重离子束注入小麦胚乳诱发的突变效应

采用 75MeV u16O8+ 离子 (降能至 36MeV u ,使其在胚乳中的射程约为 2 4mm ) ,从种子顶部垂直注入胚乳 ,通过“嫁接”技术后进行萌发。处理后观测结果表明 ,当代根尖细胞染色体的微核率和畸变率与注入剂量呈正相关 ;测定了当代抗氧化酶活性、丙二醛 (MDA)含量和蛋白质含量的变化 ;经多代大田培育获得了矮杆与各种穗型的变异 ,且具有遗传性。结果显示离子注入胚乳不仅对生物的修复系统有较大影响 ,而且能够诱发后代突变。

K-600中子发生器辐射防护的改进

目的　对K -60 0中子发生器原有的辐射防护做出评价 ,提出改进措施。方法　使用高灵敏度中子探测器和γ监测器 ,对中子发生器运行时n、γ辐射进行了全面的测量并对辐射场围周的防护设施进行改造。结果　改造前在中子厅西、南屏蔽墙外表面有贯穿辐射 ,特别是中子发生器建筑物项部表面有明显的贯穿辐射 ,并且在距离辐射源 3 0～ 40m处呈现峰值 ,显示出天空反射的效果。改造后辐射场外部周围贯穿辐射大为减弱。结论　通过改进措施达到了降低贯穿辐射的目的

基于MSP430F149的串口通讯设计

文章介绍了美国TI公司新一代16位Flash型MSP430F149系列单片机的结构、特性和功能,并给出了该单片机与上位机(PC)利用串行口进行通讯的实例,详细介绍了如何利用VC++6.0进行串口通讯程序的编制,重点介绍了Windows API实现异步通讯的方法。

基于MSC1210单片机的串口通讯设计

本文介绍了内核兼容8051的MSC1210单片机结构、特性和功能,并给出了该单片机与上位机(PC)利用串行口进行通讯的实例,详细介绍了如何利用VC++6.0进行串口通讯程序的编制,重点介绍了Windows API实现异步通讯的方法。

高电荷态金属离子的产生实验研究

　为满足兰州重离子加速器的实验要求,在14.5GHz高电荷态ECR离子源上做了一系列产生金属离子的实验,尝试了多种方法,包括炉子加热及MIVOC(MetallicIonformVolatileCompounds)两种方法,其中,用炉子做的结果较理想。实验主要研究了铜、锌、镍多种电荷态离子的产生,具有代表性的是39euA的Cu13+,30euA的Zn15+和29euA的Ni10+。分别给出了这三种金属离子产生的多电荷态束流峰谱图,以及实验的一些其它现象及结果,并对其进行了讨论与总结。

Light alkenes preparation by the gas phase oxidative cracking or catalytic oxidative cracking of high hydrocarbons

The preparation of light alkenes by the gas phase oxidative cracking (GOC) or catalytic oxidative cracking (COC) of model high hydrocarbons ( hexane, cyclohexane, isooctane and decane in the GOC process and hexane in the COC process) was investigated in this paper. The selection for the feed in the GOC process was flexible. Excellent conversion of hydrocarbons ( over 85%) and high yield of light alkenes ( about 50%) were obtained in the GOC of various hydrocarbons including cyclohexane at 750 degreesC. In the GOC process, the utilization ratio of the carbon resources was high; CO dominated the produced COX (the selectivity to CO2 was always below 1%); and the total selectivity to light alkenes and CO was near or over 70%. In the COC of hexane over three typical catalysts (HZSM-5, 10% La2O3/HZSM-5 and 0.25% Li/MgO), the selectivity to COX was hard to decrease and the conversion of hexane and yield of light alkenes could not compete with those in the GOC process. With the addition of H-2 in the feed, the selectivity to COX was reduced below 5% over 0.1% Pt/HZSM-5 or 0.1% Pt/MgAl2O4 catalyst. The latter catalyst was superior to the former catalyst due to its perfect performance at high temperature, and with the latter, excellent selectivity to light alkenes ( 70%) and the conversion of hexane (92%) were achieved at 850 degreesC ( a yield of light alkenes of 64%, correspondingly).

Synthesis of substituted pyridyl ureas by selenium dioxide-catalyzed carbonylation

A series of commercially useful substituted pyridyl ureas have been synthesized via selenium dioxide-catalyzed reductive carbortylation of substituted nitrobenzene or substituted nitropyridine with amine as co-reagent and carbon monoxide as carbonyl reagent instead of phosgene in one-pot reaction. The recycling reusability of catalyst was also tested. It was also found that selenium dioxide-catalyzed reductive carbonylation of nitroaromatics exhibited reaction-controlled phase-transfer phenomena of the catalyst. (C) 2003 Elsevier B.V. All rights reserved.

Selective formation of aromatic amines by selenium-catalyzed reduction of aromatic nitro compounds with CO/H2O under atmospheric pressure

An efficient method for the catalytic reduction of aromatic nitro compounds to the corresponding aromatic amines is reported. In the presence of selenium as a catalyst, the aromatic nitro compounds are quantitively reduced by CO/H2O to form the corresponding amines under atmospheric pressure. The reduction occurs in high selectivity regardless of other reducible functionalities present on the aromatic ring. There exists a phase transfer process of the catalyst selenium in the reaction. (C) 2004 Elsevier B.V. All rights reserved.

Preparation of monolithic column and its application in p-CEC

A novel monolithic stationary phase having long alkyl chain ligands was introduced and evaluated in pressurized-capillary electrochromatography of small neutral and charged compounds. The monolithic column was prepared by the in situ copolymerization of ethylene dimethacrylate, 1-hexadecene, allyl alcohol and 2-acrylamido-2-methyl-1-propanesulfonic acid in a quaternary porogenic solvent mixture consisting of 1,4-butanediol, cyclohexanol, dodecanol and water.

Cluster assistant generation of C2+ and C3+ ions in nanosecond laser ionization of seeded benzene beam

Cluster assisted photoionization processes of benzene, which was seeded in argon, induced by an intense 25 ns Nd-YAG laser has been studied by means of time-of-flight mass spectrometry. At the laser intensity of 10(11) W/cm(2), multicharged ions Cq+ (q = 2-3) with kinetic energy up to 150 eV were observed in the mass spectra. Strong evidences Support that these ions are formed in the Coulomb explosion of multicharged benzene cluster ions. (C) 2004 Elsevier B.V. All rights reserved.

The geometry of the NO2- anion: ab initio calculations and Franck-Condon analysis

Geometry optimization and harmonic vibrational frequency calculations have been performed on the (X) over bar (2)A(1) state of NO2 and (X) over bar (1)A(1) state of NO2-. Franck-Condon analyses and spectral simulations were carried out on the NO2((X) over bar (2)A(1))-NO2-((X) over bar (1)A(1)) photo detachment process. In addition, the equilibrium geometry parameters, r(NO)= 1.248 +/- 0.005 Angstrom and angle(ONO) 116.8 +/- 0.5degrees, of the (X) over bar (1)A(1) state of NO2-, are derived by employing an iterative Franck-Condon analysis procedure in the spectral simulation. Our conclusions regarding the anion geometry suggest a reinterpretation of the results of Woo et al. (C) 2004 Published by Elsevier B.V.

Prediction of soil organic carbon partition coefficients by soil column liquid chromatography

To avoid the limitation of the widely used prediction methods of soil organic carbon partition coefficients (K-OC) from hydrophobic parameters, e.g., the n-octanol/water partition coefficients (K-OW) and the reversed phase high performance liquid chromatographic (RP-HPLC) retention factors, the soil column liquid chromatographic (SCLC) method was developed for K-OC prediction. The real soils were used as the packing materials of RP-HPLC columns, and the correlations between the retention factors of organic compounds on soil columns (k(soil)) and K-OC measured by batch equilibrium method were studied. Good correlations were achieved between k(soil) and K-OC for three types of soils with different properties. All the square of the correlation coefficients (R-2) of the linear regression between log k(soi) and log K-OC were higher than 0.89 with standard deviations of less than 0.21. In addition, the prediction of K-OC from K-OW and the RP-HPLC retention factors on cyanopropyl (CN) stationary phase (k(CN)) was comparatively evaluated for the three types of soils. The results show that the prediction of K-OC from k(CN) and K-OW is only applicable to some specific types of soils. The results obtained in the present study proved that the SCLC method is appropriate for the K-OC prediction for different types of soils, however the applicability of using hydrophobic parameters to predict K-OC largely depends on the properties of soil concerned. (C) 2004 Elsevier B.V. All rights reserved.

DNA分析技术及其在植物研究中的应用

从DNA/DNA杂交、RFLP分析、DNA的限制酶图谱和核苷酸序列分析、PCR技术、DNA指纹技术、RAPD分析等六个方面详细描述DNA分析技术在植物学研究中的应用 ,并讨论了DNA分析技术与植物系统学的关系。

MutL融合蛋白的高效表达及其伴侣功能研究(英文)

DNA错配修复蛋白MutL和其它的修复蛋白相互作用来共同完成大肠杆菌甲基介导的错配修复过程 .为研究修复蛋白MutL的体外生物功能构建了融合蛋白Trx His6 Linkerpeptide MutL(THLL)的表达载体并使其高效表达及易于纯化 .mutL基因片段是以E .coliK 12基因组为模板经PCR扩增获得 ,并通过基因的体外拼接成功构建了融合蛋白THLL表达载体pET32a linkerpeptide mutL .重组菌株E .coliAD4 94 (DE3) pET32a linkerpeptide mutL经过IPTG的诱导表达了融合蛋白THLL .收集菌体细胞、超声波破碎后离心取上清进行SDS PAGE分析 ,结果表明有一与预期分子量(84kD)相应的诱导表达条带出现 ,其表达量约占全细胞蛋白的 30 %且以可溶形式存在 .利用固定化金属离子 (Ni2 +)配体亲和层析柱纯化融合蛋白THLL ,其纯度达到 90 % .通过非变性凝胶电泳分析 ,对融合蛋白THLL在DNA错配修复过程中的分子伴侣生物功能进行了系统研究 .结果表明 ,THLL能增加融合蛋白Trx His6 Linkerpeptide MutS (THLS)与含有错配碱基DNA双链的结合 ,但受ATP的浓度变化影响很大