全文获取类型
收费全文 | 372篇 |
免费 | 19篇 |
专业分类
林业 | 31篇 |
农学 | 8篇 |
基础科学 | 1篇 |
78篇 | |
综合类 | 15篇 |
农作物 | 22篇 |
水产渔业 | 24篇 |
畜牧兽医 | 163篇 |
园艺 | 17篇 |
植物保护 | 32篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 7篇 |
2018年 | 6篇 |
2017年 | 4篇 |
2016年 | 14篇 |
2015年 | 7篇 |
2014年 | 16篇 |
2013年 | 14篇 |
2012年 | 30篇 |
2011年 | 34篇 |
2010年 | 14篇 |
2009年 | 19篇 |
2008年 | 34篇 |
2007年 | 30篇 |
2006年 | 17篇 |
2005年 | 21篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 20篇 |
2001年 | 9篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 4篇 |
1997年 | 5篇 |
1996年 | 2篇 |
1995年 | 3篇 |
1993年 | 6篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 3篇 |
1989年 | 2篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
排序方式: 共有391条查询结果,搜索用时 15 毫秒
91.
We compared gross N fluxes by 15N pool dilution in a coarse-textured agricultural soil when 15N was applied to the soil NH4+ pool by either: (i) mixing a 15NH4NO3 solution into disturbed soil or (ii) injection of 15NH3 gas into intact soil cores. The two techniques produced similar results for gross N mineralization rates indicating that NH4+ production in soil was not altered by soil disturbance, method of application (gas vs. solution), or amount of N applied. This was not the case for immobilization rates, which were twofold higher when 15N label was applied to the soil NH4+ pool with the mixing technique compared to the injection technique. This was attributed to the fact that more NH4+ was applied with the mixing technique. Estimates of gross nitrification were accompanied by large error terms meaning differences between 15N labeling methods could not be accurately assessed for this process rate. 相似文献
92.
Filip Coppens Gonzague Alavoine Olivier Delfosse Sylvie Recous 《Soil biology & biochemistry》2009,41(6):1335-1337
Lyophilisation of K2SO4 soil extracts has been proposed as a sample preparation technique before elemental analysis of carbon or nitrogen. However, previous measurements, based on wet oxidation or catalytic combustion, indicated that C measurements in lyophilised samples not always proved to be accurate. To determine whether the C analysis was affected by the lyophilisation process, an exploratory study was conducted to investigate the potential effects of the sample pre-treatment and of the lyophilisation process itself. This paper puts forward that the use of soil extracts, previously stored at −20 °C, may affect the recovery of salt in the samples and that contamination of the soluble carbon with exogenous C during lyophilisation is feasible. Therefore we recommend to use freshly prepared soil extracts for lyophilisation and always to include an internal standard among the unknown samples to account for a possible contamination. 相似文献
93.
Alowanou Géorcelin Goué Azando Erick V. B. Adenilé Adam D. Koudandé Delphin O. Chrysostome Christophe A. M. Hounzangbé-Adoté Sylvie M. 《Tropical animal health and production》2020,52(1):309-319
Tropical Animal Health and Production - Gastrointestinal (GI) nematodes remain a major constraint on livestock production throughout the world. This study assessed the in vivo efficacy of the... 相似文献
94.
Sylvie Dufour Nadine Le Belle Sylvie Baloche Yves-Alain Fontaine 《Fish physiology and biochemistry》1989,7(1-6):157-162
Treatment of sham-operated female silver eels with carp pituitary extract stimulated ovarian development and induced increases
in pituitary gonadotropin (GTH) and gonadoliberin (GnRH) contents. Both effects of carp pituitary extract were abolished in
ovariectomized eels, indicating the involvement of the gonads. Endogenous sexual steroids, the secretion of which was increased
during sexual maturation, should be responsible for the stimulation of GTH and GnRH levels. Ovariectomy itself had no significant
effect on pituitary GTH and GnRH contents, reflecting the fact that, at the silver stage, sexual steroid levels are too low
to exert any significant effect on pituitary GTH and GnRH. The positive feedback control exerted by the gonads on GTH and
GnRH levels during sexual maturation, in the eel as well as in some other teleosts, would produce an amplification of the
pubertal stimulation of the hypothalamo-pituitary-gonadal axis. 相似文献
95.
C. Grosclaude R. Olivier J.-C. Pizzuto Corinne Romiti Sylvie Madec 《Forest Pathology》1988,18(7):385-390
Application of the technique of trapping Ceratocystis fimbriata f. platani for the study of the persistance in affected trees . The study of the persistance of Ceratocystis fimbriata f. platani in affected trees is achieved by trapping of the fungus which is carried out on small branches of London plane, stripped of their bark. If C. fimbriata is present in samples of wood to be tested, it becomes visible after a few days when numerous perithecia form on the trap. Trapping the fungus by this method has been systematically achieved with young, artificially inoculated trees: in many cases, C. fimbriata persists in the wood after a period of about 19 to 22 months. 相似文献
96.
Breyer J Wemheuer WM Wrede A Graham C Benestad SL Brenig B Richt JA Schulz-Schaeffer WJ 《Veterinary microbiology》2012,157(1-2):23-31
Prion diseases are diagnosed by the detection of their proteinase K-resistant prion protein fragment (PrP(Sc)). Various biochemical protocols use different detergents for the tissue preparation. We found that the resistance of PrP(Sc) against proteinase K may vary strongly with the detergent used. In our study, we investigated the influence of the most commonly used detergents on eight different TSE agents derived from different species and distinct prion disease forms. For a high throughput we used a membrane adsorption assay to detect small amounts of prion aggregates, as well as Western blotting. Tissue lysates were prepared using DOC, SLS, SDS or Triton X-100 in different concentrations and these were digested with various amounts of proteinase K. Detergents are able to enhance or diminish the detectability of PrP(Sc) after proteinase K digestion. Depending on the kind of detergent, its concentration - but also on the host species that developed the TSE and the disease form or prion type - the detectability of PrP(Sc) can be very different. The results obtained here may be helpful during the development or improvement of a PrP(Sc) detection method and they point towards a detergent effect that can be additionally used for decontamination purposes. A plausible explanation for the detergent effects described in this article could be an interaction with the lipids associated with PrP(Sc) that may stabilize the aggregates. 相似文献
97.
Analyses of recent classical swine fever (CSF) epidemics in the European Union have shown that silent circulation of CSF virus (CSFV) occurs before the first outbreak is detected and this may lead to a large epidemic. However, severity of CSF disease signs may be linked with efficacy of disease transmission, the most severely affected animals having a higher infectivity than the less affected ones. The purpose of this study was to combine disease transmission quantification methods with CSF clinical signs quantification tools to investigate whether clinical signs, considered as infectivity markers, may allow us to calculate reliable estimates for disease transmission parameters. Data from three transmission experiments were used, varying according to the viral strain (Eystrup or Paderborn) and to the contact structure between experimentally inoculated and contact animals (direct or indirect contact). Within- and between-pen basic reproduction ratios (R0) were compared using viraemia data or clinical data. Between-pen R0 estimates were close and not significantly >1, with either strain or computation mode (using viraemia or clinical data). Conversely, within-pen R0s (Paderborn strain) computed using clinical data appeared higher than the estimates obtained using viraemia data. A models comparison (Bayes information criterion) showed a better fit of the clinical-based models, for both strains. This suggests that, in affected herds, the most severely affected animals could play a prominent role in CSFV transmission. 相似文献
98.
99.
100.
Annick Gibon David Sheeren Claude Monteil Sylvie Ladet Gérard Balent 《Landscape Ecology》2010,25(2):267-285
Natural reforestation of European mountain landscapes raises major environmental and societal issues. With local stakeholders in the Pyrenees National Park area (France), we studied agricultural landscape colonisation by ash (Fraxinus excelsior) to enlighten its impacts on biodiversity and other landscape functions of importance for the valley socio-economics. The study comprised an integrated assessment of land-use and land-cover change (LUCC) since the 1950s, and a scenario analysis of alternative future policy. We combined knowledge and methods from landscape ecology, land change and agricultural sciences, and a set of coordinated field studies to capture interactions and feedback in the local landscape/land-use system. Our results elicited the hierarchically-nested relationships between social and ecological processes. Agricultural change played a preeminent role in the spatial and temporal patterns of LUCC. Landscape colonisation by ash at the parcel level of organisation was merely controlled by grassland management, and in fact depended on the farmer’s land management at the whole-farm level. LUCC patterns at the landscape level depended to a great extent on interactions between farm household behaviours and the spatial arrangement of landholdings within the landscape mosaic. Our results stressed the need to represent the local SES function at a fine scale to adequately capture scenarios of change in landscape functions. These findings orientated our modelling choices in the building an agent-based model for LUCC simulation (SMASH–Spatialized Multi-Agent System of landscape colonization by ASH). We discuss our method and results with reference to topical issues in interdisciplinary research into the sustainability of multifunctional landscapes. 相似文献