锡石的晶体结构和形态的关系          下载免费PDF全文

柴钢  王文魁 《岩石矿物学杂志》1988,7(4):374-381

本文对不同成因类型的锡石晶体形态进行了研究,并从PBC(周期性键链)理论出发,讨论了锡石晶体形态与晶体结构的关系。笔者认为,锡石晶体具有三种F面,即s{111}、e{101}、m{110},与Hartman对同样结构类型的金红石晶面性质划分有所差异。据锡石晶面结构性质所推导的理想晶体形态图,与晶体测量所得到的天然晶体形态图总体上相吻合。  相似文献   

Responses of the tropospheric ozone and odd hydrogen radicals to column ozone change     

S. C. Liu  M. Trainer 《Journal of Atmospheric Chemistry》1988,6(3):221-233

The response of tropospheric ozone to a change in solar UV penetration due to perturbation on column ozone depends critically on the tropospheric NO _x (NO+NO₂) concentration. At high NO _x or a polluted area where there is net ozone production, a decrease in column ozone will increase the solar UV penetration to the troposphere and thus increase the tropospheric ozone concentration. However, the opposite will occur, for example, at a remote oceanic area where NO _x is so low that there is net ozone destruction. This finding may have important implication on the interpretation of the long term trend of tropospheric ozone. A change in column ozone will also induce change in tropospheric OH, HO₂, and H₂O₂ concentrations which are major oxidants in the troposphere. Thus, the oxidation capacity and, in turn, the abundances of many reduced gases will be perturbed. Our model calculations show that the change in OH, HO₂, and H₂O₂ concentrations are essentially independent of the NO _x concentration.  相似文献   

Bond—Valence Sum and Distortion of Coordination Polyhedra     

章礼明 《中国地球化学学报》1993,12(1):92-96

By using the Lagrange‘s intermediate value theorem,it is derived mathematically that the structur-al distortion of a coordination polyhedron may lead to an increase in bond-valence sum of the cen-tral atom of ion .The applicabilities of the bond-valence model are discussed in the following two cases:the modeling of crystal structure ,and the indication of distortion degree of a coordination polyhedron.Also it is shown that a distorted polyhedron should be in favor of a longer average bond length or a smaller coordination number.  相似文献   

电气石和水之间的氢同位素分馏   总被引：1，自引：0，他引：1  

钱雅倩  郭吉保 《地球学报》1994,15(Z1):189-196

作者对电气-水体系氢同位素平衡分馏和动力学分馏和动力学分馏开展了实验研究，丰富了羟基矿物氢同位素分馏资料。本文对该研究的实验技术、分析方法作了介绍，并对实验结果进行讨论与国外已有的该方面的资料作了对比。在800-650℃时电气石和水之间氢同位素平衡分馏系数与温度间线性关系为103lna电气石-水=-28.24（106/T2）+2.60；交换速率常数与温度间关系为lnk2=-0.19-6.70（103/T）  相似文献   

Identification and occurrence of novel C₃₆–C₅₄ 3,4-dialkylthiophenes with an unusual carbon skeleton in immature sediments     

M.E.L. Kohnen  T.M. Peakman  J.S.Sinninghe Damste  J.W. de Leeuw 《Organic Geochemistry》1990,16(4-6)

A series of novel long-chain 3,4-dialkylthiophenes (C₃₆–C₅₄) was identified in a number of sediments ranging from Pleistocene to Cretaceous. The identifications were based on mass spectral characterisation, desulphurisation and mass spectral data of synthesised model compounds. These organic sulphur compounds are probably formed by sulphur incorporation into mid-chain dimethylalkadienes with two methylenic double bonds. These putative precursor lipids are unprecedented and may be considered rather unusual. The distribution of 3,4-dialkylthiophenes in sediments varies considerably with the depositional palaeoenvironment, indicating that these compounds have a potential as molecular markers reflecting changes in palaeoenvironment.  相似文献   

宁南山区雹块氘含量的分析          下载免费PDF全文

杨颂禧  马伟  陈玉山 《大气科学》1991,15(3):24-30

由10个大雹块(长轴47—64mm)切片中的43个氘样分析得知:雹块的平均δD值为-93.8‰,其相应高度为海拔807m(-14.7℃),干生长层的平均δD值为-101.8‰,相应高度为8803m(-19.5℃),湿生长层的平均δD值为-91.5‰,相应高度为7413m(-11.4℃)。氘含量与冰晶平均长度之间有较好的统计关系。  相似文献   

The effect of gas-phase chemistry on aqueous-phase sulfur dioxide oxidation rates     

William R. Stockwell 《Journal of Atmospheric Chemistry》1994,19(3):317-329

The rates and mechanisms of both gas and liquid phase reactions for the oxidation of sulfur dioxide play an important role in the production of atmospheric acids and aerosol particles. Rhodeet al. (1981) concluded that sulfate production rates were highly non-linear functions of sulfur dioxide emission rates. Their modelling study used an HO _x termination mechanism for the HO—SO₂ reaction in the gas-phase. Stockwell and Calvert (1983) determined that one of the products of the overall reaction of HO with sulfur dioxide was an HO₂ radical. The National Research Council (1983) using a version of the Rhodeet al. (1981) model modified to include HO₂ production from the HO—SO₂ reaction concluded that sulfate production becomes much more linear with respect to reductions in sulfur dioxide emissions. However, the cause of this increased linearity was not explained by the National Research Council report. It is demonstrated that the increased linearity is due to the coupling of gas-phases and aqueous phase chemistry. The gas-phase sulfur dioxide oxidation mechanism has a very significant effect on hydrogen perodide production rates.  相似文献   

电镀金刚石钻头镀层与钢体结合强度研究     

潘秉锁  杨洋  杨凯华 《地质与勘探》2005,41(3):92-94

采用直接剪切试验,研究了稀土添加量、镀液pH值和电流密度对结合强度的影响;并结合试样断口的扫描电镜分析结果,对镀层的破坏形式进行了讨论.  相似文献   

试论西部大开发与国防建设   总被引：3，自引：0，他引：3  

陈耀西  陈红根 《地域研究与开发》2001,20(1):46-49

根据我国国土形状呈三叶螺旋浆形的特征，指出了我国经济建设，国防建设和行政管理均应实行中心辐射型结构模式，述了我国经济建设与国防建设相结合的措施，将经济区以国防功能区分为核心经济区，纽带经济区，支撑经济区，有序建成这三类经济区，以适应形势发展的需要，扩大我国的战略防御向纵深发展。  相似文献   

塔里木盆地东部地区天然气地球化学特征及成因探讨(之二)   总被引：17，自引：2，他引：17  

陈践发  徐永昌  黄第藩 《沉积学报》2001,19(1):141-144

天然气的组分和碳、氢同位素组成特征研究表明塔里木盆地已发现的天然气均为热解气。通过气源对比可知,该盆地东部地区的天然气主要有两种类型 :1)是来自震旦纪到下古生界海相腐泥型母质的油型气,其甲烷、乙烷、丙烷δ13C值,分别为-44.5‰～-33.8‰、- 42‰～-2 8.1‰和-35.4‰～-2 8.4‰,其甲烷的氢同位素组成大于- 2 0 0‰;2 )是产自中生代陆相腐殖型源岩的煤型气,其甲烷、乙烷、丙烷的δ13C值分别为-40.5‰～-33.1‰、- 2 9.7‰～-2 1.3‰和-2 6.3‰～-2 0.3‰,其甲烷的氢同位素组成小于-2 0 0‰。将天然气的地化特征与地质背景相结合判断可知,在塔北隆起地区一些天然气藏是由成熟 (高成熟 )阶段的油型气与过成熟阶段的油型气混合形成,另一些天然气藏是由成熟阶段的油型气和成熟阶段的煤型气混合形成.  相似文献