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991.
UHF surface velocities radar is developed based on the successful ocean state measuring and analyzing radar system. The design method for UHF radar system is presented. It is designed to operate at UHF channel, and the transmit power is under 5W. Maximum range of field test over fresh water can be a kilometer. The field tests at Tangsun River and at Majiatan and Gaohazhou proved that USVR System can be used successfully. 相似文献
992.
创新是知识经济时代对现代编辑传播的核心要求.《编辑创新与现代传播》对这一命题做了四个方面的重要诠释:创新思维乃基础、创新能力为根本、理论创新应先行、实践创新是目的,从而以创新为理论圆点,构建了现代编辑主体的自我超越与发展之途,为编辑主体行为实践提供了具有活性的生命因子. 相似文献
993.
LIU JinGuo WANG YueChao LI Bin MA ShuGen 《科学通报(英文版)》2007,52(23):3299-3304
With the aim to discover water, life and resources in other planets, robotic sampling instrument is a crucial part of the space exploration robot. To remove dusty and weathered surfaces and expose the fresh rock underneath the planetary surface, a robotic rock grinder is considered to replace the geolo- gist’s rock hammer to carry out the geological investigation. A primary prototype of the robotic rock grinder with three degrees of freedom has been developed in this paper. Planetary transmission system is used in the grinding driving system with two inputs (rotation motor and revolution motor) and two outputs (grinding wheel and cutting brush). The grinding wheel with two teeth has been used to abrade the rock. The cutting brush is used to sweep the debris. The third actuator is to feed the grinding sys- tem. Kinematics of the grinding system has been analyzed. To get a continuous and smooth fresh face over the rock, grinding trajectory of the grinding wheel has been discussed and planned. Lastly, abra- sion experiments have been made to testify the feasibility and the basic function of this system. 相似文献
994.
FENG ShuJie MA JunHong LIN Fei WANG Ling PAN QingHua 《科学通报(英文版)》2007,52(24):3346-3354
Magnaporthe oryzae is a model for plant pathogenic filamentous fungi. We have assembled a simple sequence repeat (SSR)-based physical map of the species, using in silico sequence data. A set of 120 SSR markers was developed from the genomic sequence of the reference isolate 70-15. These markers were readily amplified from the genomic DNA of other isolates, and high levels of allelic variation characterised the parental isolates of the two crosses tested. All the markers were locatable to one of the seven M. oryzae chromosomes. An SSR-based physical in silico map was constructed, and pre-existing SSR and RFLP loci were integrated into the map, along with 23 Avr (avirulence) genes and two other genes of importance to the plant/pathogen interaction. This map provides a platform for population genetics and functional genomics studies in the model pathogen, and even in other evolu- tionally related pathogens. 相似文献
995.
DANG Ge MA ShuYing ZHOU YunLiang 《科学通报(英文版)》2007,52(24):3403-3415
With energetic ion measurements on FAST satellite, the morphologic features of quiet-time ionospheric O ion upflowing at altitudes of 2000 to 4000 km are drawn out for the first time. The pre-noon cusp/cleft is the predominant region of upflowing occurrence for O with lower energy. Meanwhile the pre-dawn sector near the equatorward edge of the plasma convection dominates the occurrence for the higher energy O ions. No matter whether the energy is lower or higher, the upflows occur often over a wide MLT range of lower latitudes outside the auroral oval. The upflowing within the pre-midnight (21:00― 22:00 MLT) auroral oval carrys larger energy fluxes, with extremely large fluxes for higher energy O appearing near the polar cap boundary. For altitudes of 2000―4200 km under observation, the ion conics occur much more frequently than ion beams. Ion beams are rarely found below 3000 km, while the conics occur uniformly over the observed altitudes. 相似文献
996.
描述了用时间Petri网(TPN)在装备战场抢修系统(BDAR)建模中的优势,在给出了一种基于时间Petri网通信导航装备战场抢修系统的建模方法和步骤的基础上,建立了一个通信导航装备战场抢修系统的TPN模型,并进行实例分析,验证模型是可行的。 相似文献
997.
矿山三维实体建模 总被引:5,自引:0,他引:5
采用大型矿床三维软件Surpac构建了凡口铅锌矿深部矿床地质数据库,建立起了该矿的地表三维模型、深部矿体(-320以下)三维实体模型、主要断层三维模型、巷道工程三维模型以及矿体块体模型;分别采用普通克立格法和距离反比法对矿体金属元素品位进行了估值,运用估值结果分别按各金属元素和各中段进行了储量的统计计算,并将计算结果与矿山实际勘探获得的储量结果进行了对比分析.实践表明,所建模型和品位、储量计算结果可靠,从而有效地实现了该矿山深部矿体、岩层、断层、井巷工程等地下空间体的三维可视化,并为矿山深部矿床的有效开采和勘探设计及施工奠定了坚实的基础. 相似文献
998.
本论文报道一种快捷高效的PCR—dot—blot新方法.该方法利用手动芯片点样仪将微量PCR产物(约100pgDNA)点样,并采用North2 South Biotin Random Prime DNA Labeling and Detection Kit(PIERCE)完成快速斑点杂交.通过鉴定转基因烟草证明这种方法是可行而有效的.这种新方法节省材料,效率极高,特别适合大批量鉴定转基因植物. 相似文献
999.
JIANG Yong MA TongHui 《科学通报(英文版)》2007,52(6):771-776
The asparagine-proline-alanine sequences (NPA motifs) are highly conserved in aquaporin water channel family. Crystallographic studies of AQP1 structure demonstrated that the two NPA motifs are in the narrow central constriction of the channel, serving to bind water molecules for selective and effi-cient water passage. To investigate the importance of the two NPA motifs in the structure, function and biogenesis of aquaporin water channels, we generated AQP1 mutations with NPA1 deletion, NPA2 de-letion and NPA1,2 double deletion. The coding sequences of the three mutated cDNAs were subcloned into the mammalian expression vector pcDNA3.1 to form expression plasmids. We established stably transfected CHO cell lines expressing these AQP1 mutants. Immunofluorescence indicated that all the three mutated AQP1 proteins are expressed normally on the plasma membrane of stably transfected CHO cells, suggesting that deletion of NPA motifs does not influence the expression and intracellular processing of AQP1. Functional analysis demonstrated that NPA1 or NPA2 deletion reduced AQP1 water permeability by 49.6% and 46.7%, respectively, while NPA1,2 double deletion had little effect on AQP1 water permeability. These results provide evidence that NPA motifs are important for water per-meation but not essential for the expression, intracellular processing and the basic structure of AQP1 water channel. 相似文献
1000.
^226Ra evidence for the ecosystem shift over the past 40 years in the North Pacific Subtropical Gyre 总被引:1,自引:0,他引:1
YANG JunHong CHEN Min QIU YuSheng LI YanPing MA Qiang LUE E ZHANG Run HUANG YiPu 《科学通报(英文版)》2007,52(6):832-838
Surface seawater was collected for ~(226)Ra measurement in the North Pacific Subtropical Gyre from July to October, 1999 and October to December, 2003. Combined with the historical data reported for this sea area, a declined trend of surface ~(226)Ra concentrations was observed since 1960s, indicating the ecosystem shift in response to global warming. On one side, the enhanced stratification of the upper water column resulting from global warming reduced the ~(226)Ra input from the depth, on the other, the temporal increase of biological production resulting from the climate-related ecosystem structure change strengthened the ~(226)Ra removal from the surface ocean. Both the physical and biological processes resulted in the decrease of surface ~(226)Ra concentrations in the North Pacific Subtropical Gyre. The temporal trend of surface ~(226)Ra concentrations was consistent with the trends of chlorophyll a, silicate, phosphate and primary production previously reported. This study provided ~(226)Ra evidence for the ecosystem shift under global change. 相似文献