985 resultados para ~(46)Sc
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Isothermal and nonisothermal crystallization kinetics of nylon-46 were investigated with differential scanning calorimetry. The equilibrium melting enthalpy and the equilibrium melting temperature of nylon-46 were determined to be 155.58 J/g and 307.10 degreesC, respectively. The isothermal crystallization process was described by the Avrami equation. The lateral surface free energy and the end surface free energy of nylon-46 were calculated to be 8.28 and 138.54 erg/cm(2), respectively. The work of chain folding was determined to be 7.12 kcal/mol. The activation energies were determined to be 568.25 and 337.80 kJ/mol for isothermal and nonisothermal crystallization, respectively. A convenient method was applied to describe the nonisothermal crystallization kinetics of nylon-46 by a combination of the Avrami and Ozawa equations.
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树枝状化合物具有规整的结构,其分子体积、形状和功能基可在分子水平上精确控制[1].它的出现对于经典的有机高分子界是一个冲击,它是化学、生命科学和材料科学等多学科的交叉点,成为当前学术界的一大研究热点.我国这方面的研究起步较晚,至今仅有陈永明[2]、薄…
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The synergistic extraction of Sc(III) from H2SO4 solution with bis(2, 4, 4-trimethylpentyl)monothiophosphinic acid(HBTMPTP, HL) and branched chain alkyl phosphine oxide mixture (Cyanex 925, B) in n-hexane has been investigated, The results indicated that synergistic effect was showed in low acidity (c(H2SO4) < 0.25 mol/L). The composition of the extracted complex of Sc(III) has been determined to be Sc(HL2)(2)B-3(SO4)(1/2) by the method of slope analysis, The mechanism of the synergistic extraction of Sc(III) may be : Sc3+ + 2(HL)(2(O)) + 3B((O)) + 1/2SO(4)(2-)reversible arrow(K12)Sc(HL2)(2)B-3(SO4)(1/2(O)) + 2H(+) ScL(HL2)(2(O)) + 3B((O)) + H+ + 1/2SO(4)(2-)reversible arrow(beta')Sc(HL2)(2)B-3(SO4)(1/2(O)) + 1/2(HL)(2(O)) Sc(SO4)(1.5)B-2(O) + B-(O) + 2(HL)(2(O))reversible arrow(beta')Sc(HL2)(2)B-3(SO4)(1/2(O)) + 2H(+) + SO42- Their equilibrium constants have been calculated to be lgK(13)=6.77+/-0.12, lg beta'=7.71, lg beta '' = 0.10, respectively, The IR spectra and FAB-MS of the saturated synergistic extraction complex of Sc(III) have been discussed as well.
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研究了二(2,4,4-三甲基戊基)单硫代膦酸(HBTMPTP,HL)和支链三烷基氧化膦(Cyanex925,B)的正己烷溶液在H2SO4介质中对Sc(III)的萃取性能,结果表明,在较低酸度(CH2SO4〈0.25mol/L)时存在协同效应,用斜率法确定了Sc(III)的协萃配合物的组成为Sc(HL2)2B3(SO4)1/2,计算了协萃反应的平衡常数,讨论了协萃配合物的IR谱和FAB-MS.
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With XRD, R-T, and ac chi measurements a comparative study on the doping effects of 3d elements in Bi(1.5)Pb(0.2)Sr(2)Ca(2)Cu(2.8)M(0.2)O(y) (M = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, or Zn) has been carried out. The effects of the former five members are significantly different, both on phase formed and on T-c, from the latter four. It seems that the effect on phase stabilization correlates with the valency of the doped cation. In connection with the instability of the 2223 phase, the correlation has been discussed.
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The solvent extraction of Sc(III), Zr(IV), Th(IV), Fe(III) and Lu(III) with Cyanex 302 (bis(2,4,4-trimethylpentyl)monothiophosphinic acid) and Cyanex 301 ( bis(2,4,4-trimethylpentyl) dithiophosphinic acid) in n-hexane from acidic aqueous solutions has been investigated systematically. The effect of equilibrium aqueous acidity on the extraction with these reagents was studied. The separation of Th(IV), Fe(III) and Lu(III) from Sc(III), or the separation of other metals from Lu(III) with Cyanex 302, can be achieved by controlling the aqueous acidity. However, Cyanex 301 exhibited a poor selectivity for the above metals, except for Lu(III). The extraction of these metals with Cyanex 272, Cyanex 302 and Cyanex 301 has been compared. The stripping percentages of Sc(III) for Cyanex 302 and Cyanex 301 in a single stage are near 78% and 75% with 3.5 mol/L and 5.8 mol/L sulphuric acid solutions, respectively. The effects of extractant concentration and temperature on the extraction of Sc(III) were investigated. The stoichiometry of the extraction of Sc(III) with Cyanex 302 was determined. The role of different components of Cyanex 302 in the extraction of Sc(III) was discussed.
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The extraction equilibrium data of sulphuric acid and scandium(III) with bis(2,4,4-trimethylpentyl)phosphinic acid (H[BTMPP]) from sulphuric acid solutions have been obtained. There are two extraction mechanisms of scandium(III) with H[BTMPP] at different
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南海是西太平洋最大的边缘海之一,位于欧亚板块、印-澳板块以及太平洋板块之间。南海海底扩张停止(15.5Ma, Briais et al., 1993) 后的板内火山作用,影响着中国南部、中南半岛、大洋基底和分裂的微大陆片段的广大地区。对南海新生代玄武岩进行地球化学研究,不仅对于理解南海板内火山作用的深部地幔过程有着重要意义,而且对南海形成演化及含油气盆地形成的深部动力学机制有着深远意义。 南海新生代玄武岩K-Ar/Ar-Ar年龄为3.8-7.9Ma, 表明为晚中新世以来的岩浆活动产物,与周边地区的碱性火山岩在年龄上的一致性。岩石学特征表明,南海新生代玄武岩的矿物组合为橄榄石、单斜辉石、斜长石,与特征的碱性玄武岩的矿物组合一致。由橄榄石所计算的南海底潜在地幔温度(Tp)平均值为1661℃, 暗示南海地区下的地幔可能存在热量异常,为海南地区存在地幔柱的观点提供了证据。单斜辉石富钙、钛,由单斜辉石-熔体平衡温压计计算的岩浆房深度分别为:碱玄岩岩浆房深度约49km(对应压力为1.46~1.48 GPa);粗面玄武岩岩浆房约25km(对应压力为0.76 GPa);玄武岩岩浆房约15km(对应压力为0.44GPa)。由碱玄岩→粗面玄武岩→玄武岩,平衡温度(K)依次降低:从1535~1498→1429→1369。由斜长石微晶所计算的岩浆喷出地表的温度为989℃。 主量元素特征表明,岩石类型主要为碱玄岩,有少量的粗面玄武岩和玄武岩,属于碱性系列。微量元素方面,大离子亲石元素(LILE)以及高场强元素(HFSE)特别是Nb、Ta、Ti、Y等元素均呈现富集现象,Yb、Sc、Sr以及K、U、Th等生热元素相对亏损,微量元素及稀土元素分布岩石类似板内OIB微量元素的全球平均值。同位素地球化学研究表明,源区存在两个混合端员并具Dupal Pb异常:一个为DMM,位于软流圈或岩石圈地幔中;另一个为EM2源区,可能来自位于核-幔边界处的海南地幔柱而非大陆底岩石圈地幔。研究表明,南半球Dupal异常不存在全球范围内的地区专属性,本区存在的Dupal异常与南半球Dupal异常可能不存在联系。在南海新生代玄武岩的成因过程中,海南地幔柱在为岩石圈地幔的部分熔融作用提供所需的热量同时,也在物质上作出了贡献。南海盆新生代碱性玄武岩由不同程度的部分熔融作用,以及岩浆在上升期间或者在高位岩浆房中的橄榄石等矿物分离结晶作用所形成,同时还可能发生了堆晶作用。构造环境判别表明,玄武岩浆在上升到地表过程中几乎未受到地壳混染。 南海新生代玄武岩的地球化学研究表明,在玄武质岩浆的深部地幔演化过程中,海南地幔柱可能起着重要的作用。通过引入海南岛地幔柱这个概念,本文建立了一个新的有关南海形成演化的初步的概念性模型:(1)50-32Ma,印度洋板块-欧亚板块碰撞及其所导致的太平洋板块后退的综合效应为南海地区提供了一个伸展环境,此伸展环境为地幔柱物质的上升提供了通道;(2)32-21Ma,当地幔柱柱头到达软流圈时, 通过侧向物质流开始同扩张中心发生相互作用,促进了南海的扩张,并在26-24Ma期间发生了洋脊重新就位事件,使扩张中心从原来的18°N附近(即现今西北海盆的中心)调整到15.5°N附近(即现今的东部亚盆);(3)21-15.5Ma, 随着地幔柱效应的逐渐增强,热点-洋脊相互作用越来越强烈,在大约21Ma发生了洋脊的再次重新就位事件,诱发了西南海盆的扩张;(4)15.5-现在,由于印澳板块前缘与巽他大陆碰撞,使得南海大约在15.5Ma停止扩张,并沿着南沙海槽及吕宋海沟向菲律宾岛弧及巴拉望地块之下俯冲,而南海热点继续活动,在地表处直到第四纪还有碱性玄武岩喷出。
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浮游动物在海洋生态系统物质循环和能量流动中起着至关重要的作用。浮游动物物种组成、生物量和次级生产力的变化会改变生态系统的结构和功能。在黄海生态系统中如何描述这个过程,并使它易于模拟是本论文的研究目的。生物量和生产力是海洋生态系统食物网的基础。谁是浮游动物生物量和次级生产力的基础?哪些种类在生态系统中起关键作用?这些问题在黄海这样的温带陆架边缘海区很难回答,原因是物种组成、生物量和生产力的季节变化显著。因此,在对黄海食物产出的关键过程进行模拟时,需要应用既准确又简便的方法来对浮游动物群落的生态过程进行模拟。在对黄海浮游动物群落结构和物理海洋学特征进行充分的分析之后,浮游动物功能群的方法被确定用来进行黄海生态系统结构和功能的模拟。 根据浮游动物的粒径、摄食习性和营养功能,黄海浮游动物被分为6个功能群:大型浮游甲壳动物功能群(Giant crustacean,GC)、大型桡足类功能群(Large copepods, LC)、小型桡足类功能群(Small copepods,SC)、毛颚类功能群(Chaetognaths)、水母类功能群(Medusae)和海樽类功能群(Salps)。GC、LC和SC是按照粒径大小而划分的功能群,他们是高营养层次的主要食物资源。毛颚类和水母类是两类胶质性的肉食性浮游动物功能群,他们与高营养层次竞争摄食饵料浮游动物;海樽类与其他浮游动物种类竞争摄食浮游植物,而本身的物质和能量却不能有效的传递到高营养层次。本文研究报道了浮游动物各功能群的时空分布、基于浮游动物动能群的黄海生态区划分、饵料浮游动物功能群的生产力、毛颚类对浮游动物的摄食压力以及中华哲水蚤(Calanus sinicus)的摄食生态学。 春季,浮游动物生物量为2.1 g m–2,GC、LC和SC对生物量的贡献率分别为19, 44 和 26%。高生物量的LC和SC功能群主要分布于山东半岛南岸的近岸海域,而GC主要分布在远岸站位。夏季,浮游动物的生物量为3.1 g m–2,GC贡献了73%。GC、LC和SC主要分布在黄海的中部海域。秋季,浮游动物生物量为1.8 g m–2,GC、LC和SC的贡献率相似,分别为36, 33和23%,高生物量的GC和LC分布在黄海中部,而SC主要分布在远岸站位。GC和LC是冬季浮游动物生物量(2.9 g m–2)的优势功能群,分别贡献率了57%和27%,高生物量的GC、LC和SC都分布在黄海的中部海域。与GC、LC和SC相比,毛颚类生物量较低,主要分布于黄海的中北部海域。水母类(本文中指小型水母类)和海樽类斑块分布明显,主要分布于黄海沿岸和北部海域。属于不同功能群的约10个种类为浮游动物的优势种,控制着浮游动物群落的动态。 春季,黄海可以被分成4个浮游动物生态区,浮游动物生物量的分布中心位于山东半岛南岸近岸海域,与第一个生态区相对应,LC和SC在分布中心起主要的控制作用;夏、秋和冬季,黄海分别被分成3、4和3个生态区,浮游动物生物量的分布中心均位于黄海的中部海域,均与各季节的第一个生态区相对应,GC和LC是分布中心生态区的优势功能群,对分布中心起主要的控制作用。黄海冷水团(YSCBW)在GC、LC和SC的空间分布模式中起着重要的作用。黄海不同季节浮游动物生态区的空间分布模式及生态区中起控制作用的优势功能群类别有着重要的生态学意义。 我们将饵料浮游动物功能群细化为0.16–0.25 mm、0.25–0.5 mm、0.5–1 mm、1–2 mm和 >2 mm5个粒径组。应用生物能量学的方法研究了不同粒径浮游动物的生产力。结果表明:浮游动物次级生产力5月份最高,为91.9 mg C m–2 d–1,其次是6月和9月,分别为75.6 mg C m–2 d–1和65.5 mg C m–2 d–1,8月、3月和12月较低,仅为42.3 mg C m–2 d–1、35.9 mg C m–2 d–1和27.9 mg C m–2 d–1。根据这些结果,黄海浮游动物年次级生产力为18.9 g C m–2 year–1。0.16–0.25 mm和 0.25–0.5 mm 两个粒径组对浮游动物次级生产力的贡献率为58–79%,即相对应的SC功能群的周转率(P/B, 0.091–0.193 d–1)要高于GC和LC。 黄海毛颚类功能群的优势种类为强壮箭虫(Sagitta crassa)、纳嘎箭虫(S. nagae)、肥胖箭虫(S. enflata)和百陶箭虫(S. bedoti)。我们对这四种箭虫的生产力和对浮游动物生物量和生产力的摄食压力进行了研究。结果表明:黄海毛颚类总的生物量为98–217 mg m–2,总的生产力为1.22–2.36 mg C m–2 d–1。黄海毛颚类的生物量占浮游动物总生物量的6.35–14.47%,而生产力仅占浮游动物总生产力的2.54–6.04%。强壮箭虫和纳嘎箭虫是黄海毛颚类功能群的绝对优势种,控制着黄海毛颚类群落的动态。黄海毛颚类总的摄食率为4.24–8.18 mg C m–2d–1,对浮游动物现存量和生产力总的摄食压力分别为为0.94%和12.56%。黄海冬季,浮游动物的现存量和生产力为0.4 g C m–2和0.026 g C m–2d–1,而毛颚类的摄食压力却达到了全年的最大值,为1.4%和20.94%。因此,毛颚类的摄食可能对冬季浮游动物群落结构造成重要的影响。通过不同体长组箭虫的摄食率可以推断,黄海毛颚类全年主要摄食小型桡足类,对SC功能群的摄食压力最大。但是在夏季黄海冷水团形成的月份,毛颚类对前体长为2 mm的LC功能群中的种类摄食压力也较大,但此时,由于优势种中华哲水蚤进入滞育阶段,因此毛颚类的摄食会对其种群数量造成严重的影响。 中华哲水蚤在春、秋季的摄食率分别为2.08–11.46和0.26–3.70 µg C female–1 day–1,与微型浮游生物的现存量呈显著的正相关。春季,在黄海的北部,中华哲水蚤通过摄食微型浮游生物吸收的碳量能够满足其代谢和繁殖需求,而在黄海的南部和秋季黄海冷水团锋区附近,中华哲水蚤必须通过摄食其他类型的食物资源来维持其代谢和生殖需求。较低的摄食率、无产卵以及种群中CV期桡足幼体占优势表明,秋季中华哲水蚤在黄海冷水团区域内处于滞育状态。中华哲水蚤优先摄食微型原生动物,并且春季中华哲水蚤总的生长效率(GGE, 3–39%)与食物中微型原生动物的比例呈显著的正相关,表明微型原生动物具有较高的营养价值。但是,因较低的产卵率(0.16–12.6 eggs female–1 day–1)而导致的中华哲水蚤较低的总生长效率(13.4%),可能就是由于其食物中的必需营养成分含量不足(或缺乏)造成的。 本文从生物量的角度,对黄海浮游动物各功能群的时空分布、生态区划分进行了研究报道,对GC、LC和SC功能群的生产力、毛颚类对浮游动物的摄食压力和中华哲水蚤的摄食生态学进行了较为深入的研究,这些结果为黄海食物产出的关键过程的模拟提供了基础资料。今后的研究重点应搞清楚黄海水母类对浮游动物次级生产力的摄食压力和海樽类在食物产出模型中产生的负效应的程度,浮游动物各功能群的组成、季节变化和空间分布模式的长期变化,尤其是在气候变化和人类活动的影响下,将是今后研究的重点。
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Introduced species often start with limited genetic variability, which is problematic for selective breeding. The problem of inbreeding can be exasperated by hermaphroditism. The bay scallop Argopecten irradians irradians is a hermaphroditic species that has been introduced to and now supports a major aquaculture industry in China. Positive response to selection for fast growth was observed in one of the less inbred stocks in a previous study. In this study, we evaluated selection for the second generation to determine if response to selection can be sustained in this introduced population of a hermaphroditic species. Response to selection, realized heritability for the second generation, cumulative (over two generations), current (for the second generation) and residual (from the first generation) genetic gains were estimated by comparing three different types of lines: SS (selected for two generation), SC (selected for the first generation only) and CC (unselected for two generations). The SS line grew significantly faster (P < 0.05) than the other two lines, indicating that the second generation selection for faster growth is still effective. Response to selection and realized heritability for the second generation were 0.612 +/- 0.101 and 0.349 +/- 0.057, respectively, which are similar to those observed for the first generation. The cumulative, current, and residual gains were 17.56 +/- 5.30%, 10.63 +/- 2.46%, and 6.25 +/- 3.13%, respectively. The sustained response to selection for the second generation observed here suggests that considerable genetic variability exists in this population and that future efforts on selective breeding are likely to be fruitful. (c) 2005 Elsevier B.V. All rights reserved.
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Using knowledge of geology, geochemistry, coal petrology, mineralogy, by means of a variety of advanced measuring methods such as inductively coupled plasma mass spectrometry (ICP-MS), inductively coupled atomic emission spectrometry (ICP-AES), X-ray powder diffraction (XRD), scanning electron microscopy with energy-dispersive spectrometer(SEM-EDS), sequential chemical extract and density fractions, the characteristics of trace elements and minerals in Jurassic Beipiao coal mine under inland limnetic sedimentary environment and in late Permian Jianxin and Qiaotou coal mines under paralic swamp sedimentary environment were studied. Compared with the average concentration in the world bituminous coals, the Beipiao coal was characterized by relatively high contents of Sc, Ti, Cr, Co, Ni, Zn, Se, Sr, Zr, Y, Ba, REE and Th, and lower contents of V, Rb, Cd, Sn, Pb, Bi and U; while the Jianxin coal was relatively enriched in Li, Sc, Ga, Sr, Y, Nb, Sb, Th and U, with low concentration of Be, Co, Ni, Cu, Ge, Zr, Mo, Cd, Cs, Ba, Pb and Bi; and the Qiaotou coal was enriched in Li, Sc, Sr, Nb, Ta, Zr, REE, Hf, Th and U, with low concentration of Be, V, Co, Ni, Cu, Ge, Mo, Cd, Cs, Ba, Tl, Pb and Bi. The concentrations of Ca, Mg and K in Beipiao coal are higher than those in Jianxin coal and Qiaotou coal, while Fe, S and Ti in Beipiao coal are lower than those in Jianxin coal and Qiaotou coal. The proximate analysis of coal samples was carried out, which indicated that Beipiao coal was medium- to high- ash (5.92-60.68%) with low sulphur coal, and Jianxin coal and Qiaotou coal was medium to high ash (8.85-46.33%) with high sulphur. The reflectivity was measured, which explained that Beipiao coal belonged to high volatile bituminous coal, Jianxin coal was low volatile bituminous coal and Qiaotou coal was low volatile anthracite. Quantitative maceral analyses were studied. The characteristics of rare earth elements (REE) were investigated, which showed that the total contents of REE were higher than that of the world's average content. With the increase of coal's metamorphic grade, the total contents of REE decreased from 98.5 X 10"6 of Beipiao coal to 94.2 X 10"6 of Jianxin coal, and to 75.9 X 10"6 of Qiaotou coal, and 5Eu reduced which indicated that the element Eu depleted. The characteristics of REE was controlled by the metamorphic grade of coal. And REE were mainly absorbed in clay minerals in Beipiao coal samples, while in Jianxin and Qiaotou coal mines, REE were primarily related to clay mineral and pyrite. The variation of trace elements in vertical direction of coal seams was studied, and the results showed that different trace elements differed greatly. The correlation between trace elements and ash were determined. Four major trace elements (aluminium-silicates, sulphide, carbonate and phosphate) accounted for the occurrence and distribution of most elements studied were determined. Coal samples were separated by density fraction, which showed that Cr, Cu, Mo and Pb were closely related to inorganic matters mainly distributed in P >2.6 and dropped remarkably in the density fractions P <2.3 . The occurrences of Co, Cr, Ni, As, Se, Mo, U were studied directly and quantitatively using sequential chemical extract with six steps, which showed that Co. Ni, Mo and U were mainly in the form of mineral, and As, Se chiefly in the form of organic state, while Cr mostly in the form of organic state and mineral. Major mineral phases presented in the Beipiao coal were Kaolinite, illite, quartz, calcite, and small amount of siderite, barite. While major mineral phases in Jianxin and Qiaotou coal were pyrite, kaolinite, and small amount of marcasite, rutile, sphalerite. This is the first time that the chromite in the coal was discovered in China, which indicates that Cr occurrence appeared in the form of chromite. The ratio of Sr/Ba, Sr/Ca and V/Ni in Beipiao coal mine under inland limnetic is smaller than that of in Jianxin and Qiaotou coal mines under paralic swamp. The ratio of K/Na and Th/U of Beipiao coal mine is higher than that of Jianxin and Qiaotou coal mine, which proved that Beipiao coal was not affected by sea water and Jianxin and Qiaotou coal were affected by sea water. Trace elements such as Cr, Ni, Mo in minerals were analyzed by SEM-EDS. The factors controlling the enrichment of trace elements can be divided into syngenetic stage factors and epigenetic stage factors.
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赣中变质岩带主要由变泥砂质岩石和少量斜长角闪岩组成。30个变泥砂质岩石样品分析表明,稀土元素分布模式显示明显富集轻稀土元素及Eu负异常[∑REE=129~296μg/g,δEu=0.51~0.86,(La/Yb)N=3.95~12.91,其小相容元素比值高(Th/Sc=0.57~3.59、La/Sc=1.46~12.4、La/Yb=5.84~19.0、La/Sm=4.69~6.87、Th/U=3.40~6.42),大离子亲石元素富集,Zr、Hf、Sc、Ti、Y、HREE和Sr含量较低,其原岩应为一套砂泥质岩石,沉积于远离陆地的克拉通大陆架浅海环境;δBa=0.10~0.93,Nd同位素亏损地幔模式年龄tDM=1597~2525Ma,εNd(0)=-9.9~-15.8,其源区物质主体由占元占代富铝富钾的花岗质岩石和(或)碎屑沉积岩构成,经历了较强的化学风化作用。
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2003
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2002
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2003