105 resultados para 551
Resumo:
Morphology and mechanical properties of polypropylene (PP)/high density polyethylene (HDPE) blends modified by ethylene-propylene copolymers (EPC) with residual PE crystallinity were investigated. The EPC showed different interfacial behavior in PP/HDPE blends of different compositions. A 25/75 blend of PP/HDPE (weight ratio) showed improved tensile strength and elongation at break at low EPC content (5 wt %). For the PP/HDPE = 50/50 blend, the presence of the EPC component tended to make the PP dispersed phase structure transform into a cocontinuous one, probably caused by improved viscosity matching of the two components. Both tensile strength and elongation at break were improved at EPC content of 5 wt %. For PP/HDPE 75/25 blends, the much smaller dispersed HDPE phase and significantly improved elongation at break resulted from compatibilization by EPC copolymers. (C) 1995 John Wiley & Sons, Inc.
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The present paper reports some definite evidence for the significance of wavelength positioning accuracy in multicomponent analysis techniques for the correction of line interferences in inductively coupled plasma atomic emission spectrometry (ICP-AES). Using scanning spectrometers commercially available today, a large relative error, DELTA(A) may occur in the estimated analyte concentration, owing to wavelength positioning errors, unless a procedure for data processing can eliminate the problem of optical instability. The emphasis is on the effect of the positioning error (deltalambda) in a model scan, which is evaluated theoretically and determined experimentally. A quantitative relation between DELTA(A) and deltalambda, the peak distance, and the effective widths of the analysis and interfering lines is established under the assumption of Gaussian line profiles. The agreement between calculated and experimental DELTA(A) is also illustrated. The DELTA(A) originating from deltalambda is independent of the net analyte/interferent signal ratio; this contrasts with the situation for the positioning error (dlambda) in a sample scan, where DELTA(A) decreases with an increase in the ratio. Compared with dlambda, the effect of deltalambda is generally less significant.
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The electrical and magnetical properties of LaSr(2-x)Ca(x)V3O9 +/- y have been investigated. The compounds are antiferromagnetic. They show a metallic conduction other than semiconductivity. The trivalent and tetravalent vanadium ions coexist in the system. The magnetic susceptibility increases and the resistivity decreases at room temperature with the increase of x value. It is shown that the change of the valency state of vanadium obviously influences the electrical and magnetical properties of the system.
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Thalli from a brown alga Undaria pinnatifida were soaked by CaCl2 solution with different concentration and time at 4 degreesC, the effect of CaCl2 solution on efficiency and influorescence emission spectra of chloroplasts were examined. The results show that the efficiency of collected chloroplasts is increased markedly after soaking in CaCl2 solution. According to the results of collected efficiency and characteristic of influorescence emission spectra at room temperature of chloroplasts, it was suggested that soaking in the 0.2 mol/L CaCl2 solution for 10 min is optimum. Under this condition, the efficiency of collected chloroplasts is as 5 fold as control group, and the characteristics of chloroplasts obtained by CaCl2 soaking are similar to that of traditional method.
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以奥利亚罗非鱼(Oreochromis aureus)为实验对象,设计了3种不同的摄食类型,分别是鲜活饵料组、饥饿3周后饱食投喂组和人工饲料组。鲜活饵料组投喂冰冻赤子爱胜蚓,利用蚯蚓体内丰富的营养成分和活性物质,以期获得奥利亚罗非鱼良好的生长状况;饥饿后饱食组是指饥饿3周后,以人工饲料饱食投喂2周,用于研究饥饿与补偿生长获得快速生长时血液理化指标的变化情况;人工饲料组作为对照组。纯淡水条件下养殖,水温25±2℃。测定了奥利亚罗非鱼在3种摄食类型饲喂下某些血液生理生化指标变化的情况,并将指标变化情况与增重率做相关性分析,试图找出能够反映奥利亚罗非鱼生长性能的血液生理生化指标。 研究结果表明,奥利亚罗非鱼在饥饿3周后获得了补偿生长,补偿生长时的增重率和特定生长率显著高于人工饲料组(P<0.05),高于鲜活饵料组,但差别不显著;相关性分析研究表明血清总蛋白、胆固醇、四碘甲状腺原氨酸(T4)与增重率极显著相关(P<0.01),血红蛋白显著相关(P<0.05),红细胞、白细胞、碱性磷酸酶高度相关(相关系数为0.580、0.551和0.557),因此,建议血清总蛋白、胆固醇和血红蛋白可作为能够反映罗非鱼生长性能的新指标。 根据序列设计引物,PCR反应条件:变性温度:95 ℃,3 min;退火温度:57℃,20 sec;延伸温度:72℃,5 min,共36个循环,从牙鲆、黑鲪和鲈鱼中克隆出胰岛素样生长因子(IGF-Ⅰ)部分序列,首次证实了IGF-Ⅰ在3种海水鱼中的存在。 利用蛋氨酸与ZnSO4•7H2O,在pH 5.5、80℃下,反应1小时,采用蛋氨酸与硫酸锌2:1的配料比,合成出了产物蛋氨酸螯合锌,蛋氨酸螯合锌外观白色,粉状,室温下微溶于水,不溶于乙醇,并用原子吸收光谱法测定其含锌量为15%,螯合率为88.2%。
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Organic carbon (OC), total nitrogen (TN), and Pb-210 in core sediment were measured to quantify the burial of organic carbon and the relative importance of allochthonous and autochthonous contributions during the past one hundred years in Jiaozhou Bay, North China. The core sediment was dated using Pb-210 chronology, which is the most promising method for estimation of sedimentation rate on a time scale of 100-150 years. The variation of the burial flux of organic carbon in the past one hundred years can be divided into the following three stages: (1) relatively steady before 1980s; (2) increasing rapidly from the 1980s to a peak in the 1990s, and (3) decreasing from the 1990s to the present. The change is consistent with the amount of solid waste and sewage emptied into the bay. The OC:TN ratio was used to evaluate the source of organic carbon in the Jiaozhou Bay sediment. In the inner bay and bay mouth, the organic carbon was the main contributor from terrestrial sources, whereas only about half of organic carbon was contributed from terrestrial source in the outer bay. In the inner bay, the terrestrial source of organic carbon showed a steady change with an increase in the range of 69%-77% before 1990 to 93% in 2000, and then decreased from 2000 because of the decrease in the terrestrial input. In the bay mouth, the percentage of organic carbon from land reached the highest value with 94% in 1994. In the outer bay, the sediment source maintained steady for the past one hundred years.
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We collected the diseased blades of Laminaria japonica from Yantai Sea Farm from October to December 2002, and the alginic acid decomposing bacterium on the diseased blade was isolated and purified, and was identified as Alterornonas espejiana. This bacterium was applied as the causative pathogen to infect the blades of L. japonica under laboratory conditions. The aim of the present study was to identify the effects of the bacterium on the growth of L. japonica, and to find the possibly effective mechanism. Results showed that: (1) The blades of L. japonica exhibited symptoms of lesion, bleaching and deterioration when infected by the bacterium, and their growth and photosynthesis were dramatically suppressed. At the same time, the reactive oxygen species (ROS) generation enhanced obviously, and the relative membrane permeability increased significantly. The contents of malonaldehyde (MDA) and free fatty acid in the microsomol membrane greatly elevated, but the phospholipid content decreased. Result suggested an obvious peroxidation and deesterrification in the blades of L. japonica when infected by the bacterium. (2) The simultaneous assay on the antioxidant enzyme activities demonstrated that superoxide dismutase (SOD) and catalase (CAT) increased greatly when infected by the bacterium, but glutathione peroxidase (Gpx) and ascorbate peroxidase (APX) did not exhibit active responses to the bacterium throughout the experiment. (3) The histomorphological observations gave a distinctive evidence of the severity of the lesions as well as the relative abundance in the bacterial population on the blades after infection. The bacterium firstly invaded into the endodermis of L. japonica and gathered around there, and then resulted in the membrane damage, cells corruption and ultimately, the death of L. japonica.
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青海南北二地寒冻雏形土分布区,由于海拔高度及地理环境不同,气候变化差异显著.但分析二地地温变化特征发现,青南青北地温分布趋势基本相似,差异不甚明显.这主要与二地土壤质地和湿度、植被覆盖程度不同等有关.表明地温变化是在气候引起变化的基础上叠加了局地土壤-植被性状影响下的结果.当年冬春地温低时,对应牧草产量较高,而地温较高的年份则牧草产量低,究其原因可能与地温低,土壤冻结深厚坚实,地表蒸发减小,易贮存较多的土壤水分有关.
Resumo:
Multitracer technique was used to study the uptake and distribution of some relatively long half-life radionuclides Be, Na, Mn, Co, Sc to growing cucumber (Cucumis Sativus L.) with two different treatments. In Hoagland solution, only Mn-54 and Co-60 accumulated in the every part of plants. Mn-54, Co-60 and other radionuclides were absorbed in distilled water. The results indicate that there were major differences in the accumulation of trace elements between the two different treatments.
Resumo:
铁氧化物铜—金矿床是一类具许多共同特征但成因联系不太密切的矿床类型,近来已成为国外铜—金勘探的主要矿床类型之一。该类矿床以矿石中含有大量的铁氧化物(磁铁矿或赤铁矿)且伴有很强的区域性钠(—钙)质蚀变为特征,可以产于元古代克拉通内或新生代大陆边缘岛弧环境,其周围具火成岩或含蒸发盐层,时空上与之有关的侵入岩为磁铁矿系列花岗岩,矿化主要产于近区域主断裂的羽状次级断裂中。部分该类矿床的形成与一定的主岩类型有关,而多数矿床可能由高盐度H2O——CO2——盐混合流体的不混溶作用形成,且矿化通常与钾化有关。对成矿流体是主要来自岩浆还是受围岩控制尚有争论,成矿模式有蒸发盐来源模式、外来流体加热模式和岩浆——热液流体模式。但对部分该类矿床详细的流体包裹体和稳定同位素研究表明成矿流体主要源于岩浆。对该类矿床进行地球物理勘探需要考虑磁铁矿、硫化物和Cu—Au矿化之间的相互关系。在我国开展对该类矿床的研究将有益于发现新的铜资源基地。
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在研究了黔西南及邻区中-晚三叠世地层的层序界面特征、地层结构和堆叠型式之后,将其划分为5个沉积层序,并描述了层序内各体系域的特点,在此基础上,通过综合研究已取得的生物地层资料,将其与Haq等列出的三叠纪生物地层时带进行对比,初步标定了各沉积层序及体系域的界面年龄(层序1底界年龄239.4Ma;层序2底界年龄238Ma;层序3底界年龄233Ma;层序4底界年龄227Ma,顶界年龄223Ma),从而建立了本区分辨率较高的中-晚三叠世地层格架。格架中层序地层的组合样式,在2级海平面缓慢下降的背景下,受盆地构造沉降的影响较大。当层序处于构造沉降的加速期时,呈退积型组合方式(如层序1和层序3);而当层序处于构造沉降的平缓期时,则呈进积型组合方式(如层序2和层序4)。
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上芒岗金矿由下部原生卡林型和上部 红色粘土型金矿体所组成,赋矿地层为侏罗系勐戛组砂泥质岩、白云质灰岩和二叠系沙子坡组泥硅质灰岩、白云岩。北东向上芒岗断裂构造与不整合面和岩溶的复合控制了矿床和矿体。围岩蚀变以硅化(似碧玉岩化)、黄铁矿化、碳酸盐化和粘土化为主,并具有水平与垂向分带性。地球化学研究表明,蚀变与矿化岩石的稀土含量与未蚀变泥质灰岩基本一致,成矿溶液为富CI^-型和富SO4^2-型,爆裂温度为183-378℃,δ^34S=6.471‰-21.965‰,δ^18O=9.3‰-11.6‰,δD=-70‰--77‰,^206Pb/^204Pb=19.551-20.05,^207Pb/^204Pb=15.690-16.240,^208Pb/^204Pb=38.710=40.137。红色粘土型矿石的红土化作用只达到粘土阶段。
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岩石化学与微量元素研究表明,在强经泥质灰岩中,SiO2和Au、As、Sb含量增高,CaO、CO2和MgO含量降低;在强碳酸盐化泥质灰岩中,AgO和CO2含量增高,SiO2含量降低;不同蚀变与矿化岩石的稀土含量和配分模式与未蚀变泥质灰岩基本一致。流体包裹体研究揭示,成矿溶液为富Cl^-型和富SO4^2-型,爆裂温度为183-378℃。同位素研究指示,δ^34S=(6.471-21.965)×10^-3,δ^18O=(9.3-11.6)×10^-3,δD=(-70--77)×10^-3,^206Pb=19.551-20.05,^027Pb/^204Pb=15.690-16.240,^208Pb/^204Pb=38.710-40.137;成矿流体具有岩浆水和大气降水相混合的特点,成矿物质具有壳-幔混合特征。