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   12篇
  免费   0篇
林业   2篇
农学   1篇
  8篇
畜牧兽医   1篇
  2021年   1篇
  2019年   1篇
  2017年   1篇
  2016年   2篇
  2011年   1篇
  2010年   1篇
  2008年   1篇
  2007年   2篇
  2006年   2篇
排序方式: 共有12条查询结果,搜索用时 31 毫秒
1.
This paper describes a sensitive isocratic HPLC/ECD method developed for the determination of rosmarinic acid (RA) in plant material, animal feed, and pig plasma. The plasma sample preparation only includes protein precipitation and adjustment of the pH. The applicability of the method was tested on plasma samples of pigs that were exposed to a 91-day oral intake of RA via feed enriched by aerial parts of Prunella vulgaris. The plasma was directly analyzed using the method described as well as after enzymatic hydrolysis. When no hydrolysis step was included, RA and caffeic acid (CA) were quantified in the plasma. In hydrolyzed plasma samples, several other metabolites were determined, including dihydrocaffeic, ferulic, and dihydroferulic acid. The dual-channel coulometric detection employed, as an alternative to mass spectrometry, offers good selectivity and sensitivity owing to the electrochemical properties of the phenolic constituents.  相似文献   
2.
West Nile virus lineage 2 (WNV‐2) was detected in the brain of 17 goshawks (Accipiter gentilis) that succumbed to neuroinvasive disease in the Czech Republic during 2018: twelve birds were captive and five wild. Furthermore, two wild sparrowhawks (Accipiter nisus) and three other captive birds of prey (golden eagle Aquila chrysaetos, hybrid saker falcon Falco cherrug × F. rusticolus and Harris's hawk Parabuteo unicinctus) also died due to WNV encephalitis. The 2018 outbreak in Czech raptors clearly reflects a new epidemiological situation and indicates an increasing risk of both raptor and human infection with WNV‐2 in the country.  相似文献   
3.
Morphology of ripe lodicules in wheat taxonomic species was analyzed for all ploidy levels. From the initial set of sixteen characters, the best representatives and discriminants were selected. Length of main lobe and hairiness of this lobe as well as cushion appeared as the most stable selected characters. A non-metric multidimensional scaling procedure distinguished wheat diploids in the ordination space with Triticum urartu in a separate position. Other wheats, which were recognized as narrow endemics or hybrid recombinants, were seen as extremes in this space and they surround the centre with most of threshable taxa. Morphology of the lodicule differs between unthreshable and threshable wheats as well as between units having AABB and AAGG genomes. The development of hairs, lateral lobe and cushion is a factor creating main differences between lodicules of various taxa. Wheat species characterized by the best discriminants create in the space an original sphere of points described by correlation and regression parameters of three ordination axes. Large intra-specific variation of lodicule morphology is a source of flexibility of wheat breeding system.  相似文献   
4.
5.
The paper reports on the study of DNA methylation patterns in chromosomes of an octoploid selection obtained from an amphiploid Avena barbata × Avena sativa ssp. nuda, their alteration and plant structural changes induced by 5-azacytidine (5-azaC) treatment. Subtelomere/telomere regions and some chromosomes remained heavily methylated after this practise. The increased concentration of 5-azaC strengthened the demethylation process. NOR rDNA loci on five and 5S rDNA doubled loci on three pairs of chromosomes were detected. Some 5S loci were colocalised with NORs. The number of active NORs was increased by one homologous pair after demethylation and this was related to minor loci. The NORs were mainly located on A/D genomes. Patterns of nucleoli fusion varied between main and lateral roots and demethylation increased the number of uninucleolar nuclei. Seed germination was inhibited and plant growth decreased under demethylation. 5-azaC also induced distinct anomalies in endosperm development. Extensive parts of the tissue were composed of defected cells or remained empty. Polyploidised clones of starchy or aleurone cells were observed, as were aleurone cells exhibiting new rare phenotypes.  相似文献   
6.
The International Maize and Wheat Improvement Center (CIMMYT) acts as a catalyst and leader in a global maize and wheat innovation network that serves the poor in the developing world. Drawing on strong science and effective partnerships, CIMMYT researchers create, share, and use knowledge and technology to increase food security, improve the productivity and profitability of farming systems and sustain natural resources. This people-centered mission does not ignore the fact that CIMMYT’s unique niche is as a genetic resources enhancement center for the developing world, as shown by this review article focusing on wheat. CIMMYT’s value proposition resides therefore in its use of crop genetic diversity: conserving it, studying it, adding value to it, and sharing it in enhanced form with clients worldwide. The main undertakings include: long-term safe conservation of world heritage of both crop resources for future generations, in line with formal agreements under the 2004 International Treaty on Plant Genetic Resources for Food and Agriculture, understanding the rich genetic diversity of two of the most important staples worldwide, exploiting the untapped value of crop genetic resources through discovery of specific, strategically-important traits required for current and future generations of target beneficiaries, and development of strategic germplasm through innovative genetic enhancement. Finally, the Center needs to ensure that its main products reach end-users and improve their livelihoods. In this regard, CIMMYT is the main international, public source of wheat seed-embedded technology to reduce vulnerability and alleviate poverty, helping farmers move from subsistence to income-generating production systems. Beyond a focus on higher grain yields and value-added germplasm, CIMMYT plays an “integrative” role in crop and natural resource management research, promoting the efficient use of water and other inputs, lower production costs, better management of biotic stresses, and enhanced system diversity and resilience.  相似文献   
7.
A survey of stored product pests, their natural enemies, grain storage and pest management approaches in northern Namibia was conducted. The survey revealed five types of crop commodities (pearl millet, sorghum, cowpea, maize, feed mixture) stored in four types of grain stores (baskets, bag stags-flat stores, concrete bin, metal containers). No synthetic pesticides or plastic sheeting was recorded. Wooden-ash natural pesticide is the only protectant used. Ten insect pest species were found affiliated to the orders of Coleoptera (Attagenus fasciatus, Callosobruchus subinnotatus, Cryptolestes ferrugineus, Oryzaephilus surinamensis, Rhyzopertha dominica and Tribolium castaneum), Lepidoptera (Corcyra cephalonica, Sitotroga cerealella), Psocoptera (Liposcelis paeta) and Blattodea (Blattella germanica). Out of these, seven species were recognized as new stored-products pests for Namibia. Although listed for southern Africa region, no storage pest-mites (Acari) and Sitophilus spp., Prostephanus sp. or Trogoderma sp. beetles were traced. We found four new species of natural enemies of storage pests recruiting from insects (Habrobracon hebetor, Cephalonomia wattersoni, Brachymeria sp.) and mites (Blattisocius tarsalis). The occurrence of natural enemies indicates a potential for pest bio-control in Namibian grain stores.  相似文献   
8.
This paper focuses on the biological and chemical variability of four yacon (Smallanthus sonchifolius) accessions cultivated under field conditions. Significant variations in tuber shape, weight, content of oligofructans, as well as in leaf isozymes, phenolics, and relative DNA contents were found. Accessions 6 and 88 were the most productive (up to 3.01 and 3.74 kg/plant); accession 48 was the most balanced from the yield aspect in three vegetative periods. A significantly higher content of beta-(2-->1) oligofructans was noted in accessions 48 and 88 as compared to 6 and 60. No difference in sucrose, glucose, and fructose level was observed. Only accession 6 exhibited separate acid phosphatase and esterase isoforms. Accessions 6 and 60 had the highest content of phenolics, and accession 88 had the lowest relative DNA content. Large yacon intraspecific variation may be useful in future detailed research as a good background for breeding, growing, and utilization in industrial processing.  相似文献   
9.
Relations between soil biota diversity and its contribution to the performance of some ecosystem functions were assessed based on the results obtained in undisturbed and burned spruce forests near the Central Forest Nature Biosphere Reserve (Tver oblast). In August 2014, in two 4-year-old burned areas, abiotic parameters of the soils, indicators of the state of the microbial communities, the number, taxonomic diversity, and the abundance of the main groups of soil invertebrates (testate amoebae, nematodes, enchytraeids, mites, collembolans, and the mesofauna as a whole) were determined. In the soils of the burned areas, higher CO2, CH4, and N2O emissions were observed. The number of bacterial cells remained similar, and the total length of active mycelium was not significantly different. All this implies a certain intensification of biogenic processes promoting the mobilization of carbon and nitrogen after fire. The number of most of the groups of soil animals was lower (not always significantly) in the burned area than that in the soils of the undisturbed forests. The changes in the taxonomic diversity were specific for each taxon studied. Overall, the diversity of invertebrates was related to the litter thickness. However, the high taxonomic diversity of soil fauna did not always correspond to the active functioning of the ecosystem. Thus, for some taxa, a quite close correlation was found, for instance, between the total number of species (of testate amoebae in particular) and the berry crop, as well as between the soil mesofauna population and the dead wood stock. The total diversity of the investigated taxa included in the detrital trophic web was the most reliable indicator of the carbon stock in the burned areas.  相似文献   
10.
Macleaya cordata (plume poppy) is a source of bioactive compounds, mainly isoquinoline alkaloids which are used in phytopreparations with anti-inflammatory and antimicrobial activities. In this study, the alkaloids sanguinarine, chelerythrine, their dihydro derivatives, protopine and allocryptopine and phenolics, gallic, protocatechuic, p-hydroxybenzoic, m-hydroxybenzoic, gentisic, p-coumaric, caffeic, ferulic and sinapic acids were determined in extracts prepared from M. cordata aerial part, seeds, and seed capsules using HPLC with UV detection and/or LC/MS with electrospray ionization. The highest content of sanguinarine and chelerythrine was found in capsules. Protopine and allocryptopine were major alkaloids in leaves including footstalks. The seed oil contained dihydrosanguinarine, dihydrochelerythrine and twelve fatty acids of which linoleic, oleic, palmitic and stearic acids predominated. In addition, sanguinarine reductase, a key enzyme in sanguinarine/dihydrosanguinarine equilibrium in plants, was found for the first time, in the soluble proteins of leaves. Finally, extracts were tested for antimicrobial activity using the microdilution method on standard reference bacterial strains.  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