终点的标志 meaning in English

a terminal marker

In this paper srco3 powders are first time synthesized successfully by low temperature solid state reaction with srcl2 . 6h2o and ( nh4 ) 2co3 . the size of srco3 is about 30 - 50nm . compared with liquid state method , this method produces little conglomeration and is easy to synthesize nanopowders
本论文根据低热固相化学反应原理首次以srcl _ 2 ? 6h _ 2o和( nh _ 4 ) _ 2co _ 3为原料成功合成了30 ? 50nm的srco _ 3粉体，克服了一般液相沉淀法易发生粉体团聚和难于制备纳米级srco _ 3粉体的弊端，并通过研究找到了低热固相反应终点的标志。