全文获取类型
收费全文 | 242篇 |
免费 | 24篇 |
专业分类
林业 | 33篇 |
农学 | 5篇 |
基础科学 | 1篇 |
51篇 | |
综合类 | 8篇 |
农作物 | 11篇 |
水产渔业 | 22篇 |
畜牧兽医 | 101篇 |
园艺 | 10篇 |
植物保护 | 24篇 |
出版年
2023年 | 4篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 10篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 10篇 |
2015年 | 5篇 |
2014年 | 7篇 |
2013年 | 20篇 |
2012年 | 18篇 |
2011年 | 25篇 |
2010年 | 14篇 |
2009年 | 17篇 |
2008年 | 17篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 6篇 |
2004年 | 8篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 6篇 |
2000年 | 6篇 |
1999年 | 2篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有266条查询结果,搜索用时 15 毫秒
201.
The contiguous forest landscapes of the Brigalow Belt Bioregion in Australia's subtropics, known as ‘the western hardwood forests’ are thought to be important for biodiversity conservation through the provision of continuous habitat features in an otherwise extensively cleared region. However, these forests have a long management history, as they are also important for timber production and stock grazing. Knowledge of the effect of these and other disturbances on the distribution and abundance of key structural or habitat features are limited and forest management activities thus continue uninformed. To address this knowledge gap, we investigated the effects of prescribed and non-prescribed disturbances on the distribution and abundance of six key habitat features (live and dead trees with hollows, large mature live trees, shrub abundance, downed coarse woody debris and litter cover) at 120 sites located in spotted gum Corymbia citriodora dominant forests within the western hardwoods. 相似文献
202.
Frédéric Billen Liz-Valery Guieu Frédérique Bernaerts Elise Mercier Rachel Lavoué Charlotte Tual Dominique Peeters Cécile Clercx 《The Canadian veterinary journal. La revue veterinaire canadienne》2010,51(2):164-168
This study evaluated the effect of 1% bifonazole cream in the treatment of canine sino-nasal aspergillosis (SNA). The cream was instilled through perendoscopically placed catheters into the frontal sinuses and was used either as single therapy after debridement (DC) or as adjunctive therapy after 2% enilconazole infusion (DEC). Twelve dogs were treated initially with DEC: 7 and 3 of these dogs were free of disease after 1 and 2 procedures, respectively, while 2 dogs were cured after DC was used as a second procedure. Five dogs were treated with DC only: in 3 dogs with moderate disease, cure was obtained after a single procedure while, in 2 debilitated patients, cure could not be confirmed. Topical administration of 1% bifonazole cream appears as an effective therapy in SNA, either as an adjunctive therapy to enilconazole infusion or as sole therapy in moderately affected patients. 相似文献
203.
Atmospheric concentrations of Erysiphe necator conidia were monitored for 2 years in a vineyard planted with cultivars susceptible to powdery mildew in the vine production area of Quebec, Canada. The concentrations of airborne conidia were determined and compared using two types of samplers: a Burkard volumetric sampler and a rotating-arm sampler. The coefficients of correlation between the volumetric and rotating-arm sampler placed at 45 cm from the ground was r = 0.81 and 0.82 in 2000 and 2001, respectively. The relationship between incidence of powdery mildew on the leaves of three cultivars (Chancellor, Geisenheim, and Frontenac) and the cumulative concentration of airborne conidia (based on 3 d of sampling weekly) was then studied. This relationship was similar for the three cultivars, (R2 = 0.97, 0.95, 0.97, for cvs Chancellor, Geisenheim, and Frontenac respectively) and was well described using the cumulative form of the Weibull model. Based on this model, it was possible to establish the period of high risk (highest rate of increase in powdery mildew incidence) from 645 to 5614, 2437 to 2951, and 1052 to 3061 conidia m−3 of air for the cvs Chancellor, Geisenheim, and Frontenac, respectively. An action threshold, for timing interval between fungicide sprays, of 50 conidia m−3 d−1 was evaluated under field conditions with cv Chancellor and was as good as a calendar-based program with fewer fungicide sprays under unfavourable weather conditions. Monitoring airborne inoculum could be used as a component of a risk management system for grape powdery mildew to time intervals between fungicide sprays. 相似文献
204.
Fontaine S Remuson F Fraissinet-Tachet L Micoud A Marmeisse R Melayah D 《Pest management science》2009,65(1):74-81
BACKGROUND: Genetic resistance to QoI fungicides may account for recent failures to control Venturia inaequalis (Cooke) Winter in French orchards. Two PCR-based assays were developed to detect the G143A point mutation in the fungal mitochondrial cytochrome b gene. The mutation is known to confer a high level of resistance to QoI fungicides. Occurrence of the G143A mutation in French field isolates collected from 2004 to 2007 was monitored. RESULTS: The QoI-resistant cytochrome b allele was specifically detected either following the cleavage of the amplified marker by a restriction endonuclease (CAPS assay) or its amplification using an allele-specific PCR primer. Using either method, the G143A mutation was found in 42% of the 291 field samples originating from French orchards in which apple scab proved difficult to be controlled. Monitoring of the G143A mutation in orchards located in 15 French administrative regions indicated that the mutation was detected at least once in nine of the regions, and its presence ranged from 33% to 64% of the orchards analysed in 2004 and in 2007 respectively. CONCLUSION: The PCR-based methods developed in this study efficiently reveal the presence of the G143A mutation in French V. inaequalis field populations. 相似文献
205.
Pradeep K. DASH Pratap BHATTACHARYYA Soumya R. PADHY Amaresh K. NAYAK Annie POONAM Sangita MOHANTY 《土壤圈》2023,(6):960-971
Carbon footprint (CF) quantification of major rice production systems (RPSs) is a prerequisite for developing strategies for climate change mitigation in agriculture. Total life cycle greenhouse gas emissions (LC-GHGs) from rice production to consumption might provide precise CFs for RPSs. Therefore, we assessed three segments (pre-farm, on-farm, and post-farm) of LC-GHGs under five major contrasting RPSs, i.e., aerobic rice (AR), shallow lowland rice(SLR), system of rice intensification (SRI), ... 相似文献
206.
Enrique Guemez‐Sorhouet Humberto Villarreal Ilie S. Racotta Jos Naranjo Laurence Mercier 《Aquaculture Research》2019,50(4):1198-1211
The objective of this study was to assess zootechnical and physiological performance of Litopenaeus vannamei postlarvae (PL) reared in three environments (CW, clear water; B, biofloc; BS, biofloc with artificial substrates) at three stocking densities (300, 600, 900 PL/m3) for 8 weeks. At the end of experimentation, shrimp were subjected to hypoxia, and physiological response was again assessed. During rearing, low levels of total ammonia nitrogen, nitrite (NO2?) and nitrate (NO3?) were observed in B and BS for 600 and 900 PL/m3. For 300 PL/m3, a slight accumulation of NO2? and NO3? was detected. For the same stocking density, shrimp reared in B and BS showed significantly higher weights than those grown in CW, except for final weight. No significant differences were observed in survival. The use of biofloc and artificial substrates permitted doubling density from 300 to 600 PL/m3 without affecting growth, survival, feed conversion rate and obtaining twice the biomass. Shrimp grown in B and BS stored a surplus of glycogen and carbohydrates in their hepatopancreas, which probably gave them a better physiological capacity to counteract high‐stocking densities and hypoxia. A tendency of a higher adenylate energetic charge was observed in shrimp maintained in B and BS. 相似文献
207.
Eradications as scientific experiments: progress in simultaneous eradications of two major invasive taxa from a Mediterranean island 下载免费PDF全文
Lise Ruffino Elise Krebs Aurélie Passetti Annie Aboucaya Laurence Affre Damien Fourcy Olivier Lorvelec Alain Barcelo Laurence Berville Nathalie Bigeard Lenka Brousset Hélène De Méringo Pascal Gillet Patricia Le Quilliec Yannick Limouzin Frédéric Médail Jean‐Yves Meunier Marine Pascal Michel Pascal Philippe Ponel François Rifflet Coralie Santelli Elise Buisson Eric Vidal 《Pest management science》2015,71(2):189-198
208.
Ali Karami Annie Christianus Hadi Zokaeifar Khairul Zamri Saad Fahmi T. J. Imraan Shahram Shakibazadeh Hossien Negarestan Simon C. Courtenay 《Aquaculture International》2011,19(6):1025-1034
Triploid fish are increasingly used in aquaculture because they are generally unable to reproduce successfully. Energy is
channeled into somatic growth rather than gonadal development, and in the event of escape, the animals are unlikely to breed
successfully among themselves or with wild conspecifics. This study tested the ability of recently matured triploid African
catfish (Clarias gariepinus) to produce and fertilize eggs with and without ovaprim treatment. Triploid females did not show the increase in ovary size
observed in diploid members of the same cohort between 8 and 9 months of age, or the coincident decrease in visceral fat deposits,
and this was unaffected by up to 5 weekly i.m. injections of 0.5 ml kg−1 Ovaprim. However, we observed advanced vitellogenin (Vtg) sequestration in oocytes of triploid females, albeit to a lesser
degree and with lesser cortical alveoli, compared to oocytes from diploid cohort members. Histological sections revealed a
positive trend of oocyte development up to the third weekly ovaprim injection followed by a negative gonadal development in
weeks four and five. Milt from triploid males injected 9–12 h earlier with 0.25 ml kg−1 ovaprim i.m. fertilized more diploid eggs than milt from untreated triploid males (30 vs. 20%), but none of the developing
embryos of triploid paternity survived to hatch. In contrast, milt of diploid males fertilized 49% of eggs, and 20% of the
developing embryos hatched successfully. These rates were improved in ovaprim-injected diploid males to 70% fertilization
and 33% hatch. This study demonstrates potential of overcoming non-viability of eggs from triploid female African catfish,
and enhancing the ability of triploid milt to fertilize eggs. 相似文献
209.
Romain Carrié Emilie Andrieu Annie Ouin Ingolf Steffan-Dewenter 《Landscape Ecology》2017,32(8):1631-1642
Context
The local intensity of farming practices is considered as an important driver of biodiversity in agricultural landscapes and its effect on biodiversity has been shown to interact with landscape complexity. But the influence of landscape-wide intensity of farming practices on biodiversity and its combined effect with landscape complexity have been little explored.Objective
In this study, we tested the interactive effect of the landscape-wide intensity of farming practices and landscape complexity on the local species richness and abundance of farmland wild bee communities.Methods
We captured wild bees in 96 crop fields and explored the effect of landscape-wide intensity of various farming practices along a gradient of landscape complexity (proportion of semi-natural habitats).Results
We found that species richness and abundance of wild bees were more positively influenced by landscape complexity in highly insecticide-sprayed landscapes than in less intensively managed landscapes. In contrast, we found that the positive effect of landscape complexity on bee species richness only occurred in landscapes with low nitrogen inputs.Conclusions
Our study demonstrates the interactive effects of landscape-wide farming intensity and landscape complexity in shaping the diversity of farmland wild bee communities. We conclude that the management of farming intensity at the landscape-scale could mitigate the effects of habitat loss on wild bee decline and would help to maintain pollination services in agricultural landscapes.210.