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951.
从所有已被提出和发现的230多颗超新星遗迹和1300多颗脉冲星中,总结出一个共50对脉冲星与超新星遗迹成协候选体的样本.其中至少20对因为环绕脉冲星的脉冲星风云已被探测到,其成协性应该是真实的。结合近来的观测结果,对导致这种成协对缺失现象的各种因素进行了讨论,尤其深入地讨论了这个样本中有代表性的3个很可能成协的脉冲星与超新星遗迹对。 相似文献
952.
锰银氧化矿选冶工艺的研究现状及进展 总被引:1,自引:0,他引:1
锰银氧化矿在中国是一种重要的矿床类型 ,但在目前经济技术条件下仍属于难选冶和无商业价值的矿石类型。文章对国内外锰银氧化矿选冶技术的研究现状和进展进行了比较全面的评述 相似文献
953.
Recent Developments in Trace Element Analysis by ICP-AES and ICP-MS with Particular Reference to Geological and Environmental Samples 总被引:1,自引:1,他引:1
Kathryn L. Linge 《Geostandards and Geoanalytical Research》2005,29(1):7-22
This review describes recent developments in trace element analysis using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). It aims to focus on the application of ICP techniques to geological and environmental samples. Therefore, fundamental studies in ICP-MS and ICP-AES instrumentation have largely been ignored. Whereas the majority of literature reviewed related to ICP-MS, indicating that ICP-MS is now the preferred technique for all geological analysis, there is still a steady development of ICP-AES to environmental applications. It is clear that true flexibility in elemental analysis can only be achieved by combining the advantages of both ICP-AES and ICP-MS. Two particular groups of elements (long-lived radionuclide and the platinum-group elements) stood out as warranting dedicated sections describing analytical developments these areas. 相似文献
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L. Paul Bédard 《Geostandards and Geoanalytical Research》2008,32(4):399-403
These mature analytical techniques do not show any change in publication level from the previous two years and AAS remains dominant in terms of the number of publications. The last two years have seen fewer technical improvements than in the previous review period. Some interesting papers dealing with uncertainty and quality assurance in INAA were published during 2006–2007. It is suggested that photon activation should be reconsidered because the source of electron accelerators has recently improved. A technique to preconcentrate Se for INAA determination has also been proposed. In the case of AAS, papers on analyte preconcentration continue to be more abundant than those relating to instrumental modification. Sample preparation for AAS is also active and ultrasound‐assisted leaching shows some promising applications. There were an unusual number of reviews concerned with AAS and those important to geological samples are cited here. A technique to preconcentrate Cr in water is presented and a new device to determine As and Se is showing some potential uses. Confocal X‐ray mapping continues to show interesting developments. One group developed a technique to perform XRF inside an oyster and an interesting application of μ‐XRF mapping of sediments is presented. Determination of platinum‐group elements (at μg g1 concentrations) can be carried out very quickly with an improved XRF technique. 相似文献
957.
Paul J. Sylvester 《Geostandards and Geoanalytical Research》2008,32(4):469-488
Research in 2006 and 2007 dealing with laser ablation‐(multicollector)‐inductively coupled plasma‐mass spectrometry, LA‐(MC)‐ICP‐MS, involved studies concerned with optimising the technique itself, as well as applying the method to a variety of problems in the Earth sciences. The causes of elemental and isotopic fractionation produced during laser ablation continues to be of considerable interest, with evidence mounting that processes occurring both at the ablation site and in the argon plasma of the ICP are culpable. There is growing excitement in the use of femtosecond lasers for LA‐(MC)‐ICP‐MS, with the hope that they reduce or eliminate melting and non‐congruent volatilisation at the ablation site and thus approach stoichiometric sampling. Ablation chamber design emerged as a serious concern, particularly with respect to achieving the rapid washout needed for fine‐scale compositional mapping of geological objects. LA‐MC‐ICP‐MS provided data for a wide range of isotopic systems, especially hafnium, but also B, S, Mg, Cu, Fe, Sr, Nd, Pb and U. Measurement uncertainties in LA‐ICP‐MS were discussed by several researchers, and are critically reviewed here ‐ total uncertainties for trace element concentration measurements of silicates including errors on the calibration values of common reference materials are ~10% (95% confidence limits), though the precision of individual spot measurements (50 to 100 μm) is much better, ~1% RSD, using a 193 nm laser and a sector field‐ICP‐MS. LA‐ICP‐MS U‐Pb ages for zircon and other U‐rich accessory phases are claimed by most geoanalysts to have 2s uncertainties of ~0.7 and 1.3% respectively but the actual accuracy of the method is probably only as good as ~2% (2s), when uncertainties associated with laser‐induced Pb/U fractionation are included. 相似文献
958.
渗透性曲线是反映非饱和土中水分运移的重要参数,瞬态剖面法是测定渗透性曲线的常用方法。将滤纸法应用于传统的瞬态剖面法,设计了一种土柱装置,用于测定土体的渗透性曲线。该装置包括上部能够持续给水的供水系统及下部由带环刀的土样与滤纸叠置而成的土柱。在水分下渗过程中,定期测量土样与滤纸的质量以获得土柱的含水率剖面与水头剖面,根据所测数据计算得到土?水特征曲线和渗透性曲线。用此方法测得甘肃正宁马兰黄土与第1层古土壤的渗透性曲线和土?水特征曲线,该方法测量的吸力范围大,为1~105 kPa,渗透系数范围在10?5~10?13 m/s。用常见的统计预测模型预测了土体的渗透性曲线,并与实测曲线对比发现小吸力范围预测值与实测值相符,大吸力范围预测值偏差较大。 相似文献
959.
随着世界各国对海洋资源的重视不断提高,越来越多的国家开始发展海洋遥感卫星技术,为海洋监测、海洋航运、海洋环境、海洋军事及海洋经济等领域提供支撑服务。对全球海洋遥感卫星信息及其相关参数进行统计分析,有助于掌握未来海洋遥感卫星的发展动态和趋势。根据统计分析可以看出,海洋遥感卫星正向多载荷、高分辨率、全覆盖方向发展,并对卫星的发射条件及搭载的载荷提出了新的挑战。随着载荷种类的增多及传输速率的提高,产生的卫星数据也呈现多源异构性,且数据量急剧增加。为此,只有建立大型的卫星数据中心,形成一体化的支撑体系,才能为海洋各领域提供更好的服务。 相似文献
960.
在历史气象资料数字化工作中,降水自记纸迹线提取是通过计算机软件技术手段,按照提取技术要求并结合台站观测记录和实际天气现象,对降水迹线进行分析、模拟并生成序列数据的数字化过程。根据利用软件提取降水自记纸迹线的工作实践,分析了降水自记纸迹线提取过程中遇到的异常处理个例,并提供了相应的科学处理方法。 相似文献