金属元素

The alkaline earth elements are metallic elements found in the second group of the periodic table.

碱土金属是ⅡA族中的金属元素。

All alkaline earth elements have an oxidation number of +2, making them very reactive. Because of their reactivity, the alkaline metals are not found free in nature.

所有的碱土金属元素的化合价都是+2，这使他们非常活泼，因为他们非常活泼，也不在自然界中直接出现。

Miniaturization of hydroxide of alkaline-earth metal and solubility of salt, flame reaction of alkaline-earth metal ions, separation and identify of alkaline-earth metal ions was investigated.

系统探讨碱土金属氢氧化物及其盐的溶解性、碱土金属元素的焰色反应、碱土金属离子的分离和鉴定等微型化实验，并将其设计成新的微型实验应用于无机化学实验教学，效果良

Electrical porcelain body ; material performance ;α-Al2O3; alkaline-earth metal component

电瓷材料；材料性能；α-Al_2O_3；碱土金属元素化合物

A combosition of high performance porcelain body material was development for manufacturing solid core post insulators of 500 kV/20 kN and above,α-Al2O3 was introduced for enhancing mechanical strength and alkaline-earth metal components were introduced as flux and "alkaline-restrainer".

为了满足生产550kV/20kN以上棒形产品的要求，对高性能电瓷材料配方进行了研究，在配方中添加α-Al2O3，可提高电瓷材料强度；添加碱土金属元素化合物，可起到强熔剂与"压碱效应"的作用。

It is concluded that, first, geochemical data of the surface soils can clearly distinguish two kind of soils, that is, juvenile soils, for example, purple soils, which inherits most geochemical characteristics of the parent rocks or materials, and anthropic soils, the geochemical characteristics of which have been greatly changed as the results of intensive impact from variety of agricultural uses. Second, different soils have typical indicator elements association respectively due to different parent rocks or materials and utilization, such as purple soils, yellow soils (low alkali and alkaline-earth metal contents and pH value), paddy soils (high organic element and heavy metal elements contents) and fluvo-aquic soils (high rock-forming accessory mineral elements contents) and so on. Consequently, it can be suggested that elements association is an important indicator for two key factors (parent materials and anthropic activities) of soil classification. Third, some differences exist between soil genesic classification and result of cluster analysis, because geochemical characteristics of surface soils can not completely represent the foundation applying to soil genesic classification, that is, condition and process of soil-forming, and soil property.

结果表明：浅层土壤的地球化学数据能较好地用来区分两类土壤，即紫色土一类的幼年土壤（在很大程度上继承了母岩、母质的地球化学特征）和受强烈人为活动水耕、早耕熟化的土壤（外来物质的不断加人显著地改变了浅层土壤原有的地球化学性质）；(2)各类土壤因母岩母质和利用方式不同，各具明显的标志性元素组合特征，如紫色土、黄壤（低碱和碱土金属元素和pH值）、水稻土（高有机元素、肥料元素和重金属元素）和潮土等，因此，这些元素组合是土壤分类两个要素的重要参照系；(3)浅层土壤的地球化学特征不可能完整地体现成土条件、成土过程和土壤属性这三个发生分类依据，因此，聚类分析结果与发生类型之间存在一定的差异。

Products Introduction: Silicon cycle, the department of the first type IV elements, is a non-metallic element, atomic number 14, atomic weight 28.80; density of 2.33g/m3; melting point of 1410 ℃; boiling point of 2355 ℃; resistively for 2140Ω.M; includes two types of stereotypes and crystal allotrope.

硅周期系第 IV 类元素，是非金属元素，原子序数14，原子量为28.80；密度为2.33g /m3；熔点为1410℃；沸点为2355℃；电阻率为2140Ω。m ；有无定型和晶体两种同素异形体。

Meanwhile, the concentration of Pb,Zn and other heavy metals is rather high in the oxidation zone and decreasesdownward to levels that are unbelievably low for Pb-Zn mine tailings. Theseobservations suggest that heavy metals should be re-immobilized by secondaryminerals, rather than primary minerals, in the oxidation zone, and could be leachedout from suboxic environment due to low rate oxidative dissolution which preventsthe precipitation of secondary minerals in significant amount. Thus, cover scenarioswhich establish a suboxic environment beneath the cover layer might not always beeffective in preventing heavy metal release from mine tailings.Sequential extraction studies indicate that, in addition to heavy metal leaching,oxidation of the mine tailings increased the mobility of residual Zn, and Cu, while Pb remains immobile due to the formation of anglesite (PbSO4). Using the seven-step extraction technique developed by Dold (J. Geochem. Explor., 2003, 80: 55-68), galena dissolves in significant amount at step 2 most probably due to the strong complexing of Pb2+ by acetate, while other metal sulfides dissolve at step 6, which suggest that this extraction technique could not be used to evaluate the mobility of lead in natural environment

重金属含量均低于新鲜尾矿，但以硬化层中的含量最高(Pb、Zn含量分别为0.47%和0.93%)，往下大幅度降低，表明尾矿风化过程中形成的次生矿物对Pb、Zn等重金属元素有较强的固定作用，而次氧化带的淋溶作用造成了金属元素的大量流失；(4)与新鲜尾矿相比，硬化层中铅的可迁移性大大降低，硬化层之下尾矿样品中铅的可迁移性也不同程度降低，这是由于硫化物氧化产生的硫酸根与尾矿中的铅反应形成铅矾(PbSO_4)的缘故；(5)氧化作用使尾矿中的zn、Cu等重金属的可迁移性不同程度地增大，其中对锌的可迁移性影响最大，铜的可迁移性与铁比较相似，铅则容易与硫化物氧化形成的SO_4~(2-)反应形成铅矾(PbSO_4)；(6)为了减少尾矿污染和修复矿山环境，人们提出了各种不同的尾矿覆盖方案，本文的研究结果表明，这些方法不一定能够有效地阻滞污染元素的迁移。

The purpose of the study is to investingate the feasibility of closed-microwave method instead of traditional aqua regia hotplate reflux method for heavy metal determination in soil.

中文摘要本研究利用密闭微波法消化土壤，并以火焰式原子吸收光谱法分析镉、铜、铅、锌四种金属元素，目的在探讨以密闭微波法取代传统王水热板回流消化法，测定土中重金属之可行性。

A soft white precious univalent metallic element having the highest electrical and conductivity of any metal occurs in argentite and in free form used in coins and jewelry and tableware and photography .

白色柔软的珍贵单价金属元素，对电和最高的金属，在辉银矿中或以自由状态存在，用于制造硬币，珠宝和餐具，亦用于摄影。

According to the clear water experiment, aeration performance of the new equipment is good with high total oxygen transfer coefficient and oxygen utilization ratio.

曝气设备的动力效率在叶轮转速为120rpm～150rpm时取得最大值，此时氧利用率和充氧能力也具有较高值。

The environmental stability of that world - including its crushing pressures and icy darkness - means that some of its most famous inhabitants have survived for eons as evolutionary throwbacks, their bodies undergoing little change.

稳定的海底环境─包括能把人压扁的压力和冰冷的黑暗─意谓海底某些最知名的栖居生物已以演化返祖的样态活了万世，形体几无变化。