学科分类
/ 1
2 个结果
  • 简介:ThesafelandingofChina’sfirstspacemanonthegrasslandofnorthChina’sInnerMongoliaThursdaymorninghasmadeChinathethirdcountryintheworldthathassuccessfullysentmanintospacefollowingtheUnitedStatesandtheformerSovietUnion.

  • 标签: 高中 英语 注释读物 阅读训练
  • 简介:DearEditor,Bomb-radiocarbonanalysisofmoderncarbonhasbeenappliedinmanyfieldsofecology.Themethodallowsde-terrniningtheresidencetimeofcarboninphotosyntheticproductsandthusaUorganicmatterinecosystems.Theatmospheric14Csignaturewillsoondropbelowthepre-bomblevelduetofixationofatmosphericcarboninter-restrialandmarineecosystemsandhighratesoflac-freefossilfuelcombustion.Hence,thetimeisrunningoutforbomb-radiocarbonapplication.Insectcollectionsshelteranimmensequantityofspecimensstoredinalcohol.Weshowhowthosespecimenscanbeusedforexploringthetrophicstructureoffoodwebsbycomparingtheirisotopicradiocarbonsignature.

  • 标签: