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421.
Marine sediments were dissolved by HNO3-HF-HCIO4 in a sealed container at low pressure; I-IF was evaporated in an open container and salts were dissolved in HCl by heating, then transferred to 2% HNO3 solution. A total of 45 elements, including Li, Be, So, Ti, V, Cr, Mn, Co, Ni, Cu, Zn, Ga, Rb, Sr, Y, Zr, Nb, Mo, Cd, In, Sb, Cs, Ba, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Hf, Ta, W, TI, Pb, Bi, Th and U, were measured by inductively coupled plasma mass spectrometry (ICP-MS). Condi-tions and sample experiments showed that this procedure defines a good experimental method which has the advantages of clear interference, easy operation and reliable results. The concentrations of the 45 elements could be used for resource exploration, envi-ronmental assessment and academic research. 相似文献
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We show that, over the next two decades, the current radar and optical astrometric technology is adequate to allow detection of the Yarkovsky effect acting on at least two dozen NEAs from a variety of orbital regimes and with effective diameters ranging from about ten meters up to several kilometers. The Yarkovsky effect will likely be detected for objects of rarer spectral types X, C, and E, as well as the more common S and Q. The next predicted detection of the Yarkovsky effect is for 4179 Toutatis in October 2004, which would be also the first multi-kilometer case. The Asteroid 25143 Itokawa, with a likely detection at the end of 2005, could offer an important test due to the independent “ground-truth” measurements of the asteroid mass and surface thermal inertia expected from the Hayabusa spacecraft. Earth co-orbital asteroids (e.g., 2000 PH5 or 2003 YN107) are the best placed for rapid determination of the Yarkovsky effect, and the timespan between discovery of the object and detection of the Yarkovsky effect may be as short as 3 years. By 2012, the motion of potential Earth impactor (29075) 1950 DA will likely reveal the magnitude of the Yarkovsky effect, which in turn will identify which of two possible pole orientations is correct. Vis-a-vis the 2880 impact, this new information will allow a substantial improvement in the quality of long term predictions. 相似文献
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X射线荧光光谱法测定土壤样品中碳氮硫氯等31种组分 总被引:3,自引:3,他引:3
利用新型的ZSX Primus Ⅱ型X射线荧光光谱仪采用粉末压片法直接测定土壤样品中的C、N、S、Cl等31种元素。各元素分析晶体为N采用RX45,C采用RX61,Na、Mg采用RX25,C1、S、P采用Ge,Si、Al采用PET,其余元素均采用LiF200。结果表明,方法的检出限、精密度和准确度对绝大多数元素而言,均可满足多目标地球化学调查样品分析的质量要求: 相似文献
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Reducing Influence of Gravity Model Error in Precise Orbit Determination of Low Earth Orbit Satellites 总被引:1,自引:0,他引:1
GUO Jinlai HU Min ZHAO Qile GUO Daoyu 《地球空间信息科学学报》2007,10(2):105-110
Based on the orbit integration and orbit fitting method, the influence of the characters of the gravity model, with different precisions, on the movement of low Earth orbit satellites was studied. The way and the effect of absorbing the influence of gravity model error on CHAMP and GRACE satellite orbits, using linear and periodical empirical acceleration models and the so-called "pseudo-stochastic pulses" model, were also analyzed. 相似文献