中裂球(mesomere) 在后生动物的卵裂期,其卵裂球的大小有明显的差异,此时称中形的卵裂球为中裂球。在端黄卵,一般从动物极向植物极,由于卵裂球所含卵黄多而成为大裂球。但海胆在16细胞期时,因小裂球在植物极一端形成,而中裂球为动物半球的8个细胞,后来形成外胚层。
棘球蚴属、线中绦虫属和裂头绦虫属的绦虫引起的感染比较罕见,这些绦虫感染通常无明显症状。
Rare tapeworm infections are caused by species of the genera Echinococcus, Mesocestoides, and Spirometra. There are usually no symptoms.
最近,新型压裂球应用触角延伸至桥塞和射孔完井作业中。
More recently, dissolving balls have been deployed with bridge plugs for plug and perf completions.
迄今为止,高强度可分解压裂球主要应用于油田的滑动套筒完井作业中。
To date, the main oilfield application for high strength dissolvable materials has been for dissolvable frac balls used with sliding sleeve completions.
应用推荐