高电荷态离子Ar~(q+)与Nb作用产生的X射线谱

利用光谱技术在超导离子源SECRAL上研究了10~20keV·q的Arq+(q=16,17)离子入射在金属Nb表面产生的X射线谱.实验结果表明,高电荷态Ar16+离子在金属表面中性化过程中存在着多电子激发,Ar16+的K壳层电子被激发产生空穴,级联退激发射Ar的Kα特征X射线.Ar空心原子的K层发射X射线的强度随入射离子的动能减弱,靶原子Nb的L层发射X射线强度随入射离子动能的增加而增强.Ar17+单离子的Kα-X射线产额比Ar16+单离子的Kα-X射线产额大3个数量级.

观赏植物诱变育种的研究现状和展望

本文综述了观赏植物辐射诱变育种的研究现状,并对花卉辐照诱变的手段、方法、处理材料和适宜辐照剂量、辐照机理与方法及应用作了总结,同时对观赏植物辐射诱变育种存在的问题及发展方向进行了探讨。

超重核合成理论模型简介

介绍并讨论了研究超重核合成的主要理论模型以及近年来在研究重核熔合机制和超重核合成理论模型方面的进展。

Boron isotopic fractionation during seawater evaporation

IEECAS SKLLQG

动量相关作用对两体耗散同位旋效应的重要性

利用同位旋相关的量子分子动力学 ,研究了中能重离子碰撞中动量相关的状态方程对原子核阻止基于两体耗散的同位旋效应的影响 .计算结果表明原子核阻止对同位旋相关和同位旋无关的核子 -核子碰撞截面 (两体耗散 )的差值强烈地依赖于动量相关势 ,即在有动量相关势的情况下原子核阻止对同位旋相关和同位旋无关的核子 -核子碰撞截面的差值大于没有动量相关势的情况 .这就意味着动量相关作用明显地提高了原子核阻止对于核子 -核子碰撞截面的灵敏性 .因此 ,在考虑动量相关势的情况下 ,原子核阻止可以更准确地作为提取同位旋相关的核子 -核子碰撞截面的一个探针

重离子辐照苯并呋咱N-氧化物对其抗菌作用的影响

用重离子 12 C6+ ,16O8+辐照苯并呋咱 N-氧化物 ,结果表明 ,重离子 16C8+可使其结构改变10 %以上 ,382 nm、2 6 2 nm、2 4 0 nm特征峰随其含量的下降而变低平 ,并生成多种辐射产物 ,辐射后抗菌作用明显增强

Double neutron/proton ratio of nucleon emissions in isotopic reaction systems as a robust probe of nuclear symmetry energy

The double neutron/proton ratio of nucleon emissions taken from two reaction systems using four isotopes of the same element, namely, the neutron/proton ratio in the neutron-rich system over that in the more symmetric system, has the advantage of reducing systematically the influence of the Coulomb force and the normally poor efficiencies of detecting low energy neutrons. The double ratio thus suffers less systematic errors. Within the IBUU04 transport model the double neutron/proton ratio is shown to have about the same sensitivity to the density dependence of nuclear symmetry energy as the single neutron/proton ratio in the neutron-rich system involved. The double neutron/proton ratio is therefore more useful for further constraining the symmetry energy of neutron-rich matter.

Investigation of add-back effects in a segmented Clover detector

The resolution and the summing characteristics of an EXOGAM segmented Clover germanium detector has been studied for use it in gamma spectroscopic experiments. The measurements have been performed with standard radioactive sources of Eu-152, Ba-133 and beta-delayed gamma-rays from Ir-176 decay. The data analytic results, realized by software, are presented in this paper.

大黄素甲基化衍生物的生物活性

在实验室内以天然存在的大黄素(emodin)为原料合成了甲基化衍生物大黄素甲醚(physcion)和三甲氧基大黄素(trimethoxyemodin),并进行了杀菌和杀虫活性研究,发现3个蒽醌类化合物对黄瓜白粉病(Sphaerotheca fuliginea)的活性有明显差异,其EC90值分别为56.291、3.382、102.699mg/L,大黄素甲醚的活性远高于大黄素、三甲氧基大黄素和对照药剂三唑酮,说明大黄素母环上3-OH以甲基取代杀菌活性会显著提高,而3个羟基均被甲基取代活性会降低。在对甜菜夜蛾(Spodoptera exigua)幼虫的活性测定中,发现三甲氧基大黄素对甜菜夜蛾幼虫的生理活动具有明显的抑制作用,在4000mg/L下对2龄和3龄幼虫的体重增长抑制率分别为99.6%和99.2%,而大黄素和大黄素甲醚则对其无明显影响。

镉胁迫对小麦幼苗生长及生理特性的影响

主要研究了重金属Cd污染对小麦生长和部分生理特性的影响。结果表明,叶绿素含量在0 2 5mmol·L-1Cd处理浓度时达到峰值,随Cd浓度的增加,含量下降。超氧化物歧化酶(SOD)、过氧化物酶(POD)活性随Cd浓度的增加而增加。丙二醛含量和细胞膜透性同样呈上升趋势。根系活力表现为先升高后下降的变化趋势。Cd胁迫下,小麦的生长受到一定程度的抑制,并随溶液中Cd浓度的增加,抑制加重

Dinoflagellate Cysts as Indicators of Cultural Eutrophication in the Oslofjord, Norway

Dinoflagellate cyst records were analysed from four sediment cores from the inner Oslofjord. The cores covered the pre-industrial period, and the most important period of human population growth associated with industrial development of the region, from the mid-1800s to the present, including the reported development of cultural eutrophication. Comparisons between the cyst records and the known history of eutrophication suggest cyst signals that should prove useful for tracing the development of eutrophication. The eutrophication signal consisted of a doubling of total cyst concentration, and a marked increase in one species in particular,Lingulodinium machaerophorum(from <5 to around 50% of the assemblages) with increased eutrophication. In the core considered most representative of general water quality in the inner fjord, these trends reversed back to pre-industrial levels during the 1980s and 1990s when improved sewage treatment took effect.

知识和智慧的载体

前　　言　　在新世纪开初 ,欣逢《植物生理学通讯》创刊 5 0周年。本刊新组建的编委会决定循 4 0周年时的前例 ,也举行一次活动(包括出版“特辑”和召开座谈会 )。于是我们约请了一些人士撰写了纪念文稿 ,同时也收到了一些自发来稿 ,编辑了这个“特辑”。作者从九十高龄的娄成后先生 ,直到年轻的在读研究生 ,他们在文章中高度评价了本刊的作用和成就 ,同时也对本刊寄予了殷殷厚望 ,可以说代表了当今植物生理学界几代人的心声。这里 ,谨向他们表示由衷的感谢 !文稿中大都冠有“祝贺《植物生理学通讯》创刊 5 0周年”的副标题 ,为避免重复 ,一律舍去了。还有几篇文章题目雷同 ,我们作了改动。并此说明。———编者