[tag=CC] [word=has] [lemma=□] □
[tag=CC] [word=has] [lemma=become] □
[tag=CC] [word=has] [lemma=a] □
So , for Saskatchewan , globalization began a long time ago and has become a way of life . From an ahead-of-its-time conference in the mid - 80s , we developed a comprehensive , campus-wide AIDS effort , which continues to this day and has become a national model . And they know fully well that apart from moral support , there is little that India can offer , because in almost all matters , India herself now needs US help and has become a US underling . Tree ring is a kind of natural archives , on which the isotopic analysis is important to study global climate and environmental change.The authors mainly provide a comprehensive introduction to the fractionation models of carbon , hydrogen and oxygen isotope in plants , their research techniques and the extract methods from cellulose.That results show isotopic tracer can record the message of climatic variation and has become a powerful tool for paleoclimate reconstruction and for the modern environment changing research.Especially studying on PAGES , the cellulose isotopic analyses of imbedded old tree ring have become the mainly quantitative means of environmental evolvement.In addition , China is a typical monsoon country , research in tree ring stable isotope seasonal variation can give us a lot of important information on that.Up to now , the research techniques and works on tree ring in our country are still in its earlier stage , and remain many limitations.It needs further accumulate basic research materials , intensify regional contrast and intercross studies on relative subjects .