香港大学预科

经济增长率维持7.5％最理想 对于今年的经济,国内外主要机构预测的情况大致是:中国社会科学院预测8.6％,中国证券市场研究与设计中心预测8.4％,北京天则研究所的预测是8.5％,中国财政大学证券期货研究所的预测是8.9％,香港怡富证券的预测是8％,美国摩根士丹利的预测是8.5％,亚

We observed for the first time (to our knowledge) a new type of all optical double-quasi-steady-state photorefractive spatial soliton in a Cu:KNSBN crystal.The soliton was created without an applied electric field but with an inducing laser beam.An all optical switching effect was found in the formation of the soliton.