共查询到20条相似文献，搜索用时 109 毫秒
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氢化物原子荧光分析已广泛应用于化探，水质等样品痕量汞的测定，其主要特点是灵敏度高，分析过程简单，笔者在文献[1-6]的基础上对环境地质及生态样品中痕量汞进行了测试研究，认为以上样品共同的特点是，在分解和测定的过程中产生大量的气泡，形成气腔胶，与待测离子产生的气体同时共存，一者降低载气的传输效益，从而降低灵敏度，二 者产生假信写，影响分析结果的精密度和准确度，本文选用无极放是灯作光源，氯化亚锡作还原剂，改用氯化物发生器，克服了方法[1,2]的不足，取得了满意的结果。 相似文献
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双叉同时进液—火焰氢化法原子荧光测定钒触媒中砷 总被引：1，自引：0，他引：1
氢化法原子吸收成原子荧光的商品仪器,多采用电热石英炉原子化,进样为间歇方式。灵敏度虽高,但读数为瞬时峰值,炉温较难控制,待测元素的原子化随温度而变,影响测定结果的重现性。本文利用双叉同时进液氢化物发生器及乙炔火焰原子化原子荧光测定As,操作简便快速,并可进行稳定连续的峰高读数,原子化温度也易于控制,有较好的精密度和准确度。用此法对钒触媒及一些矿物中0.0x％～x％的As进行了测定,结果满意。 相似文献
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冯梦龙 《华北地质矿产杂志》2014,(2):88-89
随着社会不断发展,网络数字测图系统得到进一步的改进和完善,在GPS与PDA技术基础上,该系统已经逐渐向数据采集方面工作。随着地理信息技术不断发展,数字测图系统会完全实现GIS数据采集,提升工作效率。本文基于GPS与PDA技术使用下,对网络数字测图系统进行了研究。 相似文献
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本文着重介绍了原子荧光光谱仪在黄金矿山中的应用。该仪器与化学法和其它类型的仪器相比较,具有灵敏度高（DL：〈1×10-9）、重现性好（RSD：〈2.0%）、分析速度快等优点。同时简单介绍了目前测定金的一些其它方法,包括原子吸收和发射光谱、化学分析等方法在应用过程中的优缺点和所遇到的情况,论证了原子荧光光谱仪在黄金矿山金... 相似文献
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纵波各向异性裂缝预测方法是目前应用比较广泛、效果较好的一种裂缝预测方法；但传统椭圆拟合方法的准确性受到一系列因素的影响，致使裂缝密度反演结果不准确。本次研究根据Ruger方程精确式推导各向异性介质中储层裂缝密度的计算方法，该方法首先利用入射角、方位角、Thomsen各向异性三参数以及介质弹性参数的函数来计算纵波反射系数，然后根据纵波反射系数计算待测储层中裂缝的切向各向异性系数，最后根据各向异性系数计算待测储层的裂缝密度。利用该方法在四川盆地正坝南地区通过实际纵波AVOA数据反演法向和切向裂隙弱度预测裂缝密度，裂缝参数反演结果与钻井信息吻合；表明该方法能够用于裂缝储层预测，确定研究区裂缝发育情况。 相似文献
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论述了应力应变智能网络化测式系统实现的原理和方法,并与当前国内同类系统进行了比较分析;同时,也简要介绍了该系统在隔河岩水利枢纽安全监测系统中的应用情况。该系统在岩土工程实行实时安全监测的推广应用方面具有一 定的推广价值。 相似文献
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Atsushi Kyono 《Physics and Chemistry of Minerals》2013,40(9):717-731
The structural diversity of arsenic sulfide molecules in compositions between As4S6 and As4 was investigated using ab initio quantum chemical calculations. The As4S6 molecule consists of four trigonal pyramid coordinations of As atoms bonding to three S atoms. In the As4S5 composition, only one type of molecular configuration corresponds to an uzonite-type molecule. In the As4S4 composition, two molecular configurations exist with realgar-type and pararealgar-type molecules. Three molecular configurations are in the As4S3 composition. The first configuration comprises trigonal pyramidal As atom coordinations of two types: bonding to two S atoms and one As atom, and bonding to one S atom and two As atoms. The second is the molecular configuration of dimorphite. The third comprises trigonal pyramidal As atom coordinations of two types: bonding to three As atoms, and bonding to one As atom and two S atoms. The As4S2 composition allows molecular configurations of two types. One is comprised of trigonal pyramidal As atom configurations of one type bonding to two As atoms and one S atom. The other comprises trigonal pyramidal As atom coordinations of three types: bonding to two S atoms and one As atoms, bonding to one S atom and two As atoms, and bonding to three As atoms. The As4S molecule has trigonal pyramidal As atom coordinations of two types: bonding to one S atom and two As atoms, and bonding to three As atoms. The As4S composition permits only one molecular configuration, which suggests that the mineral duranusite comprises the As4S molecular geometry. In all, ten molecular configurations are predicted in the molecular hierarchy of the arsenic sulfide binary system. The simulated Raman spectral profiles are helpful in searching for undiscovered arsenic sulfide minerals. 相似文献
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1987年8月王宁等报道具有八次对称轴准晶的高分辨图象,呈现出正八边形相嵌的图案。本文认为从配位多面体理论上对八次对称存在的可能性加以研究是有必要的,为此提出了具有十次配位的等腰三角十六面体和一系列带帽反棱柱,精确地求出了这些十六面体的顶点间的夹角、棱长和晶面法线与四次轴间的夹角等几何参数,作为应用对于Cr—V—Ni—Si八次对称准晶,设Ni原子（简称原子A）位于多面体中心,而V,Cr,Si原子（简称原子B）位于顶点上,原子A和B之半径分别为1.24（?）和1.32（?）,间隙0≤（?）（?）≤0.6（?）.则:（1）若原子A和B按等腰三角十六面体配位且A,B的键长为（2.56+δ）（?）,则原子B间的键长为1.08（2.56+δ）（?）或1.29（2.56+δ）（?）;（2）若原子A和B按带帽反棱柱配位且呈“紧密堆积”,则原子A和B之间的键长为（2.56+δ）（?）或（2.56+δ）(0.511+（0.261+[0.08/（2.56+δ）]n）1/2（?） 相似文献
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金刚石中晶格氢的UHF法计算分析 总被引：1，自引：0，他引：1
对金刚石中晶格氢进行了UHF法计算，结果表明，空穴吸引1～4个氢原子均可以稳定存在。空穴具有吸引较多氢原子在其周围的倾向，最多可以达到4个氢原子。当空穴吸引1个氢原子时，氢原子倾向于直接存在于碳晶格空穴中，不改变化学键的键长，即以顺磁性氢的状态存在时更为稳定。 相似文献
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Katja Eder Laura M. Otter Limei Yang Dorrit E. Jacob Julie M. Cairney 《Geostandards and Geoanalytical Research》2019,43(3):385-395
In this study atom probe tomography was used to study nacre, an important biocomposite material that is challenging to prepare and analyse by atom probe and, when successful, yields data that is challenging to interpret. It was found that these challenges mainly arise from the insulating and heterogeneous nano‐scale properties of nacre. We outline our current best practice for preparing and running atom probe tips, such as using a low acceleration voltage (< 3 kV) and current (≤ 50 pA) to avoid damage to the microstructure, and using transmission electron microscopy to confirm that the region of interest is located close to the apex of the atom probe tip. Optimisation of the preparation parameters led to several successful atom probe experiments, with one of the data sets containing part of an organic membrane and others showing organic inclusions within the reconstruction. 相似文献
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Employing first-principles methods, the docking sites for H were determined and H, Al, and vacancy defects were modeled with an infinite periodic array of super unit cells each consisting of 27 contiguous symmetry nonequivalent unit cells of the crystal structure of stishovite. A geometry optimization of the super-cell structure reproduces the observed bulk structure within the experimental error when P1 translational symmetry was assumed and an array of infinite extent was generated. A mapping of the valence electrons for the structure displays mushroom-shaped isosurfaces on the O atom, one on each side of the plane of the OSi3 triangle in the nonbonded region. An H atom, placed in a cell near the center of the super cell, was found to dock upon geometry optimization at a distance of 1.69 Å from the O atom with the OH vector oriented nearly perpendicular to the plane of the triangle such that the OH vector makes a angle of 91° with respect to [001]. However, an optimization of a super cell with an Al atom replacing Si and an H atom placed nearby in a centrally located cell resulted in an OH distance of 1.02 Å with the OH vector oriented perpendicular to [001] as observed in infrared studies. The geometry-optimized position of the H atom was found to be in close agreement with that (0.44, 0.12, 0.0) determined in an earlier study of the theoretical electron density distribution. The docking of the H atom at this site was found to be 330 kJ mol–1 more stable than a docking of the atom just off the shared OO edge of the octahedra as determined for rutile. A geometry optimization of a super cell with a missing Si generated a vacant octahedra that is 20% larger than that of the SiO6 octahedra. The valence electron density distribution displayed by the two-coordinate O atoms that coordinate the vacant octahedral site is very similar to those displayed by the bent SiOSi angles in coesite. The internal distortions induced by the defect were found to diminish rather rapidly with distance, with the structure annealing to that observed in the bulk crystal to within about three coordination spheres. 相似文献
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The limit of solid solution of SiO2 in nephelines has been determinedat 700? C and a water pressure of 15, 000 lb/sq. in. X-ray dataare given for the determination of the composition of nephelinesin equilibrium with alkali feldspar at 700? C. The break in the plot of lattice parameters against chemicalcomposition for nephelines in the system NaAISiO4–KAISiO4(Tuttle & Smith, 1958) is found to persist in the ternarysystem and occurs when six out of the eight alkali atom sitesare filled by Na. 相似文献
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流域科学研究中的观测和模型系统建设 总被引：6，自引：5，他引：1
流域是地球系统的缩微,是自然界的基本单元。流域科学从基础研究角度可以被看作是地球系统科学研究方法在流域尺度上的具体体现;从流域综合管理的应用角度看,流域科学是在流域尺度上通过对自然资源和人类活动的优化配置而为可持续发展服务的应用科学。流域观测系统和模型系统的建设是发展流域科学的前提。提出了建立遥感—地面观测一体化的、覆盖流域能水和生物化学循环及社会经济活动的流域观测系统的设想,规划了系统各组成部分,以高效、高分辨率、高精度、多尺度、集成和现代化为流域观测系统的基本衡量准则。流域模型系统可概括为“水—土—气—生—人”集成模型的发展,[JP2]应该科学目标和流域管理目标并重,既要发展具有综合模拟能力的流域集成模型,也要建成流域水土资源和社会经济资源可持续利用决策支持系统。流域集成模型应由分布式水文模型、陆面过程模型、地下水模型、渠系模型、动态植被模型和社会经济模型构成。 相似文献