全文获取类型
收费全文 | 296篇 |
免费 | 40篇 |
国内免费 | 2篇 |
专业分类
林业 | 13篇 |
农学 | 3篇 |
22篇 | |
综合类 | 25篇 |
农作物 | 8篇 |
水产渔业 | 11篇 |
畜牧兽医 | 242篇 |
园艺 | 3篇 |
植物保护 | 11篇 |
出版年
2023年 | 6篇 |
2022年 | 6篇 |
2021年 | 8篇 |
2020年 | 12篇 |
2019年 | 7篇 |
2018年 | 19篇 |
2017年 | 14篇 |
2016年 | 18篇 |
2015年 | 8篇 |
2014年 | 20篇 |
2013年 | 24篇 |
2012年 | 10篇 |
2011年 | 13篇 |
2010年 | 18篇 |
2009年 | 19篇 |
2008年 | 11篇 |
2007年 | 15篇 |
2006年 | 13篇 |
2005年 | 9篇 |
2004年 | 8篇 |
2003年 | 3篇 |
2002年 | 2篇 |
2001年 | 5篇 |
2000年 | 3篇 |
1999年 | 2篇 |
1998年 | 15篇 |
1997年 | 10篇 |
1996年 | 11篇 |
1995年 | 9篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1988年 | 2篇 |
排序方式: 共有338条查询结果,搜索用时 31 毫秒
271.
de Freitas Rosa Paula Aguiar Mônica Lopes Bernardo André 《Water, air, and soil pollution》2017,228(7):1-20
Water, Air, & Soil Pollution - Sediment losses as concentrations and yields were measured for a year from 12 segments of a newly constructed (buried) natural gas pipeline on the US Forest... 相似文献
272.
273.
274.
Biofloc and food contribution to grow‐out and broodstock of Farfantepenaeus brasiliensis (Latreille, 1817) determined by stable isotopes and fatty acids
下载免费PDF全文
![点击此处可从《Aquaculture Research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Eden Magaña‐Gallegos Rodrigo González‐Zúñiga Miguel Arevalo Gerard Cuzon Elisa Chan‐Vivas Korinthia López‐Aguiar Elsa Noreña‐Barroso Eduardo Pacheco Manuel Valenzuela Carlos Maldonado Gabriela Gaxiola 《Aquaculture Research》2018,49(5):1782-1794
The aim of this study was to use the natural dietary markers (stable isotopes and fatty acids) during grow‐out in a biofloc system and for the egg production of Farfantepenaeus brasiliensis shrimp. Egg production was compared for two broodstock origins: biofloc and a wild origin. To delineate the relative contribution to shrimp muscle and eggs, IsoSource software was used. The most important source that contributed to grow‐out shrimp was biofloc ≥250 μm. According to the principal component analysis (PCA) applied to the fatty acid profile of food sources, the first component explains 84.4% of the variability, and the most important source of fatty acids for this component was biofloc ≥250 μm. The most important fresh food sources that contributed to egg production were Artemia biomass, polychaetes and semi‐moist feed for both broodstock origins. According to a PCA analysis of the fatty acid profiles, the most important fresh foods were polychaetes and semi‐moist feed. In conclusion, both isotopic signature and fatty acid profile of the food sources can be used successfully to determine the integration of carbon in the diets of shrimp. 相似文献
275.
Carbon dioxide emission from european estuaries 总被引:1,自引:0,他引:1
M Frankignoulle G Abril A Borges I Bourge C Canon B Delille E Libert JM Theate 《Science (New York, N.Y.)》1998,282(5388):434-436
The partial pressure of carbon dioxide (pCO2) in surface waters and related atmospheric exchanges were measured in nine European estuaries. Averaged fluxes over the entire estuaries are usually in the range of 0.1 to 0.5 mole of CO2 per square meter per day. For wide estuaries, net daily fluxes to the atmosphere amount to several hundred tons of carbon (up to 790 tons of carbon per day in the Scheldt estuary). European estuaries emit between 30 and 60 million tons of carbon per year to the atmosphere, representing 5 to 10% of present anthropogenic CO2 emissions for Western Europe. 相似文献
276.
277.
DK Rendell TE Rentsch JM Smith DS Chandler APL Callinan 《New Zealand veterinary journal》2013,61(6):313-317
AIM: To determine associations between resistance of Ostertagia (= Teladorsagia) spp to macrocyclic lactone (ML) anthelmintics and history of use of anthelmintics, by type, on commercial sheep farms in temperate regions of southern South Australia and Victoria, Australia. METHODS: Faecal egg count reduction tests (FECRTs) were conducted during a 2.5-year period (from August 2001 to January 2004) and records of the type of anthelmintic used in the 5 years preceding the FECRTs were collected from commercial sheep farms (n=103) in southern South Australia and Victoria, and data analysed retrospectively. ML resistance was defined as <95% reduction of Ostertagia spp 10–14 days after treatment with ivermectin (IVM), orally, at half the manufacturer's recommended dose rate. Use of anthelmintics in the preceding 5 and 10 years on each property was classified according to the nett number of years each of the following classes of drug had been used: IVM oral liquid (IVO), IVM controlled-release capsules (CRCs), abamectin (ABA), moxidectin (MOX) or a non-ML an- thelmintic. The prevalence of ML resistance, by property, was analysed for associations with prior use of anthelmintics. RESULTS: Resistance by Ostertagia spp to ML anthelmintics was evident on 51/103 (49.5%) properties. The prevalence of resistance was lowest (23%) on properties on which MOX had not been used, and was significantly higher (64–77%) on properties on which MOX had been used for ≥2 of the preceding 5 years (p<0.001). In contrast, the prevalence of resistance was highest (70–74%) on the properties on which IVM, or IVM and/ or ABA, had not been used in the previous 5 years (on which the use of MOX was predominant), and was markedly lower (20– 42%) on properties that had used IVM or IVM and/or ABA for at least one of the preceding 5 years. Prevalence of resistance was higher for properties on which the only ML anthelmintic used was MOX (19/29=66%) than for those on which the only ML used was IVO (2/19=11%; p<0.001). Properties on which the only ML used was MOX were 2.72 times more likely to have resistance than properties on which the only ML used was IVO (95% confidence interval (CI) = 1.01–5.08). CONCLUSION: Use of MOX for ≥2 of the preceding 5 years was associated with a higher prevalence of resistance to ML by Ostertagia spp on sheep farms in south eastern Australia than the use of IVO. 相似文献
278.
Dynamical coupling of multiscale land change models 总被引:1,自引:1,他引:0
Evaldinolia Moreira Sérgio Costa Ana Paula Aguiar Gilberto Câmara Tiago Carneiro 《Landscape Ecology》2009,24(9):1183-1194
No single model or scale can fully capture the causes of land change. For a given region, land changes may have different impacts at different places. Limits and opportunities imposed by biophysical and socio-economic conditions, such as local policies and accessibility, may induce distinct land change trajectories. These local land change trajectories may, in turn, indirectly affect other places, as local actions interact with higher-level driving forces. Such intraregional interdependencies cannot be captured by studies at a single scale, calling for multiscale and multilocality studies. This paper proposes a software organization for building computational models that support dynamical linking of multiple scales. This structure couples different types of models, such as cell-space models with agent-based models. We show how results in multiscale models can flow both in bottom-up and top-down directions, thus allowing feedback from local actors to regional scales. The proposal is general and independent of specific software, and it is effective to model intraregional, bottom-up and top-down interactions in land change models. To show the model’s potential, we develop a case study that shows how a multiscale model for the Brazilian Amazonia can include feedbacks between local to regional scales. 相似文献
279.
This is the first report of Scaphoideus titanus, the main vector of flavescence dorée, for Madeira (Portugal) and also for Macaronesia. This new record currently represents its southernmost occurrence in Europe. This leafhopper is present in most of the primary wine production regions in the north of Madeira island. There were no symptoms of flavescence dorée disease during the monitoring period from 2010 to 2017. The ability of S. titanus to survive in regions with a subtropical climate suggests that it may also live in the most meridional areas of the Mediterranean region where, until now, it has been absent. 相似文献
280.
Wanderley José de Melo Priscila de Stéfani Aguiar Gabriel Maurício Peruca de Melo Valéria Peruca de Melo 《Soil biology & biochemistry》2007,39(6):1341-1347
Sewage sludge produced by the SABESP wastewater treatment plant (Companhia de Saneamento Básico do Estado de São Paulo), located in Barueri, SP, Brazil, may contain high contents of nickel (Ni), increasing the risk of application to agricultural soils. An experiment was carried out under field conditions in Jaboticabal, SP, Brazil, with the objective of evaluating the effects on soil properties and on maize plants of increasing rates of a sewage sludge rich in Ni that had been applied for 6 consecutive years. The experiment was located on a Typic Haplorthox soil, using an experimental design of randomized blocks with four treatments (rates of sewage sludge) and five replications. At the end of the experiment the accumulated amounts of sewage sludge applied were 0.0, 30.0, 60.0 and 67.5 t ha−1. Maize (Zea mays L.) was the test plant. Soil samples were collected 60 d after sowing at depths of 0-20 cm for Ni studies and from 0 to 10 cm and from 10 to 20 cm for urease studies. Sewage sludge did not cause toxicity or micronutrient deficiencies to maize plants and increased grain production. Soil Ni appeared to be associated with the most stable fractions of the soil organic matter and was protected against strong extracting solutions such as concentrated and hot HNO3 and HCl. Ni added to the soil by sewage sludge increased the metal concentration in the shoots, but not in the grain. The Mehlich 3 extractor was not efficient to evaluate Ni phytoavailability to maize plants. Soil urease activity was increased by sewage sludge only in the layer where the residue was applied. 相似文献