全文获取类型
收费全文 | 2583篇 |
免费 | 150篇 |
国内免费 | 2篇 |
专业分类
林业 | 177篇 |
农学 | 52篇 |
基础科学 | 14篇 |
441篇 | |
综合类 | 440篇 |
农作物 | 70篇 |
水产渔业 | 161篇 |
畜牧兽医 | 1154篇 |
园艺 | 70篇 |
植物保护 | 156篇 |
出版年
2023年 | 19篇 |
2022年 | 31篇 |
2021年 | 57篇 |
2020年 | 60篇 |
2019年 | 80篇 |
2018年 | 69篇 |
2017年 | 65篇 |
2016年 | 71篇 |
2015年 | 53篇 |
2014年 | 66篇 |
2013年 | 115篇 |
2012年 | 175篇 |
2011年 | 221篇 |
2010年 | 99篇 |
2009年 | 63篇 |
2008年 | 169篇 |
2007年 | 144篇 |
2006年 | 163篇 |
2005年 | 137篇 |
2004年 | 129篇 |
2003年 | 128篇 |
2002年 | 111篇 |
2001年 | 31篇 |
2000年 | 40篇 |
1999年 | 26篇 |
1998年 | 19篇 |
1997年 | 19篇 |
1996年 | 8篇 |
1995年 | 21篇 |
1994年 | 14篇 |
1993年 | 6篇 |
1992年 | 16篇 |
1991年 | 11篇 |
1990年 | 25篇 |
1989年 | 19篇 |
1988年 | 19篇 |
1987年 | 19篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 14篇 |
1980年 | 9篇 |
1979年 | 12篇 |
1978年 | 13篇 |
1977年 | 7篇 |
1975年 | 11篇 |
1974年 | 8篇 |
1973年 | 12篇 |
1971年 | 11篇 |
1970年 | 10篇 |
1966年 | 6篇 |
排序方式: 共有2735条查询结果,搜索用时 15 毫秒
1.
Mark D. Rawling Nicola Pontefract Ana Rodiles Ilektra Anagnostara Eric Leclercq Marion Schiavone Mathieu Castex Daniel L. Merrifield 《Journal of the World Aquaculture Society》2019,50(6):1108-1122
Fish were fed a single‐strain yeast fraction (SsYF; 2 g/kg) or a multistrain yeast fraction (MsYF; 0.8 g/kg) for 10 weeks. The results demonstrated significant (p ≤ 0.03) elevations in weight gain, specific growth rate, protein efficiency ratio, and feed conversion ratio in fish fed the yeast fraction‐supplemented diets. In the distal intestine, a significant elevation in microvilli density was observed after 5 and 10 weeks of dietary supplementation with MsYF and SsYF, respectively, compared to control fed fish (p < 0.001). A significant elevation (p = 0.02) in the perimeter ratio was observed in fish fed diets supplemented with the yeast fractions. After 10 weeks of feeding on the experimental diets, Rt‐qPCR demonstrated a significant downregulation (p < 0.05) in the stress response genes, heat‐shock protein 70 (hsp70) and proliferating cell nuclear antigen (pcna), in fish fed diets supplemented with the yeast fractions. Significant (p < 0.05) elevations in interleukin 1‐beta (il1β) and interleukin‐10 (il10) gene expression were observed in fish fed diets supplemented with the MsYF compared to the other dietary groups. These findings suggest that feeding an MsYF specifically at a lower incorporation rate < 1 g/kg, compared to a commercial SsYF at 2 g/kg, is effective in improving the intestinal health status and growth performance of European seabass. 相似文献
2.
Outbreaks of infection due to a parapoxvirus were reported on eight New Zealand deer farms. Scabby lesions were seen variably on the muzzle, lips, face, ears and neck of red deer (Cervus elaphus) with morbidity rates reaching 100%. On three farms multifocal lesions were also present on the velvet. Deaths were reported on two properties where the lesions were extensive and secondary bacterial infections had occurred. On one of these farms multifactorial disease was suspected. Poxvirus particles were seen by negative contrast electron microscopy in scab material from all eight properties. Morphologically the deer virus resembled a parapoxvirus, but restriction endonuclease analysis showed its DNA fragment patterns were distinct from those of orf (contagious ecthyma) virus. 相似文献
3.
In conscious pigs the influence of intravenous infusion of live E. coli (7×108/kg), of the equivalent amount of endotoxin (20 g/kg) or of a high dose of endotoxin (2.5 mg/kg) on the hemodynamic, clinical and pathological parameters and on survival rate was studied. E. coli and endotoxin infusion resulted in pulmonary hypertension, systemic arterial hypotension, a decrease in cardiac output and an increase in heart rate. Clinical signs were characterized by respiratory and nervous disturbances, whereas necropsy revealed hemorrhages and edema in several organs. Although these findings were similar in the three groups, a marked difference in lethality was observed. Infusion of E. coli or of the high dose of endotoxin resulted in a significant mortality, whereas all pigs survived the infusion of the low dose of endotoxin. This suggests that the lethal pathophysiological mechanisms may only become activated when a sufficient amount of endotoxin is released into the circulation. 相似文献
4.
Prevalence of gastrointestinal nematodes in dairy heifers in western Canada 总被引:3,自引:2,他引:1
下载免费PDF全文
![点击此处可从《The Canadian veterinary journal. La revue veterinaire canadienne》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Cox WR Lemiski D 《The Canadian veterinary journal. La revue veterinaire canadienne》1989,30(8):666-668
A survey was conducted to estimate the prevalence of gastrointestinal nematodes in grazing dairy replacement heifers in western Canada. Fecal samples were collected from 566 animals on 34 farms distributed over the three prairie provinces. Fecal egg counts were performed using a modified Wisconsin centrifugation technique. The overall mean farm fecal egg count was 16.0 eggs per gram feces (range 0.7-78.1 epg). Gastrointestinal nematodes were demonstrated on every farm examined, and 93.3% of all individuals tested were positive. 相似文献
5.
6.
7.
8.
Eric Lim Teik Chung Michael Predith Frisco Nobilly Anjas Asmara Samsudin Faez Firdaus Abdullah Jesse Teck Chwen Loh 《Tropical animal health and production》2018,50(8):1727-1732
Brachiaria decumbens is an extremely productive tropical grass due to its aggressive growth habit and its adaptation to a varied range of soil types and environments. As a result of the vast availability, treated B. decumbens demonstrates as a promising local material that could be utilised as an improved diet for sheep and goats. Despite the fact that the grass significantly increases weight gains in grazing farm animals, there were many reports of general ill-thrift and sporadic outbreaks of photosensitivity in livestock due to the toxic compound of steroidal saponin found in B. decumbens. Ensiling and haymaking were found to be effective in removing toxin and undesirable compounds in the grass. Biological treatments using urea, activated charcoal, polyethylene glycol, and effective microorganisms were found to be useful in anti-nutritional factor deactivation and improving the nutritive values of feedstuffs. Besides, oral administration of phenobarbitone showed some degree of protection in sheep that fed on B. decumbens pasture. In this review, we aim to determine the effect of B. decumbens toxicity and possible treatment methods on the grass to be used as an improved diet for small ruminant. 相似文献
9.
10.