全文获取类型
收费全文 | 192篇 |
免费 | 8篇 |
专业分类
林业 | 18篇 |
农学 | 12篇 |
基础科学 | 5篇 |
38篇 | |
综合类 | 12篇 |
农作物 | 12篇 |
水产渔业 | 10篇 |
畜牧兽医 | 58篇 |
园艺 | 10篇 |
植物保护 | 25篇 |
出版年
2022年 | 6篇 |
2021年 | 13篇 |
2020年 | 8篇 |
2019年 | 15篇 |
2018年 | 10篇 |
2017年 | 14篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 3篇 |
2013年 | 8篇 |
2012年 | 15篇 |
2011年 | 17篇 |
2010年 | 15篇 |
2009年 | 7篇 |
2008年 | 10篇 |
2007年 | 7篇 |
2006年 | 6篇 |
2005年 | 10篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2001年 | 3篇 |
1998年 | 1篇 |
1991年 | 1篇 |
排序方式: 共有200条查询结果,搜索用时 187 毫秒
101.
Morpho-physiological and molecular analysis were conducted to identify useful root indexes of sugar beet nutrient uptake capacity
and productivity. Root architectural parameters, root elongation rate, sulfate uptake rate and glucose and fructose content
in the root apex, traits involved in the plant response to sulfate stress, were evaluated in 18 sugar beet genotypes characterized
by different root yield. Morpho-physiological traits, determined on 11-day-old seedlings grown in hydroponics under sulfate
deprivation, showed variations from 59 to 197% and were significantly correlated (P < 0.01) with root yield. Under field conditions, the highest root yield genotype (L18), which has the highest root phenotypic
values following sulfate shortage, also showed the greatest root length density and leaf relative water content, with respect
to the lowest root yield genotype (L01). Bulk segregant analysis based on AFLP analysis, done on a segregating progeny obtained
from the cross between the two lines L01 × L18, allowed the identification of two AFLP markers associated to the root elongation
rate parameter that showed the highest variation among all the analyzed root traits. The genetic diversity of root adaptive
traits and the use of marker-assisted selection aimed at increasing sugar yield under water and nutrient stress in sugar beet
breeding programmes are discussed. 相似文献
102.
103.
Daniele Castagneri Emanuele Lingua Giorgio Vacchiano Paola Nola Renzo Motta 《Annals of Forest Science》2010,67(3):304-304
104.
There is a general consensus that most subsidies to fisheries, particularly fuel subsidies, are harmful to both the economy and the environment. As the World Trade Organization struggles to come to an agreement on fisheries subsidies, understanding the position of the negotiating countries is crucial. As we move toward more sustainable regulations, we must ensure that no loopholes exist for countries to evade binding regulations. In this note, we use the example of the United States to illustrate how arguments for exemptions can lead to such loopholes. The United States provides interesting insight, as it appears that their support for a ban on fisheries subsidies may be contingent upon a legal pun, which would allow them and other countries to carry on subsidizing fuel to their fishing fleets into the future. 相似文献
105.
Moritz Mittelbach Andrey M Yurkov Daniele Nocentini Massimo Nepi Maximilian Weigend Dominik Begerow 《BMC ecology》2015,15(1)
Background
Studies on the diversity of yeasts in floral nectar were first carried out in the late 19th century. A narrow group of fermenting, osmophilous ascomycetes were regarded as exclusive specialists able to populate this unique and species poor environment. More recently, it became apparent that microorganisms might play an important role in the process of plant pollination. Despite the importance of these nectar dwelling yeasts, knowledge of the factors that drive their diversity and species composition is scarce.Results
In this study, we linked the frequencies of yeast species in floral nectars from various host plants on the Canary Islands to nectar traits and flower visitors. We estimated the structuring impact of pollination syndromes (nectar volume, sugar concentration and sugar composition) on yeast diversity.The observed total yeast diversity was consistent with former studies, however, the present survey yielded additional basidiomycetous yeasts in unexpectedly high numbers. Our results show these basidiomycetes are significantly associated with ornithophilous flowers. Specialized ascomycetes inhabit sucrose-dominant nectars, but are surprisingly rare in nectar dominated by monosaccharides.Conclusions
There are two conclusions from this study: (i) a shift of floral visitors towards ornithophily alters the likelihood of yeast inoculation in flowers, and (ii) low concentrated hexose-dominant nectar promotes colonization of flowers by basidiomycetes. In the studied floral system, basidiomycete yeasts are acknowledged as regular members of nectar. This challenges the current understanding that nectar is an ecological niche solely occupied by ascomycetous yeasts.Electronic supplementary material
The online version of this article (doi:10.1186/s12898-015-0036-x) contains supplementary material, which is available to authorized users. 相似文献106.
107.
Vicente Martins Gomes Rodrigo Moreira Ribeiro Alexandre Pio Viana Ricardo Moreira de Souza Eileen Azevedo Santos Daniele Lima Rodrigues Odimar Ferreira de Almeida 《European journal of plant pathology / European Foundation for Plant Pathology》2017,148(3):699-708
Interaction between the phytonematode Meloidogyne enterolobii and the fungus Fusarium solani has caused direct and indirect losses in the entire guava production chain and consequent extermination of guava plantations throughout Brazil. The combined action of these two pathogens is known as “guava decline”. In order to obtain and assess Psidium spp. interspecific hybrids for resistance to the nematode M. enterolobii, interspecific crosses of P. guineense (susceptible araçá) x P. cattleyanum (resistant araçá); P.guineense (susceptible araçá) x P. guajava (susceptible guava) and P. cattleyanum (resistant araçá) x P. guajava (susceptible guava) were conducted. These crosses resulted in hybrid immune, susceptible and resistant to Meloidogyne enterolobii. The chi-square test rejected the hypothesis of monogenic inheritance with incomplete dominance, which corroborates that this trait has polygenic action. Predictions of genetic values ??and parameters were obtained by the REML / BLUP procedure, at individual level. Finally, the 30 selected individuals (immune and resistant) were obtained, which will be backcrossed with guava for the recovery of the agronomic traits desired and subsequent release of a new cultivar. 相似文献
108.
109.
110.
Iacono E Cunto M Zambelli D Ricci F Tazzari PL Merlo B 《Veterinary research communications》2012,36(2):107-118
Domestic cats are preferred models for normal physiology and several human diseases. In the present study feline fetal fluids and membranes were evaluated as possible sources of MSCs. Samples were recovered from 4 pregnant queens after ovarian-hysterectomy. Gestational sacs were separated from uterine wall; after allantoic and amniotic fluids aspiration and chorion-allantois and amniotic membranes separation, all cell lineages were cultured into 25 cm(2) flasks, in DMEM/TCM199, in a 5% CO(2) incubator at 38.5 °C. At passage 3, chondrogenic, osteogenic and adipogenic differentiation ability were evaluated by culturing cell monolayers in differentiating media for 21 days. Cellular characterization with CD90, CD44, CD105, CD73, CD34, CD14, CD45, was performed by flow cytometry. In all samples, adherent fibroblastoid spindle-shaped cells were observed. Positive von Kossa and Alizarin Red staining confirmed osteogenesis. Alcian blue staining of matrix glycosaminoglycans illustrated chondrogenesis, and positive Oil Red O lipid droplets within cell cytoplasm suggested adipogenesis. All cell lines isolated were positive for CD90, CD44, CD105 and negative for CD34, CD14 and CD45; as unexpected and different from human cells, feline cells resulted negative for CD73. Based on this preliminary results, fetal fluids and membranes could represent an alternative sources for mesenchymal stem cells in feline species. 相似文献