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   105篇
  免费   3篇
林业   8篇
农学   2篇
  23篇
综合类   3篇
农作物   9篇
水产渔业   5篇
畜牧兽医   46篇
园艺   3篇
植物保护   9篇
  2023年   1篇
  2022年   3篇
  2021年   4篇
  2020年   2篇
  2019年   9篇
  2018年   3篇
  2017年   3篇
  2016年   4篇
  2015年   4篇
  2014年   6篇
  2013年   1篇
  2012年   8篇
  2011年   6篇
  2010年   2篇
  2009年   10篇
  2008年   10篇
  2007年   8篇
  2006年   7篇
  2005年   2篇
  2004年   3篇
  2003年   3篇
  2002年   6篇
  2000年   1篇
  1996年   2篇
排序方式: 共有108条查询结果,搜索用时 31 毫秒
51.
52.
Yam (Dioscorea spp.) is a major staple food whose production is hampered by viral diseases. However, the prevalence, diversity, transmission, and impact of yam-infecting viruses remain poorly documented. This study reports on the symptomatology, prevalence, and molecular diversity of eight viruses in 38 D. rotundata accessions from a germplasm collection and 206 F1 hybrid progenies maintained in Côte d'Ivoire. Mean severity scores as assessed from leaf symptoms ranged from 2 to 4 in the germplasm collection and from 1 to 3 in F1 hybrids, respectively. Dioscorea mosaic-associated virus (DMaV), potexviruses, and yam mosaic virus (YMV) were detected by PCR-based diagnosis tools in single and mixed infections in both the D. rotundata collection and F1 progenies, whereas badnaviruses were detected only in the germplasm collection. In contrast, cucumber mosaic virus (CMV), yam macluraviruses, yam asymptomatic virus 1 (YaV1), and yam mild mosaic virus (YMMV) could not be detected. No correlation could be established between severity scores and indexing results. Phylogenetic analysis performed on partial viral sequences amplified from infected samples unveiled the presence of two putative novel viral species belonging to genera Badnavirus and Potexvirus and provided evidence for plant-to-plant transmission of YMV, DMaV, and yam potexviruses.  相似文献   
53.
Human amebiasis is caused by the protozoan Entamoeba histolytica. This protozoan is responsible for muco-hemorrhagic diarrhoea and liver abscess in affected populations. E. histolytica can be asymptomatic commensally confined to the intestinal lumen or can result in invasion of the colonic mucosa leading to ulceration and/or liver abscesses. Recently, human colonic explants have been identified as valuable in the study of host-parasite interactions. Here we investigated the potential of porcine colonic explants as an alternative to human tissues which are far less available. Porcine colonic explants were cultured with two strains of E. histolytica, one virulent (HM1:IMSS) and one avirulent (Rahman). Results from histopathological and real-time PCR analysis showed that porcine explants cultured with virulent ameba trophozoites react similarly to their human counterparts with an invasion of the tissue by the trophozoites and the triggering of typical innate immune response against the parasite. On the contrary, explants cultured with avirulent ameba trophozoites were preserved. The study open the way to the use of porcine colonic explants in the study of the complex interactions between the parasite and the host.  相似文献   
54.
55.
The main objective of this study was to assess the impact of the application of an antagonistic strain of Trichoderma atroviride on the native microbial soil communities. The structures of the fungal and bacterial communities were assessed by T-RFLP (terminal restriction fragment length polymorphism) method, based on T-RFLP analysis of 18S and 16S rRNA genes, respectively. Results showed that the introduction of the strain I-1237 into two soils slightly modified the microbial diversity, only for a short period of time. Nine months post-inoculation resilience took place, resulting in similar structures of the fungal and bacterial communities in the inoculated and control soils.  相似文献   
56.
The contamination of 27 urban topsoils has been assessed around two lead and zinc smelters (Metaleurop Nord and Umicore) in the North of France. Eighteen trace elements have been analysed (Ag, As, Bi, Cd, Co, Cr, Cu, Hg, In, Ni, Pb, Sb, Se, Sn, Tl, Th, U and Zn). The investigation included the study of the vertical distribution of Cd, Pb and Zn as indicators of pollution. It was shown that Cd, In, Pb, Sb and Zn were major pollutants followed in lesser quantities by Ag, Bi, Cu and Hg. In addition, As, Ni, Se, Sn and Tl were present at levels slightly higher than regional agricultural values. The other elements (Co, Cr, Th and U) were at endogenous levels. The observations have highlighted the strong heterogeneity of the physico-chemical parameters of urban soils and the existence of heavy contamination of the under layers by Cd, Pb and Zn. A potential transfer of metals from the topsoil to the deeper layers and especially Cd and Zn, is not excluded. Indeed the soil rework is not the only factor explaining contamination level of the deeper layers of the studied soils. The comparison of the studied element concentrations in urban soils with nearby local agricultural values shows that the dust emission originating from the Metaleurop and Umicore smelters were not the only source of contamination. Thus a large contamination of the studied urban soils by Sb and In could be explained by domestic combustion of coal for heating.  相似文献   
57.
The behaviour of metals mainly depends on soil p H, carbonate contents and contamination level, which should be considered for the management of contaminated soils. In this study, kitchen garden topsoils(0–25 cm) were sampled from the area around three smelters in France, with different Cd and Pb contamination levels. Effect of a phosphate amendment(a mixture of diammonium phosphate and hydroxyapatite) on the environmental availability and phytoavailability of Cd and Pb was evaluated by different chemical extractions and cultivating lettuce(Lactuca sativa L.), respectively. Changes in the distribution of Cd and Pb were found in most contaminated soils after phosphate amendment. An increase of Cd and Pb in the residual phase was highlighted in almost all carbonated contaminated soils, whereas a decrease of Pb in the exchangeable, water and acid-soluble phase was observed in most contaminated soils with the lowest carbonate contents. The concentrations of extractable Cd and Pb using calcium chloride and acetic and citric acids generally decreased after the soil amendment. Lettuces grown on amended soils were acceptable for human consumption as regard to Pb concentration. In contrast, some lettuces were unacceptable for human consumption, since the concentrations of Cd in the leaves were higher than the European legislation limit. Surprisingly, in carbonated soils with very low concentration of Cd, the Cd concentrations in lettuce reached up to the European legislation limit, making the lettuce unacceptable for human consumption.Our study highlighted the fact that the total metal concentration in soils does not always allow to predict the metal accumulation in the edible parts of vegetables in order to make a judgement about their acceptability or unacceptability for human consumption.  相似文献   
58.
It is well known that mass transfer of a solid compound into a liquid phase is characterized by mutual properties of both sides. Solubilization capacity of the liquid phase is primary affected by its composition in inorganic species inducing salting in/out effect evaluated by Setschenow constant, generally defined at 298.15 K. On the other hand, the equilibrium process is highly influenced by polar compatibility issue. Therefore, the study of such transfer is essential in order to set the role of each party participating in the solid–liquid equilibrium. Thus, a comparison of transfer magnitude and feasibility of carbaryl from pure water, to seawater, and lab-made seawater was held. To do so, solubility of the compound was experimented at different temperature in multiple media. Solubility determination is based on the saturation of a specific heated fluid passing through a saturation cell. The solute transported is subsequently trapped in a specific extraction column. Back flashing method is then applied to dissolve the compound. After validation, aqueous solubility of carbaryl was studied as function of temperature ranging from (273.15 to 318.15 K) at atmospheric pressure. In addition, solubility was determined in pure, seawater, and corresponding lab-made water, thus solubility values ranged from 3.57E-06 to 3.49E-05 in pure water, from 3.04E-06 to 2.53E-05 in seawater and from 6.51E-06 to 3.61E-05 in lab-made water. As a result, thermophysical properties of transfer and usage of lab-made water on the mass transfer properties divergence was spotted. The Salting out phenomenon observed for carbaryl was interpreted by the internal pressure theory that suggests the reduction of internal cavities in the presence of salt, making solubilization process more difficult to achieve. Thus, showing an overall endogenic process with a positive Gibbs free energy of transfer that is highly affected by the magnitude of salting out effect and the temperature. The molar entropy of transfer increases versus temperature caused by the disorder of solvent molecules due to the dissolution process.  相似文献   
59.
Implementation of conservation breeding programs is a key step to ensuring the sustainability of many endangered species. Infectious diseases can be serious threats for the success of such initiatives especially since knowledge on pathogens affecting those species is usually scarce. Houbara bustard species (Chlamydotis undulata and Chlamydotis macqueenii), whose populations have declined over the last decades, have been captive-bred for conservation purposes for more than 15 years. Avipoxviruses are of the highest concern for these species in captivity. Pox lesions were collected from breeding projects in North Africa, the Middle East and Central Asia for 6 years in order to study the diversity of avipoxviruses responsible for clinical infections in Houbara bustard. Molecular and phylogenetic analyses of 113 and 75 DNA sequences for P4b and fpv140 loci respectively, revealed an unexpected wide diversity of viruses affecting Houbara bustard even at a project scale: 17 genotypes equally distributed between fowlpox virus-like and canarypox virus-like have been identified in the present study. This suggests multiple and repeated introductions of virus and questions host specificity and control strategy of avipoxviruses. We also show that the observed high virus burden and co-evolution of diverse avipoxvirus strains at endemic levels may be responsible for the emergence of novel recombinant strains.  相似文献   
60.
The Virology Laboratory of the Central Laboratory of Animal Diseases in Ivory Coast at Bingerville received samples of wild and domestic avian species between February and December 2006. An RT-PCR technique was used to test for avian influenza (AI) and highly pathogenic AI subtype viruses. Among 2125 samples, 16 were type A positive; of which, 12 were later confirmed to be H5N1. Fifteen of these 16 type A positive samples were inoculated into the chorioallantoic cavity of 11-day-old embryonated hens' eggs for virus isolation. Eight produced virus with hemagglutination titres from 1/64 to 1/512. The 4/16 M-RT-PCR positive samples, which were H5N1 negative, were shown to be H7 subtype negative. The diagnostic efficiency of the laboratory for the surveillance of H5N1 in Ivory Coast was demonstrated. The positive cases of H5N1 were from a sparrowhawk (Accipter nisus); live market poultry and in free-range poultry, where the mortality rate was approximately 20% (2/10) and 96.7% (29/30) respectively. Currently, investigations into intensive poultry farms have proved negative for H5N1. No human cases have been reported this time.  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