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内标元素强度筛选法在激光诱导击穿光谱定量分析土壤标样中铁钛锶的应用 被引量:7
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作者 赵书瑞 王华丽 卢孟柯 《冶金分析》 CAS CSCD 北大核心 2018年第7期33-37,共5页
利用激光诱导击穿光谱(LIBS)技术进行光谱定量分析时,由于实验条件不稳定造成的测量结果检出限高、测量精确度低的问题一直是一个亟待解决的难题。实验选取地质矿产部化探分析质量监控站的标准土壤样品为分析样品,以波长为1 064nm的Nd∶... 利用激光诱导击穿光谱(LIBS)技术进行光谱定量分析时,由于实验条件不稳定造成的测量结果检出限高、测量精确度低的问题一直是一个亟待解决的难题。实验选取地质矿产部化探分析质量监控站的标准土壤样品为分析样品,以波长为1 064nm的Nd∶YAG激光器为激发光源,脉冲重复频率1Hz,通过激光诱导击穿光谱实验装置采集土壤样品在420~440nm范围内的等离子体光谱图。采用以内标法为基础的数据平均处理和内标元素强度筛选法(即以选定的内标元素谱线强度为参考,进行数据筛选)处理数据分别分析了待测样品中的Fe、Ti和Sr元素的含量并进行了对比,利用内标元素强度筛选法测得Fe、Ti和Sr的质量分数分别为68.4mg/g、10 777μg/g和75.5μg/g,相对误差由平均法测得的10.60%、3.20%和8.57%降低为2.01%、0.21%和1.95%。说明内标元素强度筛选法处理数据可以减少数据处理量,简化数据处理过程并提高分析精度,尤其适用于激光能量输出不稳定、时间延迟较难控制的实验条件下的物质成分定量分析。 展开更多
关键词 激光诱导击穿光谱(LIBS) 内标法 谱线相对强度 内标元素强度筛选法 土壤
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内标元素强度筛选法在激光诱导击穿光谱定量分析铝合金样品中的应用
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作者 王华丽 赵书瑞 +1 位作者 卢孟柯 赵志巍 《冶金分析》 CAS 北大核心 2020年第3期9-15,共7页
利用激光诱导击穿光谱技术进行光谱定量分析时,由于实验条件不稳定造成的测量结果检测限差、测量准确度低的问题一直备受研究者的关注。实验选取铝合金标准样品为分析样品,以输出波长为1064 nm的Nd∶YAG激光器为激发光源,设置脉冲重复频... 利用激光诱导击穿光谱技术进行光谱定量分析时,由于实验条件不稳定造成的测量结果检测限差、测量准确度低的问题一直备受研究者的关注。实验选取铝合金标准样品为分析样品,以输出波长为1064 nm的Nd∶YAG激光器为激发光源,设置脉冲重复频率1 Hz,通过激光诱导击穿光谱实验装置采集样品在260~300 nm、300~330 nm范围内的等离子体光谱。采用以内标法为基础的内标元素强度筛选法处理数据,分析了铝合金待测样品E113中Mn、Mg、Fe和Cu元素的含量,并且与常规的数据平均法进行了比较。测得其质量分数分别为5.92、4.79、4.06、39.00 mg/g,测量结果的相对误差由数据平均法的9.80%、3.70%、13.30%、3.47%分别降为5.52%、0.40%、4.92%、3.23%;Mn、Mg、Fe、Cu各元素的检测限由数据平均法的0.205、0.207、0.755、6.150 mg/g下降为0.163、0.176、0.674、1.71 mg/g。此结果说明根据内标元素谱线强度进行数据筛选的数据预处理法同样适用于基体元素含量近似相同的铝合金样品分析,实验结果基本符合金属样品定量分析的要求,此数据处理方法为实验条件不稳定下的元素定量分析提供了一种新的思路。 展开更多
关键词 激光诱导击穿光谱 内标法 检测限 内标元素强度筛选法 数据平均法
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在发射光谱分析中氨基酸对元素谱线强度的影响 被引量:1
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作者 陈凤翔 李能 +1 位作者 王晓青 廖琼 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 1989年第4期36-40,共5页
随着生物无机化学研究的深入,生物体中微量元素的分析日益重要。目前,生物体中微量元素的分析方法主要是火焰光度、原子吸收、原子发射及荧光分析等。发射光谱分析具有可同时测定多种元素的优点。但是,无论使用何种方法,生物试样的基体... 随着生物无机化学研究的深入,生物体中微量元素的分析日益重要。目前,生物体中微量元素的分析方法主要是火焰光度、原子吸收、原子发射及荧光分析等。发射光谱分析具有可同时测定多种元素的优点。但是,无论使用何种方法,生物试样的基体效应是值得注意的。我们在用发射光谱法分析出物体试样时也发现。 展开更多
关键词 发射光谱分析 氨基酸 元素谱线强度
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全新世低纬地区古环境演化与北大西洋之间的联系——以湖光岩玛珥湖元素和元素比值记录为例 被引量:6
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作者 吴旭东 沈吉 汪勇 《沉积学报》 CAS CSCD 北大核心 2011年第5期926-934,共9页
通过湖光岩玛珥湖沉积物高分辨率的Fe/Mn比值、Rb/Sr比值、Sr元素强度和550℃烧失量的研究,重建了湖光岩地区全新世以来的古环境演化历史,即:早全新世是气候适宜期,气候温暖湿润,中、晚全新世开始气候逐渐干旱化。这种气候演化模式体现... 通过湖光岩玛珥湖沉积物高分辨率的Fe/Mn比值、Rb/Sr比值、Sr元素强度和550℃烧失量的研究,重建了湖光岩地区全新世以来的古环境演化历史,即:早全新世是气候适宜期,气候温暖湿润,中、晚全新世开始气候逐渐干旱化。这种气候演化模式体现了全新世季风演化的全球性。湖光岩玛珥湖沉积物反映的全新世以来的冷暖变化事件与北大西洋浮冰碎屑记录之间既存在联系又存在差异。这说明在全新世背景下,低纬地区的古气候演化与北大西洋存在一定程度的联系。低纬地区全新世古环境演化是低纬过程和高纬作用叠加的结果。 展开更多
关键词 元素强度及其比值 全新世 北大西洋 低纬地区
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湖光岩玛珥湖沉积物反映的全新世以来古环境演化 被引量:15
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作者 吴旭东 沈吉 汪勇 《海洋地质与第四纪地质》 CAS CSCD 北大核心 2011年第4期155-162,共8页
对广东湖光岩玛珥湖沉积物550℃烧失量(loss on ignition,LOI)和Ti、Al、Si、K元素强度分析表明,烧失量主要反映了流域生产力水平的变化,而Ti、Al、Si、K 4种元素被证明主要来自于流域,反映了径流输入的变化。11 000~7 800cal.aBP,湖... 对广东湖光岩玛珥湖沉积物550℃烧失量(loss on ignition,LOI)和Ti、Al、Si、K元素强度分析表明,烧失量主要反映了流域生产力水平的变化,而Ti、Al、Si、K 4种元素被证明主要来自于流域,反映了径流输入的变化。11 000~7 800cal.aBP,湖光岩地区的气候温暖、湿润;7 800cal.aBP之后,气候迅速变冷、变干,虽然7 800cal.aBP之后气候也发生了一系列的冷、暖波动,但是其温暖程度已远远不及早全新世的水平。湖光岩地区全新世千年尺度气候演化格局和亚洲季风区的其他记录基本一致,即全新世早期为气候适宜期;全新世中、晚期温度降低,气候变干。湖光岩地区全新世中期的降温程度比亚洲季风区其他地质记录的反映更剧烈,这可能是地理位置差异造成的全新世季风演化差异性的体现。湖光岩地区全新世中后期的气候演化过程可能与厄尔尼诺系统存在联系。 展开更多
关键词 古环境 烧失量 元素强度 湖光岩玛珥湖 全新世
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基于激光诱导击穿光谱对长白山黑猪肉部位分类 被引量:1
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作者 林晓梅 孙浩然 +4 位作者 许毓婷 林京君 王跃 王振兴 高勋 《光谱学与光谱分析》 SCIE EI CAS CSCD 北大核心 2021年第1期299-304,共6页
猪肉内部结构成分复杂,各部位的成分相似,分辨较为困难。结合激光诱导击穿光谱技术,通过光谱分析的方式提高分类精度。以5种不同部位的长白山黑猪肉(里脊肉、梅花肉、后腿肉、前腿肉、五花肉)作为待测样品,通过冷藏、切片等预处理方法,... 猪肉内部结构成分复杂,各部位的成分相似,分辨较为困难。结合激光诱导击穿光谱技术,通过光谱分析的方式提高分类精度。以5种不同部位的长白山黑猪肉(里脊肉、梅花肉、后腿肉、前腿肉、五花肉)作为待测样品,通过冷藏、切片等预处理方法,探究激光诱导击穿光谱技术鉴别猪肉脂肪与肌肉及其不同部位的可行性。首先通过采集猪肉脂肪样品与肌肉样品的LIBS谱线信息发现,猪肉中Mg,K,Fe,Cu,Ca和Na等元素较为丰富,并在脂肪样品光谱中发现C—N键,与肌肉样品LIBS谱线信息相比,脂肪样品受其内部水分、有机质成分影响致使其谱线信息背景和噪声信号干扰较大,二者谱线信息存在一定差异,说明LIBS可对脂肪组织与肌肉组织进行鉴别。通过对目标元素Ca,Na,Mg,K和Al其LIBS特征谱线强度进行检测,计算Mg/Ca,Al/Ca,Na/Ca和K/Ca比值,发现与Al/Ca和Mg/Ca相比,Na/Ca和K/Ca各部位元素比值分布差异明显,在此基础上,根据Na/Ca和K/Ca比值,计算猪肉各部位元素分布决策阈值[(1-α)=90%]。发现与Al/Ca和Mg/Ca比值相比,Na/Ca和K/Ca更能明显的反应出各部位元素分布的不同。其比值分布阈值基本可对猪肉各部位进行区分。以前腿肉与后腿肉为例,前腿肉Na/Ca和K/Ca比值分别分布在1.29~1.58和0.31~0.42,后腿肉Na/Ca和K/Ca比值分别分布在0.98~1.18和0.15~0.23。其元素比值分布无明显重叠。最后,为提高LIBS技术对猪肉不同组织分类的可靠性,将光谱元素强度比值数据与主成分分析法相结合,基本可以实现对猪肉各部位的分类,说明元素特征谱线强度比值在对猪肉各部位分类时具有一定的预测精度。该工作证明,使用激光诱导击穿光谱技术对猪肉进行分类识别等定性分析时具有一定可行性,有望适用于其他生物组织检测分析。 展开更多
关键词 激光诱导击穿光谱 猪肉分类 元素强度 主成分分析
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岩石剪切面纳米粒子层的近期研究进展 被引量:8
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作者 孙岩 舒良树 +3 位作者 陆现彩 刘浩 Aiming Lin K.Kosaka 《自然科学进展》 北大核心 2007年第10期1331-1337,共7页
20世纪90年代,在各类岩石剪切面中相继发现纳米级和微米级超微粒子结构,近期结合力学、物理学成因研究又有新的进展.在超微观上,通过国内外的实例实测,从岩石剪切面纳米粒子层赋存展布的普遍性,结构特征的层次性,成因机制的非线性和功... 20世纪90年代,在各类岩石剪切面中相继发现纳米级和微米级超微粒子结构,近期结合力学、物理学成因研究又有新的进展.在超微观上,通过国内外的实例实测,从岩石剪切面纳米粒子层赋存展布的普遍性,结构特征的层次性,成因机制的非线性和功能效应的多样性四个方面,进行简要阐述,萃取更多信息.进而初步揭示了剪切摩擦黏性发育与纳米粒子形成间的共生关系,和剪切运动中岩石的分离、分凝和分层作用首先由纳米粒子层的滑移启动开始的.并分析了岩石塑性流变实质上是超微粒子(纳米-微米级磨粒)的运动,以及岩石剪切面纳米粒子层一些特殊的物理和化学地质作用等.诚然,纳米粒子层蕴涵的信息是丰富的,该项研究还处于起步开拓阶段,仅试图为构造地质学和相关学科领域提出新的理念和新的探讨平台. 展开更多
关键词 剪切面 纳米粒子 摩擦黏性 塑性流变 高场强度元素
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Effect of minor B addition on microstructure and properties of AlCoCrFeNi multi-compenent alloy 被引量:11
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作者 陈秋实 卢一平 +2 位作者 董勇 王同敏 李廷举 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第9期2958-2964,共7页
The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys(x = 0,0.01,…,0.09 and 0.1,mole fraction) were investigated.The AlCoCrFeNi high entropy alloy exh... The influences of slight amount of B element on the microstructure and properties of AlCoCrFeNiBx high entropy alloys(x = 0,0.01,…,0.09 and 0.1,mole fraction) were investigated.The AlCoCrFeNi high entropy alloy exhibits equiaxed grain structures with obvious composition segregation.However,with the addition of B element,the alloys exhibit dendrite structures.Inside the dendrites,spinodal decomposition structure can be clearly observed.With the addition of B element,the crystal structures change from(B2 + BCC) to(B2 + BCC + FCC) structures,and the hardness firstly increases from HV 486.7 to HV 502.4,then declines to HV 460.7(x ≥ 0.02).The compressive fracture strength firstly shows a trend of increasing,and then declining(x ≥ 0.08).The coercive forces and the specific saturation magnetizations of the alloys decrease as B addition contents increase,the decreasing coercive forces show a better soft magnetic behavior. 展开更多
关键词 high entropy alloy B element microstructure compressive properties HARDNESS magnetic properties
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激光剥蚀电感耦合等离子体质谱小激光斑束线扫描定量分析技术 被引量:9
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作者 赵令浩 孙冬阳 +2 位作者 胡明月 詹秀春 曾令森 《分析化学》 SCIE EI CAS CSCD 北大核心 2018年第6期931-937,共7页
采用激光剥蚀-扇形磁场电感耦合等离子体质谱(LA-SF-ICP-MS)技术建立了小激光斑束(<15μm)线扫描定量分析方法。对比了硅酸盐矿物LA-ICP-MS分析中不同激光进样模式(点剥蚀和线扫描)对于元素信号强度和分馏效应的影响。小激光斑束点... 采用激光剥蚀-扇形磁场电感耦合等离子体质谱(LA-SF-ICP-MS)技术建立了小激光斑束(<15μm)线扫描定量分析方法。对比了硅酸盐矿物LA-ICP-MS分析中不同激光进样模式(点剥蚀和线扫描)对于元素信号强度和分馏效应的影响。小激光斑束点剥蚀分析元素信号强度随时间下降明显,并且剥蚀过程中元素深度分馏效应影响明显。深度分馏效应主要是由于各元素倾向于富集在不同粒径颗粒中,而不同大小颗粒在剥蚀坑附近发生冷凝沉淀的几率差异造成。实验结果表明,相对于内标元素Ca,Na、K、Cr、Co、Cd和U等元素富集在更小颗粒中;Cu、Zn、V、Mn、Fe、Ni、Tl、W、Rb、Cs等元素与Ca富集行为相似;Al、Y、Sc、Zr、Nb、Hf、Ta、Th和REE等元素易进入大颗粒中。线扫描分析具有高且稳定的元素信号强度,分析过程中剥蚀行为一致,不受深度剥蚀效应的影响。采用双剥蚀池结构进样系统研究单脉冲激光剥蚀信号结构,不同元素信号强度降低至50%需0.8~1.2 s;降低至20%需1.2~1.6 s;降低至背景值需2~3 s。本研究通过优化仪器参数降低信号叠加作用的影响,在均质和非均质样品(榍石)线扫描分析中,获得了准确的元素含量和元素比值。线扫描定量分析技术可有效降低激光斑束(≤15μm),相对于采用线扫描元素强度分布研究,数据更加直观,可表现元素比值的变化特征。通过调整激光斑束大小和扫描速度可在不同分辨率尺度下全面了解矿物中元素的分布特征。 展开更多
关键词 激光剥蚀电感耦合等离子体质谱 线扫描定量分析 元素信号强度及分馏效应 榍石
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Effects of Ti and Be addition on microstructure and mechanical properties of Mg_(58.5)Cu_(30.5)Y_(11) bulk metallic glass
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作者 邱克强 王琳 +1 位作者 任英磊 李荣德 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2015年第2期477-482,共6页
Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 (mole fraction) were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. Th... Based on the Mg58.5Cu30.5Y11 alloy, 10% Ti, 10% Be and 10% Ti70Be30 (mole fraction) were respectively added to the alloy and samples with a diameter of 3 mm were fabricated by conventional Cu-mold casting method. The phase constituent, thermal stability and microstructure of the alloys were investigated by using X-ray diffraction, differential scanning calorimetry and scanning electron microscopy, respectively. The effects of alloying elements Ti and Be on the microstructure and mechanical properties of Mg58.sCu3o.sYll alloy were discussed. The results show that CuTi phase is distributed in (Mg0.585Cu0.305Y0.11)90Ti10 and (Mg58.5Cu30.5Y11)90(Ti0.7Be0.3)10 alloys, while CuYBe glassy phase containing CuY crystals is embedded in the matrix of (Mg58.5Cu30.5Y11)90Be10 alloy. Under uniaxial compressive loading, the largest compressive fracture strengths for (Mg58.5Cu30.5Y11)90Ti10, (Mg58.5Cu30.5Y11)90Be10 and (Mg58.5Cu30.5Y11)90(Ti0.7Be0.3)10 alloys are 797.6, 952.6 and 1007.8 MPa, respectively, and the strengths are increased by about 17%, 40% and 48% compared with Mg58.5Cu30.5Y11 alloy. The strength reliability for the three alloys is much improved according to the strength distribution region of 10 samples of each alloy. 展开更多
关键词 Mg-based alloy alloying element TI BE MICROSTRUCTURE strength reliability
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高速铣削时硬质合金刀具与NAK80模具钢化学性能匹配研究 被引量:1
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作者 曾伟国 夏琴香 +1 位作者 谭升洪 梁根森 《工具技术》 2020年第5期23-27,共5页
高速铣削加工时温度较高,易引起刀具与工件之间产生化学反应,加剧刀具与工件磨损,缩短刀具寿命。实现刀具材料和工件材料的化学性能匹配,可有效保证模具型面加工质量和提高生产效率。化学性能匹配主要从刀具材料与工件材料的氧化以及扩... 高速铣削加工时温度较高,易引起刀具与工件之间产生化学反应,加剧刀具与工件磨损,缩短刀具寿命。实现刀具材料和工件材料的化学性能匹配,可有效保证模具型面加工质量和提高生产效率。化学性能匹配主要从刀具材料与工件材料的氧化以及扩散方面进行研究。通过理论计算得到刀具与工件材料的化学反应自由能;结合高温氧化试验,研究NAK80模具钢的高温氧化产物并探究其抗氧化性能;基于变系数浓度扩散模型,利用元素扩散试验获得了NAK80模具钢与刀具材料间的元素扩散强度。结果表明,NAK80模具钢的氧化程度随温度升高而加剧,温度高于1300K可发生完全氧化;NAK80模具钢中的Fe元素扩散深度随硬质合金刀具中Co元素含量的增加而增加。 展开更多
关键词 高速铣削 化学性能匹配 NAK80 抗氧化性能 元素扩散强度
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Characterization of A390 aluminum alloy produced at different slow shot speeds using vacuum assisted high pressure die casting 被引量:11
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作者 Wen-bo YU Zi-hao YUAN +1 位作者 Zhi-peng GUO Shou-mei XIONG 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2017年第12期2529-2538,共10页
The effects of vacuum assistance on the microstructure and mechanical properties of high pressure die cast A390alloy at different slow shot speeds were evaluated.Plate-shaped specimens of hypereutectic A390aluminum al... The effects of vacuum assistance on the microstructure and mechanical properties of high pressure die cast A390alloy at different slow shot speeds were evaluated.Plate-shaped specimens of hypereutectic A390aluminum alloy were produced on a TOYO BD?350V5cold chamber die casting machine incorporated with a self-improved TOYO vacuum system.According to the results,the vacuum pressure inside the die cavity increased linearly with the increasing slow shot speed at the beginning of mold filling.Meanwhile,tensile properties of vacuum die castings were deteriorated by the porosity content.In addition,the average primary silicon size decreased from23to14μm when the slow shot speed increased from0.05to0.2m/s,which has a binary functional relationship with the slow shot speed.After heat treatment,microstructural morphologies revealed that needle-shaped and thin-flaked eutectic silicon particles became rounded while Al2Cu dissolved intoα(Al)matrix.Furthermore,the fractography revealed that the fracture mechanism has evolved from brittle transgranular fracture to a fracture mode with many dimples after heat treatment. 展开更多
关键词 A390 aluminum shot speed vacuum assisted high pressure die casting (VHPDC) Si distribution tensile strength heat treatment
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Microstructure and mechanical properties of as-cast Mg-Sn-Ca alloys and effect of alloying elements 被引量:4
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作者 K.SURESH K.P.RAO +2 位作者 Y.V.R.K.PRASAD N.HORT K.U.KAINER 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2013年第12期3604-3610,共7页
The effect of Sn, Ca, Al, Si and Zn addition on the compressive strength of cast Mg-Sn-Ca (TX) alloys was studied in the temperature range of 25-250 °C and correlated with the microstructure. The Sn to Ca mass ... The effect of Sn, Ca, Al, Si and Zn addition on the compressive strength of cast Mg-Sn-Ca (TX) alloys was studied in the temperature range of 25-250 °C and correlated with the microstructure. The Sn to Ca mass ratio up to 2.5 contributes to the formation of Mg2Ca phase at the grain boundaries and CaMgSn in the matrix, while a ratio of 3 gives only CaMgSn phase mostly in the matrix. While the compressive strength decreases with the increase in temperature, for Sn/Ca up to 2.5, a plateau occurs in 100-175 °C, which is attributed to the strengthening by Mg2Ca. However, for ratio of 3, the strength is lower and decreases more gradually. Mg-3Sn-2Ca (TX32) has the highest strength and the addition of 0.4%Al increases its strength but simultaneous addition of Si lowers the strength. Likewise, the addition of Zn improves its strength but simultaneous addition of Al slightly decreases the strength. The results are correlated with the types of intermetallic phases that form in various alloys. 展开更多
关键词 Sn/Ca ratio Mg-Sn-Ca alloys alloying additions microstructure compressive strength
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Effect of Y on microstructure evolution and mechanical properties of Mg−4Li−3Al alloys 被引量:11
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作者 Li-li CHANG Jing GUO Xiao-jing SU 《Transactions of Nonferrous Metals Society of China》 SCIE EI CAS CSCD 2021年第12期3691-3702,共12页
To obtain magnesium alloys with a low density and improved mechanical properties,Y element was added into Mg−4Li−3Al(wt.%)alloys,and the effect of Y content on microstructure evolution and mechanical properties was in... To obtain magnesium alloys with a low density and improved mechanical properties,Y element was added into Mg−4Li−3Al(wt.%)alloys,and the effect of Y content on microstructure evolution and mechanical properties was investigated by using optical microscopy,scanning electron microscopy and tensile tests.The results show that mechanical properties of as-cast Mg−4Li−3Al alloys with Y addition are significantly improved as a result of hot extrusion.The best comprehensive mechanical properties are obtained in hot-extruded Mg−4Li−3Al−1.5Y alloy,which possesses high ultimate tensile strength(UTS=248 MPa)and elongation(δ=27%).The improvement of mechanical properties of hot-extruded Mg−4Li−3Al−1.5Y alloy was mainly attributed to combined effects of grain refinement,solid solution strengthening and precipitation strengthening. 展开更多
关键词 Mg−Li−Al alloy Y element MICROSTRUCTURE ultimate tensile strength ELONGATION
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Role of Nitrogen and Nutrients in Crop Nutrition 被引量:4
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作者 Vicente Torres-Olivar Oscar Gabriel Villegas-Torres +5 位作者 Martha Lilia Dominguez-Patifio Hoctor Sotelo-Nava Antonio Rodrlguez-Martme Rosa Maria Melgoza-Aleman Luis Alonso Valdez-Aguilar Irfin Alia-Tejacal 《Journal of Agricultural Science and Technology(B)》 2014年第1期29-37,共9页
Nutrition is an important factor for the growth and development of plants. Among the main nutritional elements, there are nitrogen (N) and calcium (Ca). The N comes from two forms of inorganic ions, ammonium (NH... Nutrition is an important factor for the growth and development of plants. Among the main nutritional elements, there are nitrogen (N) and calcium (Ca). The N comes from two forms of inorganic ions, ammonium (NH4+) and nitrate (NO3) whose functions in the plant are the increase in leaf area and improving the succulence of many crops, among other essential physiological processes. Both the deficit and excess NO3- have a negative impact on plants increasing susceptibility to insect pests and pathogens, while Ca as divalent ion absorbed Ca2+ plays an important role in control of physiological disorders and the resistance of plants to diseases to increase the mechanical strength. The N and Ca have a close relationship in the nutritional role of the plant, because the Ca absorption acting nitrates, so that a proper balance affects plants better growth and higher strength. 展开更多
关键词 IONS ABSORPTION NITRATE AMMONIUM concentration.
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A numerical method for multiple cracks in an infinite elastic plate 被引量:1
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作者 闫相桥 武海鹏 《Journal of Harbin Institute of Technology(New Series)》 EI CAS 2005年第4期351-357,共7页
This article examines the interaction of multiple cracks in an infinite plate by using a numerical method. The numerical method consists of the non-singular displacement discontinuity element presented by Crouch and S... This article examines the interaction of multiple cracks in an infinite plate by using a numerical method. The numerical method consists of the non-singular displacement discontinuity element presented by Crouch and Startled and the crack tip displacement discontinuity elements proposed by the author. In the numerical method implementation, the left or the right crack tip element is placed locally at the corresponding left or right crack tip on top of the constant displacement discontinuity elements that cover the entire crack surface and the other boundaries. The numerical method is called a hybrid displacement discontinuity method. The following test examples of crack problems in an infinite plate under tension are included: “ center-inclined cracked plate”, “interaction of two collinear cracks with equal length”, “interaction of three collinear cracks with equal length”, “interaction of two parallel cracks with equal length”, and “interaction of one horizontal crack and one inclined crack”. The present numerical results show that the numerical method is simple yet very accurate for analyzing the interaction of multiple cracks in an infinite plate. 展开更多
关键词 multiple cracks stress intensity factor boundary element method crack tip element displacement discontinuity method
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Tribology Performance and Adhesive Strength Evaluation of TiAlSiN Coating 被引量:1
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作者 姜峰 谢鸿 +1 位作者 融亦鸣 言兰 《Transactions of Tianjin University》 EI CAS 2011年第4期248-253,共6页
Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch ... Scratch test and friction test were performed to evaluate the internal and external interface behaviors of TiAISiN coating, respectively. The critical compressive and shearing stress of coating failure during scratch test were calculated and the values are 30.84 MPa and 4.98 MPa respectively. The average friction coefficients of TiAISiN coat- ing against 2Crl2Ni4Mo3VNbN steel are 0.70 (sliding speed 50 m/rain), 0.63 (sliding speed 100 m/min), and 0.81 (sliding speed 150 m/min). The elements diffusion was analyzed by EDS. A1 and Si element of coating material dif- fuse to the steel disc, except Ti element. The oxidation decreases with the increase of sliding speed, but the adhesion increases with the increase of sliding speed. More A1 element diffuses to the steel disc at the high sliding speed, but the diffusion of Si element keeps almost constant at dlfferent sliding speeds. 展开更多
关键词 TiAISiN coating internal and external interface scratch test ball-on-disc friction test
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Stability and Influence Factors Analysis of Wharf Slope on Slippery Stratum
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作者 LI Peng-fei LIU Ming-wei DAI Ru-lin 《International Journal of Technology Management》 2014年第7期34-37,共4页
With the growing tension of port shoreline resource in Three Gorges Reservoir area, many wharfs can only be constructed on slippery stratum with poor geological condition, which means buckling failure occurs easily. F... With the growing tension of port shoreline resource in Three Gorges Reservoir area, many wharfs can only be constructed on slippery stratum with poor geological condition, which means buckling failure occurs easily. FEM strength reduction method is used in analyzing slope stability of a wharf in Chongqing, and its accuracy is verified by comparing the acquired results with the computation of traditional limit equilibrium method. On this basis, the influences of reservoir water level variation, overload and backfill material behind the retaining wall, and soil share strength of wharf slope on slippery stratum are analyzed. Analysis shows that, there' s a most adverse water level in wharf slope, and the engineering proposals with a certain practical significance such as improve the drainage behind retaining wall, controll overload and improve the strength of backfill soil and subsoil are suggested. 展开更多
关键词 slippery stratum STABILITY factors analysis strength reduction method
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同步辐射X射线荧光光谱测定沉积物中元素含量的归一方法研究——以四海龙湾纹层沉积物为例 被引量:7
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作者 凌媛 孙青 +6 位作者 朱庆增 陈栋梁 徐伟 谢曼曼 单雅冰 王宁 储国强 《第四纪研究》 CAS CSCD 北大核心 2014年第6期1327-1335,共9页
同步辐射X射线荧光光谱分析(SRXRF)是一种基于同步加速器光源与X射线荧光光谱分析(XRF)相结合的原位分析方法,可以直接对沉积物进行扫描获得每个点的能谱图,从而计算元素含量的相对变化。但是由于荧光光谱定性和定量分析中存在的问题,... 同步辐射X射线荧光光谱分析(SRXRF)是一种基于同步加速器光源与X射线荧光光谱分析(XRF)相结合的原位分析方法,可以直接对沉积物进行扫描获得每个点的能谱图,从而计算元素含量的相对变化。但是由于荧光光谱定性和定量分析中存在的问题,国内发表文献中各种XRF原位分析数据均以相对含量或者计数表示。本文通过对各种标准物质(土壤、沉积物和岩石)的SRXRF分析,结合标准样品的定量数据,对同步辐射X射线荧光光谱的定量方法进行了研究。鉴于元素质量数和谱线强度的差异,不同元素需要运用不同的归一方法。对于K和Ca元素,采用ROI_(0-195)背景归一;Ti元素采用ROI_(293-303)背景归一;Mn元素采用ROI_(214-222)背景归一;而较高序数的元素Fe采用拟合康普顿散射峰归一。通过上述归一方法,我们获得了K、Ca、Ti、Mn和Fe元素的定量标准曲线,相关系数分别为0.89、0.98、0.96、0.93和0.98。运用标准样品对各元素的定量标准曲线进行检验,结果表明:Fe元素含量预测的平均相对偏差小于10%,K、Ca和Ti的平均相对偏差小于20%,Mn的相对偏差较大,为35.9%。从总体上看,SRXRF获得的数据可以基本满足湖泊沉积物中元素分析的定量化需求。为验证SRXRF方法能否揭示元素含量的季节性变化,我们对四海龙湾纹层沉积物进行了分析,按选定的归一方法计算样品中元素特征谱线的强度,利用各元素的标准曲线计算岩芯沉积物中元素含量。K、Ca、Ti、Mn和Fe元素含量具有明显的季节韵律变化,浅色碎屑微层中Ti和Ca含量较高,而Mn和Fe丰度的高值对应于暗色有机质-碎屑混合层。初步研究结果表明同步辐射X射线荧光光谱分析可以揭示湖泊中沉积的元素的季节性变化,对研究过去季节-年尺度的古气候、古环境变化具有重要的科学意义。 展开更多
关键词 同步辐射 X射线荧光光谱分析 归一方法 元素谱线强度 元素含量
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Influence of static pre-loading on the dynamic bending strength of concrete with particle element modeling 被引量:4
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作者 WU Ming Xin ZHANG Chu Han 《Science China(Technological Sciences)》 SCIE EI CAS CSCD 2015年第2期284-296,共13页
Experimental tests show that static pre-loading has a significant effect on the dynamic strength of concrete.Based on meso-scale particle element model,numerical simulations of dynamic bending tests with pre-loading a... Experimental tests show that static pre-loading has a significant effect on the dynamic strength of concrete.Based on meso-scale particle element model,numerical simulations of dynamic bending tests with pre-loading are performed.Complete stress–strain relationships are then obtained.Significant increase in dynamic strength is found when the pre-loadings are imposed within the elastic limit of concrete.However,when the imposition of pre-loadings reaches the plastic or softening range,dynamic strengths may gradually decrease along with the increase in pre-loadings.The distribution of energy components and the failure modes are discussed to explain the mechanisms of the phenomena. 展开更多
关键词 CONCRETE static pre-loading dynamic bending strength rate effect particle element modeling
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