全文获取类型
收费全文 | 1152篇 |
免费 | 68篇 |
专业分类
林业 | 132篇 |
农学 | 33篇 |
基础科学 | 4篇 |
232篇 | |
综合类 | 116篇 |
农作物 | 46篇 |
水产渔业 | 91篇 |
畜牧兽医 | 505篇 |
园艺 | 13篇 |
植物保护 | 48篇 |
出版年
2023年 | 5篇 |
2022年 | 8篇 |
2021年 | 24篇 |
2020年 | 29篇 |
2019年 | 32篇 |
2018年 | 30篇 |
2017年 | 27篇 |
2016年 | 29篇 |
2015年 | 26篇 |
2014年 | 32篇 |
2013年 | 67篇 |
2012年 | 70篇 |
2011年 | 73篇 |
2010年 | 47篇 |
2009年 | 37篇 |
2008年 | 60篇 |
2007年 | 55篇 |
2006年 | 58篇 |
2005年 | 48篇 |
2004年 | 45篇 |
2003年 | 36篇 |
2002年 | 38篇 |
2001年 | 20篇 |
2000年 | 13篇 |
1999年 | 8篇 |
1998年 | 5篇 |
1996年 | 10篇 |
1995年 | 6篇 |
1993年 | 8篇 |
1992年 | 20篇 |
1991年 | 15篇 |
1990年 | 16篇 |
1989年 | 10篇 |
1988年 | 14篇 |
1987年 | 12篇 |
1986年 | 15篇 |
1985年 | 8篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1982年 | 6篇 |
1976年 | 5篇 |
1974年 | 5篇 |
1973年 | 6篇 |
1972年 | 6篇 |
1966年 | 5篇 |
1869年 | 6篇 |
1868年 | 7篇 |
1867年 | 9篇 |
1866年 | 5篇 |
1863年 | 8篇 |
排序方式: 共有1220条查询结果,搜索用时 15 毫秒
1.
2.
J L?fstedt J A Roth R F Ross W C Wagner 《American journal of veterinary research》1983,44(7):1224-1228
In a study of susceptibilities of sows from 2 herds to experimentally induced Escherichia coli mastitis, a marked difference was seen. The "susceptible" sows were from a conventional herd and "resistant" sows were from a specific-pathogen-free herd. The purpose of the study was to determine whether deficient neutrophil function was associated with increased susceptibility to E coli-induced mastitis. Four in vitro procedures were used to evaluate polymorphonuclear leukocyte (PMN) function: (i) random migration under agarose, (ii) ingestion of 125I-iododeoxyuridine-labeled Staphylococcus aureus, (iii) quantitative nitroblue tetrazolium reduction, and (iv) iodination. After parturition and intramammary inoculation with E coli, sows from the susceptible herd were neutropenic and the neutrophils which were present in the peripheral blood had reduced function. Specifically, there were depressed random migration under agarose, S aureus ingestion, and iodination when compared with PMN function in resistant sows. These data indicate that susceptibility to E coli mastitis was associated with deficiencies in PMN numbers and function. Potential causes of the neutrophil dysfunction are discussed and include possible systemic hormonal aberrations or the presence of an inapparent viral or bacterial infection. 相似文献
3.
Acquired resistance triggered by elicitins in tobacco and other plants 总被引:17,自引:0,他引:17
Philippe Bonnet Eva Bourdon Michel Ponchet Jean -Pierre Blein Pierre Ricci 《European journal of plant pathology / European Foundation for Plant Pathology》1996,102(2):181-192
Elicitins are a family of proteins excreted byPhytophthora spp. They exhibit high sequence homology but large net charge differences. They induce necrosis in tobacco plants which then become resistant to the tobacco pathogenPhytophthora parasitica var.nicotianae. In stem-treated plants, resistance was not restricted to the site of elicitin application, but could be demonstrated by petiole inoculation at all levels on the stem. Resistance was already maximum after two days and lasted for at least two weeks. It was effective not only towardsP. p. var.nicotianae infection, but also against the unrelated pathogenSclerotinia sclerotiorum. In contrast to dichloroisonicotinic acid, an artificial inducer of systemic acquired resistance, which was increasingly effective with doses ranging from 0.25 to 5mole per plant, the basic elicitin cryptogein exhibited a threshold effect, inducing near total resistance and extensive leaf necrosis above 0.1 nmole per plant. Between 1 and 5 nmole, acidic elicitins (capsicein and parasiticein) protected tobacco plants with hardly any necrotic symptom. Elicitins exhibited similar effects in various tobacco cultivars andNicotiana species, although with quantitative differences, but induced neither necrosis nor protection in other SolanaceÆ (tomato, petunia and pepper). Among 24 additional species tested belonging to 18 botanical families, only some BrassicaceÆ, noticeably rape, exhibited symptoms in response to elicitins, in a cultivar-specific manner. Elicitins appear to be natural specific triggers for systemic acquired resistance and provide a tool for unraveling the mechanisms leading to its establishment.Abbreviations AR
acquired resistance
- HR
hypersensitive response
- INA
2,6-dichloroisonicotinic acid
- Ppn
Phytophthora parasitica var.nicotianae
- SAR
systemic acquired resistance 相似文献
4.
5.
6.
7.
8.
9.
10.
Scott HM Sorensen O Wu JT Chow EY Manninen K 《The Canadian veterinary journal. La revue veterinaire canadienne》2007,48(4):397-406
A province-wide cross-sectional seroprevalence and agroecological risk factor study of Mycobacterium avium subspecies paratuberculosis (MAP) and Neospora caninum (NC) infection among cattle in 100 cow-calf herds in Alberta was conducted. The seroprevalence of MAP in adult cattle was 1.5% across all herds. Using a widely accepted herd test cutpoint of 2 or more seropositive cows out of 30 animals tested, 7.9% of herds were estimated to be infected (95% confidence interval (CI): 2.3-23.4%). Seroprevalence of MAP differed by agroecological region; specifically, cattle and herds in areas with high soil pH (> 7.0), southern latitudes, and arid climates had a moderately reduced risk of infection (P < 0.10). Seroprevalence of NC infection was 9.7% among adult beef cattle province-wide--these levels also varied by agroecological region--with 91.0% of herds infected overall. 相似文献