OF geology mineral resources

＜正＞TO EMPHASIZE THE DISTINGUISHED SUBJECTS OF THIS PERIODICAL,THE NAME“BULLETIN OF nanjing INSTI- TUTE OF geology AND mineral resources,ACADEMY OF GEOLOGICAL SCIENCES”WILL BE CHANGED INTO

关键词：

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 1994年第3期7卷 175-182页

作者： Guo Caigen (The Research institute of Helicopter Technology, nanjing University of Aeronautics and Astronautics, nanjing china 210016)

A new design method for prehminary parameters is proposed. The analyticmodels of the optimization design are established according to the requirements of helicopter flight performance- stability, engine and weight. The optinial preliminary projectof design to meet the requirements of critenon for helicopter design is worked out byapplying the computer and optimization techniques. The inethod can be used for theanalysis of helicopters for prehminary parameters that are used in practice and for theanalysis of sensibility for preliminary parameters, too. The method is shown to be veryuseful by the example and application in the new design of helicopters.

关键词： helicopters optimization design computer aided design

Activation of fly ashes by the high temperature and high alkalinity in ASR tests

在线全文

学校读者我要写书评

暂无评论

Science china(Technological Sciences) 2011年第S1期54卷 28-32页

作者： CAI YueBo ,DING JianTong & BAI Yin State Key Laboratory of Hydrology-Water resources and Hydraulic Engineering,nanjing Hydraulic Research institute,nanjing 210029,china State Key Laboratory of Hydrology-Water resources and Hydraulic Engineering Nanjing Hydraulic Research Institute Nanjing China

High temperature and high alkalinity are typical testing conditions to accelerate the appraisal process of the suppressing effect of fly ashes on alkali silica reaction(ASR),but the reaction mechanism of fly ashes would be quite different under such conditions compared to the normal condition of temperature and *** make a reasonable analysis of the suppressing effect of fly ashes,13 types of fly ashes were tested in this paper by both the accelerated mortar bar test method and the 60°C accelerated concrete prism test *** results showed that the effect of fly ashes would be magnified under the condition of high temperature and high *** XRD analysis showed that all the phases of fly ash could react with the hot alkaline solution except for mullite and a small amount of *** ash could be significantly activated by the 80°C 1 mol/L NaOH solution,and form mainly C-S-H phase and P type zeolite,but its effect on inhibiting ASR was exaggerated *** to the mortar strength test and the ASR suppressing test results,C-S-H phase contributed to mortar strength,but its amount did not decide the ASR suppressing effect of fly ash.

关键词： fly ash Alkali silica reaction Activation

The species diversity of fusulinaceans and high-frequency sea-level changes in the Carboniferous-Permian boundary section at Xikou, Zhen'an County,Shaanxi Province, china

在线全文

学校读者我要写书评

暂无评论

Science china Earth Sciences 2006年第7期49卷 673-683页

作者： ZHANG Haijun1, WANG Xunlian2, DING Lin1, XIA Guoying3 & WANG Lei2 1. institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, china 2. Faculty of Earth Sciences and mineral resources, china University of Geosciences, Beijing 100083, china 3. Tianjin institute of geology and mineral resources, Tianjin 300170, china institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China Faculty of Earth Sciences and mineral resources China University of Geosciences Beijing China Tianjin institute of geology and mineral resources Tianjin China

The study on the interrelation between sea-level changes and biodiversity with its evolu-tion has great significance for understanding the impact of global changes on organic evolution and exploring the inherent laws of life-environment coevolution in geological history. In this paper, the stratigraphic distribution of fusulinacean fauna in the Carboniferous-Permian boundary section at Xikou, Zhen’an County, Shaanxi Province, is analyzed quantitatively, and the relationship between the species diversity of fusulinaceans and relative sea-level changes is discussed. As a whole, the spe-cies numbers of fusulinacean fauna experience a rapid increase and an obvious decline in Xikou, Zhen’an County, from the Late Carboniferous to the Early Permian. There is a significant increase in species diversity around the Carboniferous-Permian boundary, which is one of the biggest bio-events of the fusulinacean fauna, and represents the radiation of Pseudoschwagerininae subfamily in the studied area. Integrated fusulinacean species diversity into sequence stratigraphic framework, de-tailed study suggests that the species diversity of the fusulinaceans is closely related to its relative stratigraphic location, and is essentially controlled by the sea-level changes, especially by the high-frequency sea-level changes. Generally, the species diversity of fusulinaceans is low, and the number of first and last appearance datum is small in the lower unit of high-frequency depositional cycle formed during the quick rise of the sea level; whereas the species diversity of fusulinaceans is high, and the number of first and last appearance datum is large in the upper unit of high-frequency cycle formed during the slow fall of the sea level. Within the third-order depositional sequence, the species diversity of the fusulinaceans at the first flooding surfaces and the maximum flooding surfaces is low, and it increases upward. The fusulinacean species diversity is low within the transgressive syst

关键词： fusulinaceans, species diversity, high-frequency cyclothem, sequence stratigraphy, sea-level changes, Carboniferous-Permian boundary, Zhen'an, Shaanxi.

FRETTING FATIGUE AND ANALYSIS OF BLADE TO DISC TENON JOINT

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Aeronautics 1992年第1期 45-51页

作者： He Ming-jian (nanjing Aeronautical institute,nanjing, 210016)

The fretting fatigue of blade to disc dovetail joint has been studied with methods ofcalculation and test. Because the disc works at very high rotating speed, the test will be difficultand very expensive. Structure model must be designed to modulate the blade to discjoint. In this paper an axial dovetail joint and a circumferential dovetail joint have beenstudied with the structure model. The distribution of stress and displacement in the cuntactsurface and bulk, contact state at interface, fretting damage and initiation of crack, andspread of crack have been described. Calculated results were verified by test. Study wasundertaken at room temperature. The methods of calculation and test are useful not onlyfor dovetail joint but also for fir-tree joint and other kinds of tenon joints.

关键词： FRETTING FATIGUE AND ANALYSIS OF BLADE TO DISC TENON JOINT DISC