YS型冲击器多功能结构的试验研究

作为当今五大钻探技术之一的液动冲击回转钻探的技术核心是液动冲击器。生产实践证明YS型冲击器是性能优良的液动冲击器。试验研究表明YS型冲击器的有眼阀壳换成无眼阀壳就可改作气动冲击器,这样YS型冲击器配备一个无眼阀壳就成为多功能冲击器,而且这种多功能冲击器的气动性能,接近于其液动性能也接近于同样规格的气动冲击器的性能。     

Genome sequence variation analysis of two SARS coronavirus isolates after passage in Vero cell culture

SARS coronavirus is an RNA virus whose replication is error-prone, which provides possibility for escape of host defenses, and even leads to evolution of new viral strains during the passage or the transmission. Lots of variations have been detected among different SARS-CoV strains. And a study on these variations is helpful for development of efficient vaccine. Moreover, the test of nucleic acid characterization and genetic stability of SARS-CoV is important in the research of inactivated vaccine. The whole genome sequences of two SARS coronavirus strains after passage in Vero cell culture were determined and were compared with those of early passages, respectively. Results showed that both SAPS coronavirus strains have high genetic stability, although nearly 10 generations were passed. Four nucleotide variations were observed between the second passage and the llth passage of Sinol strain for identification of SARS inactivated vaccine. Moreover, only one nucleotide was different between the third passage and the 10th passage of Sino3 strain for SARS inactivated vaccine. Therefore, this study suggested it was possible to develop inactivated vaccine against SARS-CoV in the future.     

增量理论弹塑性问题的局部坐标有限分析法

提出了一种在不规则四边形网格上求解二维增量理论弹塑性边值问题的局部坐标有限分析法计算格式。算例表明，这一方法是有效的。