Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective stra...Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective strategy for promoting sustainable agriculture in this region.Using twenty maize cultivars,plant dry matter production,N absorption and accumulation,yield formation,and NUE in summer maize were investigated under three N levels in two growing seasons.Based on their yield and yield components,these maize cultivars were categorized into four groups including efficient-efficient(EE)cultivars,high-nitrogen efficient(HNE)cultivars,low-nitrogen efficient(LNE)cultivars and nonefficient-nonefficient(NN)cultivars.In both two seasons,the EE cultivars improved grain yield together with increased plant biomass,and enhanced accumulative amounts as well as higher average grain yields than the other cultivar groups under deficient-N conditions.Significant correlations were observed between yield and kernel numbers(KN),dry matter(DM)amount and N accumulation at both post-silking and maturity stages.DM and N accumulation at late growth stage(i.e.,from silking to maturity)contributed largely to the enhanced yield capacity and improved NUE under N-deficient conditions.Compared with the NN cultivars,the EE cultivars also showed increased N assimilation amount(NAA)and N remobilization content(NRC),and elevated N remobilization efficiency(NRE),NUE and nitrogen partial factor productivity(PFPN).Our investigation has revealed N-associated physiological processes and may provide guidance for cultivation and breeding of high yield and NUE summer maize under limited N conditions in the NCP.展开更多
Objective： To investigate the stability and three-dimensional movements of the atlantoaxial joint after artificial atlanto-odontoid joint （AAOJ） arthroplasty by comparing with a conventional method. Methods： Afte...Objective： To investigate the stability and three-dimensional movements of the atlantoaxial joint after artificial atlanto-odontoid joint （AAOJ） arthroplasty by comparing with a conventional method. Methods： After anterior decompression, 24 human ca- daveric spinal specimens of C0-C3 were randomly divided into two groups： Group A receiving artificial AAOJ arthroplasty; Group B experiencing anterior transarticular screw （ATAS） fixation. Two groups underwent flexibility test in intact and instrumented states. Rotational angle of the C0-C3 segments was measured to study the immediate stability and function of anterior decompression with AAOJ arthroplasty compared with the intact state and ATAS fixation. Results： Compared with the intact state, anterior decompression with AAOJ arthroplasty resulted in a sig- nificant decrease in the range of motion （ROM） and neu-tral zone （NZ） during flexion, extension and lateral bending （P〈0.05）; however, with regard to axial rotation, there was no significant difference in ROM and NZ （P〉0.05）. Com- pared with anterior decompression with ATAS fixation, an- terior decompression with AAOJ arthroplasty during flexion, extension and lateral bending, significant differ- ence was found in ROM and NZ （P〉0.05）; however, as for axial rotation, there was a significant increase in ROM and NZ （P〈0.05）. Conclusion： The self-designed AAOJ has an excellent biomechanical performance, which can restore excellent in- stant stability and preserve the movement of the atlanto- axial joint.展开更多
基金supported by the National Key Research and Development Program of China (2018YFD0300503)
文摘Over-use of N fertilizer in crop production has resulted in a series of environmental problems in the North China Plain(NCP).Thus,improvement of nitrogen use efficiency(NUE)in summer maize has become an effective strategy for promoting sustainable agriculture in this region.Using twenty maize cultivars,plant dry matter production,N absorption and accumulation,yield formation,and NUE in summer maize were investigated under three N levels in two growing seasons.Based on their yield and yield components,these maize cultivars were categorized into four groups including efficient-efficient(EE)cultivars,high-nitrogen efficient(HNE)cultivars,low-nitrogen efficient(LNE)cultivars and nonefficient-nonefficient(NN)cultivars.In both two seasons,the EE cultivars improved grain yield together with increased plant biomass,and enhanced accumulative amounts as well as higher average grain yields than the other cultivar groups under deficient-N conditions.Significant correlations were observed between yield and kernel numbers(KN),dry matter(DM)amount and N accumulation at both post-silking and maturity stages.DM and N accumulation at late growth stage(i.e.,from silking to maturity)contributed largely to the enhanced yield capacity and improved NUE under N-deficient conditions.Compared with the NN cultivars,the EE cultivars also showed increased N assimilation amount(NAA)and N remobilization content(NRC),and elevated N remobilization efficiency(NRE),NUE and nitrogen partial factor productivity(PFPN).Our investigation has revealed N-associated physiological processes and may provide guidance for cultivation and breeding of high yield and NUE summer maize under limited N conditions in the NCP.
基金The program was supported by Medical Research Found of Zhejiang Provincial Health Department，Ningbo Natural Science Foundation
文摘Objective： To investigate the stability and three-dimensional movements of the atlantoaxial joint after artificial atlanto-odontoid joint （AAOJ） arthroplasty by comparing with a conventional method. Methods： After anterior decompression, 24 human ca- daveric spinal specimens of C0-C3 were randomly divided into two groups： Group A receiving artificial AAOJ arthroplasty; Group B experiencing anterior transarticular screw （ATAS） fixation. Two groups underwent flexibility test in intact and instrumented states. Rotational angle of the C0-C3 segments was measured to study the immediate stability and function of anterior decompression with AAOJ arthroplasty compared with the intact state and ATAS fixation. Results： Compared with the intact state, anterior decompression with AAOJ arthroplasty resulted in a sig- nificant decrease in the range of motion （ROM） and neu-tral zone （NZ） during flexion, extension and lateral bending （P〈0.05）; however, with regard to axial rotation, there was no significant difference in ROM and NZ （P〉0.05）. Com- pared with anterior decompression with ATAS fixation, an- terior decompression with AAOJ arthroplasty during flexion, extension and lateral bending, significant differ- ence was found in ROM and NZ （P〉0.05）; however, as for axial rotation, there was a significant increase in ROM and NZ （P〈0.05）. Conclusion： The self-designed AAOJ has an excellent biomechanical performance, which can restore excellent in- stant stability and preserve the movement of the atlanto- axial joint.
