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   102篇
  免费   3篇
林业   4篇
农学   5篇
基础科学   1篇
  7篇
综合类   12篇
农作物   5篇
水产渔业   2篇
畜牧兽医   40篇
园艺   3篇
植物保护   26篇
  2021年   1篇
  2018年   1篇
  2017年   3篇
  2016年   6篇
  2015年   4篇
  2014年   2篇
  2013年   4篇
  2012年   6篇
  2011年   10篇
  2010年   6篇
  2009年   2篇
  2008年   6篇
  2007年   12篇
  2006年   5篇
  2005年   5篇
  2004年   7篇
  2003年   3篇
  2002年   5篇
  2001年   4篇
  2000年   4篇
  1999年   1篇
  1997年   2篇
  1984年   1篇
  1974年   1篇
  1973年   1篇
  1971年   1篇
  1970年   1篇
  1967年   1篇
排序方式: 共有105条查询结果,搜索用时 15 毫秒
91.
EU agriculture is currently in transition from conventional crop protection to integrated pest management (IPM). Because biocontrol is a key component of IPM, many European countries recently have intensified their national efforts on biocontrol research and innovation (R&I), although such initiatives are often fragmented. The operational outputs of national efforts would benefit from closer collaboration among stakeholders via transnationally coordinated approaches, as most economically important pests are similar across Europe. This paper proposes a common European framework on biocontrol R&I. It identifies generic R&I bottlenecks and needs as well as priorities for three crop types (arable, vegetable and perennial crops). The existing gap between the market offers of biocontrol solutions and the demand of growers, the lengthy and expensive registration process for biocontrol solutions and their varying effectiveness due to variable climatic conditions and site‐specific factors across Europe are key obstacles hindering the development and adoption of biocontrol solutions in Europe. Considering arable, vegetable and perennial crops, a dozen common target pests are identified for each type of crop and ranked by order of importance at European level. Such a ranked list indicates numerous topics on which future joint transnational efforts would be justified. © 2016 Society of Chemical Industry  相似文献   
92.
During the past years, nrDNA ITS sequences have supported the identification of many powdery mildew fungi because comprehensive analyses showed that differences in these sequences have always correlated with the delimitation of different species and formae speciales of the Erysiphales. Published data, obtained using direct sequencing of the PCR products, suggested that even one to five nucleotide differences in the ITS sequences delimit different, albeit closely related, species, and/or indicate differences in host range patterns. Here we show that such differences in the ITS sequences can be detected even in a single sample of a powdery mildew fungus. We sequenced the ITS region in 17 samples, representing six powdery mildew species, both directly and after cloning the PCR products. Among these, samples of O. longipes exhibited two or three, samples of O. neolycopersici three or four, those of an Oidium sp. from Chelidonium majus up to seven, and a sample of another Oidium sp. from Passiflora caerulea two different ITS types determined after cloning. No ITS nucleotide polymorphisms were found in samples of O. lycopersici and Erysiphe aquilegiae. This suggests that some powdery mildew taxa are more variable at the ITS level than others. Thus, although the ITS sequences determined by direct sequencing represent robust data useful in delimitation and phylogenetic analysis of distinct species of the Erysiphales, these need to be used with precaution, and preferably determined after cloning, especially when dealing with closely related taxa at species and sub-species levels. With this method a hitherto undetected genetic diversity of powdery mildews can be revealed.  相似文献   
93.
Oestrogen (E2) and thyroid hormones (THs) are key regulators of cerebellar development. Recent reports implicate a complex mechanism through which E2 and THs influence the expression levels of each other's receptors (ERs and TRs) to precisely mediate developmental signals and modulate signal strength. We examined the modulating effects of E2 and THs on the expression levels of their receptor mRNAs and proteins in cultured cerebellar cells obtained from 7-day-old rat pups. Cerebellar granule cell cultures were treated with either E2, THs or a combination of these hormones, and resulting receptor expression levels were determined by quantitative PCR and Western blot techniques. The results were compared to non-treated controls and to samples obtained from 14-day-old in situ cerebella. Additionally, we determined the glial effects on the regulation of ER-TR expression levels. The results show that (i) ER and TR expression depends on the combined presence of E2 and THs; (ii) glial cells mediate the hormonal regulation of neuronal ER-TR expression and (iii) loss of tissue integrity results in characteristic changes in ER-TR expression levels. These observations suggest that both E2 and THs, in adequate amounts, are required for the precise orchestration of cerebellar development and that alterations in the ratio of E2/THs may influence signalling mechanisms involved in neurodevelopment. Comparison of data from in vitro and in situ samples revealed a shift in receptor expression levels after loss of tissue integrity, suggesting that such adjusting/regenerative mechanisms may function after cerebellar tissue injury as well.  相似文献   
94.
In order to compound a new drug comblnatlon agalnst canlne otitis externa (OE), 515 dogs affected wlth OE were subjected to physical examlnatlon and mlcroblologlcal analysis of their ear exudates. OE was erythematous-cerumlnous In 83 per cent and suppurative In 17 per cent of the patlent material. Erythematous-cerumlnous lnflammatlons were characterlsed by severe prurltus and accumulatlon of brownlsh, greasy cerumen In the audltory canal. The yeast Malassezla jmchydermat/s was Isolated from the ears of 76 per cent of the dogs, often In comblnatlon wlth Staphylococcus lntermedlus bacterla. M pachydermatls showed the most sensltlvlty, In decreasing order of efflcacy, to ketoconazole, econazole, clotrlmazole, mlconazole and nystatln. S lntermedlus Isolates were most sensltlve to amoxyclllln-clavulanlc acld, enrofloxacln, cephalexln and gentamlcln. The mlcroorganlsm most frequently Isolatcbd from dogs wlth suppurative OE was Pseudomonas aewglnosa; In some cases Proteus, Streptococcus and Pasteurella were also Isolated. The P aeruglnosa Isolates showed the highest sensltlvlty to gentamlcln, polymyxln B and tobramycln.  相似文献   
95.
Simultaneous detection of three porcine viruses by multiplex PCR   总被引:2,自引:0,他引:2  
Specific oligonucleotide primers were selected and combined in a multiplex arrangement, in order to detect simultaneously three economically important porcine viruses by polymerase chain reaction (PCR). The pathogen panel was comprised of viruses that cause reproductive failure in infected herds: Aujeszky's disease virus (ADV), porcine parvovirus (PPV) and porcine respiratory and reproductive syndrome virus (PRRSV). In order to reduce the time required for the detection of the pathogens, the assay was optimised to a RapidCycler PCR instrument. The multiplex PCR assay was shown to be specific, sensitive and rapid, because the results were read in less than 60 min after sample preparation. Due to its speed, efficiency and sensitivity, the described rapid multiplex PCR assay serves as a useful novel tool in the veterinary diagnostic laboratories for the quick and complex detection of these important porcine pathogens.  相似文献   
96.
97.
Journal of Plant Diseases and Protection - Twenty-four stone fruit trees showing typical symptoms of plum pox virus (PPV) were tested for PPV using ELISA, RT-PCR, real-time RT-PCR and RT-LAMP. The...  相似文献   
98.
The relative efficiency of single-pass electrofishing of longer stream sections vs. double-pass electrofishing of shorter reaches was evaluated in small (<5 m wide) wadable lowland streams in the Lake Balaton basin, Hungary. Two hundred meters long stream sections at 8 sites were divided into ten 20 m long sampling units each. These units were used to estimate the representativeness of species richness, species composition and relative abundance data at each level of sampling effort (single vs. double-pass, and number of sampling units pooled) using rarefaction and similarity-based approaches. Assemblage variables showed strong response to the length of the stream sampled (number of sampling units pooled). However, no differences were found between the single- and double-pass methods at any level of sample size for any assemblage variable. Estimates of species richness and species occurrence distributions required more sampling effort than estimates of species relative abundances, using any evaluation method. If a proxy estimate of sample representativeness cannot be obtained in the field, a minimum sampling of single-pass electrofishing of 100 m long sections may be necessary even in small wadable streams with low level of habitat and assemblage diversity to get a relatively unbiased picture on assemblage characteristics.  相似文献   
99.
100.
Kiss Z 《Science (New York, N.Y.)》2002,297(5580):335-6; author reply 335-6
  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