全文获取类型
收费全文 | 2816篇 |
免费 | 167篇 |
国内免费 | 5篇 |
专业分类
林业 | 161篇 |
农学 | 53篇 |
基础科学 | 18篇 |
459篇 | |
综合类 | 451篇 |
农作物 | 153篇 |
水产渔业 | 148篇 |
畜牧兽医 | 1269篇 |
园艺 | 85篇 |
植物保护 | 191篇 |
出版年
2023年 | 19篇 |
2021年 | 34篇 |
2020年 | 50篇 |
2019年 | 52篇 |
2018年 | 46篇 |
2017年 | 59篇 |
2016年 | 68篇 |
2015年 | 53篇 |
2014年 | 59篇 |
2013年 | 130篇 |
2012年 | 150篇 |
2011年 | 199篇 |
2010年 | 93篇 |
2009年 | 82篇 |
2008年 | 133篇 |
2007年 | 145篇 |
2006年 | 124篇 |
2005年 | 129篇 |
2004年 | 116篇 |
2003年 | 127篇 |
2002年 | 93篇 |
2001年 | 50篇 |
2000年 | 57篇 |
1999年 | 38篇 |
1998年 | 25篇 |
1997年 | 19篇 |
1996年 | 16篇 |
1995年 | 14篇 |
1993年 | 16篇 |
1992年 | 39篇 |
1991年 | 31篇 |
1990年 | 27篇 |
1989年 | 35篇 |
1988年 | 39篇 |
1986年 | 29篇 |
1985年 | 25篇 |
1984年 | 27篇 |
1983年 | 14篇 |
1981年 | 15篇 |
1980年 | 18篇 |
1979年 | 19篇 |
1978年 | 21篇 |
1975年 | 21篇 |
1974年 | 27篇 |
1973年 | 24篇 |
1972年 | 22篇 |
1971年 | 22篇 |
1970年 | 21篇 |
1967年 | 17篇 |
1947年 | 17篇 |
排序方式: 共有2988条查询结果,搜索用时 31 毫秒
21.
22.
23.
24.
25.
26.
Lien VANDE MAELE Marc HEYNDRICKX Dominiek MAES Nele DE PAUW Maxime MAHU Marc VERLINDEN Freddy HAESEBROUCK An MARTEL Frank PASMANS Filip BOYEN 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2016,78(2):325-328
The antibacterial potential of organic acids and essential oil components against Brachyspira
hyodysenteriae, the causative pathogen of swine dysentery, was evaluated. Minimum inhibitory
concentrations (MIC) of 15 compounds were determined at pH 7.2 and pH 6.0, using a broth microdilution assay.
In addition, possible synergism was determined. MIC values for the three tested strains were similar. For
organic acids, MIC values at pH 6.0 were lower than at pH 7.2. B. hyodysenteriae was most
sensitive to cinnamaldehyde and lauric acid, with MIC values <1.5 mM. Most antibacterial effects of binary
combinations were additive, however, for thymol and carvacrol, synergism could be observed. In
vitro results demonstrate the antibacterial action of certain essential oil components and organic
acids against B. hyodysenteriae. 相似文献
27.
28.
Field Evaluation of Cocksfoot,Tall Fescue and Phalaris for Dry Marginal Environments of South‐Eastern Australia. 1. Establishment and Herbage Production 下载免费PDF全文
S. G. Clark Z. N. Nie R. A. Culvenor C. A. Harris R. C. Hayes G. D. Li M. R. Norton D. L. Partington 《Journal of Agronomy and Crop Science》2016,202(2):96-114
Newly developed candidate cultivars of cocksfoot (Dactylis glomerata L.), phalaris (Phalaris aquatica L.) and tall fescue (Festuca arundinacea Schreb. = syn. L. arundinaceum (Schreb) Darbysh.) were evaluated over four years for persistence and productivity against current commercial cultivars in small plots at five locations selected for lower and less reliable rainfall and difficult soils (low pH and high Al) in south‐eastern Australia known to be marginally too dry for these grass species. The five locations were ‐ representing summer dominant rainfall, Inverell, in northern New South Wales (NSW); ‐ representing uniform rainfall; Trungley Hall, (medium rainfall), and Beckom (lower rainfall) both in southern NSW; and; representing a winter dominant pattern ‐ Eversley, (higher rainfall), and Bealiba, (lower rainfall), in central Victoria. The objective was to determine if the new candidate cultivars were more likely to persist and to be productive than current commercial cultivars. The study showed that most phalaris and cocksfoot treatments were highly productive in high rainfall years at one or both sites in southern NSW. However, all treatments had become much less productive by the end of the experimental period due to plant loss under hot, dry conditions in the final summer. At Bealiba in central Victoria, cocksfoot was the most productive species with several cocksfoot treatments of both subsp. hispanica and subsp. glomerata still present at the final harvest despite a hot and dry final summer‐autumn. Tall fescue was the most productive species in the two higher rainfall environments (Inverell, Eversley) although most treatments of all species performed well at those sites. Continental tall fescues were more productive on average than Mediterranean tall fescues at the strongly acidic Eversley site. As a result of this work, two of the new cocksfoot candidates (Moroccan Fine and AVH48 Selection) and one of the tall fescue candidates (Summer Active 1) have been licensed for commercial development and release. 相似文献
29.
Agnes Agunos Sheryl P. Gow David F. Lger Logan Flockhart Danielle Daignault Andrea Desruisseau Erin Zabek Frank Pollari Richard J. Reid-Smith 《Canadian journal of veterinary research》2021,85(1):27
Eggs are important to the diet of Canadians. This product is one of the supply-managed commodities in Canada, but unlike other commodities, where food safety risks are extensively explored and reported, information on the prevalence of enteric organisms (e.g., Salmonella, Campylobacter) and antimicrobial resistance (AMR) in layers in Canada are limited. This study was conducted to determine the prevalence of select bacteria and the associated AMR patterns in layer flocks using 2 sample matrices. Farms were located within FoodNet Canada and the Canadian Integrated Program for Antimicrobial Resistance Surveillance sentinel sites (SS). Fecal samples (Ontario: ONSS1a, ONSS1b) and environmental sponge swabs (British Columbia: BCSS2a) were collected. Salmonella prevalence was 29% and 8% in ONSS1a and ONSS1b, respectively, and 7% in BCSS2a. S. Kentucky and S. Livingstone were the most frequently isolated serovars and no S. Enteritidis was detected. Campylobacter was not detected in the BC sponge swabs but was isolated from 89% and 53% of Ontario fecal samples (ONSS1a and ONSS1b, respectively). Seven C. jejuni from Ontario were ciprofloxacin-resistant. Escherichia coli prevalence was high in both sample types (98%). Overall, tetracycline resistance among E. coli ranged from 26% to 69%. Resistance to ceftiofur (n = 2 isolates) and gentamicin (n = 2) was relatively low. There were diverse resistance patterns (excludes susceptible isolates) observed among E. coli in Ontario (10 patterns) and British Columbia (14 patterns). This study revealed that fecal samples are more informative for farm-level monitoring of pathogen and AMR prevalence. Without further validation, sponge swabs are limited in their utility for Campylobacter detection and thus, for public health surveillance. 相似文献
30.