全文获取类型
收费全文 | 224篇 |
免费 | 9篇 |
专业分类
林业 | 18篇 |
农学 | 14篇 |
52篇 | |
综合类 | 8篇 |
农作物 | 11篇 |
水产渔业 | 20篇 |
畜牧兽医 | 90篇 |
园艺 | 2篇 |
植物保护 | 18篇 |
出版年
2023年 | 3篇 |
2022年 | 3篇 |
2021年 | 7篇 |
2020年 | 9篇 |
2019年 | 13篇 |
2018年 | 8篇 |
2017年 | 12篇 |
2016年 | 8篇 |
2015年 | 7篇 |
2014年 | 7篇 |
2013年 | 12篇 |
2012年 | 11篇 |
2011年 | 18篇 |
2010年 | 13篇 |
2009年 | 7篇 |
2008年 | 22篇 |
2007年 | 16篇 |
2006年 | 12篇 |
2005年 | 6篇 |
2004年 | 9篇 |
2003年 | 5篇 |
2002年 | 10篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 1篇 |
1997年 | 3篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1985年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有233条查询结果,搜索用时 46 毫秒
71.
Seu R Phillips RJ Alberti G Biccari D Bonaventura F Bortone M Calabrese D Campbell BA Cartacci M Carter LM Catallo C Croce A Croci R Cutigni M Di Placido A Dinardo S Federico C Flamini E Fois F Frigeri A Fuga O Giacomoni E Gim Y Guelfi M Holt JW Kofman W Leuschen CJ Marinangeli L Marras P Masdea A Mattei S Mecozzi R Milkovich SM Morlupi A Mouginot J Orosei R Papa C Paternò T Persi del Marmo P Pettinelli E Pica G Picardi G Plaut JJ Provenziani M Putzig NE Russo F Safaeinili A Salzillo G 《Science (New York, N.Y.)》2007,317(5845):1715-1718
Mars' polar regions are covered with ice-rich layered deposits that potentially contain a record of climate variations. The sounding radar SHARAD on the Mars Reconnaissance Orbiter mapped detailed subsurface stratigraphy in the Promethei Lingula region of the south polar plateau, Planum Australe. Radar reflections interpreted as layers are correlated across adjacent orbits and are continuous for up to 150 kilometers along spacecraft orbital tracks. The reflectors are often separated into discrete reflector sequences, and strong echoes are seen as deep as 1 kilometer. In some cases, the sequences are dipping with respect to each other, suggesting an interdepositional period of erosion. In Australe Sulci, layers are exhumed, indicating recent erosion. 相似文献
72.
Scordino M Di Mauro A Passerini A Maccarone E 《Journal of agricultural and food chemistry》2005,53(3):651-658
The adsorption-desorption performances of commercial resins (two polystyrene-divinylbenzene copolymers and one methacrylic) were tested in column studies for the selective recovery of anthocyanins and hydroxycinnamates from pigmented pulp wash (PW), a byproduct of blood orange juice processing. Methanol, ethanol, and their mixtures with different percentages of water as eluents were tested in order to investigate the selective desorption of these natural antioxidants with the goal of minimizing the presence of other compounds, mostly flavanones and limonoids, in the concentrated eluates. The results indicated that polystyrene-divinylbenzene resins were able to adsorb a major amount of anthocyanins and hydroxycinnamates and to desorb them in more-concentrated fractions. No selectivity was observed using pure methanol and ethanol which resulted in concentrates with no further separation of components from the starting raw PW. The ethanol/water concentrates showed higher yields than the fractions attained using methanol/water; however, a lower selectivity toward anthocyanin pigments was observed. The best performing resin, EXA-118, together with the mixture methanol/water 50:50 (v/v) as best eluent, appears to be the most suitable system to obtain highly concentrated extracts. Thus, it was chosen to perform a larger experiment, to analyze the selectivity of the removal upon an increase in elution volume. 相似文献
73.
74.
75.
Mauro Galetti Henrique C. Giacomini Christine S.S. Bernardo Ricardo S. Bovendorp Paulo Rubim Camila I. Donatti Rodrigo A. Begotti Rodrigo de A. Nobre Carlos A. Peres 《Biological conservation》2009,142(6):1229-1241
Large mammal faunas in tropical forest landscapes are widely affected by habitat fragmentation and hunting, yet the environmental determinants of their patterns of abundance remain poorly understood at large spatial scales. We analysed population abundance and biomass of 31 species of medium to large-bodied mammal species at 38 Atlantic forest sites (including three islands, 26 forest fragments and six continuous forest sites) as related to forest type, level of hunting pressure and forest fragment size using ANCOVAs. We also derived a novel measure of mammal conservation importance for each site based on a “Mammalian Conservation Priority index” (MPi) which incorporates information on species richness, population abundance, body size distribution, conservation status, and forest patch area. Mammal abundance was affected by hunting pressure, whereas mammalian biomass of which was largely driven by ungulates, was significantly influenced by both forest type and hunting pressure. The MPi index, when separated into its two main components (i.e. site forest area and species-based conservation index Ci), ordered sites along a gradient of management priorities that balances species-focused and habitat-focused conservation actions. Areas with the highest conservation priority were located in semi-deciduous forest fragments, followed by lowland forests. Many of these fragments, which are often embedded within large private landholdings including biofuel and citrus or coffee crops, cattle ranches and pulpwood plantations, could be used not only to comply with environmental legislation, but also enhance the prospects for biodiversity conservation, and reduce edge effects and hunting. 相似文献
76.
77.
Thaylise V. Parodi Mauro A. Cunha Alexssandro G. Becker Carla C. Zeppenfeld Dirlaine I. Martins Gessi Koakoski Leonardo Gil Barcellos Berta M. Heinzmann Bernardo Baldisserotto 《Fish physiology and biochemistry》2014,40(2):323-334
This study investigated the efficacy of the essential oil (EO) of Aloysia triphylla as an anesthetic for albino and gray strains of silver catfish, Rhamdia quelen. Juveniles were exposed to concentrations between 20 and 800 μL L?1 EO of A. triphylla to evaluate time of induction and recovery from anesthesia. In another experiment, both strains were divided into four groups such as 0 (control), 30, 40, or 50 μL L?1 EO and transported for 5 h. The longest time for anesthetic induction and recovery was observed in the albinos. Both strains reached anesthesia in the 100–800 μL L?1 (11.1–1.24 min) range, without mortality, being 200 μL L?1 the best response considering time to anesthesia (5.35 min). Albinos transported with all EO concentrations showed higher values of carbon dioxide in the water of transport, but lower levels were observed in grays transported with 40 and 50 μL L?1 EO when compared to control fish. The same concentrations did not prevent significant whole-body cortisol rise at the end of transport in the albino strain. Juveniles of both strains transported with EO presented lower ion loss to the water compared to control fish. The EO of A. triphylla is an effective anesthetic for albino and gray silver catfish. This EO increases whole-body cortisol levels in the albino strain, but as it reduces net ion loss as in the gray strain, it can be also recommended for transport. 相似文献
78.
Monica Montefalcone Giancarlo Albertelli Carlo Nike Bianchi Mauro Mariani Carla Morri 《水产资源保护:海洋与淡水生态系统》2006,16(1):29-42
- 1. The status of a Posidonia oceanica meadow in front of the town of Sanremo, Italy, was studied through a combined use of benthic mapping and synthetic indices.
- 2. Mapping was accomplished by integrating side scan sonar imagery and data collected by scuba diving along transects placed perpendicularly to the coastline. A thematic map (scale 1:5000) was produced. Extent of the meadow, occurrence of dead matte areas, and morphology of the lower limit (with new definition) are all described.
- 3. Two synthetic environmental indices were applied to transect data in order to quantify the status of the meadow: the Conservation Index and the Substitution Index. The former is related to the proportion of dead matte; the latter is a novel index measuring the amount of replacement of the ‘constructional’ seagrass P. oceanica by the ‘non‐constructional’ seagrass Cymodocea nodosa. The potential of a ‘phase shift’ in Ligurian Sea seagrass meadows is discussed.
- 4. The approach here proposed, based on detailed mapping plus synthetic indices, may provide immediate information to evaluate the state of Mediterranean Posidonia oceanica for monitoring and management.
79.
80.
Gabriel Ignacio Ramírez-Flores Javier Del Angel-Caraza Israel Alejandro Quijano-Hernández Don A. Hulse Brian S. Beale José Mauro Victoria-Mora 《Veterinary research communications》2017,41(2):129-137
Osteoarthritis (OA) is a chronic, degenerative disease affecting the articular cartilage and subchondral bone that causes pain and inhibits movement. The stifle’s joint fibrous capsule contains the synovial membrane, which produces cartilage nutrients. A ruptured cranial cruciate ligament injures the joint and produces OA. Osteoarthritis diagnosis starts with clinical radiographic and ultrasonographic tests, although the latter is not used very much in dog and cat clinics for this purpose. The objective of this study was to establish the correlation among the results of orthopedic, radiographic, ultrasonographic examinations and structural anatomical changes revealed by arthroscopic evaluation to diagnose stifle joint OA and determine risk factors in the dogs affected. Of 44 clinical cases of OA included in the study, 88.64% had ruptured of cranial cruciate ligaments. The correlation between synovial fluid effusion and osteophytosis was of 0.84. It was concluded that there is good diagnostic agreement between synovial fluid effusion and osteophytosis when dealing with stifle joint OA. Risk factors for dogs regarding the development of stifle joint OA included: ruptured cranial cruciate ligaments or patella luxation, female dogs and weight over 10 kg. 相似文献