The resulting 30 - membered ring structure produces an oval projection when viewed parallel to the b axis 沿平行于b轴的方向上生成了一个奇特的30元环结构。
2.
Here , we report 3 cases among a four - membered family afflicted with this disease entity 病例（父亲） ：两眼角膜呈现多形性的内皮细胞退化变性，两眼角膜内皮细胞只有1100 /平方公厘。
3.
Purine a simple nitrogenous organic molecule with a double - ring structure ? a 6 - membered pyrimidine ring fused to a 5 - membered imidazole ring 嘌呤：一种简单的含氮有机分子，具一个双环结构? ?六元嘧啶环融合成一个五元咪唑环。
4.
Meanwhile , it was detected that the excess a13 + ions , to compensate the positive charge caused by the substitution of partial mg " ions by ti ions , occupy the t2 site in the six - membered rings in the sample of 1 . 8 mgo 0 . 2tio2 2 . 2 a12o34 . 6sio2 2tio2 ? 2 . 2al2o3 ? 4 6sio2中用作价态补偿的过量al3 +全部进入六元环t2位宜上。 xps的研究发现， zn ‘ ” 、 t广的同溶使茧青石结构中的川、 st等元素出现了多种化学状态。
5.
A novel ring - enlargement oxidation of polyphenyl substituted cyclopentadienes in air ( or molecular oxygen ) promoted by perchloric acid was described , in which an oxygen atom was inserted into the cyclopentadiene - ring , forming a six - membered pyrylium salts 摘要报导了空气（或氧气）存在的条件下，由高氯酸引发多苯基取代环戊二烯发生新颖的碳碳键断裂扩环反应，在此反应中，氧原子插人到环戊二烯环中形成相应的六元环吡喃盐类化合物。
6.
Avermectins are a series of 16 - membered macrocyclic lactones produced by streptomyces avermitilis with potent anthelmintic and insecticidal activity . they are the most effective agricultural pesticides and antiparasitic agents , and used widely in medical , veterinary and agricultural fields 阿维链霉菌( streptomycesavermitilis )产生的阿维菌素( avermectins )是一组高效、低毒、广谱的杀虫抗生素，在医药、农业和畜牧业生产中具有良好的应用价值和广阔的市场前景。
