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排序方式: 共有1055条查询结果,搜索用时 109 毫秒
91.
Relative position determination of a lunar rover using high-accuracy multi-frequency same-beam VLBI 总被引:2,自引:0,他引:2
LIU QingHui CHEN Ming XIONG WeiMing QIAN ZhiHan LI JinLing HAO WangHong WANG GuangLi ZHENG WeiMin GUAN Di ZHU RenJie WANG WeiHua ZHANG XiuZhong JIANG DongRong SHU FengChun PING JinSong & HONG XiaoYu Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai China Center for Space Science Applied Research Beijing Lunar Explorer Engineering General Department Beijing ... 《中国科学:物理学 力学 天文学(英文版)》2010,(3)
Multi-frequency same-beam VLBI means that two explorers with a small separation angle are simultaneously observed with the main beam of receiving antennas. In the same-beam VLBI, the differential phase delay between two explorers and two receiving telescopes can be obtained with a small error of several picoseconds. The differential phase delay, as the observable of the same-beam VLBI, gives the separation angular information of the two explorers in the celestial sphere. The two-dimensional relative position on the plane-of-sky can thus be precisely determined with an error of less than 1 m for a distance of 3.8×105 km far away from the earth, by using the differential phase delay obtained with the four Chinese VLBI stations. The relative position of a lunar rover on the lunar surface can be determined with an error of 10 m by using the differential phase delay data and the range data for the lander when the lunar topography near the rover and the lander can be determined with an error of 10 m. 相似文献
92.
A number of novel strobilurin analogues containing substituted N-phenylpyrimidin-2-amines were synthesized.The structures of these new compounds were confirmed by ~1H NMR,IR and elemental analysis.Biological evaluation in the greenhouse showed several compounds have good fungicidal activities at 25 mg/L. 相似文献
93.
After the cultured cells from Hyoscyamus muticus + Nicotiana tabacum somatic hybridswere cocultivated with different virulent strains of Agrobacterium tumefaciens harboringoctopine- type Ti plasmid or nopaline- type Ti plasmid using the transformation procedurein vitro developed in the present investigation, the TiT- DNA genes were introducedinto the host cells. The onc genes and ocs or nos genes located on TiT- DNA were expres-sed in transformed colonies derived from the cocultivated cells. Although the platingefficiencies of recipient cells were reduced by the agrobacterial treatment, the frequenciesof phytohormone autotrophy ranged from 33.9 to 76 .8% in the cells infected with viru-lent strains in hormone- free conditions, and the frequencies of opine synthase activityamounted to 9.7- 47 .5%. Teratomatous shoots were regenerated from the transformed col-onies. During the course of culture the shoots were no longer to lengthen when theygrew up to 1 -3 cm in length, and they could not be rooted. Follo 相似文献
94.
A new macrolide glycoside,cuneataside F was isolated from the n-butanol extract of the stem of Sargentodoxa cuneata. The structure was elucidated on the basis of extensive 1D and 2D NMR as well as HRESI-MS spectroscopic analysis. 相似文献
95.
本文研究了在非离子表面活性剂Tween 80存在下Al(Ⅲ)与O-NPF显色反应的条件,在pH9.0~11.0的HBO_3-Na_2CO_3缓冲溶液中可形成稳定的紫色络合物,最大吸收波长为564nm,铝量在0~5μg/25ml范围符合比尔定律,采用双波长法摩尔吸光系数高达1.81×10~5。本法具有简便、快速、灵敏度高、准确性好等优点。 相似文献
96.
W. Schultes R. Nübel A. Gramberg British Fuel Research Board A. Sanielevici und A. Tian 《Fresenius' Journal of Analytical Chemistry》1935,102(3-4):113-116
Ohne Zusammenfassung 相似文献
97.
<正>Two new eudesmane derivatives were isolated from the leaves and flowers of Verbesina virginica,along with the known 6-O-β-E -p-coumaroyl-4α-hydroxyeudesmane(1).Their structures were determined as 6-O-β-Z-p-coumaroyl-4α-hydroxyeudesmane(2) and 6-O-α-E-p-coumaroyl-1β-4α-dihydroxyeudesmane(3) by spectroscopic methods. 相似文献
98.
<正>A series of phthalonitrile blending resins were prepared from 4-aminophenoxyphthalonitrile(APN) and 4,4'-bis(3,4- dicyanophenoxy)biphenyl(BPH) by directly powder-mixing and copolymerization.Differential scanning calorimeter(DSC) and dynamic rheology were used to study the curing reaction behaviors of APN/BPH blends,and the results indicated that the introduction of APN accelerated the curing rate of BPH,and the existence of BPH decreased the curing temperature of APN/BPH systems.The thermal stability of postcured APN/BPH resins was investigated by thermogravimetric analysis(TGA),and the TGA results indicated that the crosslinked polymers of APN/BPH systems possessed good thermal stability. 相似文献
99.
在醋酸/水体系的工业分离中,溶液中的氢键对分离效率有很大影响.本文采用两种第一性原理方法,即从头算分子动力学模拟(AIMD)和量子化学计算(QCC),对由单个醋酸和不同水分子所组成聚合体的氢键相互作用进行了研究,采用极化统一模型和自洽反应场模型计算得到了聚合体在水溶液中的热力学数据.从QCC计算的气相和水溶液中的聚合自由能表明六元环在两种状态下都为最优结构,热力学数据反映出的各种结构的相对稳定性与AIMD模拟的环分布符合得相当一致.研究表明,由于存在醋酸和水分子间的氢键作用,稀醋酸/水溶液中的醋酸分离要比在浓醋酸溶液中困难得多. 相似文献
100.
Modelling of multi-bodies in close proximity under water waves——Fluid resonance in narrow gaps 总被引:1,自引:0,他引:1
LU Lin TENG Bin CHENG Liang SUN Liang & CHEN XiaoBo Center for Deepwater Engineering Dalian University of Technology Dalian China State Key Laboratory of Structural Analysis for Industrial Equipment State Key Laboratory of Coastal Offshore Engineering School of Civil Resource Engineering The University of Western Australia Crawly Australia Centre for Offshore Research... 《中国科学:物理学 力学 天文学(英文版)》2011,(1)
Viscous fluid model and potential flow model with and without artificial damping force(f=-μV,μ the damping coefficient and V the local averaging flow velocity) are employed in this work to investigate the phenomenon of fluid resonance in narrow gaps between multi-bodies in close proximity under water waves.The numerical results are compared with experimental data available in the literature.The comparison demonstrates that both the viscous fluid model and the potential flow model are able to predict the res... 相似文献