10MeV质子等时性回旋加速器的设计研究

给出10MeV质子等时性回旋加速器的等时性磁场设计,中心区的设计以及加速后最终的束流品质,该加速器可作为正电子断层扫描装置的配套设备,用于生产中短寿命放射性同位素等.它沿半径方向只用一套线圈励磁,等时性磁场的建立完全由磁极形状决定.中心区的设计满足了轨道中心化的要求,并给出较大的横向和纵向接受度,以获得足够的束流强度.经过172圈加速后,最终的束流品质满足要求.

古气候研究中气候模式的发展与应用

IEECAS SKLLQG

重离子注入生物材料质量沉积效应评述

前人曾用重离子束注入生物小分子 ,借助先进的仪器分析手段 ,对重离子注入质量沉积进行了初步研究 ,但质量沉积对处于生命状态下的活生物体组织细胞和生物大分子所带来的生物学效应 ,即质量沉积效应的研究还未见报道。将来可用放射性重离子束注入活细胞和生物分子 ,借助放射自显影示踪、放射性测量和分子生物学等研究技术对重离子注入质量沉积效应开展进一步研究

北方稻田生态系统养分渗漏规律研究

1994～ 1 996年开展了 5种不同模式水稻田生态系统主要养分 N、P、K在整个生育期间随渗漏水淋失规律的研究。结果表明 :不同模式的水稻田生态系统中 ,淋失的 N素养分主要以 NO- 3- N为主 ,NH+ 4 - N淋失仅占很少部分 ,并且随着深度的增加 ,NO- 3- N的淋失逐渐增大 ,而NH+ 4 - N的淋失则逐渐减小。淋失的 P、K养分量很小 ,且随深度的变化其变化量亦不大

流动注射氢化物发生-原子吸收分光光度法测定血清中的硒

<正> 硒是人体健康必需的微量元素之一。对维持正常代谢起着重要的调节作用。长期缺硒可导致克山病发生,会使受孕率显著下降,频繁出现流产、难产和死胎,还会并发贫血症等。然而,过量的硒对人体也有害,能导致胃肠疾病,神经过敏和紫斑病的发生。由此可见,硒和人体健康有着十分密切的关

黄土高原地区可持续发展指标体系与评价方法设计

黄土高原地区在我国经济发展总体布局中居于承东启西、协调东西关系的重要战略地位 ,实现其可持续发展对于西部大开发具有较强的示范和带动作用。在全面分析黄土高原可持续发展态势的基础上 ,对本区可持续发展指标体系的结构框架和可持续发展评价方法进行了初步研究 ,设计出了包括高级综合指标、基本指标和元素指标 3个类型的层次性可持续发展指标体系结构框架、熵技术支持下确定可持续发展指标权重的层次分析法以及用于黄土高原地区可持续发展全面综合评价的集成评价模型 ,为规范和引导该区的可持续发展进程提供了科学依据

中国东北西部地区荒漠化发展前沿区域的遥感研究

依据 1 996年 7～ 9月和 1 988年 8～ 1 0月两个时期的LandsatTM遥感信息 ,分别对中国东北西部地区荒漠化发展前沿的典型区域吉林省乾安县的盐渍化、吉林省梨树县土地沙化变化和乌尔吉木伦河与新开河间的土地利用状况 ,进行遥感解译和实地调查。分析研究结果表明 ,东北西部这三个区域的生态环境 1 996年比 1 988年有所恶化 ,主要表征为盐渍化和沙化土地向东有较强发展和蔓延 ,撂荒地显著扩大 ,与沙化土地面积量级接近。由此东北西部应该成为我国荒漠化和生态环境治理的重点区域

温度对Ti_(45)Zr_(35)Ni_(20)合金电化学贮氢性能的影响

采用真空熔炼法制备了Ti45Zr35Ni20合金,研究了合金在不同温度下的电化学贮氢性能。结果表明,Ti45Zr35-Ni20电极的电化学性能随着温度而变化,温度从323 K升高到343 K时,电极的活化次数从22次减少到8次,放电容量从86.1 mAh/g增到135.0 mAh/g,快速放电能力也有所提高,然而,高温使电极的循环稳定性显著下降,自放电率增大。

Preparation of nanoparticles of bipyridineruthenium and silicotungstate and application as electrochemiluminescence sensor

The novel nanoparticles, [Ru(bPY)(3)](2)SiW12O40 center dot 2H(2)O(2) were firstly synthesized and characterized by elemental analysis, IR, and TEM. The nanoparticles were used to fabricate a chemically modified carbon paste electrode (CPE) by dispersing nanoparticles and graphite powder in silicone grease. Thus-prepared CPE shows bifunctional electrocatalytic activities towards the reduction of nitrite and the oxidation of oxalate, and exhibits sensitive electrochemiluminescence (ECL).

An Engineering-Purpose Preparation Strategy for Ammonium-Type Ionic Liquid with High Purity

A new strategy for preparing ammonium-type ionic liquid (IL) by acid/base neutralization reaction was proposed. The method contributed to preparing hydroxide-based ammonium IL and resulting task specific ionic liquid (TSIL) with high purity using a low-costly and environment-friendly synthetic. route. Halide contamination in the prepared ILs could be markedly decreased than those prepared by well-established anion metathesis method. Moreover, some novel TSILs composed of cations and anions with big steric hindrances could be prepared by this method. Physicochemical properties of the bifunctional TSILs, i.e., density, water content, decomposition temperature, and munal solubility, were also studied in this article.

Determination of reserpine in urine by capillary electrophoresis with electrochemiluminescence detection

A fast and sensitive approach to detect reserpine in urine using micellar electrokinetic capillary chromatography with electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) detection is described. Using a 25 mum i.d. capillary as separation column, the ECL detector was coupled to the capillary in the absence of an electric field decoupler. Field-amplified injection was used to minimize the effect of ionic strength in the sample and to achieve high sensitivity. In this way, the sample was analyzed directly without any pretreatment. The method was validated for reserpine in the urine over the range of 1 x 10(-6) - 1 x 10(-4) mol/L with a correlation coefficient of 0.996. The RSD for reserpine at a level of 5 mumol/L was 4.3%. The LOD (S/N = 3) was estimated to be 7.0 x 10(-8) mol/L. The average recoveries for 10 mumol/L reserpine spiked in human urine were 94%.

CE coupling with end-column electrochemiluminescence detection for chiral separation of disopyramide

CE with electrochemiluminescence, (ECL) detection technique was successfully applied for the chiral separation of a kind of class IA antiarrhythmic racemic drug. To the best of our knowledge, this is the first report of ECL detection used in chiral CE. To get better detection sensitivity and good enantioresolution at the same time, the conditions of capillary inlet and outlet buffer were systematically optimized. Unlike the traditional chiral separation method, the buffers we used in the capillary inlet and outlet differed from each other in terms of buffer pH, ionic strength, type of BGE as well as buffer composition. Under the optimum conditions, baseline enantioseparation and highly sensitive detection of the enantiomers were achieved. Wide linear relationship of each enantiomer was achieved in the range of 5 x 10(-7) to 2 x 10(-5) mol/L with relative coefficients of 0.996 and 0.997, respectively. The detection limits were estimated to be 8 x 10(-8) and 1.0 X 10(-7) mol/L (S/N = 3) for the enantiomers, respectively. In addition, a successful application of this new method to the chiral separation of the racemic drug in spiked plasma samples confirmed the validity and applicability of the chiral CE-ECL method.