检索结果-南通市图书馆

Relationships between tree-ring width index and NDVI of grassland in Delingha

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2006年第9期51卷 1106-1114页

作者： HE Jicheng1,3.& sHAO Xuemei1,21. Institute of Geographical sciences and Natural Resources Research, chinese academy of sciences, beijing 100101, China 2. Institute of Tibetan Plateau Research, chinese academy of sciences, beijing 100085, China 3. graduate school of chinese academy of sciences, beijing 10003., China Institute of Geographical sciences and Natural Resources Research Chinese Academy of Sciences Beijing China graduate school of chinese academy of sciences Beijing China Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing China

Using five well-replicated Qilian juniper (sabina przewalskii Kom.) tree-ring width index se- ries, monthly normalized difference vegetation index (NDVI) of grassland, and climatic data from 1982 to 2001, the relationships between tree-ring width index, NDVI of grassland, and climatic data were analyzed firstly. Then, the relationship between tree-ring width index and NDVI of grassland was explored. The re- sults showed that: (1) Temperature and precipitation in June influenced tree-ring width index and NDVI of grassland deeply in Delingha. (2) There were sig- nificant relationships between five tree-ring width index series (DLH1-DLH5) and monthly NDVI of grassland from June to september, with the most significant relationship being between tree-ring width index series and NDVI of grassland in August. (3. The PC1 (the first principal component derived from DLH1-DLH5 series) exhibited good agreement with monthly NDVI of grassland in the grass growth sea- son (from June to september) and the averaged NDVI in the growth season, which was attributed to their common responses to water-supply limit in Delingha. This study may allow an increase in studying the past dynamics of grassland in Delingha in that the variation of grassland NDVI during the last millennium has been reconstructed from PC1.

关键词：圆柏祁连山 NDVI 草原年轮宽度指数

A tentative study for the prediction of the CME related geomagnetic storm intensity and its transit time

在线全文

学校读者我要写书评

暂无评论

science China(Technological sciences) 2005年第6期48卷 648-668页

作者： ZHAO Xinhua1,2 & FENG Xueshang1,3.1. sIGMA Weather Group, Key Laboratory of space Weather, Center for space science and Applied Re-search, chinese academy of sciences, beijing 100080, China 2. {3. school of the chinese academy of sciences, beijing 10003., China 3. school of Geophysics and Geoinformation systems, China university of Geosciences, beijing 100083. China 1. sIGMA Weather Group Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences 100080 Beijing China 2. graduate school of the chinese academy of sciences 100039 Beijing China 3. school of Geophysics and Geoinformation systems China University of Geosciences 100083 Beijing China

Using 80 CME-ICME events during 1997.1―2002.9, based on the eruptive source locations of CMEs and solar magnetic field observation at the photosphere, a current sheet magnetic coordinate (CMC) system is established in order to study the propagation of CME and its geoeffectiveness. In context of this coordinate system, the effect of the eruptive source location and the form of heliospheric current sheet (HCs) at the eruptive time of CME on the geomagnetic storm intensity caused by CME and the CME’s transit time at the Earth is investigated in detail. Our preliminary conclusions are: 1) The geomagnetic disturbances caused by CMEs tend to have the so-called “same side-opposite side effect”, i.e. CMEs erupt from the same side of the HCs as the earth would be more likely to arrive at the earth and the geomagnetic disturbances associated with them tend to be of larger magnitude, while CMEs erupting from the opposite side would arrive at the earth with less probability and the corresponding geomagnetic disturbance magnitudes would be relatively weaker. 2) The angular separation between the earth and the HCs affect the corresponding disturbance intensity. That is, when our earth is located near the HCs, adverse space weather events occur most probably. 3. The erupting location of the CME and its nearby form of HCs will also affect its arrival time at the earth. According to these conclusions, in this context of CMC coordinate we arrive at new prediction method for estimating the geomagnetic storm intensity (Dstmin) caused by CMEs and their transit times. The application of the empirical model for 80 CME-ICME events shows that the relative error of Dst is within 3.% for 59% events with Dstmin≤?50 nT, while the averaged absolute error of transit time is lower than 10 h for all events.

关键词： coronal mass ejections, current sheet magnetic coordinate system, geomagnetic storm intensity, transit time, prediction method.

Forecasting the summer rainfall in North China using the year-to-year increment approach

在线全文

学校读者我要写书评

暂无评论

science China Earth sciences 2009年第4期52卷 532-539页

作者： FAN Ke1, LIN MeiJing1,2 & GAO YuZhong3.1 Nansen-Zhu International Research Center, Institute of Atmospheric Physics, chinese academy of sciences, beijing 100029, China 2 {3. university of the chinese academy of sciences, beijing 100049, China 3.Heilongjiang Meteorological Administration, Harbin 15003., China Nansen-Zhu International Research Center Institute of Atmospheric Physics Chinese Academy of Sciences Beijing 100029 China graduate university of the chinese {3. of sciences Beijing 100049 China Heilongjiang Meteorological Administ

A new approach to forecasting the year-to-year increment of rainfall in North China in July-August (JA) is proposed. DY is defined as the difference of a variable between the current year and the preceding year (year-to-year increment). NR denotes the seasonal mean precipitation rate over North China in JA. After analyzing the atmospheric circulation anomalies associated with the DY of NR, five key predictors for the DY of NR have been identified. The prediction model for the DY of NR is established by using multi-linear regression method and the NR is obtained (the current forecasted DY of NR added to the preceding observed NR). The prediction model shows a high correlation coefficient (0.8) between the simulated and the observed DY of NR throughout period 1965-1999, with an average relative root mean square error of 19% for the percentage of precipitation rate anomaly over North China. The prediction model makes a hindcast for 2000-2007, with an average relative root mean square error of 21% for the percentage of precipitation rate anomaly over North China. The model reproduces the downward trend of the percentage of precipitation rate anomaly over North China during 1965-2006. Because the current operational prediction models of the summer precipitation have average forecast scores of 60%-70%, it has been more difficult to forecast the summer rainfall over North China. Thus this new approach for predicting the year-to-year increment of the summer precipitation (and hence the summer precipitation itself) has the potential to significantly improve operational forecasting skill for summer precipitation.

关键词： annual increment North China precipitation prediction prediction skill

Formal analysis and design of multi-party 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) 2006年第2期49卷 155-174页

作者： QING sihan1,2,3.& LI Gaicheng1,3.1. Engineering Research Center for Information security Technology, Institute of software, chinese academy of sciences, beijing 100080, China 2. beijing Zhongke Ansheng Corporation of Information Technology, beijing 100080, China 3. graduate school of the chinese academy of sciences, beijing 10003., China 1. Engineering Research Center for Information security Technology Institute of Software Chinese Academy of Sciences Beijing 100080 China 2. beijing Zhongke Ansheng Corporation of Information Technology Beijing 100080 China 3. graduate school of the chinese academy of sciences Beijing 100039 China

Based on the origin of message items and channel combination between transacting parties, and events and relations among events, this paper presents a concise, precise, and hierarchical model for general fair exchange protocols, formally specifies various security requirements which are able to reflect inherent requirements for fair exchange protocols more rigorously, and partition these security requirements with fine granularity. This work helps analyze, debug, and design multi-party fair exchange protocols more effectively and elaborately,

关键词： fair exchange logical protocol formal model security requirement.

Cloning and expression of putative ethylene receptor genes in soybean plant

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 1152-1160页

作者： Xie Zongming1,2,3. Lei Gang1,2, Wuriyanghan Hada1,2, Tian Aiguo1, Zhang Jinsong1 and Chen shouyi1(1. National Key Laboratory of Plant Genomics, Institute of Genetics and Developmental Biology, chinese academy of sciences, beijing 100101, China 2. {3. school of chinese academy of sciences, beijing 10003., China 3. Xinjiang academy of Agricultural and Reclamation science, shihezi 83.000, China) National Key Laboratory of Plant Genomics Institute of Genetics and Developmental Biology Chinese Academy of Sciences Beijing 100101 China graduate school of chinese academy of sciences Beijing 100039 China Xinjiang academy of Agricultural and Reclamation science Shihezi 832000 China

Ethylene plays important roles in plant growth, development, and stress responses, and ethylene receptors have been identified and studied extensively in various plant species. Here we report the cloning of four ethylene receptor genes from soybean, i.e. GmETR1, GmERs1, GmETR2 and GmEIN4. Construction of the phylogenic tree showed that GmETR1 and GmERs1 belong to subfamily I whereas GmETR2 and GmEIN4 belong to subfamily II. The four ethylene receptor genes showed different tissue-specific expression patterns in roots, stems, leaves, cotyledons, flowers, pods and seeds of soybean. These genes were differentially regulated by various abiotic stresses and plant hormones. The possible roles of the four genes in soybean plant were also discussed.

关键词： abiotic stress expression analysis ethylene receptor plant hormone soybean.

Chronology of Holocene lacustrine sediments in Co Ngoin, central Tibetan Plateau

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 2006年第9期49卷 991-1001页

作者： WU Yanhong1, WANG sumin1& HOU Xinhua1,3.1. Key Laboratory of Lake sedimentation and Environment, Nanjing Institute of Geography and Limnology, chinese academy of sciences, Nanjing 210008, China 2. Institute of Tibetan Plateau Research, chinese academy of sciences, beijing 10085, China 3. graduate university of chinese academy of sciences, beijing 10003., China 1. Key Laboratory of Lake sedimentation and Environment Nanjing Institute of Geography and Limnology Chinese Academy of Sciences Nanjing 210008 China 2. Institute of Tibetan Plateau Research Chinese Academy of Sciences Beijing 10085 China 3. graduate university of chinese {3. of sciences Beijing 100039 China

Chronology is the basis for using lacustrine sediments to reconstruct the history of en-vironmental change. Radioactive-nuclides such as 14C, 210Pb and 13.Cs dating are mainly used to establish the chronology for recent several ten thousand years. Because of being mixed with “dead carbon”, the measured 14C age is always older than the actual age which is recognized as “reservoir effect”. Cs is a kind of active metal element, and easy to migrate vertically in the sediment that leads to the error of the time marker. 210Pb dating should make sure to select CIC model or CRs model. On the Tibetan Plateau, most of the lakes are alkaline closed lake where Cs is more moveable in the sediment and the reservoir effect caused by “dead carbon” on 14C dating is stronger. Based on the analysis on results of 14C, 210Pb and 13.Cs of the lacustrine sediments from Co Ngoin, central Tibetan Plateau, we use the simple regression method to re-calculate the 14C calendar ages, and establish the time sequence for cores CE-1 and CE-2 with result of 210Pb CRs model for the upper 3. cm and re-calculated 14C calendar age for sediments bellow 3. cm. since 1400 cal. a BP, sedimentation inter-rupted for more than 1000 years. According to this time sequence, variations of environmental proxies confidently reflect the major climatic events in Holocene.

关键词： 14C, 210Pb and 13.Cs, chronology, lacustrine sediments, climatic event, Co Ngoin, central Tibetan Plateau.

A puzzle of the radio-quiet quasar PG 1407+265:Are optical and X-ray emissions produced from a relativistic jet?

在线全文

学校读者我要写书评

暂无评论

science China(Physics,Mechanics & Astronomy) 2011年第1期54卷 183-186页

作者： CHEN Liang 1,2,3.& BAI JinMing 1,2 1 National Astronomical Observatories/Yunnan Observatory,chinese academy of sciences,Kunming 650011,China 2 Key Laboratory for the structure and Evolution of Celestial Objects,chinese academy of sciences,Kunming 650011,China 3.graduate university of chinese academy of sciences,beijing 100049,China 1. National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China2. Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China

PG 1407+265 is a radio quiet quasar that has a relativistic *** this report,we show some peculiar properties of its optical and X-ray emissions,which indicate possible non-thermal origins produced from the *** use a simple synchrotron + synchrotron self Compton (ssC) model to fit the emissions with different ratios of energy densities between the magnetic field and electrons (η≡U B/U e),which predicts a different γ-ray *** First LAT AGN Catalog (1LAC) did not include PG 1407+265,which indicates an upper limit of γ-ray *** upper limit constrains the ratio to be unreasonably large (η≥10 4-5).This inversely indicates that the optical and X-ray emissions may not be produced from the beaming *** discuss the physical implications of these results.

关键词： active galactic nuclei jet non-thermal emission PG 1407+265

Periodicity of Retzius lines in fossil Pongo from south China

在线全文

学校读者我要写书评

暂无评论

chinese science Bulletin 2012年第7期57卷 790-794页

作者： HU Rong1,2,3. ZHAO LingXia1,2 & WU XinZhi2 1 Key Laboratory of Evolutionary systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, beijing 100044, China 2 Laboratory of Human Evolution, Institute of Vertebrate Paleontology and Paleoanthropology, chinese academy of sciences, beijing 100044, China 3.graduate university of chinese academy of sciences, beijing 100049, China Laboratory of Human Evolution Institute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences Beijing 100044 China

Periodicity of Retzius lines is a key factor in dental development. In this study, we examined the periodicity of Retzius lines in fossil Pongo from south China using polarized light microscope observation of dental ground sections. The periodicities all of the 15 teeth were 9 d. Comparisons of periodicity were made with extant primates, fossil apes and hominins. Periodicity of fossil Pongo from south China was relatively long but fell within the variation of extant Pongo, Gorilla and modern human, and longer than periodicity of Pan and other extant primates. Fossil Pongo from south China was similar to Lufengpithecus and sivapithecus, shorter than Gigantopithecus and longer than European and African fossil apes and most early hominins in periodicity. Generally, the periodicities of Asian large-body fossil apes were longer than the periodicities of European and African large-body fossil apes in Miocene. Difference among species and trend of evolution in periodicity were analyzed and discussed. We found that periodicity might gradually increase from Proconsul in early Miocene to several fossil apes in Miocene and then Gigantopithecus in Pleistocene. In addition, this study made correlate analysis between periodicity and body mass respectively in males and females of six extant apes and five fossil apes, and found that periodicity positively correlated with body mass.

关键词：周期性变化中国南方大猩猩化石灵长类动物早中新世类人猿显微镜观察

On conformal measures for infinitely renormalizable quadratic polynomials

在线全文

学校读者我要写书评

暂无评论

science China Mathematics 2005年第10期48卷 1411-1420页

作者： HUANG Zhiyong~1 JIANG Yunping~(2,3. & WANG Yuefei~3.1. school of Information,Renmin university of China,beijing 100872,China 2. Department of Mathematics,Queens College,City university of New York,NY 113.7,UsA Department of Mathematics,{3. school,City university of New York,New York,NY 10016,UsA 3. academy of Mathematics and systems science,chinese academy of sciences,beijing 100080,China 1. school of Information Renmin University of China 100872 Beijing China 2. Department of Mathematics Queens College City University of New York 11367 NY USA 3. Department of Mathematics Graduate School City University of New York 10016 New York NY USA 4. academy of Mathematics and systems science Chinese Academy of Sciences 100080 Beijing China

We study a conformal measure for an infinitely renormalizable quadratic polynomial. We prove that the conformal measure is ergodic if the polynomial is unbranched and has complex bounds. The main technique we use in t... 详细信息

关键词： Julia set, conformal measure, three-dimensional puzzle, infinitely renormalizable quadratic polynomial.