全文获取类型
收费全文 | 930篇 |
免费 | 54篇 |
专业分类
林业 | 102篇 |
农学 | 33篇 |
基础科学 | 2篇 |
196篇 | |
综合类 | 67篇 |
农作物 | 65篇 |
水产渔业 | 56篇 |
畜牧兽医 | 326篇 |
园艺 | 33篇 |
植物保护 | 104篇 |
出版年
2023年 | 7篇 |
2022年 | 9篇 |
2021年 | 17篇 |
2020年 | 19篇 |
2019年 | 26篇 |
2018年 | 52篇 |
2017年 | 42篇 |
2016年 | 46篇 |
2015年 | 21篇 |
2014年 | 43篇 |
2013年 | 42篇 |
2012年 | 55篇 |
2011年 | 93篇 |
2010年 | 38篇 |
2009年 | 36篇 |
2008年 | 55篇 |
2007年 | 64篇 |
2006年 | 50篇 |
2005年 | 43篇 |
2004年 | 39篇 |
2003年 | 37篇 |
2002年 | 28篇 |
2001年 | 13篇 |
2000年 | 10篇 |
1999年 | 8篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 6篇 |
1994年 | 2篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1990年 | 4篇 |
1989年 | 3篇 |
1988年 | 2篇 |
1987年 | 4篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1975年 | 2篇 |
1974年 | 2篇 |
1973年 | 4篇 |
1972年 | 2篇 |
1969年 | 3篇 |
1966年 | 2篇 |
1965年 | 2篇 |
1963年 | 2篇 |
1932年 | 1篇 |
1926年 | 2篇 |
1918年 | 2篇 |
排序方式: 共有984条查询结果,搜索用时 15 毫秒
981.
Dimitrova D Moutafchieva R Kanelov I Dinev T Lashev L 《Veterinary journal (London, England : 1997)》2009,179(3):462-464
The aims of the present study were to determine the disposition of tobramycin after single intravenous (IV) and intramuscular (IM) injections in ducks, and to establish any sex-related differences. Tobramycin sulfate was administered as a 2.5% water solution in a cross-over design at a dose of 5 mg/kg to 12 healthy ducks (six males and six females). Concentrations of the drug in serum were determined by a microbiological assay. The serum pharmacokinetic values for tobramycin were best represented using a one- or two-compartment open model, depending on the method of administration. Non-compartment analysis was also performed after IV administration. Tobramycin had a low degree of distribution and a relatively fast elimination. The mean volume of distribution in ducks (males and females) was higher than that reported in pigeons but lower than in chickens, with a slower rate of elimination. The IM injection resulted in a fast and complete absorption. The rate of elimination after IM administration was about twice as slow as in other avian species. Sex-related variations in tobramycin pharmacokinetics were similar to those reported for kanamycin and apramycin in hens and roosters. 相似文献
982.
Milovanović V Radulović N Todorović Z Stanković M Stojanović G 《Plant foods for human nutrition (Dordrecht, Netherlands)》2007,62(3):113-119
The hydro-alcoholic extracts of five Equisetum species, E. arvense L., E. sylvaticum L., E. fluviatile L., E. palustre L. and E. telmateia Ehrh., growing-wild in Serbia were evaluated for their genotoxicity, antimicrobial activity, antioxidant capacity and the results
related to the total phenol content and HPLC flavonoid profiles. The total phenol content was 92–349 μmol expressed as equivalents
of chlorogenic acid per g of dried plant material. Main identified compounds were kaempferol-, quercetin- glycosides and caffeic
acid derivatives. E. telmateia extract showed the greatest antioxidant capacity. Almost all tested microorganisms demonstrated some degree of sensitivity
to the examined extracts. All tested extracts at 62.5 μg/ml showed higher incidence of micronucleus formation than in the
control sample. The obtained data allowed mutual comparison of examined species and their assessment as possible sources of
antioxidants, antimicrobials and/or genotoxic substances. 相似文献
983.
Blandina R Lugendo Ivan Nagelkerken Narriman Jiddawi Yunus D Mgaya Gerard Van Der Velde 《Fisheries Science》2007,73(6):1213-1223
ABSTRACT: By using a seine net, fish samples were taken from the nonestuarine Chwaka Bay (Zanzibar, Tanzania) from the mangroves, mud/sand flats and seagrass beds. Sampling was done twice per month between November 2001 and October 2002. In total, 150 fish species belonging to 55 families were identified. Diversity ( H' ) ranged from 1.9 in mud/sand flats to 3.4 within the Chwaka seagrass beds. Mean density of fishes was significantly higher in the mangrove creeks than in any other habitat (mean = 238.7 ind./1000 m2 ). Highest, but non-significantly different mean biomasses were recorded in the mangrove creeks (1.7 kg/1000 m2 ) and in the Marumbi seagrass beds (1.6 kg/1000 m2 ). The mangrove channel had the lowest biomass (0.6 kg/1000 m2 ). A high overlap in species composition (as high as 93.4% similarity) was found for adjoining habitats (i.e. mangrove creeks and mangrove channel), while habitats that were far apart showed low overlap (6.6% similarity for the Marumbi seagrass beds and mangrove creeks). On average, 58.4 and 63.2% in terms of abundance and biomass, respectively, of the fish assemblage of Chwaka Bay were of commercial fishery importance. Thus, Chwaka Bay appears to be an important juvenile habitat for various commercially important fish species. 相似文献
984.
Stefanija Šestanović Jelena Peković Slavica Matijević Živana Ninčević Gladan 《Aquaculture Research》2016,47(4):1040-1054
The effects of farming on planktonic microbial communities were investigated at the coastal sea bass/sea bream farm in the oligotrophic middle Adriatic Sea. Analyses of nutrients, chlorophyll a, cyanobacteria (Prochlorococcus), heterotrophic bacteria and nanoflagellates (both pigmented and heterotrophic) were carried out on samples taken during six seasonal cruises at different water depths. Farming activity increased the natural concentrations of some nutrients (ammonium, nitrite, phosphate, dissolved inorganic nitrogen) and changed their seasonal pattern. The values still remained typical for oligotrophic environ‐ments demonstrating no risk for eutrophication. Enhanced nutrient supply provoked an immediate increase in abundances of both autotrophic and heterotrophic microbial groups (except pigmented nanoflagellates) and chlorophyll a. The effect of farming was more visible for the heterotrophic microbial component. Results from this study reveal a potential common pattern of microbial response to farming in the oligotrophic environments. It also suggests the importance of heterotrophic microbial web in transferring the matter and energy released from the fish farms in nutrient poor environments. 相似文献