简介：JewelryandpreciousstonesontheworldmarkethaveanannualtransactionvolumeofoverUS$100billion.Since1985,theyhaveenjoyedalargegrowthinexportsfromChina.In1990,theexportvolumewasUS$157million,in1991——US$250million,in1992——US$250million,in1993——US$670millionandin1994——US$750

简介：By"concealedexplosionofmagma",wemeantheexplosiveproessofmagmaundersubterraneanconcealedconditionswhichisessen-tiallysimilartovolcaniceruptionseenatthesurface;theonlydiffer-"nceisthatthelattertakesplaceinanopenenvironmentatthesurface’`vhiletheformertinasemi-openenvironmentbelowathincovernearlhesurfac

简介：宝贵金属支持相互作用在热稳定性和催化性能起一个重要作用汽车用尽催化剂。支持是为在催化剂的活跃混合物的一个搬运人而且能改进宝贵金属的分散并且在高温度压制宝贵金属的sintering不仅；同时，高贵金属能也提高氧化还原作用表演和支持的氧存储能力。金属支持相互作用的机制主要包括电子相互作用，合金的形成和金属的里面的散开进支持或由支持盖住。宝贵金属支持相互作用的形式和度取决于许多因素，包括宝贵金属，支持和金属的种类，和准备方法的内容。关于强壮的金属支持相互作用(SMSI)的研究结果为与优秀性能开发一种新催化剂给了理论支持。这篇论文考察了相互作用现象和宝贵金属的机制(磅，Pd，Rh)并且支持象Al2O3，CeO2，和基于CeO2的氧化物在那样汽车用尽催化剂。影响SMSI开发的SMSI和催化剂的因素也被讨论。

简介：Thecharacterofthemagmaticrocksandoredeposits,formed-in’theregionsoftectonicmagmaticactivity(TMA)or"Diwa"dcpendsincertaindegreeonthebasementstructuretypes,andpartiallyonproportionsbetwccn"basalt~andgranitc-sedimentarylaycrthickncsses.Magma-andore-formationinTMA-structurcswcreconncctcdwithpowcrfulhcat

简介：TheEastTianshanisaremoteGobiarealocatedineasternXinjiang,northwesternChina.Inthepastseveralyears,anumberofgold,porphyrycopper,andFe(-Cu)andCu-Ag-Pb-Znskarndepositshavebeendiscoveredthereandareattractingexplorationinterest.TheEastTianshanislocatedbetweentheJunggarblocktothenorthandearlyPaleozoicterranesoftheMiddleTianshantothesouth.ItispartofaHercynianorogenwiththreedistinctE-W-trendingtectonicbelts:theDevonian-EarlyCarboniferousTousuquan-DananhuislandarconthenorthandtheCarboniferousAqishan-Yamansuriftbasintothesouth,whichareseparatedbyrocksoftheKanggurtagshearzone.Theporphyrydeposits,datedat322Ma,arerelatedtothelateevolutionarystagesofasubduction-relatedoceanicorcontinentalmarginarc.Incontrast,theskarn,gold,andmagmaticNi-Cudepositsareassociatedwithpost-colli-sionaltectonicsatca.290-270Ma.TheseLateCarboniferous-EarlyPermiandepositsareassociatedwithlarge-scaleemplacementanderuptionofmagmaspossiblycausedbylithospheredelaminationandriftingwithintheEastTianshan.

简介：Thepyrolyzedcarbonsupportedferrumpolypyrrole(Fe-N/C)catalystsaresynthesizedwithorwithoutselecteddopants,p-toluenesulfonicacid(TsOH),byafacilethermalannealingapproachatdesiredtemperatureforoptimizingtheiractivityfortheoxygenreductionreaction(ORR)inO2-saturated0.1mol/LKOHsolution.Theelectrochemicaltechniquessuchascyclicvoltammetry(CV)androtatingdiskelectrode(RDE)areemployedwiththeKoutecky-LevichtheorytoquantitativelyobtaintheORRkineticconstantsandthereactionmechanisms.ItisfoundthatcatalystsdopedwithTsOHshowsignificantlyimprovedORRactivityrelativetotheTsOH-freeone.TheaverageelectrontransfernumbersforthecatalyzedORRaredeterminedtobe3.899and3.098,respectively,forthecatalystswithandwithoutTsOH-doping.Theheat-treatmentisfoundtobeanecessarystepforcatalystactivityimprovement,andthecatalystpyrolyzedat600℃givesthebestORRactivity.Anonsetpotentialandthepotentialatthecurrentdensityof-1.5mA/cm2forTsOH-dopedcatalystafterpyrolysisare30mVand170mV,whicharemorepositivethanthosewithoutpyrolized.Furthermore,thecatalystdopedwithTsOHshowshighertolerancetomethanolcomparedwithcommercialPt/Ccatalystin0.1mol/LKOH.TounderstandthisTsOHdopingandpyrolyzedeffect,X-raydiffraction(XRD),scanningelectronmicroscope(SEM)andX-rayphotoelectronspectroscopy(XPS)areusedtocharacterizethesecatalystsintermsoftheirstructureandcomposition.XPSresultsindicatethatthepyrrolic-Ngroupsarethemostactivesites,afindingthatissupportedbythecorrespondencebetweenchangesinpyridinic-NcontentandORRactivitythatoccurwithchangingtemperature.SulfurspeciesarealsostructurallyboundtocarbonintheformsofC–Sn–C,anadditionalbeneficialfactorfortheORR.