全文获取类型
收费全文 | 954篇 |
免费 | 78篇 |
专业分类
林业 | 72篇 |
农学 | 15篇 |
基础科学 | 5篇 |
263篇 | |
综合类 | 69篇 |
农作物 | 51篇 |
水产渔业 | 201篇 |
畜牧兽医 | 276篇 |
园艺 | 28篇 |
植物保护 | 52篇 |
出版年
2024年 | 3篇 |
2023年 | 8篇 |
2022年 | 9篇 |
2021年 | 32篇 |
2020年 | 28篇 |
2019年 | 47篇 |
2018年 | 40篇 |
2017年 | 41篇 |
2016年 | 48篇 |
2015年 | 43篇 |
2014年 | 54篇 |
2013年 | 69篇 |
2012年 | 67篇 |
2011年 | 92篇 |
2010年 | 42篇 |
2009年 | 40篇 |
2008年 | 60篇 |
2007年 | 52篇 |
2006年 | 48篇 |
2005年 | 53篇 |
2004年 | 39篇 |
2003年 | 35篇 |
2002年 | 25篇 |
2001年 | 5篇 |
2000年 | 8篇 |
1999年 | 5篇 |
1998年 | 5篇 |
1997年 | 2篇 |
1996年 | 2篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 1篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1954年 | 1篇 |
排序方式: 共有1032条查询结果,搜索用时 15 毫秒
991.
Miguel Gozalo‐Marcilla Klaus Hopster Frank Gasthuys Anna Elisabeth Krajewski Andrea Schwarz Stijn Schauvliege 《Veterinary anaesthesia and analgesia》2014,41(2):212-219
ObjectiveTo compare the effects of a constant rate infusion (CRI) of dexmedetomidine and morphine to those of morphine alone on the minimum end-tidal sevoflurane concentration necessary to prevent movement (MACNM) in ponies.Study designProspective, randomized, crossover, ‘blinded’, experimental study.AnimalsFive healthy adult gelding ponies were anaesthetized twice with a 3-week washout period.MethodsAfter induction of anaesthesia with sevoflurane in oxygen (via nasotracheal tube), the ponies were positioned on a surgical table (T0), and anaesthesia was maintained with sevoflurane (Fe‘SEVO 2.5%) in 55% oxygen. Monitoring included pulse oximetry, electrocardiography and measurement of anaesthetic gases, arterial blood pressure and body temperature. The ponies were mechanically ventilated and randomly allocated to receive IV treatment M [morphine 0.15 mg kg?1 (T10-T15) followed by a CRI (0.1 mg kg?1 hour?1)] or treatment DM [dexmedetomidine 3.5 μg kg?1 plus morphine 0.15 mg kg?1 (T10-T15) followed by a CRI of dexmedetomidine 1.75 μg kg?1 hour?1 and morphine 0.1 mg kg?1 hour?1]. At T60, a stepwise MACNM determination was initiated using constant current electrical stimuli at the skin of the lateral pastern region. Triplicate MACNM estimations were obtained and then averaged in each pony. Wilcoxon signed-rank test was used to detect differences in MAC between treatments (a = 0.05).ResultsSevoflurane-morphine MACNM values (median (range) and mean ± SD) were 2.56 (2.01–4.07) and 2.79 ± 0.73%. The addition of a continuous infusion of dexmedetomidine significantly reduced sevoflurane MACNM values to 0.89 (0.62–1.05) and 0.89 ± 0.22% (mean MACNM reduction 67 ± 11%).Conclusion and clinical relevanceCo-administration of dexmedetomidine and morphine CRIs significantly reduced the MACNM of sevoflurane compared with a CRI of morphine alone at the reported doses. 相似文献
992.
993.
994.
Juan García-de-Lomas Miguel Clavero Carlos M. García Desireé Alba José María Torres Alfonso Jurado Virginia Cantero Rosario Navarro Francisco Hortas 《水产资源保护:海洋与淡水生态系统》2021,31(6):1543-1547
- The knowledge and awareness that the general public has about aquatic invertebrates is often poor, even when they are highly threatened. The frequent lack of popular names and the unattractiveness of the scientific ones may be among the factors hindering the knowledge of these organisms and, consequently, the awareness of their conservation status and the willingness to conserve them.
- Linderiella baetica (Crustacea, Branchiopoda, Anostraca) was discovered in 2007 in southern Spain and is considered a critically endangered species. However, being a small invertebrate inhabiting generally unappreciated temporary ponds, this species was completely unknown by the general public, even in the area in which it occurs.
- To increase the knowledge and awareness of L. baetica, 1,347 children from five schools within its distribution area participated in a contest to select a common name for this newly described taxon. The winning name, gambilusa (Andalusian shrimp), will be used in the future by the Spanish Ministry of Environment and hopefully by the general public to identify the species.
- The contest was found to have increased the knowledge about the target species in a sustained manner, as 1 year later, 93% of the children recognized gambilusa as a crustacean, 75% remembered its typical habitat, and 89% broadly identified its geographical distribution.
- This kind of name-choosing contest is applicable for different regions and taxa to raise awareness on the conservation of threatened but poorly known biota.
995.
996.
997.
Gregory C. Luther Soeprapto Mangoendihardjo Miguel A. Altieri Eddy Mahrub 《国际虫害防治杂志》2013,59(3):166-175
Abstract Two field trials were conducted for the purposes of comparing various soybean pest management schemes and setting preliminary economic thresholds that could be used by farmers as part of an integrated pest management (IPM) programme. Both trials tested the same four treatments: (1) a pest management scheme that followed the type of plan that many farmers in Java use, (2) and (3) two schemes utilizing different economic thresholds set by researchers, and (4) an untreated control. The pest management schemes are compared regarding various aspects, including yield and profitability. In both trials the plans did not differ significantly in profitability; however, in each trial the same threshold scheme had the highest mean values for both yield and profitability. Therefore, a pest control system based on this threshold scheme is recommended, with some refinements in certain threshold levels for specific pest guilds where the trials show refinements to be appropriate. It is advised that farmers use the threshold levels recommended here as starting points, and then make adjustments according to the soybean variety used, abundance of natural enemies present, economic factors, etc. 相似文献
998.
Patricia G. Cardoso Eduarda Pereira Tiago F. Grilo Armando C. Duarte Miguel A. Pardal 《Water, air, and soil pollution》2012,223(1):421-428
Mercury bioaccumulation kinetics of two important macrobenthic species, the polychaete Hediste diversicolor and the bivalve Scrobicularia plana, were evaluated following a dietary pathway (i.e. contaminated algae), through a mesocosm laboratory experiment. Both studied
species presented a similar model of Hg bioaccumulation kinetics, a linear pattern of accumulation through time being the
mercury accumulation in the organisms proportional to the mercury concentration in the food. Mercury bioaccumulation rates
were higher in the polychaete H. diversicolor (reaching approximately 0.15 μg g−1 at the end of the experiment) than in the bivalve S. plana (≈0.07 μg g−1), which could be related to their feeding strategies, ingestion rates and assimilation efficiencies. Moreover, the mercury
bioaccumulation revealed to be quite a fast process especially for the polychaete, and despite the fact that this species
is not an edible organism, it is an important prey item, which can greatly contribute to the transport of contaminants to
higher trophic levels. Therefore, the bioaccumulation of mercury by these important macrobenthic species, especially the bivalves,
represents a non-negligible risk for humans. 相似文献
999.
Manuela de Lucas Miguel Ferrer Marc J. Bechard Antonio R. Muñoz 《Biological conservation》2012,147(1):184-189
Wind is increasingly being used as a renewable energy source around the world. Avian mortality is one of the negative impacts of wind energy and a new technique that reduces avian collision rates is necessary. Using the most frequently-killed species, the griffon vulture (Gyps fulvus), we studied its mortality at 13 wind farms in Tarifa, Cadiz, Spain, before (2006–2007) and after (2008–2009) when selective turbine stopping programs were implemented as a mitigation measure. Ten wind farms (total of 244 turbines) were selectively stopped and three wind farms (total of 52 turbines) were not. We found 221 dead griffon vultures during the entire study and the mortality rate was statistically different per turbine and year among wind farms. During 2006–2007, 135 griffon vultures were found dead and the spatial distribution of mortality was not uniformly distributed among turbines, with very few turbines showing the highest mortality rates. The 10 most dangerous turbines were distributed among six different wind farms. Most of the mortalities were concentrated in October and November matching the migratory period. During 2008–2009, we used a selective stopping program to stop turbines when vultures were observed near them and the griffon vulture mortality rate was reduced by 50% with a consequent reduction in total energy production of by the wind farms by only 0.07% per year. Our results indicate that the use of selective stopping techniques at turbines with the highest mortality rates can help to mitigate the impacts of wind farms on birds with a minimal affect on energy production. 相似文献
1000.
Cotrim BA Joglar J Rojas MJ del Olmo JM Macias-González M Cuevas MR Fitó M Muñoz-Aguayo D Planells MI Farré M de Fonseca FR de la Torre R 《Journal of agricultural and food chemistry》2012,60(4):1067-1074
A new route for the synthesis of fatty alcohol derivatives of hydroxytyrosol and other olive oil phenolic compounds was developed to allow the preparation of unsaturated derivatives. The biological activity of synthesized compounds was evaluated. Most of the compounds presented a significant antioxidant activity on low-density lipoprotein (LDL) particles. The activity of the tested products was significantly influenced by the number and position of unsaturations as well as modifications on the polar head of the synthesized compounds. Some of them presented modulation of food intake in rats and, due to their molecular similarity with CB(1) endogenous ligands, the endocannabinoid system and PPAR-α were also evaluated as potential targets. The pharmacodynamics could not be totally explained by CB(1) and PPAR-α receptor interactions because only two of the four compounds with biological activity showed a CB(1) activity and all of them presented low PPAR-α affinity, not justifying its whole in vivo activity. The hydroxytyrosol linoleylether (7) increased LDL resistance to oxidation with a capacity similar to that of hydroxytyrosol and was the most active in vivo compound with a hypophagic effect comparable to that of oleoylethanolamine. We consider that this compound could be a good lead compound for future drug development in obesity treatments. 相似文献