首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   164篇
  免费   6篇
  国内免费   3篇
林业   17篇
农学   24篇
基础科学   1篇
  5篇
综合类   39篇
农作物   15篇
水产渔业   1篇
畜牧兽医   1篇
园艺   3篇
植物保护   67篇
  2024年   1篇
  2022年   7篇
  2021年   8篇
  2020年   4篇
  2019年   8篇
  2018年   1篇
  2017年   5篇
  2016年   11篇
  2015年   1篇
  2014年   2篇
  2013年   4篇
  2012年   13篇
  2011年   10篇
  2010年   9篇
  2009年   16篇
  2008年   11篇
  2007年   12篇
  2006年   7篇
  2005年   7篇
  2004年   7篇
  2003年   2篇
  2002年   6篇
  2001年   1篇
  2000年   1篇
  1999年   5篇
  1998年   1篇
  1997年   1篇
  1996年   4篇
  1995年   1篇
  1994年   1篇
  1992年   1篇
  1989年   1篇
  1988年   2篇
  1987年   2篇
排序方式: 共有173条查询结果,搜索用时 140 毫秒
31.
在前期引、选、育种基础上,通过品种比较和区域试验进行良种筛选,选育出大峰、高城、广银3个加工用日本栗新品种,具有丰产、稳产、加工品质优良、抗栗瘿蜂、果个大的特点,嫁接3~5年生大峰平均产5.03kg/株、高城平均产5.75kg/株、广银平均产5.53kg/株。  相似文献   
32.
Sunflower broomrape (Orobanche cumana Wallr.) is a parasitic plant that infects sunflower (Helianthus annuus L.) plants. In this work, sunflower plants were grown under greenhouse conditions in pots with the substrate infested or non-infested with broomrape seeds. At different numbers of days after sowing, plant height, internode lengths, number of leaves, head diameter, mineral composition of leaves, and potassium (K) concentration in stem were measured. The negative effects of broomrape parasitism were assessed from 57 d after sowing, when broomrape started to emerge. Parasitized plants exhibited lower shoot dry weight, height, and head diameter than control plants. The reduction in internode lengths was associated with a decrease in the gradient of K concentration from basal to apical stem. The mineral composition of leaves was also affected in parasitized plants. The concentrations of calcium (Ca), magnesium (Mg), manganese (Mn), and zinc (Zn) in leaves of parasitized plants were lower than those of the control plants, while there were few differences for K, phosphorus (P), iron (Fe), and copper (Cu). The effects of parasitism are discussed in relation to their competition for resources and to perturbations of the host physiology such as hormonal and water balance.  相似文献   
33.
Orobanche and Phelipanche species are root parasitic plants some of which infect important crops, causing extensive damage. In an attempt to unravel molecular systematic in these genera using protein markers, we established the protein profile of twelve species by two-dimensional gel electrophoresis (2-DE). Proteins were detected by Sypro Ruby staining and the gel images were digitalised and analysed. The 2-DE maps contained from 30 to 140 protein spots for the analysed species. A virtual master gel was built with spots present in all species and revealing the presence of 260 protein spots. Only one protein was monomorphic, while 143 were unique to a single species. Proteins were scored for the presence or absence of homologous spots to create a binary matrix. Phylogenetic analysis was carried out using maximum parsimony and distance method. The trees obtained were rooted using Cistanche phelypaea as an out-group. Both analyses showed Orobanche as a monophyletic group. AMOVA analysis revealed phenotypic diversity between species within genera, as well as a considerable level of variation between genera. This is a first step to help in the phylogenetic classification of parasitic plants by means of proteomics.  相似文献   
34.
吴卓珈 《安徽农业科学》2008,36(4):1428-1430
为规范朱砂根苗木生产、提高苗木的商品质量,根据多年对朱砂根生产技术的探索,对朱砂根标准化生产技术进行总结。  相似文献   
35.
Phelipanche and Orobanche species (broomrapes) are root holoparasitic plants that cause severe damage to economically important crops. Phelipanche and Orobanche spp. are widespread in Mediterranean areas, in Asia and in Southern and Eastern Europe, attacking dicotyledonous crops and depending entirely on their hosts for all nutritional requirements. Phelipanche aegyptiaca , Phelipanche ramosa and Orobanche cernua are extremely troublesome weeds on tomatoes. These noxious parasites exert their greatest damage prior to their shoot emergence and flowering; therefore, the majority of field loss may occur before diagnosis of infection. This review summarises the four main control measures for the weedy root parasites Phelipanche and Orobanche in tomato, namely chemical and biological control, resistant varieties and sanitation. Some of these methods are commercially widely used by farmers in Israel (chemical control), some are in the final stages of development towards commercialisation (resistant varieties and sanitation), and some still require further development and improvement before commercial implementation (biological control). The review presents an up-to-date summary of the available knowledge on their use for broomrape management in processing tomatoes.  相似文献   
36.
A field survey of the Orobanchaceae family members and their hosts in Jordan was carried out from 2003 to 2007. The intensity of parasite infection on different hosts and the severity of the infestation were evaluated. The results showed the presence of seven species of Orobanche and three species of Cistanche . The Orobanche species were found parasitizing 86 plant species belonging to 24 botanical families. Most of the species attacked by Orobanche were from the Compositae (20 species), Solanaceae (11 species), Leguminosae (nine species), Umbelliferae (seven species), Cruciferae (seven species), Cucurbitaceae (four species), Labiatae (four species), and Rosaceae (four species) families. Other families were represented by one-to-three species. Cistanche attacked 20 species of forage wild shrubs, fruit trees, and forest trees of seven families, mostly belonging to the Chenopodiaceae (seven species) and Leguminosae (three species) families. Previously unreported hosts for both genera include: Amygdalus communis , Olea europaea , and Quercus coccifera , which were parasitized by Orobanche palaestina ; A. communis , O. europaea , Prunus armeniaca , and Prunus persica , which were parasitzed by Orobanche cernua ; O. europaea and A. communis , which were parasitzed by Orobanche schultzii ; Haloxylon persicum , which was parasitzed by Cistanche lutea ; Punica granatum , Alhagi maurorum , Casuarina equisetifolia , Centaurea postii , and Prosopis farcta , which were parasitzed by Cistanche tubulosa ; and Achillea spp., Anabasis syriaca , H. persicum , Haloxylon salicornicum, Suaeda spp., and Zilla spinosa , which were parasitzed by Cistanche salsa . Certain Orobanche species were completely destructive to the cultivated crops. The results indicated the high potential of both parasitic genera to spread and to attack new hosts, while the threat they impose to agriculture in Jordan will probably result from poor management and deficiences in farmers' training.  相似文献   
37.
本研究以新疆地区危害最严重的向日葵列当和瓜列当为研究对象,通过室内水培试验和室外盆栽模拟轮作试验来探究焉耆垦区轮作模式对两种列当的防除效果。结果表明,室内水培试验中各轮作作物的根系分泌物及萃取相刺激瓜列当种子的萌发率均在20.0%以下,但刺激向日葵列当种子产生的萌发率达到了50.0%以上;室外盆栽模拟轮作试验中,甜菜、小麦、辣椒与加工番茄轮作后,瓜列当的寄生数量未显著降低;但与向日葵轮作后,向日葵列当的寄生数量显著减少了60.0%以上。不同品种甜菜、辣椒和小麦地上部甲醇提取液刺激瓜列当种子的萌发率均低于10.0%,但是刺激向日葵列当种子的萌发率均达70.0%以上。本研究表明新疆焉耆垦区轮作种植模式不能有效防除瓜列当,但模式中的轮作作物均能够有效防除向日葵列当。本研究结果为防除新疆焉耆垦区向日葵列当和瓜列当提供理论依据。  相似文献   
38.
向日葵列当Orobanche cumana是一种检疫性恶性寄生杂草。本研究采用透析法制备了一种水溶性氟乐灵纳米制剂(Tf-OR-CC),评价其对向日葵列当的室内毒力和田间药效。种子发芽毒力测定结果表明:在独脚金内酯类似物GR24的诱导下,用5μg/mL Tf-OR-CC处理向日葵列当种子,7 d后表现出良好的抑制发芽活性,列当种子发芽率为28.5%,与对照相比差异显著。消解动态试验表明,Tf-OR-CC消解半衰期比48%氟乐灵乳油延长6.56 d,说明Tf-OR-CC具有一定的缓释作用。田间药效试验结果表明,滴灌施用有效成分含量为75 g/667 m~2Tf-OR-CC 45 d后,向日葵列当寄生率为32.1%,寄生强度为5.3,Tf-OR-CC制剂对向日葵列当的田间防效为36.3%。该方法可为向日葵滴灌施药技术防治向日葵列当提供科学依据。  相似文献   
39.
向日葵列当对向日葵生产带来严重危害,目前向日葵生产中主要通过化学除草、选择抗性品种进行防除。通过合理轮作是减轻列当危害的有效手段,但是如何选择轮作作物、其防除效果如何并不清晰。采用向日葵连作重茬土壤进行盆栽试验,并进行田间调查,研究结果表明:向日葵与燕麦、小麦和马铃薯轮作均可不同程度地降低向日葵列当寄生率,其中向日葵—燕麦—向日葵轮作对列当耗减最多,与对照组(向日葵连作)相比列当寄生率降低30%。向日葵—燕麦—向日葵—燕麦—向日葵、向日葵—小麦—向日葵—小麦—向日葵轮作列当寄生率均低于50%,两者差异不显著,而显著低于向日葵—马铃薯—向日葵—马铃薯—向日葵轮作处理。田间调查结果显示向日葵的花盘直径与列当寄生数呈负相关,地膜覆盖对向日葵列当寄生影响不大。综合得出,燕麦是一种良好的向日葵列当诱捕作物,适合在内蒙古等食用向日葵主产区推广应用。  相似文献   
40.
为研究列当多糖抗新城疫病毒(NDV)活性,用水提醇沉法提取列当总多糖及4种分级多糖,并通过苯酚硫酸法及红外光谱对列当多糖进行检测。通过MTT法测定各级多糖对鸡胚成纤维细胞(CEF)的安全浓度。以3种加药方式(先加多糖后接种病毒、先接种病毒后加多糖、多糖和病毒感作后加)加药,检测列当多糖对新城疫病毒的阻断作用、抑制作用及直接杀灭作用。结果表明,列当总多糖及4种分级多糖均具有抗NDV活性,其中对NDV的抑制作用及阻断作用强于对NDV的直接杀灭作用。50%、80%梯度醇沉的列当多糖(OSP50、OSP80)及总多糖(OSPt),阻断作用下的病毒抑制率分别为19.50%、33.10%和22.30%,抑制作用下的病毒抑制率分别为19.00%、21.90%和22.60%,杀灭作用下对NDV的抑制率分别为,14.70%、17.50%和13.30%,其余各组多糖阻断作用、抑制作用及杀灭作用下的病毒抑制率均低于上述3组多糖。说明OSP50、OSP80及OSPt的抗NDV活性较好,可以作为进一步研究的材料。  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