全文获取类型
收费全文 | 282篇 |
免费 | 9篇 |
专业分类
林业 | 20篇 |
农学 | 14篇 |
基础科学 | 2篇 |
110篇 | |
综合类 | 13篇 |
农作物 | 27篇 |
水产渔业 | 10篇 |
畜牧兽医 | 63篇 |
园艺 | 10篇 |
植物保护 | 22篇 |
出版年
2022年 | 1篇 |
2021年 | 9篇 |
2020年 | 4篇 |
2019年 | 8篇 |
2018年 | 3篇 |
2017年 | 8篇 |
2016年 | 9篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 20篇 |
2012年 | 17篇 |
2011年 | 32篇 |
2010年 | 16篇 |
2009年 | 12篇 |
2008年 | 30篇 |
2007年 | 14篇 |
2006年 | 11篇 |
2005年 | 9篇 |
2004年 | 14篇 |
2003年 | 17篇 |
2002年 | 9篇 |
2001年 | 2篇 |
2000年 | 1篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 5篇 |
1993年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1980年 | 3篇 |
1979年 | 1篇 |
1977年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有291条查询结果,搜索用时 15 毫秒
41.
Costagliola A Britti D Russo V Meomartino L Castagna F Giordano D Insabato L Paciello O 《Avian diseases》2011,55(1):147-150
A common seagull (Larus fuscus) was found near the southern coast of Italy by the veterinarians of the local wild animal rescue center. Physical examination of the bird revealed an ulcerated mass involving a majority of the oral cavity; the mass did not allow for normal feeding. After the bird died necropsy was performed and the mass was histologically and immunohistochemically examined. The morphology and the immunoreactivity for Melan-A and S-100 antigens led to a diagnosis of malignant melanoma. This is the first case of malignant melanoma described in a seagull, and herein we compare the characteristics of the present case with malignant melanoma already described in domestic animals. 相似文献
42.
In this study, an experimental challenge was carried out by feeding Nero Siciliano pigs with acorn to evoke melanin-like pigmentation and support the hypothesis that it is caused by ingested material. Twelve pigs were studied, 6 fed with acorns and 6 fed commercial feed. At slaughter, all the animals fed on acorns showed black discolouration of almost all lymph nodes. The lymph nodes were normal in size and shape. Histochemical tests performed on tissues allowed us to identify and differentiate the pigment. Immunohistochemical staining for macrophage markers showed macrophages containing a variable amount of melanin-like granules. Our data, and the well-known steps of melanin formation, confirm that swine enzymes could act on phenolic substances found in acorns. 相似文献
43.
Alessandra Lagomarsino Anna Benedetti Sara Marinari Letizia Pompili M. Cristina Moscatelli Pier Paolo Roggero Roberto Lai Luigi Ledda Stefano Grego 《Biology and Fertility of Soils》2011,47(3):283-291
Five soils characterised by different agro-forest managements, typical of Mediterranean environment and with increasing human
impact were chosen in Sardinia (Italy): two vineyards with different management systems, a rotation hay crop-pasture and a
forest (Quercus suber L.). The study aimed to investigate the relationships between C storage and microbial functionality in soil under different
managements. Pools of total organic C and microbial biomass C were determined, as well as the loss of organic C due to microbial
respiration (basal and cumulative) and several microbial indices (metabolic, mineralization, and microbial quotient) as indicators
of the microbial efficiency in the use of energy and the degree of substrate limitation for soil microbes. Enzymes were chosen
on their relevance in the C (β-cellobiohydrolase, N-acetyl-β-glucosaminidase, β-glucosidase, α-glucosidase), N (leucine aminopeptidase), S (arylsulphatase) and P (acid phosphatase)
cycling and were used as indicators of functional diversity in soil. Organic C pools and enzyme activities on average increased
noticeably in soils with a lower human impact showing the highest values in forest and the lowest in the vineyards, following
the trend of organic matter availability. The trend in functional diversity reflected the increase of microbial pool and organic
C availability: the vineyards showed a lower Shannon’s diversity index, whilst pasture and forest sites reached the maximum
levels of functional diversity. These soils showed an increase of microbial efficiency in the use of available resources and
the decrease of substrate limitation for soil microbes. 相似文献
44.
Towards an improved and more flexible representation of water stress in coupled photosynthesis-stomatal conductance models 总被引:1,自引:0,他引:1
Gregorio Egea Anne Verhoef Pier Luigi Vidale 《Agricultural and Forest Meteorology》2011,151(10):1370-1384
Coupled photosynthesis-stomatal conductance (A-gs) models are commonly used in ecosystem models to represent the exchange rate of CO2 and H2O between vegetation and the atmosphere. The ways these models account for water stress differ greatly among modelling schemes. This study provides insight into the impact of contrasting model configurations of water stress on the simulated leaf-level values of net photosynthesis (A), stomatal conductance (gs), the functional relationship among them and their ratio, the intrinsic water use efficiency (A/gs), as soil dries. A simple, yet versatile, normalized soil moisture dependent function was used to account for the effects of water stress on gs, on mesophyll conductance (gm) and on the biochemical capacity. Model output was compared to leaf-level values obtained from the literature. The sensitivity analyses emphasized the necessity to combine both stomatal and non-stomatal limitations of A in coupled A-gs models to accurately capture the observed functional relationships A vs. gs and A/gsvs. gs in response to drought. Accounting for water stress in coupled A-gs models by imposing either stomatal or biochemical limitations of A, as commonly practiced in most ecosystem models, failed to reproduce the observed functional relationship between key leaf gas exchange attributes. A quantitative limitation analysis revealed that the general pattern of C3 photosynthetic response to water stress may be well represented in coupled A-gs models by imposing the highest limitation strength to gm, then to gs and finally to the biochemical capacity. 相似文献
45.
46.
Vitis vinifera L. cv. Pinot blanc was grown in both pot and commercial vineyard under lime‐stress conditions. Dark green to very chlorotic young leaves were sampled in order to analyze chlorophyll and iron (Fe) concentration and content, area, fresh and dry weight, specific weight per area. Iron content per individual leaf was a good parameter to separate dark green leaves from chlorotic ones in both trials, while Fe concentration on DW basis was not. Chlorosis occurrence always decreased leaf dry weight and specific weight per area. 相似文献
47.
48.
Romina Beleggia Cristiano Platani Giuseppe Spano Massimo Monteleone Luigi Cattivelli 《Journal of Cereal Science》2009
Although pasta is generally not considered for its aromatic properties, some evidence proves that cereal flours release volatile compounds and they might have an effect on the aroma of the transformed products. This work reports on the characterization of the volatile components of semolina and pasta obtained from four durum wheat cultivars (Triticum durum Desf., cvs. PR22D89, Creso, Cappelli, Trinakria). Semolina samples were characterized through polar metabolite profiling and fatty acid analysis to identify potential precursors of the volatile components. The results show significant differences among the samples tested with cv. Trinakria characterized by the highest content of sugars and fatty acids. Volatile composition was investigated both in semolina and in cooked pasta using headspace solid-phase micro-extraction (HS-SPME) and identified by GC–MS. Thirty-five volatile compounds including aldehydes, ketones, alcohols, terpenes, esters, hydrocarbons and a furan were identified. Significant differences were observed between semolina and pasta samples in terms of composition and amount of the volatile compounds. During cooking an increase in aldehyde content, the appearance of ketones and a decrease in alcohol content were observed. Correlations between metabolites and volatiles demonstrate that the flavour of cooked pasta may differ significantly depending on the durum wheat cultivar employed. 相似文献
49.
Resistance to blackleg and tuber soft rot in sexual and somatic interspecific hybrids with different genetic background 总被引:1,自引:0,他引:1
Domenico Carputo Teodoro Cardi Mario Speggiorin Astolfo Zoina Luigi Frusciante 《American Journal of Potato Research》1997,74(3):161-172
Diploid interspecific hybrids from crosses betweenSolanum tuberosum haploids andS. canasense, S. multidissectum, andS. tarijense, along with tetraploid and hexaploid somatic hybrids S.tuberosum (+)S. commersonii, were screened for resistance to blackleg and tuber soft rot byErwinia carotovora subsp.atroseptica andE. carotovora subsp.carotovora. Among the diploid hybrids, those involving clone mlt la of S.multidissectum and tar 2b ofS. tarijense yielded the highest number of genotypes resistant to both blackleg and tuber soft rot. By contrast, all the hybrids involving clone tar 1lb ofS. tarijense were susceptible to both bacterial diseases. As far as resistance of somatic hybrids is concerned, the most interesting genotype was the tetraploid one which showed resistance to both blackleg and tuber soft rot Significant correlations were found betweenE. carotovora subsp.atroseptica andE. carotovora subsp.carotovora both in resistance to blackleg and in resistance to tuber soft rot, suggesting that resistance to the two subspecies is controlled by the same gene/s or that the relevant genes are linked. On the other hand, correlations between blackleg and tuber soft rot were never significant, indicating that different mechanisms may control resistance in tuber and stems. Alternatively, the resistance could be controlled by the same gene/s under a different spatial/temporal expression pattern. Twelve diploid sexual hybrids and one tetraploid somatic hybrid were selected for resistance to blackleg and/or tuber soft rot and for tuber characteristics. 相似文献
50.
Gianluca Pane Gabriele Cacciola Elisabetta Giacco Gian Luigi Mariottini Erika Coppo 《Marine drugs》2015,13(10):6440-6452
External otitis is a diffuse inflammation around the external auditory canal and auricle, which is often occurred by microbial infection. This disease is generally treated using antibiotics, but the frequent occurrence of antibiotic resistance requires the development of new antibiotic agents. In this context, unexplored bioactive natural candidates could be a chance for the production of targeted drugs provided with antimicrobial activity. In this paper, microbial pathogens were isolated from patients with external otitis using ear swabs for over one year, and the antimicrobial activity of the two methanol extracts from selected marine (Dunaliella salina) and freshwater (Pseudokirchneriella subcapitata) microalgae was tested on the isolated pathogens. Totally, 114 bacterial and 11 fungal strains were isolated, of which Staphylococcus spp. (28.8%) and Pseudomonas aeruginosa (P. aeruginosa) (24.8%) were the major pathogens. Only three Staphylococcus aureus (S. aureus) strains and 11 coagulase-negative Staphylococci showed resistance to methicillin. The two algal extracts showed interesting antimicrobial properties, which mostly inhibited the growth of isolated S. aureus, P. aeruginosa, Escherichia coli, and Klebsiella spp. with MICs range of 1.4 × 109 to 2.2 × 1010 cells/mL. These results suggest that the two algae have potential as resources for the development of antimicrobial agents. 相似文献