Signal peptide capable of efficiently directing many protein secretion in mammalian cells is one of the key elements in recombinant protein production,gene therapy and the development of DNA vaccines.In order to explo...Signal peptide capable of efficiently directing many protein secretion in mammalian cells is one of the key elements in recombinant protein production,gene therapy and the development of DNA vaccines.In order to explore the possibility of rat growth hormone signal peptide as such an element,a new vector based on the mammalian expression vector pcDNA3 was constructed by employing rat growth hormone(rGH) signal peptide as leading sequence,followed by multiple cloning sites,the myc epitope-tag and 6×his purification tag in the expression cassette.The vector was validated by successfully expressing and secretion of chick MMP-2 C-terminal PEX domain,a potential angiogenesis inhibitor,and tandem peptide repeats of myc epitope-tag in COS-7 cells.These results suggest that rat growth hormone signal peptide is effective in the mediation of recombinant protein expression and secretion,and this vector provides a new tool for universal cloning and secretion of exogenous proteins in mammalian cells.展开更多
目前,北斗三号卫星导航系统(BDS-3)新增了互操作信号B1C和B2a,为保障BDS-3的定位精度,有必要对新信号的观测数据进行全面分析。文章选取2020年4月1日至10日共10 d 19个iGMAS跟踪站的观测数据,从数据完整率、信噪比、多路径效应、电离层...目前,北斗三号卫星导航系统(BDS-3)新增了互操作信号B1C和B2a,为保障BDS-3的定位精度,有必要对新信号的观测数据进行全面分析。文章选取2020年4月1日至10日共10 d 19个iGMAS跟踪站的观测数据,从数据完整率、信噪比、多路径效应、电离层延迟变化率等4个方面进行评价,并与GPS L1/L5和Galileo E1/E5a对比,对9颗BDS-3中圆地球轨道(Medium Earth Orbit,MEO)卫星的观测数据进行评估。结果表明:B2a在数据完整率、信噪比、多路径效应方面略优于B1C,但差距不大,B1C在抑制电离层延迟变化率方面优于B2a;BDS-3的B1C/B2a与GPS、Galileo的兼容频率基本处于同一水平,在信噪比、电离层延迟变化率等方面甚至优于L1/L5、E1/E5a。展开更多
A new acquisition and tracking method is proposed for signal processing under the new signal system structure of Beidou-3 navigation satellite system(BDS-3). By starting with the analysis of the characteristics and si...A new acquisition and tracking method is proposed for signal processing under the new signal system structure of Beidou-3 navigation satellite system(BDS-3). By starting with the analysis of the characteristics and signal structure of the new signal, the local replica of the ranging code and the study of the characteristics of the ranging code are completed, which proves that the method in this paper can be used in the subsequent acquisition and tracking process. The fast Fourier transformation(FFT) search based on longer coherence time and the adaptive phase-frequency switching carrier tracking loop are proposed for signals in different modulation modes. The actual signal of Beidou-3 satellite is sampled by local experiment, and the acquisition and tracking of the Beidou-3 satellite multi-band signal is finally completed. The tracking results verify the feasibility of the proposed acquisition and tracking method.展开更多
武广高铁为中国高铁建设初期首条C T C S-3级列控系统客运专线,开通至今已近十年。为提高运行效率,满足现有运营标准,对武广高铁进行新标准达标改造。根据现行的技术标准和规范,结合现有武广高铁使用情况以及工程改造的影响范围,参考业...武广高铁为中国高铁建设初期首条C T C S-3级列控系统客运专线,开通至今已近十年。为提高运行效率,满足现有运营标准,对武广高铁进行新标准达标改造。根据现行的技术标准和规范,结合现有武广高铁使用情况以及工程改造的影响范围,参考业主等各方面意见展开分析探讨,制定符合武广实际情况的达标范围及方案。为后续早期开通的高铁线路达标改造工程提供宝贵的经验。展开更多
文摘Signal peptide capable of efficiently directing many protein secretion in mammalian cells is one of the key elements in recombinant protein production,gene therapy and the development of DNA vaccines.In order to explore the possibility of rat growth hormone signal peptide as such an element,a new vector based on the mammalian expression vector pcDNA3 was constructed by employing rat growth hormone(rGH) signal peptide as leading sequence,followed by multiple cloning sites,the myc epitope-tag and 6×his purification tag in the expression cassette.The vector was validated by successfully expressing and secretion of chick MMP-2 C-terminal PEX domain,a potential angiogenesis inhibitor,and tandem peptide repeats of myc epitope-tag in COS-7 cells.These results suggest that rat growth hormone signal peptide is effective in the mediation of recombinant protein expression and secretion,and this vector provides a new tool for universal cloning and secretion of exogenous proteins in mammalian cells.
文摘A new acquisition and tracking method is proposed for signal processing under the new signal system structure of Beidou-3 navigation satellite system(BDS-3). By starting with the analysis of the characteristics and signal structure of the new signal, the local replica of the ranging code and the study of the characteristics of the ranging code are completed, which proves that the method in this paper can be used in the subsequent acquisition and tracking process. The fast Fourier transformation(FFT) search based on longer coherence time and the adaptive phase-frequency switching carrier tracking loop are proposed for signals in different modulation modes. The actual signal of Beidou-3 satellite is sampled by local experiment, and the acquisition and tracking of the Beidou-3 satellite multi-band signal is finally completed. The tracking results verify the feasibility of the proposed acquisition and tracking method.
文摘武广高铁为中国高铁建设初期首条C T C S-3级列控系统客运专线,开通至今已近十年。为提高运行效率,满足现有运营标准,对武广高铁进行新标准达标改造。根据现行的技术标准和规范,结合现有武广高铁使用情况以及工程改造的影响范围,参考业主等各方面意见展开分析探讨,制定符合武广实际情况的达标范围及方案。为后续早期开通的高铁线路达标改造工程提供宝贵的经验。
