887 resultados para 1923
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溶剂萃取是分离稀土元素的主要方法。通过对溶剂萃取动力学的研究,不但能够从理论上深入了解萃取过程的反应机理。而且在萃取的实际应用中,也可以利用动力学因素提高分离效率和选择性。因此,稀土元素(III)和铁(III)的萃取动力学研究,对萃取机理和实际应用都具有重要意义。本文用液滴生长法分别研究了伯胺N_(1923)萃取稀土(III)及铁(III)和HEH(EHP)萃取稀土(III)的动力学。1、研究了伯胺盐(N1923H)_2SO_4从硫酸介质中萃取La(III)和Fe(III)的动力学过程。考察了La~(3+),Fe~(3+),N1923,H~+,SO_4~(2-)和温度对萃取速率的影响。结果表明,(N1923H)_2SO_4萃取La(III)和Fe(III)时,它们之间在动力学性质上差异不大。并根据实验结果,推测了萃取反应机理。推导了正向初始萃取速率的理论方程。计算了萃取反应的表观活化能。2、研究了HEH(EHP)从HCL-NaCl-NaNO_3溶液中萃取Er(III)的动力学过程。考察了Er~(3+),HEH(EHP),NO_3~-,CL~-,H~+和温度对萃取速率的影响。结果表明,在HEH(EHP)从盐酸介质中萃取Er(III)时,NO_3~-能增加该萃取体系的萃取速率。并根据实验结果,当NaNO_3作为添加剂时,推测了萃取反应机现。导出了正向初始萃取速率的理论方程。计算了萃取反应机理。导出了正向初始萃取速率的理论方程。计算了萃取反应的表观活化能。提出影响萃取速率的“表面张力效应”。3、研究了HEH(EHP)-N1923-正庚烷萃取体系从盐酸介质中萃取Er(III)的动力学过程。考察了Er~(3+),HEH(EHP),N1923,CL~-,H~+和温度对萃取速率的影响。结果表明,在盐酸介质中HEH(EHP)萃取Er(III)时,N1923对该萃取体系的萃取速率有影响。适当浓度的N1923能加快萃取速率。当N1923作为表面活性剂时,根据实验结果推测了萃取反应机理。推导了正向初始萃取速率的理论方程。计算了萃取反应的表观活化能。4、研究了HEH(EHP)从HCl-NaCl-KSCN溶液中萃取Er(III)的动力学过程。考察了Er~(3+),HEH(EHP), CL~-,SCN~-,H~+和温度对萃取速率的影响。结果表明,在HEH(EHP)从盐酸介质中萃取Er(III)时,硫氯酸盐能加快该体系的萃取速率,起着正催化作用。当KSCN作为催化剂时,根据实验结果推测了萃取反应机理。推导了正向初始萃取速率的理论方程。计算了萃取反应的表观活化能。
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黑白仰鼻猴仅分布于滇西北和藏东南境内,金沙江和澜沧江间的一个狭小区域内。根据以前的研究结果,将暗针叶林和针阔混交林定义为其适宜生境(SH)黑白仰鼻猴的适宜生境由于当地人砍树烧树形成夏季高山牧场逐渐被侵蚀。为了解云南省境内黑白仰鼻猴适宜生境的现状,我们比较了1997年卫星图片和1958年以航片为基础绘制的地形图上夏季牧场和适宜生境的面积,得到以下结果:1)1997年黑白仰鼻猴的适宜生境面积为4169平方公里;2)夏季牧场面积为1923平方公里;3)过去的40年中,适宜生境面积减少了31%(1887平方公里),夏季牧场面积增加了204%(1291平方公里);4)森林斑块的平均面积从15.6平方公.里减小到5.4平方公里。另外,夏季牧场的面积和当地人口成正相关(R2=053),这意味着黑白仰鼻猴生境的减少和破碎化是当地传统生产方式和人口增长共同作用的结果。目前在云南和西藏境内分别尚存11群和2群黑白仰鼻猴。
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从 1999 年4 月至2002 年六月间,对黑白仰鼻猴种群(Rhinopithecus bieti ) 的分布和生境状况进行了调查。与十年前的调查结果相比,本次调查新发现了4 个亚种群(指存在生境走廊的若干群体),但有5 个以前存在的群已经消失,现 存猴群数量为13 群,总体数量约为1200-1700 只。从西藏的芒康到云龙的龙马 山,随着海拔的降低,猴群可利用的植被类型也随之多样化。但由于砍伐、放牧、 开矿等因素的影响,猴群生境破碎化程度较高,连接猴群的生境走廊状况极差, 多数猴群孤立分布,并且存在小种群问题,生境走廊的维护和恢复已成为该物种 保护成功与否的关键。种群的总体数量下降了32%(不含4 个新发现的亚种群), 其中4 群数量下降,4 群持平,1 群有所增长,5 群消失,这不容乐观的状况给 我们保护敲响了警钟。此外,基于以前的研究结果,暗针叶林、针阔混交林和栎 树林均为其适宜生境,夏季高山牧场则是由当地居民为放牧而砍伐、焚烧高海拔 带的暗针叶林而形成的林间空地。我们使用了1997 年的卫星影像和1958 年的航 拍地图来估算适宜生境和夏季高山牧场的面积。结果表明;1)在1997 年,黑白 仰鼻猴的适宜生境面积为4169 km2,夏季高山牧场的面积为1923 km2。2)在近 40 年中,黑白仰鼻猴的适宜生境面积下降了31%(约1887 km2),而夏季高山牧 场的面积则增加了204%(约1291 km2)。3)森林斑块的平均面积从15.6 km2 下降到5.4 km2。此外,夏季高山牧场的面积与当地居民的人口数量增长之间呈 正相关关系 (R2 ≥ 0.53,p < 0.05)。除非当地居民的人口数量增长模式或者传统 的生产生活方式发生改变,这种破碎化趋势将继续下去。 从1999 年三月至2000 年十二月对云南塔城(99o18’E, 27 o36’N, 活动范围在 2,700 – 3700 m asl)的一群黑白仰鼻猴收集了食性和时间预算的数据。通过状态 行为扫描的方式,主要记录了树冠中单雄组食用植物种类—部位。同时用显微镜对每个月的粪便样本进行了显微分析,以此作为食性的补充数据。仰鼻猴食用属 于28 科、42 属的59 种植物,共计90 个食用的植物种类—部位,其中冬季利用 21 个植物种类—部位,春季38 个,夏季39 个,秋季47 个。另一方面,该群年 平均花费日活动时间的35%进食,33%休息,15%移动,13%社会行为。日活 动时间预算分配、摄食不同食物类别的时间、粪便中食物残留物及食用植物种 类―部位的数目存在着季节性变化。食物种类与时间分配之间和之内的相关显然 是为了最大化觅食效率与最小化能量消耗。考虑到来自北面与南面的群的相关报 道,这个种对生境的适应性似乎与其他疣猴没什么区别,并无特化之处。因此, 这个种的最终生存预期要比以前乐观。 我们利用整个塔城猴群沿地面通过开阔地或喝水的机会,使我们能记录野外 种群的大小和组成(如性比等)以及通过分析依次经过个体间的时间间隔以量化 反映社会组织单元之间和之内的空间距离,用统计分析的方式来量化描述社会组 织的模式,发现塔城猴群由9 个单雄单元(OMUs)、5 个多雄单元(MMUs)和2 个全雄单元(AMUs)组成, 单雄单元、多雄单元和全雄单元内的个体分别约占 总数的58%、34%和8%,无论在开阔峡谷地域或水潭旁,单元内的时间间隔显 著短于单元间的时间间隔(开阔峡谷地域:非配对 t 检验,df = 49; p < 0.01, 水潭:非配对t 检验,df = 35; p < 0.01)。 在单雄单元的成年不等性比和成 年雌性与婴猴的比例显著大于多雄单元(开阔峡谷地域:非配对t 检验,df = 40; p < 0.05,水潭:非配对t 检验,df = 16; p < 0.05)。在全雄单元中有大量的 性别不明的未成年个体。此外,加之某些个案描述,论述了多雄单元存在的可能 性及与全雄单元和单雄单元之间的关系。
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Polycarbodiimide (CDI) was used to improve the thermal stability of poly(L-lactic acid) (PLA) during processing. The properties of PLA containing various amounts of CDI were characterized by GPC, DSC, rheology, and tensile tests. The results showed that an addition of CDI in an amount of 0.1-0.7 wt% with respect to PLA led to stabilization of PLA at even 210 degrees C for up to 30 min, as evidenced by much smaller changes in molecular weight. melt viscosity, and tensile strength and elongation compared to the blank PLA samples. In order to examine the possible stabilization mechanism, CDI was reacted with water, acetic acid, L-lactic acid, ethanol and low molecular weight PLA. The molecular structures of the reaction products were measured with FTIR.
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Europium doped hydroxyapatite (Eu:HAp) nanosized particles with multiform morphologies have been successfully prepared via a simple microemulsion-mediated process assisted with microwave heating. The physicochemical properties of the samples were well characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectra (XPS), Fourier transform infrared spectroscopy (FT-IR), photoluminescence (PL) spectra, and the kinetic decays, respectively. The results reveal that the obtained Eu:HAp particles are well assigned to the hexagonal lattice structure of the hydroxyapatite phase. Additionally, it is found that samples exhibit uniform morphologies which can be controlled by altering the pH values. Furthermore, the samples show the characteristic D-5(0)-F-7(1-4) emission lines of Eu3+ excited by UV radiation.
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The surface of aromatic polyamide reverse osmosis composite membrane was modified by oxygen and argon plasma. The water permeability of oxygen-plasma-modified membrane increases, and the chlorine resistance of argon-plasma-modified membrane increases. The spectra of the attenuated total reflection-Fourier transform infrared and X-ray photoelectron spectroscopy and the contact angle of the water were analyzed to explain the improvement of the two performances of the composite membrane. The carboxyl groups were introduced when modified by oxygen plasma, and cross-linking occurred when modified by argon plasma. (C) 1997 John Wiley & Sons, Inc.
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本文研究了甲基膦酸二甲庚酯(P_(350),以 B 表示)与伯胺 N_(1923)(以RNH_2表示)的正庚烷溶液,在(Na,H)C1介质中对 Cd(Ⅱ)的协同萃取。用等摩尔系列法和斜率法确定二元协萃配合物组成为(RNH_3C1)_2·CdC1_2·B;求得协萃反应平衡常数1gK_(Bc)=2.08,协萃配合物的生成常数1gβ=0.70;计算了协萃反应的热力学函数△H=-14.56kJ/mol,△G=-12.07kJ/mol 和△S=-8.22J/mol·K;还讨论了协萃配合物的 IR 和NMR 谱。
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仲碳伯胺N_(1923)萃取铈(Ⅳ)的~1H,~(15)N-NMR研究表明,在萃取铈(Ⅳ)时也同时萃取H_2O和H_2SO_4进入有机相,当铈(Ⅳ)浓度较高时,铈(Ⅳ)与N_(1923)生成配合物。
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Coral bleaching, which is defined as the loss of colour in corals due to the loss of their symbiotic algae (commonly called zooxanthellae) or pigments or both, is occurring globally at increasing rates, and its harm becomes more and more serious during these two decades. The significance of these bleaching events to the health of coral reef ecosystems is extreme, as bleached corals exhibited high mortality, reduced fecundity and productivity and increased susceptibility to diseases. This decreased coral fitness is easily to lead to reef degradation and ultimately to the breakdown of the coral reef ecosystems. Recently, the reasons leading to coral bleaching are thought to be as follows: too high or too low temperature, excess ultraviolet exposure, heavy metal pollution, cyanide poison and seasonal cycle. To date there has been little knowledge of whether mariculture can result in coral bleaching and which substance has the worst effect on corals. And no research was conducted on the effect of hypoxia on corals. To address these questions, effects of temperature, hypoxia, ammonia and nitrate on bleaching of three coral species were studied through examination of morphology and the measurement of the number of symbiotic algae of three coral species Acropora nobilis, Palythoa sp. and Alveopora verrilliana. Results showed that increase in temperature and decrease in dissolved oxygen could lead to increasing number of symbiotic algae and more serious bleaching. In addition, the concentration of 0.001 mmol/L ammonia or nitrate could increase significantly the expulsion of the symbiotic algae of the three coral species. Except for Acropora nobilis, the numbers of symbiotic algae of other two corals did not significantly increase with the increasing concentration of ammonia and nitrate. Furthermore, different hosts have different stress susceptibilities on coral bleaching.
A new genus of grasshopper (orthoptera : acridoidea : Catantopidae : Cyrtacanthacridinae) from China
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This paper reports a new genus i.e. Parapachyacris gen. nov and a new species Parapachyacris taiwanensis sp. nov in Cyrtacathacridinae. The new genus is similar to Pachyacris Uvarov, 1923 and differs from the latter in: 1) foveolae lacking; 2) hind tibiae with 10 spines on inner side and 8 spines on outer side; 3) basal part of prostemal process thickened; 4) cross veins right angled with longitudinal veins in apical part of tegmina and 5) the back of body with yellow longitudinal stripe in middle. The new genus is also similar to Patanga Uvarov, 1923 and differs from the latter in: 1) foveolae lacking; 2) basal part of prostemal process thickened; 3) upper side of hind femora with three dark bands and 4) black spots of tegmina lacking. Type specimen is deposited in the National Museum of Natural Science (NMNH), Taichung, Taiwan, China.
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本文介绍用光学阵列传感器的机器人物体分类系统。传感器直接安装在机器人的两个手指上。被抓物体的阴影通过光导纤维传到安放在“安全区”的光敏元件上。计算机识别物体的轮廓后命令机器人抓握物体,并把它运送到指定的地点从而达到物体分类的目的。
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采用6种萃取剂:pH=7的0.01mol/L CaCl2、pH=7.3的0.005mol/L DTPA+0.1mol/L TEA(三乙醇胺)+0.01mol/L CaCl2、0.1mol/L NaNO3、0.43mol/L HOAc、pH=7的0.05mol/L EDTA和pH=4.65的0.5mol/L NH4OAc+0.01mol/L EDTA浸取液,对污染土壤中的重金属Cu、Zn、Cd、Pb的进行了萃取,并比较了萃取剂的萃取能力。实验结果表明,HOAc、EDTA以及NH4OAc-EDTA萃取各种重金属的能力远远大于其它几种萃取剂的萃取能力,是比较理想的萃取剂。