细辛菌核疫病Sclerotinia asari的研究——Ⅱ.侵染与发病规律

细辛菌核疫病的主要侵染来源是菌丝体。在自然条件下菌核则难以直接萌发和侵染。此菌的子囊孢子致病力很弱,构成初侵来源的可能性极小。病菌以穿透方式侵入,潜育期一般为22～48小时左右。病菌的侵染力以新生菌丝体最强;老化菌丝体较弱;形成白色菌核后则难于侵染。室内接种试验结果,侵染的起点温度为1℃±,适温为10℃左右,24℃±为侵染的临界高温,27℃以上基本不能侵染。低温(10℃左右),侵染性菌丝生长旺盛,休眠体—菌核产生的少而慢,高温 (18℃以上) 菌核产生的多而快。侵染及发病与细辛苗龄无相关性。病菌从根、茎、叶均可侵入,以伤口侵入稍快。病害的传染来源主要为带有菌丝体的病苗、病土、病种等等。田间发病规律为,首先出现中心病株,进而产生中心病点、中心病床,再经传播形成较大的中心病区。在自然传播中,农事操作等人为活动往往起着重要作用。病害基本上不能借空气传播,扩展速度较慢。但形成病田之后整个耕层被病菌占据,很难防治。由于病菌在较低的温度下旺盛活动,田间发病大致分为:春季发病期、初夏扩展期、盛夏中止期、秋季发病期和冬季休眠期五个阶段。     

玉米弯孢菌叶斑病抗性机制的初步研究

玉米弯孢菌叶斑病菌［Curvularialunata（Wakker）Boed．］侵染不同抗性品种后,寄主叶片防御酶系和PR蛋白活性的变化及叶片汁液对病菌孢子萌发有影响,研究发现：PAL,PO,SOD和β-1,3-葡聚精酶在对弯孢菌叶斑病的抗性中起到一定的作用,尤其是PR蛋白β-1,3-葡聚糖酶活性在抗性机制中发挥更为重要的作用。木质素可能是在病菌侵染初期发挥抗侵入的作用。抗病品种叶片汁液可能含有抑菌物质,病菌侵染有利于刺激这种物质抑菌作用的提高,在抗病品种中更为明显。     

白菜霜霉病侵染规律的研究

1981至1983年进行了白菜霜霉病的初次侵染来源与侵染过程的研究。试验证实,该病的初次侵染来源来自病叶内的卵孢子和带病种子。接种试验表明,病叶内卵孢子经室内保存及冰箱处理或室外越冬后分别进行定量接种,结果幼苗均易发病,并表现有限系统侵染,与播种带病种子出现的病苗症状相同。经组织解剖均发现病子叶与病茎内有大量菌丝和吸器,说明病种子内存在潜伏菌丝,一般感病品种带菌率较高。室内卵孢子发芽试验亦获得成功,卵孢子发芽前用流水冲洗7～9天,发芽适温25℃,用糠醛(100微升/升)可控制污染。用病菌孢子囊接种离体叶和幼苗进行侵染过程观察,同样发现在细胞间隙发育的菌丝,并产生吸器。离体叶培养也是保存菌源的较好方法,保存时间可达15～20天。     

小麦秆锈病侵染机率的叶部试验研究

人工气候室条件下于感病的小麦品种上研究了不同露温（５，１０，１５，２０，２５，３０℃）与不同露时（２，４，６，８，１０，１２，１４，１６，１８，２０，２２，２４ｈ）组合下小麦秆锈病的侵染机率。得出侵染最适条件范围，即露温为１５～２５℃；露时为１０～１８ｈ。本文首次在秆锈侵染的研究中应用了侵染机率的概念，组建了侵染机率（ＩＰ）因露温（ＤＴ）和露时（ＤＰ）而变的预测式：ＩＰ＝－９．８７９２＋０．２７４６（ＤＰ）＋１．４９４７（ＤＴ）－０．０３９８７（ＤＴ２）（Ｒ＝０．８８７４）     

玉米抗腐霉菌茎腐病超微结构的研究

超微结构观察表明,抗茎腐病玉米品种冀丰５８号幼苗根组织被肿吓腐霉菌侵染后,细胞迅速出现严重的质壁分离,质膜消失、各种细胞器紊乱破碎。侵入根组织的肿囊腐霉菌数量少,幼嫩且形态异常,菌丝外周或整个菌丝中出理一些电子致密物质,可能与发生过敏性坏死反应有关。感颈腐病品种掖单１３号幼苗根组织被侵染细胞的壁完整,但细胞质凝聚或细胞器发生解体。根组织内在大量胞间及胞内生长菌丝,菌丝较成熟、粗壮,含大量的泡囊及线粒体,结构正常。氟乐灵浸种后再接种肿囊腐霉,玉米根系的超微结构较单独接种肿囊霉处理有明显的不同,抗病品种的ＨＲ反应更加剧烈、迅速,甚至感病品种也被诱导产生了ＨＲ反应,尤其是被侵染细胞及其临近细胞有大量近球形的电子致密物质沉积,该物质可能与抗性有关。这些电子致密物质在抗感品种上均有出现,在单独接种肿囊腐霉处理中出现很少。     

细辛菌核疫病的研究 Ⅲ.细辛核盘菌有性世代的产生及其侵染规律

细辛核盘菌 Sclerotinia asari Wu et C.R.Wang.在罹病细辛的地上部及整个根部可以形成大量茵核;这些菌核能否直接萌发侵染或形成有性世代借空气传播。这是病害侵染循环中的中心问题。试验结果表明:细辛核盘菌的菌核在自然条件下难以直接萌生菌丝体而发生侵染;而它的主要萌发形式是产生子囊盘,由于子囊盘的产生对湿度条件要求比较严格,因此其萌发机率较低,而且其子囊孢子因受树叶阻隔,也不易放射传播。菌核可在春秋两季萌发,但秋后因天气寒冷,只能形成子囊盘柄,不能出土,春季子囊盘出土起始于4月15～20日,终止于5月20日左右。子囊孢子放射起始于4月26日,终止于5月19日。子囊孢子的寿命为48小时至33天,子囊孢子以在细辛汁液中最易萌发,并只能从叶部伤口侵入,致病力较弱,构成初侵来源的可能性极小。如果排除有性世代的空气传播,细辛菌核疫病则应确定为捡疫性病害。根据 Adams 和 Ayers(1979)报道,有许多 Sclerotinia SPP 的子囊孢子可以藉风力传播而产生侵染,杨新美(1961)、H.J.Willetts et J.A.—L Wong(1980)等也报道 Sclerotinia sclerotiorum 的主要侵染来源是子囊孢子;而 S.minor的菌核可直接萌发侵染致病。细辛核盘菌能够在病田中产生大量菌核,但它究竟能否萌发产生侵染或产生子囊孢子借空气传播,这是病害侵染循环中的一个中心问题。为弄清这个问题,作者从1979～1984年对细辛核盘菌菌核的萌发、有性世代的产生及其侵染规律进行了系统的研究,本文报道这方面的试验结果。     

人参黑斑病的研究——Ⅰ.损失调查、病原菌及发病规律

人参黑斑病可使参根减产0.4～1.6倍;重者达10倍以上。人参黑斑病菌Alternaria panax whetz.原取名西洋参;经测定辽宁的分主孢子尺度明显偏大。接种和调查29种杂草,在参场内未见其它奇主.分生孢子萌发的起点温度为1℃±;最适为20～25℃。孢子以在人参叶汁、1％糖水、露水和饱和湿度下萌芽率最高:在蒸馏水、自来水中萌芽率最低;土壤对孢子萌发有强烈抑制作用。病害的侵染来源是分生孢子,以穿透方式侵入,潜育期24～48小时,接种3～6天产生孢子,且病部可反复多次产生,每平方厘米病叶可产孢4,107～51,120个;越冬病叶也可再次产生孢子和造成侵染。孢子没有休眠期,随时可以萌发侵染,但不能为害木质化的茎秆。黑斑病具有小区内局部流行特点。孢子体形大,浮动传播较差,田间菌源的多少与发病成正相关。据辽宁的气象条件,人参产区是黑斑病的长发区。     

制种玉米黑束病在不同土壤生态环境下发病规律的研究

在甘肃张掖大规模制种过程,采用人工调控土壤生态环境和田间调查方法,针对不同土体温度、湿度、酸碱度、养分含量,研究了菌丝体的生长状况和对寄主侵染的规律,提出了抗病品种为主的栽培措施以外的以调控土壤环境为主的防治方法.结果表明:致病菌枝顶头孢霉Acrrmonium strictum W.Gams在土壤pH7.0-8.0时生长迅速;生长适温为28～32℃,较菌丝体在培养基上的适温高;当绝对含水量在10%或20%时生长迅速;肥力因子N、K、P素对该病的影响较大,养分有效N素含量高、有效P素含量低、有效K含量不足发病重;病菌对幼苗的侵染也具明显的规律性,高温高湿有利于病菌对幼苗的侵染,病情指数增高,感病品种较抗病品种病情指数低.     

终端打印机接口程序的分析与设计

用小麦白粉病菌１１个生理小种的混合菌种，对内蒙古地区小麦近缘野生植物的５个属１２个种３４份材料进行接种，全部接种成功。用其中５个属１０个种２７２２发小麦近缘野生植物产生的白粉病菌，对小麦进行回接，亦全部回接成功。小麦白粉病菌生理小种对小麦近缘野生植物的寄生，像在小麦上一样，有明显的寄生专化性。感病小近缘野生植对小麦白粉病的感病性，随生育期产长而下降。     

玉米纹枯病菌致病因子的研究

首次研究了五米纹枯病菌（RhizoctoniasolaniAG1-IA）产生的细胞壁降解酶和毒素在病程中的作用。纹枯病菌主要产生PG、PMG和Cx共3种细胞壁降解酶和毒素．细胞壁降解酶和毒素对叶片和叶鞘有明显浸解作用,其中酶比毒素作用明显,但用单一酶或毒素代替病菌接种不同抗性品种,尚不能反映品种间抗性差异。病菌产生的细胞壁降解酶活性受温度、pH、反应时间和底物浓度等因素影响。     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.     

Editorial: Special issue on recent advances in hybrid control theory and applications

正The demands of a rapidly advancing technology for faster and more accurate controllers have always had a strong influence on the progress of automatic control theory.In recent years control problems have been arising with increasing frequency in widely different areas,which cannot be addressed using conventional control techniques.The principal reason for this is the fact that a highly competitive economy is forcing systems to operate in regimes where     

Information for Authors

正Aim The Journals of Zhejiang University-SCIENCE(A/B/C)areedited by the international board of distinguished Chinese andforeign scientists,and are aimed to present the latest devel-opments and achievements in scientific research in China andoverseas to the world’s scientific circles,especially to stimulateand promote academic exchange between Chinese and for-eign scientists everywhere.     

Enhancing a leaf radiative transfer model to estimate concentrations and in vivo specific absorption coefficients of total carotenoids and chlorophylls a and b from single-needle reflectance and transmittance

The relative concentrations of different pigments within a leaf have significant physiological and spectral consequences. Photosynthesis, light use efficiency, mass and energy exchange, and stress response are dependent on relationships among an ensemble of pigments. This ensemble also determines the visible characteristics of a leaf, which can be measured remotely and used to quantify leaf biochemistry and structure. But current remote sensing approaches are limited in their ability to resolve individual pigments. This paper focuses on the incorporation of three pigments—chlorophyll a, chlorophyll b, and total carotenoids—into the LIBERTY leaf radiative transfer model to better understand relationships between leaf biochemical, biophysical, and spectral properties.Pinus ponderosa and Pinus jeffreyi needles were collected from three sites in the California Sierra Nevada. Hemispheric single-leaf visible reflectance and transmittance and concentrations of chlorophylls a and b and total carotenoids of fresh needles were measured. These data were input to the enhanced LIBERTY model to estimate optical and biochemical properties of pine needles. The enhanced model successfully estimated reflectance (RMSE = 0.0255, BIAS = 0.00477, RMS%E = 16.7%), had variable success estimating transmittance (RMSE = 0.0442, BIAS = 0.0294, RMS%E = 181%), and generated very good estimates of carotenoid concentrations (RMSE = 2.48 µg/cm², BIAS = 0.143 µg/cm², RMS%E = 20.4%), good estimates of chlorophyll a concentrations (RMSE = 10.7 µg/cm², BIAS = − 0.992 µg/cm², RMS%E = 21.1%), and fair estimates of chlorophyll b concentrations (RMSE = 7.49 µg/cm², BIAS = − 2.12 µg/cm², RMS%E = 43.7%). Overall root mean squared errors of reflectance, transmittance, and pigment concentration estimates were lower for the three-pigment model than for the single-pigment model. The algorithm to estimate three in vivo specific absorption coefficients is robust, although estimated values are distorted by inconsistencies in model biophysics. The capacity to invert the model from single-leaf reflectance and transmittance was added to the model so it could be coupled with vegetation canopy models to estimate canopy biochemistry from remotely sensed data.     

Mr. Twinn’s bombes

This article discusses the history and design of the special versions of the bombe key-finding machines used by Britain’s Government Code & Cypher School (GC&CS) during World War II to attack the Enigma traffic of the Abwehr (the German military intelligence service). These special bombes were based on the design of their more numerous counterparts used against the traffic of the German armed services, but differed from them in important ways that highlight the adaptability of the British bombe design, and the power and flexibility of the diagonal board. Also discussed are the changes in the Abwehr indicating system that drove the development of these machines, the ingenious ways in which they were used, and some related developments involving the bombes used by the U.S. Navy’s cryptanalytic unit (OP-20-G).