Turbidite deposition in the southern South China Sea during the last glacial: Evidence from grain-size and major elements records

High-resolution grain size and major element geochemical measurements were performed on the marine sediments of Core MD05-2895 to help understand the formation of turbidite sequences. Grain-size results show that these turbidite sediments contain more coarse sediment grains than normal marls. The coarse sediment grains are mostly derived from relict sediments on the Sunda Shelf. Relict sediments are composed mainly of quartz, feldspar, tephra and a few titaniferous or ferruginous heavy minerals. Corresponding to the concentration of these minerals, increases in Si/Al, K/Al, Ti/Al and Fe/Al ratios are observed in the turbidite layers. As all the observed turbidite sequences were deposited during the last glacial, the occurrence of these turbidity events is implied to be closely related to instabilities in sea-level-induced sediment supply. We suggest that deposition of sediment particles from a single turbidity current is usually controlled by a counterbalance between gravity and buoyancy, with the interaction of individual grains being of minor importance.     

注重“细节”保证“细胞培养技术”实验教学的顺利进行

细胞培养技术是医学院校研究生从事课题研究必备的一项基本技能,因此也是研究生的必修课程之一。为使学生在较短的时间内掌握有关细胞培养的基本技术,实验课的实施尤为关键,而注重实验课程中的每一"细节",则是这门课程的精髓和灵魂。     

Isotopic composition of atmospheric water vapor before and after the monsoon’s end in the Nagqu River Basin

Stable isotopes of water are widely used in scientific research to reconstruct paleoclimate and paleoenviron- ment variations[1―4]. Atmospheric water vapor plays a keyrole in the precipitation events. Therefore, the isotopic composition of atmospheric water vapor has a direct effect upon that of precipitation[5,6]. Observation of stable isotope variation of atmospheric water vapor has an important significance to indicate the moisture origins andmoisture transport in the study area. Based on …     

Paleoceangraphic significance of redox-sensitive metals of black shales in the basal Lower Cambrian Niutitang Formation in Guizhou Province, South China

TheLowerCambrianblackshalesequenceoccursinSouthChinaalonganarc parallellinearbeltex tendingmorethan 16 0 0km .Theseorganic richblackshalesformedinvariousmarineenvironmentsandtypicallycontainhigheramountsofmolybdenum ,nickel,vanadium ,andanumberofothereconomical lyimportantmetalsthandoanyothersedimentaryrocks[1,2 ] .Therefore ,thestudyoftheseblackshaleshasnotonlypaleoceangraphicimplicationbutalsoe conomicsignificance .Marinesedimentssuchasblackshalearecom plexmixturesofdetritalphasesandseawat…     

An inexact multi-objective programming approach for strategic environmental assessment on regional development plan

EnvironmentalImpactAssessment (EIA )hasbeenwidelyimplementedinChinaformorethan 2 0yearsasanimportanttoolforpreventingenvironmen talproblemscausedbyvariousconstructionprojects .Ithasbeenusedtoexamineandforecastthepotentialenvironmentalimpactsofeconomicdevelopment ,an alyzeandidentifymitigationmeasuresoralternativesaccordingly[1～ 3] .AlthoughtheEIAhasbeenre quiredbyChineseauthoritiesforalmosteverynewand/orexpansionproject ,theconditionsofenviron mentalqualityandecosystemhealthhavebeencontin…     

基于Markov网络团的查询意图识别

通过利用Markov网络团的方法来对查询意图识别.首先从人工标注搜狗查询日志中约2 250个查询作为测试数据,采用搜狗提供的分类语料(共10类)来建立Markov网络,用建立的Markov网络来对查询进行扩展,得到相关的返回结果列表,运用在分类语料训练好的分类器来对返回结果进行分类,从而完成对查询意图识别的过程.实验中采用的评价指标是11_avg和3_avg,实验结果表明该方法能够有效地提高检索效率.     

Effects of binders on the performance of electric double-layer capacitors of carbon nanotube electrodes

Electric double layer capacitors (EDLCs) or‘su percapacitors’ have many potential advantages inelectrical devices due to their large capacitance, highpower and long cycle life[1,2].Activated carbons, which exhibit a large specificsurface area ( higher than 1000 m2/g), have beenwidely used as polarizable electrodes of the capaci tors[1—3]. However, generally less than 1/3 of thesurface area of these carbons is available to the elec trolyte for the reason that they con…     

Variation of the Fe/Mn ratio of ferromanganese crusts from the Central North Pacific: implication for paleoclimate changes

Hydrogeneticferromanganesecrusts(Fe Mn crustshereafter),areinorganiccolloidprecipitatesfromseawater,whicharebelievedtohaverecorded theevolutionofelementalandisotopiccompositionsof seawaterovertime[1—7].Studiesontraceelements andisotopeshavebroughtmoreinsightsthanstudies onironandmanganesecontents.TheMn/Feratio hasbeenconsideredtoreflectwaterdepth,deep wa teroxygenation[8,9],andhasalsobeensuggestedasa reliablecriterionfordistinguishingdifferentgenetic typesofferromanganesedeposits[10].Apossi…     

Molecular phylogeny of coronaviruses including human SARS-CoV

The outbreak of SARS sets an urgent task to reveal the origin of human SARS-CoV, i.e. its relation to other known species of coronavirus, and to trace the genetic variation in the spreading process of SARS. Partial answer to the problem may be obtained from phylogenetic analy-sis of available genomes. We call a phylogenetic tree of different species of coronavirus including the human SARS-Cov a CoV Tree and that of different isolates of SARS-CoV a SARS Tree. CoV trees have been c…     

Stratigraphic architecture of the Neoproterozoic glacial rocks in the “Xiang-Qian-Gui” region of the central Yangtze Block, South China

Recently ,theinterestinglowlatitudeandlowaltitudeSnowballEarthhypothesis[1,2 ] iswidelyreco gnized ,and greatlystimulatingthestudyoftheNeoproterozoicglaciations ,whichmaybecloselyre latedtothewell knownEarlyCambrianbio radiationevent.By 1980 ,theNeoproterozoicglaciationinSouthChinaisbelievedtobedividedintotwoglaciationsandoneinterglaciation[3～ 5] ,namely ,theearlyChang’anGlaciation ,lateNantuoGlaciationandFu luInterglaciation .However ,thereweredifferentwaysofcorrelation ,themostobvious…