INTRODUCING EXOGENOUS DNA INTO PLANTS AFTER POLLINATION——DNA TRAVERSE PATHWAY OF POLLEN TUBE TO REACH EMBRYONIC SAC

The technique of introducing exogenous DNA into plants through the pathway of pollen tube after pollination has been applied since 1978 for transformation of the egg, zygote or carly embryonic cells. By introducing the erogenous DNA containing the goal gene(s) into cotton and rice, several new varieties with economic value and genetic stability are obtained. Thus molecular breeding of crops can be realized by this biotechnique.The pollen tube pathway is demonstrated by tritium-labelled cotton DNA (> 50kb). The labelled DNA is injected into cotton ovaries from the center of the top 24 h after selfing. 30 min to 8 h later, the ovaries are removed. It is clearly shown that the exogenous DNA can only pass from the micrnphyle to the opened nucellus, and then reach the embryonic sac. ~3H-DNA can be found in the embryonic sacs 30 min after injection. In more than 80％ of the embryonic sacs ~3H-DNA can be seen between 2 and 4 h after injection. No ~3H-DNA is found inside the pollen tubes. Therefore it is not th     

盛会·启示·希望——亚洲地区实验物理教学会议(LAPE)侧记

(一) 受中国联合国教科文组织全国委员会(Chinese National Commission for UNE SCO)委托,作为亚洲物理教育网(ASPEN)1983年的一次重要活动,在教育部领导下,由北京大学主办的亚洲地区实验物理教学会议(LAPE),9月12日至16日在北京大学勺园旅馆举行。来自澳大利亚、印度、马来西亚、新西兰、菲律宾、新加坡、泰国等国家和香港地区的24名来宾,以及来自国内47所高校、     

溶剂萃取-火焰原子吸收法测定银杏叶提取物中铅镉

提出了用硝酸消解，KI－MIBK系统萃取，火焰原子吸收光谱法测定银杏叶提取物中痕量铅，镉的方法，铅，镉的相对标准偏差均小于4．5％，回收率分别在96．0％－100．0％和97．0％－102．0％之间。测定结果满意。     

流动注射-邻菲啰啉协同催化化学发光法测定痕量的铜

本文拟订了邻菲啰啉-CTMAB-H_2O_2-Co(Ⅱ)-Cu(Ⅱ)协同催化化学发光体系流动注射测定痕量Cu(Ⅱ)的新方法。方法的检出限为8×10~(-12)g/ml Cu(Ⅱ),线性范围为1×10~(-10)-4×10~(-8)g/ml Cu(Ⅱ),相对标准偏差为0.9％分析速度为160样/小时。本法用于头发和水样中Cu(Ⅱ)的测定取得了满意的结果。     

钯－抗坏血酸基体改进剂石墨炉原子吸收光谱法测定食品中的痕量硒

本文用塞曼效应石墨炉原子吸收法测定食品中的硒，研究了各种基体改进剂对硒信号的改进效应，找出最佳的改进剂钯－抗坏血酸，使硒的灰化和原子化都能达到较高温度，在提高灵敏度，降低干扰方面也取得较好的效果。本方法操作简单、快速，灵敏度高，能有效地测定食品中的痕量硒。方法的回收率在９５．６％～１０４．０％之间，其相对标准偏差为３．０％，检出限为４．８５ｎｇ／ｍＬ。     

固定酚红的交联聚乙烯醇光化学pH敏感膜

An optical pH sensitive membrane for optical pH sensors has been developed by covalently immobilizing phenol red on optical transparent cross-linked polyvinyl alcohol （PVA） membrane surfaces. The phenol red was first reacted with acrylamide to form a product of acrylamide grafted phenol red （AAGP）, then the AAGP was covalently immobilized to the PVA membrane via surface grafting-polymerization using Fe^2＋/H2O2 as initiator. The performance of the pH sensitive membrane was investigated and the results showed that the pH sensitive membrane has some features including a linear response scope from pH 6.5 to 8.5 closed with phenol solution, a rapid response time （〈：20 s）, good reproducibility, reversibility, excellent stability and easiness of fabrication. These show that the pH sensitive membrane can be used as a sensitive layer for optical pH sensor.     

[(NaC9H6)Me2CC5H4]2Sm(Ⅱ)(THF)2的合成及其催化MMA聚合的研究

以茚基锂与6, 6-二甲基富瓦烯的环外双键加成反应合成了一个新型取代茂基锂 [(C9H7)Me2C]C5H4Li (1, 其中C5H4代表一取代环戊二烯基), (1)与无水三氯化钐按2∶1摩尔比反应后, 再用与稀土钐的摩尔比为3∶1的钠砂处理, 合成了二价钐的三核双金属配合物[(NaC9H6)Me2CC5H4]2Sm(Ⅱ)(THF)2 (2, 其中C9H6代表茚基). 该配合物经元素分析和红外光谱表征, 并发现 (2) 能高活性地催化甲基丙烯酸甲酯聚合, 得到等规含量较高的聚甲基丙烯酸甲酯.     

Preparation of Medium Cation Exchange Stationary Phase of Polymeric Matrix and Their Chromatographic Properties

Based on the monodisperse poly（glycidyl methacrylate-co-ethylenedimethacrylate） beads （PGMA/EDMA） with macropore as a medium, a new hydrophilic medium cation exchange （MCX） stationary phase for HPLC was synthesized by a new chemically modified method. The stationary phase was evaluated with the property of ion exchange, separability, reproducibility, hydrophilicity, effect of salt concentration, salt types, column loading and pH on the separation and retention of proteins in detail. It was found that it follows ion exchange chromatographic （IEC） retention mechanism. The measured bioactivity recovery for lysozyme was （96 ± 5）%. The dynamic protein loading capacity of the synthesized MCX packings was 21.8 mg/g. Five proteins were almost completely separated within 6.0 min at a flow rate of 4 mL/min using the synthesized MCX resin. The MCX resin was also used for the rapid separation and purification of lysozyme from egg white with only one step. The purity and specific bioactivity of the purified lysozyme was found more than 95% and 70345 U/mg, respectively.     

手性分子中的宇称破缺:D-和L-丙氨酸的变温中子结构研究

利用单晶的中子衍射研究295 K和60 K时丙氨酸对映体的结构特征以及由D到L构型转变的可能性.中子衍射数据揭示了变温过程中产生的晶格扭曲和的扭转. 通过分析宇称破缺能差EPV随二面角及扭角的变化,肯定了D-丙氨酸能量高于L-丙氨酸的结论.降温过程中D-和L-丙氨酸的弱氢键的行为的差异表明,可能是由于电弱相互作用宇称不守恒所引起.丙氨酸中子结构再次证实Cα－H…O氢键的存在.然而,比较295 K和60 K(高于和低于丙氨酸相变温度250 K)的中子衍射结构数据,表明并没有发生D型到L型的构型转化,这意味着Salam相变不是传统意义的结构相变.     

陶工尘肺辅助性诊断的方法研究——测定发中微量元素 建立判别方程

测定了陶工Ｉ期尘肺患者的头发中Ｚｎ、Ｃｕ、Ｓｅ、Ｎｉ、Ｆｅ、Ｍｎ、Ｍｇ７种金属元素，用陶工可疑患者作对照，建立Ｆｉｓｈｅｒ判别方程，对陶工尘肺进行判别。自身回代正确率９４．４４％，前瞻性回代达８３．３３％，各其流行病学指标计算均属良好。