排序方式: 共有7条查询结果,搜索用时 14 毫秒
1
1.
2.
3.
4.
Using a system to study promoter activity, we have obtained a promoter fragment from E. coli chromosomal DNA. The HBsAg geno under the control of this promoter could be expressed in E. coli. The expression products are isolated and purified by means of a column of anti-HBs cross-linked to Sepharose 4 B. The pure products are characterized through the double diffusion method on 0.6% agarose and polyacrylamido-SDS gel electrophoresis. The synthesis of high levels of HBsAg sequences in E. coli is confirmed. 相似文献
5.
6.
生产过程中对产品三维形貌的高精度实时测量是有效的质量监控手段,具有迫切的需求。本文基于三维数字图像相关(DIC-3D)方法,全场测量了印制线路板上的台阶状焊点和印制线路,得到焊点大小、高度和印制线路线宽、线高等三维形貌数字图像数据;使用台阶仪采集面内和离面形貌数据,并进行比较。实验结果表明,三维数字图像相关方法在测量印制线路板形貌时,可测量出十数微米高的印刷线路台阶,精度达3μm;对500×500pixels图像,在i7 4790k CPU硬件条件,步长3pixels、子区19×19pixels的参数下,立体图像的重建速度小于1s,可满足线路板的在线实时检测。 相似文献
7.
The synthetic leu-enkephalin (LEK) gene was joined with pBR322 and transformed toE. coli. The recombinant plasmids containing the LEK gene were selected by colony hybri-dization, and characterized by restriction mapping and Southern's technique. The lac operonwas used to control the expression of the LEK gene. A recombinant plasmid, pEL 103, inwhich the lac operon and LEK gene are transcribed in the same direction, produces LEK inE. coli. The level of LEK detected by radioimmunoassay reaches 426 ng per mg of bacte-rial protein. 相似文献
1