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1.
利用计算机辅助解析FTIR光谱法-退卷积和曲线拟合,研究了稀土离子与钙调蛋白的相互作用。结果表明:三价稀土离子能与脱钙的钙调蛋白相结合,导致蛋白质二级结构的变化。  相似文献   

2.
尿钙的测定,在研究钙代谢及钙代谢障碍疾病时是重要的。离子钙是生理活动性因素,测定离子钙比测定总钙更有意义。Schachter等推测尿总钙中有一定比例的尿离子钙。Robertsoa用生化分析尿中结合钙推测尿离子钙含量。但都不能直接测出尿离子钙,故对尿离子钙与总钙之间的变化关系不能广泛深入地研究和应用。1967年Koss研制成钙离子选择电极,为直接测定离子钙开辟了道路,在国外已广泛应用于血液中离子钙的测定。Orion研究公司曾预备用钙离子选择电极来测定尿离子钙,但迄今未见具体报道。我们于1981年初用国产钙离子选择电极,分别用标准曲线法和标准添加法连续  相似文献   

3.
绪言:掺杂纤维稀土的光学温度传感器是1979年NASA在屏蔽研究中的产物,这是识别光学温度和压力感受的新方法。稀土探针被认为是最有前途的。制造了两种纤维光学传感器:一种传感器采用稀土铕;另一种采用稀土钕。采用掺杂稀土的纤维探针理由可概括如下:稀土离子能很快的化入到大量的玻璃基质材料中;稀土离子具有光学跃迁能力,能提高在可见光和靠近红外波长处的吸收性,并有大量地低能级,光的跃迁就是这些低能  相似文献   

4.
为更好地监测离子吸附型稀土矿山的开采现状,选取赣南离子吸附型稀土矿区,采用最新高分辨率遥感数据,开展离子吸附型稀土矿矿山非法开采监测、环境破坏监测、矿山动态变化监测等示范研究。运用IKONOS数据结合矿权资料在赣南寻乌地区开展稀土矿山非法开采监测;在赣南寻乌地区提取土地荒漠化及水体污染等环境信息;利用两期QuickBird数据在赣南定南某矿区开展动态变化监测。研究表明高空间分辨率遥感数据处理与分析为离子吸附性稀土矿矿山快速、准确、动态监测提供了良好的技术手段。  相似文献   

5.
考虑稀土萃取过程具有多变量、强耦合特性,提出一种基于广义预测解耦控制(GPDC)的稀土萃取过程控制方法。首先针对模型未知的强非线性稀土萃取过程,构建基于极限学习机的组分含量系统模型,并依据模型特点设计多个稀土萃取过程GPDC控制器;然后为降低各控制回路间的耦合性,在控制器的性能指标中引入校正策略,通过回路中模型预测值与参考值的偏差自适应调整偏差权重;最后基于CePr/Nd萃取过程中采集的数据进行GPDC与常规广义预测控制器进行对比仿真实验。仿真结果显示本文采用的GPDC算法能大幅度降低控制量的超调量,控制效果显著,这为解决稀土萃取过程中多变量强耦合的优化控制问题提供了借鉴。  相似文献   

6.
近年来,在生理生化临床等方面应用离子选择性电极已开展了许多有意义的工作。其中对血液中钙的生理作用及其与蛋白质的结合的测试与研究,国际上曾组织过专门的学术讨论。人体血液中有50%以上的钙以络合物形式存在,在这些络合物中又以与白蛋白结合形  相似文献   

7.
借助计算机对稀土离子选择电极在待测离子浓度较高、酸度改变以及共存组分干扰明显的复杂体系中响应特性进行了研究。建立了四种数学模型和确定模型参数的计算机程序。模拟结果令人满意。  相似文献   

8.
测定了具有代表性的4种母质发育、3种水育型的红壤性水稻土及起源土壤的可溶性稀土(REEs)和稀土总丰度(∑REE),分析了REEs的分布特征及与∑REE的相关,研究了经酸碱调节后土壤REEs与pH值的关系,结果表明:(1)不同母质发育的供试土壤REEs平均值依石英闪长岩母质土壤系列、凝灰岩母质土壤系列、黑云母花岗岩母质土壤系列、玄武岩母质土壤系列顺序递减。(2)供试土壤REEs与∑REE的相关不显著。(3)起源土壤剖面中REEs具有明显自上而下增大的趋势,而不同水育型水稻土剖面的REEs分布各有特征,但总的趋势是自上而下减少。(4)经酸度调节后供试土壤的REEs随着土壤pH值的提高而下降,呈显著的幂函数相关。  相似文献   

9.
史生华  李玉虎 《化学传感器》1993,13(2):58-64,39
铅离子选择电极除直接用于测定铅外,还广泛地被用作指示电极电位滴定法测定硫酸根、草酸根、磷酸根等能与铅离子形成难溶盐的阴离子。关于用其间接测定其它金属离子,文献中未曾见到。本文将阐述用铅离子选择电极作指示电极测定锌镁钙等金属离子的方法。一、仪器和试剂pHS—2型酸度计(上海第二分析仪器厂)磁力搅拌器(上海南汇电讯器材厂)217型双接界饱和甘汞电极,外套管充饱和硝酸钾溶液。(江苏电分析仪器厂)铅离子选择电极:自制 Ag_2S—PbS 均相膜全固态铅离子选择电极。  相似文献   

10.
本文报告用离子选择电极法测定中药中可溶钙含量的方法。测定结果表明离子选择电极法对中草药中无机元素的研究是一种简单、快速、准确的方法。本实验的平均回收率为92.1%。  相似文献   

11.
Poly(thiophene-3-yl-acetic acid 8-quinolinyl ester) is a fluorescent material and it shows fluorescence at 540 nm. The fluorescence of poly (thiophene-3-yl-acetic acid 8-quinolinyl ester) has been studied in the presence of acids, metal ions, nucleotides and protein (l-proline). The fluorescence of polymer is quenched by the addition of HCl which could be recovered by the addition of equivalent amount of alkali. The Stern–Volmer quenching coefficient for HCl is calculated and found to be 141 M−1. Moreover quenching depends on concentration of HCl. Similarly, the fluorescence of polymer is quenched by copper, cadmium and lead metal ions and quenching is sensitive to concentrations of metal ions. The Stern–Volmer quenching coefficient is 2.285 × 103 M−1 for Cu2+ ions, 2.287 × 103 M−1 for Cd2+ ions and 3.7 × 104 M−1 for Pb2+ ions. In Al3+, Zn2+, nucleotides and protein (l-proline), the fluorescence is exorbitantly increased.  相似文献   

12.
堆的路径二分搜索算法   总被引:1,自引:0,他引:1       下载免费PDF全文
本文提出堆的路径二分搜索算法.当用堆来实现优先队列时,此算法可用较少的比较次数完成插入及删除最大元素等操作.  相似文献   

13.
The dependency of the chromaticity shifts on the concentration of Eu2+ doped in BaMgAl10O17 (BAM) was investigated under heat‐treatment and vacuum ultraviolet (VUV) irradiation. The Eu2+ ions in BAM show an asymmetrical broad emission band with a maximum at ~452 nm under excitation of VUV light at room temperature, showing that multiple crystalline cationic sites exist in the host. It was found that the chromaticity shifts greatly decrease with increasing heat‐treatment temperature. Regardless of the Eu2+ concentration, the chromaticity shifts caused by heat‐treatment are greater than that caused by VUV irradiation. Compared with conventional BAM, a solid solution of BAM with barium aluminate as a powder and film was also studied, and very few chromacity shifts were observed. It is suggested that the distribution of Eu2+ ions in different sites in a BAM lattice results in different chromaticity coordinates. By increasing the Eu2+ concentration in BAM, or under heat‐treatment and VUV irradiation, the emission band shifts towards longer wavelengths.  相似文献   

14.
细胞外空间钾离子的大量积累会导致星形胶质细胞膜去极化,星形胶质细胞膜电位变化引起的电压门控钙离子通道(VGCCs)电流内流会增加星形胶质细胞内钙离子浓度的振荡幅值,从而增强星形胶质细胞对神经元的正反馈作用。考虑星形胶质细胞VGCCs的钙离子内流,本文构建了一种包含多种离子浓度动力学行为的神经元-胶质细胞耦合模型。数值模拟结果发现,VGCCs的钙离子内流是影响星形胶质细胞内Ca^2+浓度升高的一个主要因素;VGCCs电流增强会诱发神经元产生自发性癫痫放电活动实验现象的内在机理。本文研究结果可以为星形胶质细胞钙离子代谢紊乱诱发神经系统自发性癫痫放电提供一种解释。  相似文献   

15.
《Displays》2014,35(5):261-265
A series of Sm3+ and Dy3+ doped LaBWO6 phosphors were synthesized by high temperature solid state reaction. Recorded XRD patterns proved that the titled compound in a single phase has been obtained. Sm3+ and Dy3+ doped LaBWO6 could emit orange and white light, respectively. The optimal doping concentration of Sm3+ or Dy3+ was experimentally ascertained to be 6 mol%. The critical distance of energy transfer for Sm3+ or Dy3+ doped sample is 1.540 nm. In addition, there is no cross energy transfer between the Sm3+ and Dy3+ ions in the co-doped samples. The results indicated that the electric dipole–dipole interaction is predominant energy transfer mechanism for concentration quenching of Sm3+ or Dy3+ doped LaBWO6 phosphor. The charge transfer band was observed in the excitation spectra of Sm3+ or Dy3+ doped LaBWO6 phosphors. Present investigation indicated that Sm3+ and Dy3+ doped LaBWO6 can be applied in solid state lighting and LaBWO6 is a promising host for display applications.  相似文献   

16.
This communication reports the use of glutathione mediated self assembled chains of gold nanorods as new approach for the detection of Pb2+ ions. We were prompted to study the influence of metal ions by considering the role of glutathione as detoxification agent in the body. Additionally the ability of glutathione to complex with metal ions like lead (Pb2+) and mercury (Hg2+) is well known. We studied the interaction of different metal ions including Pb2+ with the end to end assembled chains of gold nanorods. Pb2+ was found to disassemble the chains to dimeric structures. High resolution transmission electron microscopy and dynamic light scattering were used to study the ensemble. A proportional reduction in the size of the assembly was observed between concentration ranges of 0.1-0.025 mM of Pb2+. Our results indicate that analyte induced disassembly is an attractive approach to the detection of environmentally relevant components such as Pb2+.  相似文献   

17.
Nd_(0.5)Sr_(0.5)CoO_3热敏和气敏性质的研究   总被引:2,自引:0,他引:2  
本文研究了稀土复合氧化物Ln_(0.5)Sr_(0.5)CoO_8(Ln=La,Nd)敏感材料的制备.用X-射线测定了它们的晶体结构,用电子扫描显微镜测定了它们的结晶粒度、孔隙度,并制成了敏感元件.测量了它们的热敏、气敏性质,计算了活化能,还讨论了烧结时间对结晶粒度和气敏性的相互影响.  相似文献   

18.
A synthetic analogue of gramicidin A, gram-2-(nicotinamidyl)ethyl carbamate (gAN) was found to regulate the influx of potassium ions depending on its redox state. At potentials less than −0.52 (±0.05) V, the nicotinamide group in gAN is reduced and allows charge- and size-selective influx of cations. In the oxidised state, charge repulsion between the positively charged nicotinamide group and the cations prevents any influx of cations. Chronoamperometric experiments were conducted to determine permeabilities of Eu3+, Tl+, K+ ions in a BLM porated with gAN. Scanning electrochemical microscopy (SECM) experiments were conducted with two ions: permeant K+ ions and the larger (CH3)4N+ ion which blocks the channel. The switching potential for gAN, at which the channel allows flux monovalent cations, is shown to be potential and pH-dependent and temperature-independent.  相似文献   

19.
A new near infrared (NIR) fluorescent 4,4-Difluoro-4-bora-3a,4a-diaza-s-indacene (BODIPY) dye with dual functionality was synthesized and characterized. The compound 1 responds to copper ion in NIR region with high selectivity through a photo-induced electron transfer process established between the substituted benzene group in the meso position and the BODIPY core when Cu2+ binds with the four oxygen atoms in the structure, and results in the quenching of the fluorescence. The response range to copper ions was from 10 to 50 μM, and other metal ions including Li+, Na+, K+, Mg2+, Ca2+, Pb2+, Fe3+, Ag+, Hg2+, Co2+, Zn2+, Mn2+, Cd2+, Ni2+ and Al3+ had no interference. When excited at 520 nm, a new emission peak at 568 nm of compound 1 was used to detect Al3+ selectively from 30 μM to 110 μM without any interference from other metal ions including copper ions.  相似文献   

20.
CaMoO4:RE3+,Yb3+ (RE = Er, Ho, Tm) phosphors were successfully synthesized by a facile hydrothermal method. XRD patterns confirmed tetragonal structure under different RE3+ and M+ ions doping conditions. Particles shapes and sizes were confirmed by SEM and TEM analyses. Particles shape and size were well tuned by control of solution pH; spherical balls consisting of nano-grains at low pH of ∼2, rice grain shapes at moderate pH of ∼6, and thin flakes at higher pH of ∼12, were observed. Fine tunability of upconversion (UC) emission color was achieved by doping multiple RE3+ ions within a single CaMoO4 host. Blue, green and orange upconverted emission were observed by doping Tm3+, Er3+ and Ho3+ in the CaMoO4, respectively. Further, the emission colors were well tuned by the combination of Tm, Er and Ho ions and their concentrations. CaMoO4:Tm3+,Ho3+,Yb3+ exhibited perfect white emission with well tunability from cool white to warm white colors. Substitution of part of Ca ions by M+ (M = Li, Na, K, Rb) ions affected the crystal field symmetry around RE3+ ions and hence changed the transition probabilities between their f–f transition levels, consequently intensified the UC intensities. The blue (Tm3+), green (Er3+), and orange (Ho3+) upconversion intensities of CaMoO4:RE3+,Yb3+,0.10 K+ phosphors increased by 60, 50 and 40 folds compared to the unsubstituted analogues, respectively. The K substituted CaMoO4:RE3+,Yb3+,K+ phosphors exhibited intense UC emissions visible by naked eye even pumped by less than 1 mW laser power and can have potential application in displays and variety of other applications.  相似文献   

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