85 resultados para 587
Resumo:
Experiments on the corrosion fatigue behaviour of welded joints of the steel for marine platform in air and seawater, and of the joints in seawater with cathodic protection, yielded data for linear regression to obtain fatigue life curves (Delta S-N-f). The laws of corrosion fatigue in welded joints of test steel are discussed with reference to those of A(587) and A(131) steel. In these experiments, the fatigue damage occurring at all welded joints around the weld interface resulted in the cracks and fractures. The fatigue life of the specimens in seawater with cathodic protection is longer than that in seawater Without protection.
Resumo:
A capillary electrophoresis (CE) method has been developed for the determination of six bioactive flavonoids that are commonly found in health foods: hesperidin, hyperin, isorhamnetin, kaempferol, quercetin and rutin. The effects of several parameters, such as pH, buffer concentration, separation voltage and UV detector wavelength, were investigated to find the optimal conditions. Using a HbBCh-NaiB-iO? buffer (pH 9.2), the analytes can be separated within 8 min. The relative standard deviations of migration times in eight injections were between 0.77% and 0.93%, and those of the peak areas ranged from 3.8% to 8.6%. A high reproducibility and excellent linearity was observed over two orders of magnitude, with detection limits (S/N = 3) ranging from 0.34ug ml to 2.9ug ml for all the six analytes. Recoveries ranged from 80.4 % to 113.9 %. The new method is simple, reproducible and sensitive. No solid phase extraction for sample pretreatment is necessary. Analysis results are accurate in application to bee pollens.
Resumo:
巴颜喀拉山地区位于青海省南部,北纬32°20′~35°15′,东经94°50′~101°45′,面积约84 000km2,海拔高程介于3 600m至5 369m之间.本地区拥有种子植物1 116种,分属于64科,295属.区系特征概述如下:1)对属的分布区类型的分析表明,本地区植物区系以北温带成分为主,仅有9个分布区从热带延伸到温带的热带属,且在本区所含种类极少或仅有1种.2)对种的分布区类型的分析表明,大多数种(不包括中国特有种)属于中亚成分和东亚成分,且多呈中亚-喜马拉雅-中国西南或中国-喜马拉雅分布式样.以此为据所得结论是,本地区的种以温带成分为优势,具高原、高山分布的特点.3)本区东南部的生态环境和区系成分的来源均不同于其余地区.东亚分布型及其变型中国-喜马拉雅的种聚集在东南部.这里被认为是那些来源于横断山和西秦岭的区系成分的一个通道.4)对中国特有种的分析表明,本区系与横断山区系和甘肃南部区系联系最为密切.5)在高山特化作用和高山生态因子的选择之下,本区植物获得了适应寒冷和干旱的特性.6)本区植物的耐寒性常常伴随着耐旱和耐湿的双重特性,植物的这些特性也反映在它们的地理分布上.7)本区的区系性质和特点与唐古特地区基本一致,因此本植物区系应视为唐古特区系的一部分.
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测定了青海三角城牧场牛羊主要采食的18种牧草中与动物健康密切相关的14种微量元素含量,并对牧草质量进行了评价.结果表明,Zn、 Mg、Se、Mn等微量元素含量较低,当地羊群地方病与此有关;其它营养元素含量相对正常;有害元素Pb、Cd、As、Hg含量较低.比较去离子水洗涤和非洗涤的牧草,两者微量元素含量无明显差异,说明在青藏高原洁净的自然环境下,牧草所粘附泥土及其它杂质很少.
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番红花(Crocus sativus),又称藏红花、西红红、藏药中称为苟日苟木。
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系统地研究了脉石矿物方解石中流体包裹体特征及矿床的水-岩反应条件。研究结果表明,该矿床的形成与中低温热液与中高温热液的混合有关;成矿流体的H、O同位素组成在不同矿体中没有明显的差别,流体形成前曾存在流体的均一化作用;成矿流体的形成是地层循环水与变质水、岩浆水在流体储库中充分混合的结果。因此,成矿流体具有多源性.
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滇西地区基性-超基性岩、碱性岩中的长石、石榴子石、橄榄石等单矿物及羊拉铜矿区二叠世海相玄武岩的铜铅同位素组成可以代表原始地幔的铅同位素组成,由此确定的该区上地幔铅同位素组成变化范围为^206Pb/^204Pb=17.877-18.506,平均18.108,^207Pb/^204Pb=15.470-15.587,平均15.479,^208Pb/^204Pb=37.797-38.567,平均38.177。研究发现,由于受地壳物质的混染和成岩后U、Th衰变产生的放射成因铅的影响,这些幔源岩石全岩铅同位素组成已不能代表原始上地幔的铅同位素组成;金顶铅锌矿床的铅并非上地幔来源,而是相当于下地壳来源的铅与兰坪盆地沉积岩铅二者的混合铅.
Resumo:
本文利用放射成因同位素(Pb、Sr)和轻稳定同位素(C、O)对锡矿山超大型锑矿床的成矿物质来源进行了示踪,从物源角度揭示了其在规模成矿、元素发生超常富集的原因。研究表明,锡矿山锑矿床的成矿物质不可能是来自赋矿围岩;深部地幔和基底都卷入了该矿的成矿作用;富Sb的交代型地幔和富Sb的元古界基底为其大规模成矿提供了充足的矿源,两者是形成锡成山超大型锑矿床的前提条件。
Resumo:
A novel sol-gel process has been developed for the synthesis of amorphous silica-aluminas with controlled mesopore distribution without the use of organic templating agents, e.g., surfactant molecules. Ultrasonic treatment during the synthesis enables production of precursor sols with narrow particle size distribution. Atomic force microscopy analysis shows that these sol particles are spherical in shape with a narrow size distribution (i.e., 13-25 nm) and their aggregation during the gelation creates clusters containing similar sized interparticle mesopores. A nitrogen physiadsorption study indicates that the mesoporous materials containing different Si/Al ratios prepared by the new synthesis method has a large specific surface area (i.e., 587-692 m(2)/g) and similar pore sizes of 2-11 nm. Solid-state Al-27 magic angle spinning (MAS) NMR shows that most of the aluminum is located in the tetrahedral position. A transmission electron microscopy (TEM) image shows that the mesoporous silica-alumina consists of 12-25 nm spheres. Additionally, high-resolution TEM and electron diffraction indicate that some nanoparticles are characteristic of a crystal, although X-ray diffraction and Si-29 MAS NMR analysis show an amorphous material.