全文获取类型
收费全文 | 395篇 |
免费 | 54篇 |
专业分类
林业 | 8篇 |
农学 | 5篇 |
基础科学 | 2篇 |
43篇 | |
综合类 | 13篇 |
农作物 | 20篇 |
水产渔业 | 7篇 |
畜牧兽医 | 340篇 |
园艺 | 3篇 |
植物保护 | 8篇 |
出版年
2023年 | 12篇 |
2022年 | 5篇 |
2021年 | 4篇 |
2020年 | 32篇 |
2019年 | 12篇 |
2018年 | 13篇 |
2017年 | 14篇 |
2016年 | 12篇 |
2015年 | 20篇 |
2014年 | 33篇 |
2013年 | 22篇 |
2012年 | 25篇 |
2011年 | 25篇 |
2010年 | 16篇 |
2009年 | 24篇 |
2008年 | 17篇 |
2007年 | 11篇 |
2006年 | 11篇 |
2005年 | 10篇 |
2004年 | 12篇 |
2003年 | 16篇 |
2002年 | 18篇 |
2001年 | 8篇 |
2000年 | 7篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 1篇 |
1996年 | 7篇 |
1995年 | 4篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 4篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 2篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 2篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 1篇 |
1966年 | 1篇 |
1965年 | 2篇 |
1960年 | 2篇 |
1959年 | 1篇 |
1958年 | 4篇 |
1957年 | 2篇 |
排序方式: 共有449条查询结果,搜索用时 31 毫秒
101.
A pilot study of total and allergen‐specific IgE serum levels during anestrous,estrous and pregnancy in healthy female dogs
下载免费PDF全文
![点击此处可从《Veterinary dermatology》网站下载免费的PDF全文](/ch/ext_images/free.gif)
102.
Medical management of esophageal perforation secondary to esophageal foreign bodies in 5 dogs
下载免费PDF全文
![点击此处可从《Journal of Veterinary Emergency and Critical Care》网站下载免费的PDF全文](/ch/ext_images/free.gif)
103.
Lena Silvn 《Acta veterinaria Scandinavica》1965,6(1):234
The in-vitro sensitivity of 9 different strains of Mycoplasma gallisepticum has been tested using 12 different antibiotics including tetracyclines, erythromycin and tylosin. The latter antibiotic showed the highest effect followed by achromycin and terramycin. Two antibiotics with a high in-vitro effect against Mycoplasma were found in kanamycin and syntodecin. 相似文献
104.
105.
106.
Lena?St?hlEmail author Peter?H?gberg Anita?Sellstedt Roland J.?Buresh 《Agroforestry Systems》2005,65(1):67-79
A field experiment was performed in eastern Kenya to estimate N2 fixation by Sesbania sesban over an 18-month period using the 15N dilution method. The influence of three reference species, Senna spectabilis, Eucalyptus saligna and Grevillea robusta, on the estimates of N2 fixation was also assessed. Percentage Ndfa (nitrogen derived from the atmosphere) was calculated based on foliar atom excess
(FAE), above-ground atom excess (AAE) or whole tree atom excess (WAE) data. The differences in atom% 15N excess values between species and plant parts are presented and discussed. We recommend the use of several reference species
for estimating %Ndfa and that the different results obtained should be carefully considered in relation to the issues being
addressed. In this study, Senna was the most suitable of the three reference species because its N uptake pattern and phenology were very similar to those
of Sesbania. When well established, the amount of N fixed by Sesbania accounts for more than 80% of its total N content, according to FAE-based estimates. We estimated the Ndfa by Sesbania after 18 months to between 500 and 600 kg ha−1 , depending on whether FAE, AAE or WAE data were used and on the choice of reference species. The substantial accumulation
of N in planted Sesbania highlighted its potential to increase the sustainability of crop production on N-limited soils. We consider the 15N dilution method to be appropriate for quantifying N2 fixation in improved fallows in studies, similar to this one, of young trees with high N2-fixing ability. 相似文献
107.
Holden L Moen LH Sletten GB Dooper MM 《Journal of agricultural and food chemistry》2007,55(7):2536-2542
Sweet lupines are increasingly used in food production. Cause for concern has been expressed due to the increase in reported lupine-induced allergic incidents and the association between lupine and peanut allergies. In the current study, a polyclonal-monoclonal antibody-based sandwich ELISA for the detection of lupine proteins in foods was developed. The assay was sensitive to both native and processed proteins from Lupinus angustifolius and Lupinus albus and had a detection limit of 1 mug/g. Intra- and interassay coefficients of variation were <5 and <17%, respectively. A selection of 112 food samples, both with and without lupine declaration, was evaluated for their content of lupine. The data showed that the majority were in agreement with the respective labeling. However, some inconsistency was seen, typically in bread/rolls and soy flours. 相似文献
108.
Simultaneously mitigating near-term climate change and improving human health and food security 总被引:3,自引:0,他引:3
Shindell D Kuylenstierna JC Vignati E van Dingenen R Amann M Klimont Z Anenberg SC Muller N Janssens-Maenhout G Raes F Schwartz J Faluvegi G Pozzoli L Kupiainen K Höglund-Isaksson L Emberson L Streets D Ramanathan V Hicks K Oanh NT Milly G Williams M Demkine V Fowler D 《Science (New York, N.Y.)》2012,335(6065):183-189
Tropospheric ozone and black carbon (BC) contribute to both degraded air quality and global warming. We considered ~400 emission control measures to reduce these pollutants by using current technology and experience. We identified 14 measures targeting methane and BC emissions that reduce projected global mean warming ~0.5°C by 2050. This strategy avoids 0.7 to 4.7 million annual premature deaths from outdoor air pollution and increases annual crop yields by 30 to 135 million metric tons due to ozone reductions in 2030 and beyond. Benefits of methane emissions reductions are valued at $700 to $5000 per metric ton, which is well above typical marginal abatement costs (less than $250). The selected controls target different sources and influence climate on shorter time scales than those of carbon dioxide-reduction measures. Implementing both substantially reduces the risks of crossing the 2°C threshold. 相似文献
109.
Woodward G Gessner MO Giller PS Gulis V Hladyz S Lecerf A Malmqvist B McKie BG Tiegs SD Cariss H Dobson M Elosegi A Ferreira V Graça MA Fleituch T Lacoursière JO Nistorescu M Pozo J Risnoveanu G Schindler M Vadineanu A Vought LB Chauvet E 《Science (New York, N.Y.)》2012,336(6087):1438-1440
Excessive nutrient loading is a major threat to aquatic ecosystems worldwide that leads to profound changes in aquatic biodiversity and biogeochemical processes. Systematic quantitative assessment of functional ecosystem measures for river networks is, however, lacking, especially at continental scales. Here, we narrow this gap by means of a pan-European field experiment on a fundamental ecosystem process--leaf-litter breakdown--in 100 streams across a greater than 1000-fold nutrient gradient. Dramatically slowed breakdown at both extremes of the gradient indicated strong nutrient limitation in unaffected systems, potential for strong stimulation in moderately altered systems, and inhibition in highly polluted streams. This large-scale response pattern emphasizes the need to complement established structural approaches (such as water chemistry, hydrogeomorphology, and biological diversity metrics) with functional measures (such as litter-breakdown rate, whole-system metabolism, and nutrient spiraling) for assessing ecosystem health. 相似文献