BaFe[CO3]2, a new double carbonate: Synthesis,structural characterisation,and geostability implications for high and low PT     

《Chemie der Erde / Geochemistry》2021,81(2):125740

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Development and future prospects of quantitative mineral assessment in China     

《China Geology》2019,2(2):198-210

Mineral potential assessment at the Earth’s surface has been an important research for geoscientists around the world in the past five decades. The fundamental aspects of mineral assessment at different scales can be associated with the following tasks, e.g., mineral potential mapping and estimation of mineral resources. This paper summarized the history and development in terms of theories, methods technologies and software platforms for quantitative assessment of mineral resources in China, e.g. comprehensive information methodology, geological anomaly, three-component quantitative prediction method, 5P ore-finding area, integrated information assessment method, nonlinear process modeling and fractals, three dimensional mineral potential mapping, etc. At last, to discuss the future of quantitative mineral assessment in an era of big data including platform for 3D visualization, analysis and sharing, new methods and protocols for data cleaning, information enhancement, information integration, and uncertainties and multiple explanations of multi-information.© 2019 China Geology Editorial Office.  相似文献   

石英中铝、钙和镁的纳米离子探针原位分析标准物质研究     

李照阳  张刘平  郝佳龙  梁婷 《岩石学报》2017,33(10):3278-3284

石英胶结物是砂岩中重要的胶结物类型。用纳米离子探针(CAMECA Nano SIMS 50L)对石英胶结物中Al、Ca和Mg等重要微量元素进行原位分析,可为成岩作用研究提供重要基础依据。然而,由于缺乏相应的标准物质,一直不能对石英胶结物中Al、Ca和Mg进行研究。针对不均一的石英颗粒样品,文中采用细磨、混合、高温熔融(2000℃,6个小时)与快速冷却等措施,制作均一化的石英玻璃。经纳米离子探针验证,该石英玻璃中Al、Ca和Mg在亚微米尺度上是均一的,已能满足成岩作用研究的需要。随后,用电感耦合等离子体发射光谱和激光剥蚀电感耦合等离子体质谱测定了石英玻璃中Al、Ca和Mg的含量。相对灵敏度因子分析显示,这些测试结果是协调、合理的。该均一化的石英玻璃可作为亚微米尺度Al、Ca和Mg原位分析的标准物质。  相似文献   

Synthesis of Calix(aza)crown and its Oligomeric Analogue for the Extraction of Selected Metal Cations and Dichromate Anions     

Gülderen Uysal Akkus  Shahabuddin Memon  Mehmet Sezgin  Mustafa Yilmaz 《洁净——土壤、空气、水》2009,37(2):109-114

The present study reports the synthesis of a novel ionophore, calix[4]azacrown ( 5 ) bearing two amino groups at the lower rim along with its oligomeric analogue ( 6 ). The liquid‐liquid extraction properties of these compounds towards selected metal cations and dichromate anions have been evaluated. It is observed that ( 5 ) and ( 6 ) are good extractants for the selected metal cations. However, in the case of dichromate anion, only species ( 5 ) shows remarkable extraction properties at low pH, whereas species ( 6 ) shows poor extraction behavior. The results have importance especially in wastewater treatment to obtain environmentally safe industrial effluent and they should also assist supramolecular chemists in designing and synthesizing more sophisticated host molecules for the removal of toxic pollutants.  相似文献   

基于DDS技术的噪声分析及抑噪实现   总被引：2，自引：0，他引：2  

朱昊  刘文耀  梁杰  刘颉  郭海涛  郝永杰 《海洋技术学报》2005,24(1):120-123,135

直接数字合成(DDS)是一种重要的频率合成技术,具有分辨率高、频率变换快等优点,在雷达、海洋ADCP及通信等领域有着广泛的应用前景。文中对DDS技术所含有的噪声进行了剖析,并得出结论,在量化字长一定的情况下,产生波形的频率误差与参考频率有很大的关系,参考频率越高,波形质量越好,并且当信号的当参考时钟频率与所发射波形频率之比小于10：1时,波形会产生明显的失真;针对DDs技术的噪声,结合具体的数字合成芯片AD9854,提出了一种设计Butterworth滤波器去噪的方法,该方法简单,易行,具有良好的通用性。  相似文献   

气候变化科学的最新进展—IPCC第四次评估综合报告解析   总被引：69，自引：2，他引：67  

秦大河  罗勇  陈振林  任贾文  沈永平 《气候变化研究进展》2007,3(6):311-314

政府间气候变化专门委员会（IPCC）第四次评估报告综合报告于2007年11月17日在西班牙正式发布。综合报告将温室气体排放、大气温室气体浓度与地球表面温度直接联系起来,综合评估了气候变化科学、气候变化的影响和应对措施的最新研究进展。综合报告指出：控制温室气体排放量的行动刻不容缓;能否减小全球变暖所带来的负面影响,将在很大程度上取决于人类在今后二三十年中在削减温室气体排放方面所作的努力和投资。这对国际社会和各国政府制定经济社会发展政策,适应和减缓气候变化有一定的指导和促进作用。  相似文献   

氢化钠的合成、性质及应用          下载免费PDF全文

侯殿保  李海民  党亚 《盐湖研究》2013,(4):49-52,59

氢化钠是一种十分重要的无机及有机合成试剂,在精细化工领域应用广泛。由于其反应活性与纯度和分散度密切相关,近年来人们对合成高活性氢化钠的研究日趋重视。氢化钠的制备已有多种方法的报道,其中以油液分散金属钠法是可以实现工业化的重要工艺。论述了氢化钠的几种合成方法,叙述了氢化钠的性质,并简介了其应用情况。  相似文献   

Synthesis of Line Profiles and Radial Velocity Curves for X-Ray Binary Systems     

A. M. Cherepashchuk 《Astrophysics and Space Science》2006,304(1-4):263-266

Line profiles and radial velocity curves for optical stars in X-ray binaries are calculated taking into account ellipticity of the optical star and X-ray heating effect.  相似文献   

Limitations Of The Tangent Plane Approximation For Wide-field Imaging Using The Mauritius Radio Telescope   总被引：1，自引：0，他引：1  

N. Oozeer  N. Udaya Shankar 《Astrophysics and Space Science》2002,282(1):43-55

The Mauritius Radio Telescope (MRT) is a Fourier synthesis, non-coplanar T array. The primary objective of the telescope is to survey the southern sky at 151.5 MHz in the declination range -70^° to -10^°. Due to non-coplanarity, wide-field imaging and deconvolution of wide field images made using MRT are challenging problems in applications of radio interferometric techniques. This paper discusses the usefulness and limitations of the tangent plane approximation in transforming the measured visibilities to wide field images and in estimating the point spread function (PSF) required for the deconvolution. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

CSRH光传输线的长度及相位测量     

张越成  刘荣军  马玉培  许向前  王威  姬国枢 《天文研究与技术》2011,(4)

简述CSRH等长光传输线的物理意义,实现等长光传输线的几种方法,通过分析确定了光纤等长精度要求。介绍了两种测量光纤长度的方法,分析计算了CSRH光传输线的相位误差,最后描述了光传输线的相位检测方法。  相似文献