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1Preliminary study on seasonal succession and development pathway of phytoplankton community in the Bohai Sea显示文摘Phytoplankton species composition and species succession were determined in 1998-1999 based on 2 nestle investigation cruises in the Bohai Sea and two monthly monitoring stations at Penglai and Changdao for 15 months. The seasonal succession and pathway of phytoplankton community in the Bohai Sea were discussed complementarily with history data. The main process of Phytoplankton community development in the Bohai Sea was controlled by temperature and nutrient replenishes. There were two cell abundance peaks in an annual variation, the main peak in April and the secondary peak in September. In winter, the cell abundance was low due to the low temperature, the phytoplankton community was mainly made up of small-celled diataoms. In spring, the phytoplankton community was developed very quickly by small-celled diatom in suitable conditions of temperature and nutrients. In summer, the cell abundance decreased and big-celled diatoms became predominated. In autumn, because of the replenish of nutrient, big-celled diatoms and dinoflagellates formed another cell abundance peak. during the annual variation of phytoplankton community in the Bohai Sea, species succession was the main process of community development, the species sequence just occur at special areas and special periods. The evolution of phytoplankton community in the Bohai Sea accords with the hypothesis of Margalef’s phytoplankton community of four stages. But the size feature is contrary to the hypothesis, which may be caused by nutrient replenish in autumn in Bohai Sea and the top to down control.Sun Jun, Liu Dongyan, Qian Shuben (1. Marine Ecosystem Dynamic Lab, Marine Life Science College, Ocean University of Qingdao, Qingdao 266003, China. ) 2001Acta Oceanologica Sinica2001,20,2:24
2Geospatial-temporal analysis of land-use changes in the Yellow River Delta during the last 40 years显示文摘Comprehensive study on land-use change of spatial pattern and temporal process is the key component in land use/land cover changes (LUCC) study nowadays. According to the theories and methods of Geo-information Tupu (Carto-methodology in Geo-information, CMGI) for geospatial and temporal analysis and integration models of spatial pattern and temporal processes in GIS, the paper puts forward Tupu methodology of land-use change and names the basic synthetic unit of spatial-temporal information Tupu unit. Tupu unit is the synthetic unit for geospatial-temporal analysis, which is synthesized by “space·attribute·process”features and composed of relatively homogeneous geographic unit and temporal unit. Based on the spatial features of 4 stages of land-use change in 1956, 1984, 1991, and 1996, a series of Tupu on land-use change in the Yellow River Delta (YRD) are created and studied in the paper, which includes 3 temporal units of spatial-temporal Tupu, process Tupu of land-use changes during the last 40 years, and reconstructions of a series of “arisen”Tupu, “arisen”process Tupu and pattern Tupu on land-use changes in the last 40 years by remapping tables of a reclassifying system. There are 3 methods of Tupu analysis on land-use change that are used to disclose change processes of land-use spatial conversion in YRD, such as spatial query and statistics, order of Tupu units by area and land-use conversion matrixes. In order to reveal the spatial pattern of land-use change processes, we analyze spatial-temporal changes of each Tupu above in various temporal units and spatial difference of pattern Tupu in the last 40 years by dynamic Tupu units. Tupu analysis on regional land-use is a promising trial on the comprehensive research of “spatial pattern of dynamic process”and “temporal process of spatial pattern”in LUCC research. The geo-information Tupu methodology would be a powerful and efficient tool on integrated studies of spatial pattern and temporal process in geoscience.YE Qinghua1,3,4,LIU Gaohuan2,TIAN Guoliang1,CHEN Shenliang3,HUANG Chong2,CHEN Shupeng1,2,LIU Qingshen2,CHANG Jun2 & SHI Yanan2 1.State Key Laboratory of Remote Sensing Science,Institute of Remote Sensing Applications(IRSA),Chinese Academy of Science(CAS),Beijing 100101,China 2.Institute of Geographic Sciences and Natural Resources Research,CAS,Beijing 100101,China 3.State Key Laboratory of Estuarine and Coastal Research,East China Normal University,Shanghai 200062,China 4.Institute of Tibetan Plateau Research(ITPR),CAS,Beijing 100085,China Correspondence should be addressed to Ye Qinghua(email: yeqh@itpcas.ac.cn) 2004Science China Earth Sciences2004,47,11:22
3Effect of climatic change on snowmelt runoffs in mountainous regions of inland rivers in Northwestern China显示文摘Climatic change has significant impacts on snow cover in mid-latitude mountainous re- gions, in the meantime, spatial and temporal changes of snow cover and snowmelt runoffs are con- sidered as sensitive indicators for climatic change. In this study, the upper Heihe Watershed in the Qilian Mountains was selected as a typical area affected by snow cover and snowmelt runoffs in northwestern China. The changes in air temperatures, precipitation, snowfall and spring snowmelt runoffs were analyzed for the period from 1956 to 2001. The results indicate that climatic warming was apparent, particularly in January and February, but precipitation just fluctuated without a clear trend. The possible changes of snowmelt runoffs in the upper Heihe watershed in response to a warming of 4℃ were simulated using Snowmelt Runoff Model (SRM) based on the degree-day factor algorithm. The results of the simulation indicate that a forward shifting of snow melting season, an increase in water flows in earlier melting season, and a decline in flows in later melting season would occur under a 4℃ warming scenario.WANG Jian1 & LI Shuo2 1. Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. College of Geography, Nanjing Normal University, Nanjing 210097, China 2006Science China Earth Sciences2006,49,8:18
4Environmental changes reflected by the lake sediments of the South Hongshan Lake, Northwest Tibet显示文摘The 1.07-m long lake core with 1 cm interval cutting, which was obtained by drilling in the South Hongshan Lake of Northwest Tibet, was dated by the 210Pb and 137Cs methods, and a 150-year consecutive lake sedimentary sequence (1840─1997) with 1.4 year resolution was obtained. Some environmental proxies, such as the total organic carbon (TOC), total nitrogen (TN), ratio of TOC to TN (TOC/TN), trace chemistry elements (TCE), CaCO3, grain size, richness of ostracoda etc. showed that they are of well coincidence. These results implied that the environmental background varied from the cold-wet period in the late 19th century, to the warm-wet period from the end of the 19th century to the 1920s and to the warm-dry period since the 1920s. There were sub-variations since the 1920s: the cold-dry/warm-wet fluctuation from 1922 to 1960, the intensively warm-dry period since 1960 with a short cold-wet period in the mid-1970s to the end of the 1980s. The humid period from the mid-1970s to the end of the 1970s and the dry period beginning from the early 1980s were well documented by climatic data of the nearby weather station records while the grain size was well correlated to the annual precipitation. Compared with the records from Guliya ice core in the same area, the TOC proxy in the lake core indicating warm/cold conditions well corresponded to the ( 18O records representing temperature variations in the ice core. However, the proxies with dry/wet significance in the lake core were different from the variations of snow accumulation reflected by the ice core. It can be concluded that the chosen environmental proxies have clear environmental significance and the lake sediments can reflect climatic and environmental changes at high-resolution.朱立平 陈玲 李炳元 李元芳 夏威岚 李建国 2002Science China Earth Sciences2002,45,5:15
5Climatic and environmental changes over the last millennium recorded in the Malan ice core from the northern Tibetan Plateau显示文摘In this paper, climatic and environmental changes were reconstructed since 1129A.D. based on the Malan ice core from Hol Xil, the northern Tibetan Plateau. The record of δ 18O in the Malan ice core indicated that the warm-season air temperature variations displayed a general increase trend, the 20th-century warming was within the range of natural climate variability, and the warmest century was the 17th century while the warmest decade was the 1610s, over the entire study period. The “Medieval Warm Epoch” and “Little Ice Age” were also reflected by the ice core record. The dust ratio in the Malan ice core is a good proxy for dust event frequency. The 870-year record of the dust ratio showed that dust events occurred much frequently in the 19th century. Comparing the variations of δ 18O and the dust ratio, it is found that there was a strong negative correlation between them on the time scales of 101―102 years. By analyses of all the climatic records of ice cores and tree rings from the northern Tibetan Plateau, it was revealed that dust events were more frequent in the cold and dry periods than in the warm and wet periods.WANG Ninglian1,2, YAO Tandong2,1, PU Jianchen1, ZHANG Yongliang1 & SUN Weizhen1 1. Key Laboratory of Cryosphere and Environment, Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China 2. Institute of Tibetan Plateau Research, Chinese Academy of Sciences, Beijing 100085, China 2006Science China Earth Sciences2006,49,10:11
6Simulating the impacts of climate variation and land-cover changes on basin hydrology: A case study of the Suomo basin显示文摘Impacts of land cover changes on watershed hydrology have been a long-term academic concern with acute dispute. But little attention has been paid to such effects on mesoscale river basins, where the society has a closer link to river hydrology. The present study focuses on a mesoscale river basin, the Suomo Basin that is located on the upper reaches of the Yangtze River. Land covers in the basin in the years 1970, 1986 and 1999 were mapped. A lumped hydrologic model, CHARM, and a distributed hydrologic model, SWAT, were used to model the impacts of both land-cover change and climate variation on river runoff during the past four decades. The results show that the contribution of climate variation to the change of runoff regime makes up 60%―80%, while that of land cover changes only 20%.CHEN Junfeng1,2, LI Xiubin2 & ZHANG Ming2 1. Institute of Remote Sensing & GIS, Peking University, Beijing 100871, China 2. Institute of Geographical Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China 2005Science China Earth Sciences2005,48,9:10
7Alterations in DNA methylation and genome structure in two rice mutant lines induced by high pressure显示文摘By using high-pressure treatment, two mutant lines were obtained from a genetically stable japonica rice cultivar Bijing38. Genomic DNA of the mutant lines, together with the original line (Bijing38), was either undigested or digested by Hpa II/Msp I, and then subjected to molecular analy-sis using two markers, ISSR and RAPD. Results indicated that changes in the PCR amplification pro-files of both markers are apparent in the two mutant lines compared with the original rice cultivar, suggesting that there had been both sequence changes and DNA methylation modifications in the mutant lines. Southern blot analysis using diverse sequences, including two cellular genes (S2 and S3), a set of retrotransposons (Osr7, Osr36, Tos19 and more), and a MITE transposon family (mPing and Pong), confirmed the results, and indicated that changes in DNA methylation pattern, genomic structure, and possible activation of some transposons indeed occurred in the mutant lines. Moreover, these changes are stably maintained through selfed generations and in different organs. Thus, our results indicate that it is possible to obtain stable mutants in rice by high pressure treatments, and the molecular basis of the mutants may include both genetic and epigenetic changes. Therefore, high hydrostatic pressure seems a promising approach for plant mutagenesis.SHEN Sile1,3, WANG Zhenwei3, SHAN Xiaohui2, WANG Hua3, LI Ling3, LIN Xuyun2, LONG Likun2, WENG Kenan4, LIU Bao2 & ZOU Guangtian1 1. National Laboratory of Superhard Materials, Jilin University, Changchun 130012, China 2. Institute of Genetics and Cytology, Northeast Normal University, Changchun 130024, China 3. College of Life Science, Jilin University, Changchun 130012, China 4. Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China 2006Science China(Life Sciences)2006,49,2:6
8The species diversity of fusulinaceans and high-frequency sea-level changes in the Carboniferous-Permian boundary section at Xikou, Zhen'an County,Shaanxi Province, China显示文摘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 systems track, and it is high within the highstand systems track. The second-order rise and fall in sea level coincide with the bloom and decline of high order taxa of fusulinaceans.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 2006Science China Earth Sciences2006,49,7:2
9Molecular dynamics simulation study on zwitterionic structure to maintain the normal conformations of Glutathione显示文摘Molecular dynamics simulations were applied to normal conformational Glutathione (GSH) and GSH over zwitterionic and hydrophobic surfaces respectively. Conformational analysis of GSH during the simulation time on RMSD, conformational flexibility and dihedral distribution were performed. The re- sults showed that zwitterionic structure maintains the normal conformations of GSH to a better extent, which should be a first good proof of the hypothesis of 'maintain of normal structure'.YAN Han1, ZHU HaoMiao2 & SHEN Jian1,2 1 Jiangsu Research Center of Surface and Interface Chemical Engineering and Technology, Nanjing University, Nanjing 210093, China 2 Jiangsu Engineering Research Center for Bio-medical function Materials, Nanjing Normal University, Nanjing 210097, China 2007Science China Chemistry2007,50,5:1
10Global mean temperature changes during the last millennium显示文摘A synthetic study is made on the global or hemispheric mean temperature series for the last millennium worked out by Mann et al., Jones et al., Crowley and Lowery, and Briffa. The global mean temperature series reconstructed by using proxy data at 30 sites by Wang et al. and simulations from AD 1000 to 2000 by energy balance model are described and compared with the series of others. Wang's series gives greater variability and shows the highest correlation coefficient (0.83) with the simulation results. Uncertainties in the reconstructions and simulations are discussed. The errors in reconstructing a global mean temperature series according to 30 sites as used in the research are estimated. Wang's series indicate that temperature average for the 11th century is higher than the mean of the last millennium. It infers that the Medieval Warm Period predominated to some extent over the globe. However, the 20th century is no doubt the warmest century during the last millennium.GONG Daoyi 2002Progress in Natural Science:Materials International2002,12,12:1
11Calculating eustatic amplitude of Middle Permian from reefs显示文摘Methods for calculating ancient eustatic change amplitudes according to reef fabric- facies are proposed, with a new method for determining sediment-loading subsidence. Compared with methods based on non-reefal deposits, these methods are more accurate in restoration of original sediment thickness, determination of sediment-loading subsidence, as well as restoration of ancient water depth. According to the reef in Guangxi, China, the amplitude of sea-level rise during Middle Permian (Neoschwagerina-Yabeina zone) is 249.5 m. According to the coeval reef of the Guadalupe Mountains, New Mexico and Texas, the coeval sea-level rise is 247 m. With these effective methods available, it is feasible to establish more accurate eustatic curve of Phanerozoic.吴亚生 范嘉松 2002Science China Earth Sciences2002,45,3:1
12Palynological Evidence on Climate Changes in the East China Sea During Mid and Late Holocene显示文摘李珍 王永吉 刘振夏 蓝东兆 2001Marine Science Bulletin2001,3,2:0
13Refractive index changes induced by sheet beams with various intensity distributions in LiNbO_(3):Fe crystal显示文摘According to the Kukhtarev equations and a simplified model based on the photovoltaic charge carriers transport mechanism, the distributions of the index changes (DICs) in LiNbO3:Fe crystals induced by sheet beams with various intensity profiles are theoretically analyzed. The numerically simulated results coincide with the analytic expressions deduced from the simplified model. The DICs in a LiNbO3:Fe crystal induced by sheet beams with rectangular, Gaussian and square law profiles are measured by using the interferometric method. By employing the analytic expressions, the experimental data points are well fitted. By utilizing the angular spectrum theory and the ray equation, the uniformities of the intensity profiles of the writing beams along the propagation directions and the influences of the self-defocusing effect of the crystal are numerically simulated, respectively. The results show that the experimental results are reliable. The numerically simulated method and the analytic expressions can be both employed to predict the DICs induced by sheet beams with various light intensity profiles. Furthermore, utilizing writing beams with proper intensity profiles, any desired index distributions could be obtained.ZHANG Peng1, ZHAO Jianlin1, XU Honglai1, SUN Yidong2, YANG Dexing1 & WANG Meirong1 1. Institute of Optical Information Science and Technology, School of Science, Northwestern Polytechnical University, Xi’an 710072, China 2. School of Science, Xi’an Jiaotong University, Xi’an 710049, China 2005Science China(Physics,Mechanics & Astronomy)2005,48,4:0
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