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51.
Khodadadi Maral Mabit Lionel Zaman Mohammad Porto Paolo Gorji Manouchehr 《Journal of Soils and Sediments》2019,19(4):2103-2113
Journal of Soils and Sediments - One of the most fragile agro-ecosystems in Iran is represented by dry farming lands on steep hillslopes that occupy ca. 54% of the national agricultural lands.... 相似文献
52.
Disinfectant susceptibility testing of avian and swine Campylobacter isolates by a filtration method
The susceptibility testing of disinfectants against Campylobacter jejuni and Campylobacter coli strains from broilers and pigs was investigated. The filtration method European standard EN 1040 was adapted to Campylobacter cultures and validated with reference strains. Two disinfectants were tested: 1% benzalkonium chloride active matter, as quaternary ammonium compound, and 0.63% sodium hypochlorite as chlorine-releasing agent. Both disinfectants were effective against the 34 Campylobacter strains tested after 5 min exposure under in vitro conditions. No link between resistance to disinfectants and antibiotics could be observed. 相似文献
53.
American Journal of Potato Research - 相似文献
54.
Anne-Laure Janson Lionel Denis Mathieu Rauch Nicolas Desroy 《Journal of Soils and Sediments》2012,12(10):1568-1580
Purpose
Bioturbation is a major process influencing the functioning of benthic ecosystems. Although controlled experiments with species in monoculture or in artificial combinations have increased the knowledge about the role of biological diversity on geochemical processes, specific interactions have been neglected, making the extrapolation of experimental results to natural systems difficult. In this context, the main objective of this study was to measure the effects of a whole natural macrobenthic community on benthic oxygen uptake.Materials and methods
The relationships between macrofauna and oxygen uptakes were investigated in the estuarine system of the Seine, France, during the winter and fall according to the variability of river discharge. Four undisturbed sediment cores with associated macrofauna and overlying water were sampled at nine subtidal stations in order to perform whole core incubations and measure total oxygen uptake (TOU). Moreover, values of diffusive oxygen uptake (DOU) were obtained using microelectrode profiling and fauna-mediated oxygen uptake (FOU) was calculated as the difference between TOU and DOU. FOUs were thus linked to macrofaunal parameters; both traditional (species richness, abundance and biomass) and functional (trophic guilds and bioturbation modes).Results and discussion
The average FOU (±SD) ranged from 170?±?36 to 1,324?±?701???mol?m?2?h?1, and values represented 33 to 89?% of TOU. Each of the traditional macrofauna parameters had a significant and positive correlation with FOU. In addition, abundance, biomass and species number of some functional groups (e.g. suspension feeders and biodiffusors) were also correlated to FOU, supporting the diversity?Cstability hypothesis of McArthur (Ecology 36:533?C536, 1955). Nevertheless, the relationship between FOU and other functional groups such as conveyors illustrated the idiosyncratic nature of this hypothesis, underlining the difficulty of clearly identifying the role of a macrofaunal community on oxygen exchanges at the sediment?Cwater interface.Conclusions
Our results confirm the importance of functional biodiversity on mineralization processes as well as the need to take into account the whole community. They also suggest that future studies should focus on the functional consequences of species loss and the potential resilience of the communities as a way to maintain ecosystem processes. 相似文献55.
Yasser Trabelsi Foued Gharbi Abdessalem El Ghali Mansour Oueslati Mohammad Samaali Wahid Abdelli Souad Baccouche Malik Ben Tekaya Moncef Benmansour Lionel Mabit Nabiha Ben M’Barek Nafaa Reguigui Jose M. Abril 《Journal of Soils and Sediments》2012,12(5):784-796
Purpose
Ichkeul National Park, NW Tunisia, is a UNESCO Biosphere Reserve. Garaet El Ichkeul Lake is known for its seasonal variability in water level and salinity. In recent decades, the waterbody has been affected by the construction of new hydraulic structures. To reduce the impacts of dams and to maintain the sustainability of the ecosystem, a sluice was built at the outlet of the lake, and it operated for the first time in 1996. This paper describes an investigation of recent sedimentation dynamics in Ichkeul Lake, determined by radiometric dating of sediment cores.Materials and methods
A sediment core was collected with a UWITEC gravity corer at the deepest, central part of the lake in August 2009. Specific activities of unsupported lead-210 (210Pb) and caesium-137 (137Cs) were measured in the core, enabling calculation of recent sediment accumulation rates (SAR). Published radiometric data from nearby sediment cores, collected in 1997 and 1982, provide a comparison.Results and discussion
The measured excess 210Pb inventory was 5300?±?500?Bq?m?2, leading to an estimation of constant flux of 165?±?16?Bq?m?2?yr?1, a value higher than the best estimate for local atmospheric fluxes (123?±?12?Bq?m?2?yr?1) and the flux estimated from the core collected in 1982 (48?Bq?m?2?yr?1). The 137Cs inventory was 3550?±?120?Bq?m?2, two times higher than the historical 137Cs atmospheric deposition in the area. The 137Cs profile displayed a distinct peak, but the 137Cs depth-distribution did not follow the pattern expected from atmospheric deposition. Application of the constant rate of supply (CRS) model, with the reference point method, produced a chronology and SAR values comparable to those found in previous work. The whole 137Cs profile was quantitatively reconstructed from the historical records of atmospheric deposition, using the system-time-averaged (STA) model.Conclusions
The CRS and STA models provide consistent sediment accumulation results for the whole data set, considering the time resolution of the chronology (~6?years) and analytical uncertainties. Results from cores sampled in 1982, 1997 and 2009 reveal an increasing SAR trend, from ~0.25?g?cm?2?yr?1 in the early 1940s to ~0.67?g?cm?2?yr?1 at present. In the 13?years since installation of sluice gates at Tinja, SAR in the central Ichkeul Lake has not declined. Thus, if siltation continues at the present rate, shallowing of the lake will seriously affect the hydromorphology and ecology of this important lake. 相似文献56.
Lionel Mabit Katrin Meusburger Andra-Rada Iurian Philip N. Owens Arsenio Toloza Christine Alewell 《Journal of Soils and Sediments》2014,14(3):630-636
Purpose
Many environmental investigations (empirical and modelling) and theories are based on reliable information on the depth distribution of physical, chemical and biological properties in soils and sediments. However, such depth profiles are not easy to determine using current approaches, and, consequently, new devices are needed that are able to sample soils and sediments at fine resolutions.Materials and methods
We have designed an economic, portable, hand-operated surface soil/sediment sampler—the Fine Increment Soil Collector (FISC)—which allows for the close control of incremental soil/sediment sampling and for easy recovery of the material collected by a simple screw-thread extraction system. This innovative sampling system was developed originally for the beryllium-7 (7Be) approach in soil and sediment redistribution research. To ensure reliable estimates of soil erosion and sediment deposition from 7Be measurements, the depth distribution of this short-lived fallout radionuclide in soil/sediment at the resolution of millimetres is a crucial requirement. This major challenge of the 7Be approach can be met by using the FISC.Results and discussion
We demonstrate the usefulness of the FISC by characterising the depth distribution of 7Be at increments of 2.5 mm for a soil reference site in Austria. The activity concentration of 7Be at the uppermost increment (0–2.5 mm) was ca. 14 Bq kg?1 and displayed decreasing activity with depth. Using most conventional sampling devices (i.e. the scraper-plate system), the most accurate depth increment would have been 10 mm, and the activity concentration at the surface would have been considerably lower. Consequently, coarser sampling would have influenced estimates of 7Be-derived soil erosion and deposition. The potential application for other soil/sediment properties, such as nutrients (e.g. phosphorus), contaminants and carbon are also discussed.Conclusions
By enabling soil and sediment profiles to be sampled at a depth resolution of millimetres, the FISC has the potential to provide key information when addressing several environmental and geoscientific issues, such as the precise depth distributions of soil/sediment nutrients, contaminants and biological properties. 相似文献57.
Amina Yssouf Cristina Socolovschi Hamza Leulmi Tahar Kernif Idir Bitam Gilles Audoly Lionel Almeras Didier Raoult Philippe Parola 《Comparative immunology, microbiology and infectious diseases》2014
In the present study, a molecular proteomics (MALDI-TOF/MS) approach was used as a tool for identifying flea vectors. We measured the MS spectra from 38 flea specimens of 5 species including Ctenocephalides felis, Ctenocephalides canis, Archaeopsylla erinacei, Xenopsylla cheopis and Stenoponia tripectinata. A blind test performed with 24 specimens from species included in a library spectral database confirmed that MALDI-TOF/MS is an effective tool for discriminating flea species. Although fresh and 70% ethanol-conserved samples subjected to MALDI-TOF/MS in blind tests were correctly classified, only MS spectra of quality from fresh specimens were sufficient for accurate and significant identification. A cluster analysis highlighted that the MALDI Biotyper can be used for studying the phylogeny of fleas. 相似文献
58.
Bernard Nicolardot Lamia Bouziri Fabiola Bastian Lionel Ranjard 《Soil biology & biochemistry》2007,39(7):1631-1644
The effects of location (soil surface vs. incorporated in soil) and nature of plant residues on degradation processes and indigenous microbial communities were studied by means of soil microcosms incubation in which the different soil zones influenced by decomposition i.e. residues, soil adjacent to residues (detritusphere) and distant soil unaffected by decomposition (bulk soil) were considered. Plant material decomposition, organic carbon assimilation by the soil microbial biomass and soil inorganic N dynamics were studied with 13C labelled wheat straw and young rye. The genetic structure of the community in each soil zone were compared between residue locations and type by applying B- and F-ARISA (for bacterial- and fungal-automated ribosomal intergenic spacer analysis) directly to DNA extracts from these different zones at 50% decomposition of each residue. Both location and biochemical quality affected residue decomposition in soil: 21% of incorporated 13C wheat straw and 23% left at the soil surface remained undecomposed at the end of incubation, the corresponding values for 13C rye being 1% and 8%. Residue decomposition induced a gradient of microbial activity with more labelled C incorporated into the microbial biomass of the detritusphere. The sphere of influence of the decomposing residues on the dynamics of soluble organic C and inorganic N in the different soil zones showed particular patterns which were influenced by both residue location and quality. Residue degradation stimulated particular genetic structure of microbial community with a gradient from residue to bulk soil, and more pronounced spatial heterogeneity for fungal than for bacterial communities. The initial residue quality strongly affected the resulting spatial heterogeneity of bacteria, with a significance between-zone discrimination for rye but weak discrimination between the detritusphere and bulk soil, for wheat straw. Comparison of the different detrituspheres and residue zones (corresponding to different residue type and location), indicated that the genetic structure of the bacterial and fungal communities were specific to a residue type for detritusphere and to its location for residue, leading to conclude that the detritusphere and residue corresponded to distinct trophic and functional niches for microorganisms. 相似文献
59.
Destaillats F Berdeaux O Sébédio JL Juaneda P Grégoire S Chardigny JM Bretillon L Angers P 《Journal of agricultural and food chemistry》2005,53(5):1422-1427
Rumelenic (cis-9,trans-11,cis-15 18:3) acid is a naturally occurring conjugated isomer of alpha-linolenic acid (CLnA) in milk fat. Metabolism in rats was studied using a synthetic CLnA mixture, composed mainly by equimolar quantities of cis-9,trans-11,cis-15 and cis-9,trans-13,cis-15 CLnA isomers. Their metabolisms were studied by feeding high quantities of CLnA (150 mg/day) for 4 days to rats that had been reared on a fatfree diet for 2 weeks. After this period, animals were sacrificed and liver and epididymal adipose tissue lipids extracted. Six metabolites of the cis-9,trans-11,cis-15 18:3 CLnA isomers were identified as being cis-7,trans-9,cis-13 16:3, cis-11,trans-13,cis-17 20:3, cis-8,cis-11,trans-13,cis-17 20:4, cis-5,cis-8,cis-11,trans-13,cis-17 20:5, cis-7,cis-10,cis-13,trans-15,cis-19 22:5, and cis-4,cis-7,cis-10,cis-13,trans-15,cis-19 22:6 acids. Two metabolites of cis-9,trans-13,cis-15 18:3 CLnA isomer were also identified by GC-MS as being cis-7,trans-11,cis-13 16:3 and cis-5,cis-8,cis-11,trans-15,cis-17 20:5. 相似文献
60.
Giraud E Moulin L Vallenet D Barbe V Cytryn E Avarre JC Jaubert M Simon D Cartieaux F Prin Y Bena G Hannibal L Fardoux J Kojadinovic M Vuillet L Lajus A Cruveiller S Rouy Z Mangenot S Segurens B Dossat C Franck WL Chang WS Saunders E Bruce D Richardson P Normand P Dreyfus B Pignol D Stacey G Emerich D Verméglio A Médigue C Sadowsky M 《Science (New York, N.Y.)》2007,316(5829):1307-1312
Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation. 相似文献