中能重离子碰撞中库仑相互作用对动量耗散的同位旋效应

利用同位旋相关的量子分子动力学模型 ,研究了中能重离子碰撞过程中的库仑相互作用对于动量耗散的同位旋效应 .计算结果表明 :由于库仑相互作用的存在 ,使得碰撞过程中的化学不稳定区和力学不稳定区减小 ,明显地减弱了动量耗散 ;其减弱的程度与对称势的形式及强度有关 ,对称势越强则动量耗散的减弱幅度越大 .动量耗散灵敏地依赖于核子 核子碰撞截面的同位旋相关性而较弱地依赖于对称势 ,这一特征不论有无库仑相互作用均存在 .

Simulations to design an online motion compensation system for scanned particle beams

Respiration-induced target motion is a major problem in intensity-modulated radiation therapy. Beam segments are delivered serially to form the total dose distribution. In the presence of motion, the spatial relation between dose deposition from different segments will be lost. Usually, this results in over-and underdosage. Besides such interplay effects between target motion and dynamic beam delivery as known from photon therapy, changes in internal density have an impact on delivered dose for intensity-modulated charged particle therapy. In this study, we have analysed interplay effects between raster scanned carbon ion beams and target motion. Furthermore, the potential of an online motion strategy was assessed in several simulations. An extended version of the clinical treatment planning software was used to calculate dose distributions to moving targets with and without motion compensation. For motion compensation, each individual ion pencil beam tracked the planned target position in the lateral aswell as longitudinal direction. Target translations and rotations, including changes in internal density, were simulated. Target motion simulating breathing resulted in severe degradation of delivered dose distributions. For example, for motion amplitudes of +/- 15 mm, only 47% of the target volume received 80% of the planned dose. Unpredictability of resulting dose distributions was demonstrated by varying motion parameters. On the other hand, motion compensation allowed for dose distributions for moving targets comparable to those for static targets. Even limited compensation precision (standard deviation similar to 2 mm), introduced to simulate possible limitations of real-time target tracking, resulted in less than 3% loss in dose homogeneity.

含硝基腐植酸、DCD的氮肥增效剂对水稻生育性状及产量影响的试验研究

<正> 我国农业生产中的主要氮素化肥是尿素和碳酸氢铵。随着作物产量的提高,施用氮肥量也不断增加,但由于施入土壤中的尿素或碳酸氢铵分解速度快,有相当一部分氮素作物尚未吸收利用就流失或挥发而浪费掉。据测定,尿素中氮素利用率只有35％,碳酸氢铵氮素利用率仅15～25％。本试验结果表

辽宁山羊绒品质分析

辽宁山羊绒品质分析李文清麻岩＊李亚乔＊王丽霞刘丹张长恩（中国科学院沈阳应用生态研究所，沈阳１１００１５）（＊辽宁省纤维检验所）在制定《山羊原绒》国家标准过程中，先后对全国山羊绒主产区的内蒙古、新疆、辽宁、太行山地区，西北地区进行了调研，采集和索取了全...

生物制剂对沙土樟子松幼苗光合特性及养分含量的影响

采用盆栽试验研究了Pt菌剂、ABT生根粉、HRC吸水剂和FCS丰产素等生物制剂对沙地樟子松2年生幼苗光合特征和养分含量的影响,结果表明:Pt菌剂(3号)和ABT生根粉与对照相比,显著地促进了樟子松幼苗全株、地下和地上生物量生长,并增加了幼苗的根冠比值,有利地促进幼苗对养分的吸收;Pt菌剂(3号)和ABT生根粉处理的幼苗叶子养分全N、P、K含量显著地高于对照幼苗,促进了幼苗养分的平衡,为提高光合作用能力提供了物质基础;Pt菌剂(3号)和ABT生根粉处理幼苗与对照相比,光合速率和蒸腾效率显著增强。这些是提高樟子松苗木在干旱、半干旱沙地成活生长的生理基础。

采用了剪枝优化的子类型关系判定算法

静态类型化XML处理语言为处理XML数据提供了新的途径,但现有的此类语言大多数效率较低.研究此类语言的一个重要问题——子类型关系的判定,并使用剪枝优化策略对XDuce的子类型关系判定算法进行优化.实验数据显示,优化后算法的执行效率平均提高20%.该策略具有普遍性,对所有使用类似算法的静态类型化XML处理语言都有效.

全球环境管理理念对中国的启示

首先介绍了“全球环境管理”(globalenvironmentalgovernance)理念产生的背景、含义与国际发展态势．全球环境管理是一种多元化、多层面、多视角的理念,包括管理全球环境的制度、法则、规范、标准及其过程与行为．国际上,全球环境管理研究已开始从理念探讨向实践转化．在此基础上,概述了中国参与全球环境管理所面对的挑战和机遇．最后提出,为了更加有效地参与全球环境管理,我国应该：重视提炼关键科学问题,加强原始性创新研究；制定我国参与全球环境管理的发展战略；建立长期有效的高端协调机制；完善配套政策与

Phenylthiolate as a sigma- and pi-donor ligand: synthesis of a 3-D organometallic coordination polymer [K2Fe(SPh)(4)](n)

The synthesis and crystal structure of the first mixed-metal organometallic polymer network containing phenylthiolato ligands, [K2Fe(SPh)(4)](n), are investigated. The simple phenyl-thiolate acts as a sigma- and pi-donor ligand to give a 3-D potassium iron coordination polymer with both metal-carbon and metal-sulfur coordination interactions.

Voltammetric study of the sodium ion transfer across micro-water/1,2-dichloroethane interface facilitated by terminal-vinyl liquid crystal crown ether

Sodium ion transfer across micro-water/1,2-dichloroethane (DCE) interface facilitated by a novel ionophore, terminal-vinyl liquid crystal crown ether (LCCE) was studied by cyclic voltammetry. LCCEs have potential applications because of their physicochemical properties and the utilization of crown ethers as selective ionophoric units in other functionalized compounds are interesting. Host-guest-type behavior for such compounds in the liquid-crystalline state is studied. The experimental results suggest that the transfer of the sodium ion facilitated by LCCE was controlled by diffusion of LCCE from bulk solution of DCE to the interface. The diffusion coefficient of LCCE in DCE was calculated to be equal to (3.62 +/- 0.20) x 10(-6) cm(2)/s. Steady-state voltammograms are due to sodium ion transfer facilitated by the formation of 1: 1 metal (M)-LCCE complex at the interface and the mechanism tends to be transfer by interfacial complexation or dissociation (TIC or TID). The stability constant of the complex formed was determined to be log beta(o) = 5.5 in DCE phase. The influence of parameters such as concentration of sodium ion and concentration of LCCE on the sodium ion transfer was investigated.

Meldola拉蓝修饰双层类脂膜的电化学研究

双层类脂膜(BLM)作为生物膜的基本结构主体已被广泛接受。通过掺杂和化学修饰可以改变BLM的特性,并能应用于多种生物膜过程的研究。特别是制成生物传感器和双分子电子器件将有广阔的应用前景。多种有机染料被称作生物着色剂并常用于生物学、生理学、药物学和医学。一般来说,染色和着色过程包括吸附、溶解、渗透和化学反应。但染料如何影响磷脂膜仍然不十分清楚。本文选用用于生物传感器中的生物催化剂Meldola蓝来修饰BLM,并对它的传输性质进行了分析。

含联苯结构侧链液晶聚合物的合成及相行为的研究

液晶聚合物从结构上可分为3种:侧链型、主链型和主侧链型。侧链型液晶聚合物主要是聚丙烯酸酯类、聚硅氧烷类以及磷腈聚合物类。Gray等对聚丙烯酸酯类含不同取代基的联苯结构液晶聚合物进行了研究,结果表明无间隔基且取代基为氰基和饱和脂肪基时,该聚合物呈现近晶型液晶行为。为了增加介晶单元的长径比及刚性,本文在聚甲基丙烯酸酯侧链

α-羰基烯酮环二硫代缩醛化学(Ⅹ)——β,β-1,5-亚丙二硫基-α,β-不饱和酮与烯丙基Grignard试剂加成物的酸催化反应取向研究

β,β-1,5-亚丙二硫基-α,β-不饱和酮2b和2-甲基烯丙基氯化镁加成可得醇3b.在BF_3·Et_2O催化下,3b经分子内环合芳构化生成芳硫醚5b.2和烯丙基溴化镁反应得醇4,4在BF_3·Et_2O催化下经β-消除脱水生成共轭多烯类化合物6.二硫缩醛基以环和非环结构及环的大小对2与烯丙基Grignard试剂加成物在酸催化下的反应取向有重要影响.