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1.
Monoclonal antibodies against hog cholera and bovine viral diarrhoea viruses were assayed on organ tissue sections of experimentally infected animals. The animals had been infected simultaneously with both viruses. The antibodies were tested using an indirect immunofluorescence test and an indirect enzyme immunoassay with a biotin/streptavidin/peroxidase detection system. A polyclonal hyperimmune serum was used as a control in direct immunofluorescence tests. Both techniques based on monoclonal antibodies were more sensitive and more specific than the conventional test, the enzyme immunoassay being more sensitive than the immunofluorescence test. Small amounts of BVD viral antigen were demonstrable with monoclonal antibodies in most organ tissues.  相似文献   
2.
Imports of pesticides have long been subsidised for use in the cocoa agroforests of the humid forest zone of southern Cameroon. With the liberalisation of the cocoa and pesticides sectors and the devaluation of the local currency (CFA franc), farmers are facing fluctuations in the price paid for cocoa and the high cost of farm inputs. Without the support of the extension services, they themselves have developed traditional integrated control methods based on the use of plant extracts mixed with conventional pesticides. From a survey of 300 cocoa farmers, the study assesses the farmers' command of these methods, the pests controlled, the problems encountered and the institutional constraints in the definition and dissemination of integrated control methods. The study concludes with recommendations for research and development towards the better definition and dissemination of integrated control methods. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   
3.
Cocoa is a key or source of income and poverty reduction in the humid forest of Southern Cameroon. Cameroon like other African countries went through a major economic crisis in the early 1980s with a decline in international commodity prices and significant changes in macroeconomic policies. Structural adjustment reforms following the economic crisis led to removal of fertilizers and pesticides subsidies, cocoa price liberalization and the overall withdraw of Government interventions from the cocoa sub-sector. Cocoa input price increases have been compounded by the devaluation of the CFA Franc, which doubled the prices of the imported pesticides which were considered key to the control of cocoa pests. This overall economic shock led to changes in cocoa producer's production decisions as a response to minimize cost. Among the changes the use of alternatives to imported chemicals for cocoa pest control. Farmers responded to the high prices of pesticides by developing, from local botanical knowledge and pest management strategies, which include plant extracts and plant extracts mixed with pesticides at different proportions. This is a major decision given the importance of imported chemical in the cost of production of cocoa. Valuable indigenous knowledge from farmers could be used also as an effective support system for communicating and diffusing modern knowledge and technologies to farmers. The paper describes the farmer knowledge-based alternatives to chemical pesticides for pest control in cocoa fields as a response to high pest control costs. Pest management specialists are urged to take advantage of this shift in practice and assess their effectiveness for further use. Two sets of questions are posed: (1) were the conventional insecticides, with all their problems, really necessary? and (2) are the materials derived from locally grown plants effective pest management agents or are they, in some way, placebos?  相似文献   
4.
Uncoupling proteins are mitochondrial anions transporters that dissociate respiration from ATP synthesis through proton leaks. Uncoupling protein 2 reportedly plays a role in several physiological processes such as energy partitioning, nutrition, and fatty acid metabolism. The mRNA expression of rainbow trout UCP2 genes (UCP2A and UCP2B) was monitored during embryogenesis and early larval development. Both genes were recruited early and displayed similar steadily decreasing patterns from fertilization until hatching. The expression of UCP2A and UCP2B appeared significantly differentiated after hatching and during the yolk sac absorption, with UCP2A displaying higher expression. We suggest that UCP2 expression profiles in the rainbow trout embryo could be associated with the utilization of lipids as a source of energy during development.  相似文献   
5.
A study of the inheritance of sorghum resistance to head-bug Eurystylusoldi and midge Stenodiplosis sorghicola has been conducted from anF1-based complete diallel involving four parental lines (namely head-bugresistant Malisor 84-7 & 87W810, and susceptible S 34 & ICSV 197).The trial was conducted at Samanko, Mali, under both natural and artificialhead-bug infestation, in one date of sowing (DOS) in 1995 and two DOSin 1996. Head-bug visual damage scores (under both types of infestation)were indicated and analyzed in all these trials. Head-bug numbers underartificial infestation on the two DOS of 1996, and midge damage scoreunder natural infestation on the second DOS of 1996 were recorded. Allfour parents confirmed their expected level of resistance to head-bugs,while ICSV 197 confirmed its resistance to midge. Diallel analyses showedthat general combining ability (GCA) and thus additive gene effects werevery important in the inheritance of resistance to both pests. Specificcombining ability and maternal effects were generally of minor importance.Mean performance of the parents and their GCA effects were linked, whichsuggests high heritability. Head-bug resistant parents, Malisor 84-7 &87W810, with high per se resistance and negative GCA shouldtherefore be used in breeding for resistance to this pest, while for a similarreason, ICSV 197 should be used in breeding for midge resistance. Resultsconcerning independance between resistance to head-bugs and to midge,are also discussed.  相似文献   
6.
Thirty-three pestivirus strains were grown in cell culture and characterized by immunostaining with 19 monoclonal antibodies (MAbs) raised against hog cholera virus (HCV), with 42 MAbs against bovine viral diarrhoea virus (BVDV) and with 13 MAbs against border disease virus (BDV). Seven MAbs reacted with all pestivirus strains tested, eight MAbs detected only the seven HCV strains, three detected only the 16 BVDV strains. No MAb was found that was specific for BDV. BVDV and BDV strains were broadly cross-reactive with the MAbs, indicating a close relationship between these two species, whereas HCV strains were characterized as distinct from BVDV and BDV.  相似文献   
7.
8.
In this study polyphenol content, antioxidant activity, lipoxygenase (LOX) and Xanthine Oxidase (XO) inhibitory effects of n-hexane, dichloromethane, ethyl acetate and n-butanol fractions of aqueous acetone extracts from S. alba L., S. acuta Burn f and Cienfuegosia digitata Cav. were investigated. The total phenolics, flavonoids, flavonols and total tannins were determined by spectrophotometric methods using Folin-ciocalteu, AlCl3 reagents and tannic acid, respectively. The antioxidant potential was evaluated using three methods: inhibition of free radical 2,2-diphenyl-1-picrylhydramzyl (DPPH), ABTS radical cation decolorization assay and Iron (III) to iron (II) reduction activity (FRAP). For enzymatic activity, lipoxygenase and xanthine oxidase inhibitory activities were used. This study shows a relationship between polyphenol contents, antioxidant and enzymatic activities. Present results showed that ethyl acetate and dichloromethane fractions elicit the highest polyphenol content, antioxidant and enzymatic activities.  相似文献   
9.
The growth and reproduction of Eudrilus eugeniae were evaluated in four animal species wastes under laboratory conditions. Two hatchlings were introduced in 100 g of each animal waste i.e. cow, sheep, pig, and chicken after 15 days of pre-composting. Biomass gain, mortality, sexual maturity, and cocoons production were monitored periodically for 21 weeks. No mortality was observed in any waste. The maximum weight gain per worm and the highest growth rate per worm per week were obtained in chicken waste. Net biomass gain per worm were 1.01 ± 0.52 g, 1.318 ± 0.07 g, 0.87 ± 0.1 g, and 1.69 ± 0.15 g respectively for cow, sheep, pig, and chicken wastes. The highest number of cocoons produced per worm per day was obtained in chicken waste followed in decreasing order by sheep, cow, and pig waste. The mean number of cocoons produced per worm per day in chicken waste was 40.87% greater than these produced per day in pig waste.Among the four animal species, chicken, sheep, and cow were the most favourable wastes for the growth and reproduction of E. eugeniae, and hence can be recommended as feed materials in large scale vermicomposting facilities.  相似文献   
10.
Two species of mirids, Distantiella theobromae (Dist.) and Sahlbergella singularis Hagl., cause substantial damage to cocoa plantations in West Africa. Cocoa susceptibility to mirid attack was observed in the Côte d’Ivoire in a trial involving progenies obtained from crosses according to a factorial mating design, and in a trial involving clones. As spatial distribution of mirid damage was not uniform within the plots, a method was developed for experimental design of completely randomized single-tree elementary plots, based on analysis of covariance and taking into account the spatial within-plot effect of the damage caused. This method resulted into a more precise estimation of genetic effects and heritabilities adjusting for mirid susceptibility heterogeneity in the field.  相似文献   
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