首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 375 毫秒
1.
烤烟赤星病是烤烟大田后期的主要病害,是由于气候、栽培等因素在烟株间感病流行。只有通过认识烤烟赤星病的发病症状,了解其发病规律,采取“预防为主、综合防治”的植保方针,才能有效控制烤烟赤星病的发生。  相似文献   

2.
以烟田普查和系统调查为主要手段明确了2013年奉节烟区的主要病害种类及其发生流行规律,并在实践基础上根据病害的发生流行规律组配了主要病害的防控对策。2013年奉节烟区主要发生病害种类有烟草野火病、烟草赤星病、烟草黑胫病、烟草普花叶病毒病、烟草气候斑点病等5种病害。此5种病害的发生流行规律各不相同,防治时机和对策也各不相同。在防治上,不同病害的防治重点不同,主要以"预防为主、综合防控"的原则进行。  相似文献   

3.
以病菌根系侵入、系统性潜伏侵染为主要环节的病害循环;寄主—病菌接触识别;潜伏侵染和致病或发病状态转变中的寄主—病菌互作;互作的阶段性和专化性等,是近10年来对大白菜软腐病重新研究和认识的主要观点。这些观点对探讨和实施病害控制的新途径已产生重要的指导作用。  相似文献   

4.
采用免疫荧光技术成功检测到水稻叶鞘内表皮细胞中微管和微丝的分布情况.稻瘟病菌的侵染使水稻叶鞘内表皮细胞中微管、微丝排列方式发生明显的改变,这种排列方式的改变非常灵敏,且在亲和性互作和非亲和性互作之间差异明显.非亲和性互作反应中,病菌侵染早期微管、微丝均放射状向病菌侵染点分布,至寄主细胞产生过敏性坏死时,逐渐受到破坏而降解.亲和性互作反应中,微管、微丝在病菌侵染的早期则已开始降解,形成短棒状或点状结构,比较均匀地分布于整个细胞,病原菌侵染菌丝在寄主细胞中扩展时,难以观察到完整的微管、微丝.  相似文献   

5.
试验采用6种诱导接种法和叶片挑战接种法进行测定,结果表明,3种化学物质、非病原细菌的3个菌株和赤星菌6个菌株均可程度不同地诱导烟草对赤星病的系统抗性。化学因子中以IRD1抗性诱导效果最好,抗性诱导效应为54.5%,细菌因子以菌株C_2效果最好(39.2%),赤星菌株以TBA33最好(46.3%)。在茎部注射、叶部注射、伤口接种、灌根、叶面喷洒、叶面悬滴6种诱导接种方法中,化学、细菌因子以叶面喷洒和灌根效果较好,赤星菌株以叶面悬滴和叶面喷洒效果较好。  相似文献   

6.
采用黑麦草作为掩青绿肥,研究其对烟叶质量及病害产生的影响。试验表明,绿肥掩青、中期揭膜处理大田,烟株生长速度、最终长相及产量、产值好于常规盖膜栽培处理。绿肥的产量越高,对烟株的生长和产质的影响越大。绿肥同时有抑制黑胫病和赤星病发生的作用。  相似文献   

7.
水稻主要病害之一的白叶枯病,是由于水稻白叶枯病菌(Xanthomonas oryzae)侵入水稻叶或茎的维管束系,在导管内增殖而引起的,逦常沿着叶缘产生黄色的波状病斑,不久其组织就逐渐白枯,因此而得名。白叶枯病在日本,尤其是在东南亚各国的稻作上,是常常带来重大损失的病害。作者以在生物化学水平上查明白叶枯病菌侵入、感染组织时,在两者之间会发生什么样的相互作用为目的,利用由水稻芽生诱导的水稻愈合组织和 X.oryzae 系,进行了种种离体研究。结果观察到在水稻愈合组织的细胞中存在着对 X.oryzae 有抗菌性的物质,在水稻植株体内也存在着同样的物质。把水稻愈合组织置于含有 X.oryzae 及添加酪朊水解物和蛋白胨的无  相似文献   

8.
为了探寻烟草赤星病的生防药剂,减少该病害对烟草生产的影响,利用琼脂块法和管碟法从土壤中筛选烟草赤星病拮抗菌,并进行鉴定,考察其抗菌谱和发酵稳定性.结果表明:成功筛选得到一株拮抗菌株ZJNU968,其对烟草赤星病菌的抑菌圈直径达到了3.60 cm;根据菌株形态特征、生理生化特征和16S rDNA序列分析结果,鉴定该菌株为Streptomyces lunalinharesii;ZJNU968菌株对杨树溃疡病菌、水稻白叶枯病菌、番茄早疫病菌、小麦赤霉病菌和黄瓜枯萎病菌等均有较强的拮抗作用,同时,发酵液中抗菌活性物质具有较强的热稳定性、酸碱稳定性和光照稳定性.因此,ZJNU968菌株产生的代谢产物有望开发成为一种新型防治烟草赤星病菌的生物农药.  相似文献   

9.
目的筛选与无形体Ats-1互作的THP-1宿主细胞蛋白,为揭示病原体侵袭宿主的致病机理提供科学数据。方法利用分子克隆法构建p GBKT7-ats-1诱饵质粒并转化酵母Y2HGold,验证诱饵质粒是否有自激活、毒性现象;制备THP-1细胞c DNA并连接到p GADT7-Rec上,转化酵母Y187并鉴定c DNA文库质量;酵母双杂交筛选与Ats-1互作的宿主细胞靶蛋白,通过GO、String生物信息分析细胞靶蛋白可能的生物学过程。结果成功构建诱饵质粒;cDNA文库容量4×10~6克隆,插入片段100~3 000 bp,且无污染,达到建库质控要求;酵母双杂交结果显示,与Ats-1蛋白互作的宿主细胞靶蛋白7个,分别是真核延伸因子1复合体α1亚基(EEF1A1)、TIMP金属蛋白酶抑制子1(TIMP1)、锌指蛋白36,C3H样2 (ZFP36L2)、半乳糖凝集素1(LGALS1)、前胸腺素α(PTMA)、WBSCR22、吸引素(ATRN)。生物信息分析显示,与Ats-1互作的宿主靶蛋白主要参与细胞分化增殖、细胞凋亡、自噬、炎症等生物学过程。结论病原诱饵蛋白与宿主细胞靶蛋白互作是一种细胞-细胞间发生信号联系的分子水平生物学过程,可能影响病原粘附、侵袭及胞内生存,最终导致疾病发生及临床症状出现。  相似文献   

10.
杉木炭疽病菌(Glomerella cingulata)潜伏侵染的研究   总被引:2,自引:2,他引:2  
杉木针叶上炭疽病菌(Glomerella cingulata)的潜伏侵染研究结果表明:(1)杉木不同冠位、不同枝段和不同叶片部位的潜伏侵染率不同;(2)当年针叶5月中旬开始受侵,8月末达侵染高峰,当半个月平均气温低于10℃时不发生侵染,(3)针叶潜伏侵染率随杉木林地位级升高而增加,发病程度随地位级升高而降低,(4)病害症状于4~6月表现在先年枝梢的顶端,病害程度同针叶潜伏侵染率无关;(5)针叶中还原糖含量高似乎是影响病菌打破潜伏侵染的因素。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

14.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

15.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

16.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

17.
正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-  相似文献   

18.
We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-  相似文献   

19.
正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that  相似文献   

20.
<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号