全文获取类型
| 收费全文 | 258817篇 |
| 免费 | 15231篇 |
| 国内免费 | 718篇 |
专业分类
| 林业 | 23793篇 |
| 农学 | 14248篇 |
| 基础科学 | 3007篇 |
| 43903篇 | |
| 综合类 | 24846篇 |
| 农作物 | 17383篇 |
| 水产渔业 | 17039篇 |
| 畜牧兽医 | 100138篇 |
| 园艺 | 6394篇 |
| 植物保护 | 24015篇 |
出版年
| 2021年 | 2568篇 |
| 2020年 | 3015篇 |
| 2019年 | 3784篇 |
| 2018年 | 4208篇 |
| 2017年 | 4623篇 |
| 2016年 | 4989篇 |
| 2015年 | 4555篇 |
| 2014年 | 5964篇 |
| 2013年 | 16460篇 |
| 2012年 | 6615篇 |
| 2011年 | 8446篇 |
| 2010年 | 7479篇 |
| 2009年 | 8022篇 |
| 2008年 | 7737篇 |
| 2007年 | 6689篇 |
| 2006年 | 7321篇 |
| 2005年 | 6495篇 |
| 2004年 | 6362篇 |
| 2003年 | 6269篇 |
| 2002年 | 5432篇 |
| 2001年 | 5934篇 |
| 2000年 | 5559篇 |
| 1999年 | 5303篇 |
| 1998年 | 4107篇 |
| 1997年 | 4168篇 |
| 1996年 | 3897篇 |
| 1995年 | 4455篇 |
| 1994年 | 3864篇 |
| 1993年 | 3590篇 |
| 1992年 | 4269篇 |
| 1991年 | 4541篇 |
| 1990年 | 4245篇 |
| 1989年 | 4189篇 |
| 1988年 | 3697篇 |
| 1987年 | 3790篇 |
| 1986年 | 3745篇 |
| 1985年 | 3987篇 |
| 1984年 | 3657篇 |
| 1983年 | 3501篇 |
| 1982年 | 2872篇 |
| 1981年 | 2816篇 |
| 1980年 | 2771篇 |
| 1979年 | 3314篇 |
| 1978年 | 2914篇 |
| 1977年 | 2718篇 |
| 1976年 | 2521篇 |
| 1975年 | 2434篇 |
| 1974年 | 2669篇 |
| 1973年 | 2619篇 |
| 1972年 | 2399篇 |
排序方式： 共有10000条查询结果，搜索用时 703 毫秒
991.
1. Brown egg layers were fed diets differing in oil content, oil source and linoleic acid concentration and the effect on performance from 22 to 69 weeks of age was studied.
2. The birds responded with an increasing mean egg weight up to a linoleic acid intake of 2.75 g/bird d.
3. Increasing the intake of readily absorbable oil without increasing linoleic acid concentration did not increase mean egg weight. 相似文献
992.
993.
994.
To assess respiratory function in dogs with tick paralysis, respiratory measurements were recorded on 14 dogs experimentally infested with Ixodes holocyclus. There was a progressive fall in respiratory rate with no change in tidal volume, which resulted in a significant fall in minute respiratory volume in the latter stages of the disease. The fall in respiratory rate was possibly central in origin and was accompanied by an increased alveolar-arterial oxygen tension difference, probably caused by pulmonary congestion and oedema. The "grunting" respiration seen in tick paralysis was due to closure of the vocal cords during expiration and could represent an attempt to re-expand collapsed parts of the lung. 相似文献
995.
Vaccination-related anthrax in three llamas 总被引：1，自引：0，他引：1
M E Cartwright A E McChesney R L Jones 《Journal of the American Veterinary Medical Association》1987,191(6):715-716
Two llama calves died 3 days after inoculation with anthrax vaccine. Concurrent administration of ivermectin and other biologics may have enhanced the infectivity of the Sterne strain vaccine of Bacillus anthracis. This experience suggests that the Sterne strain of anthrax vaccine can induce fatal disease when given to young llamas and should be used only with extreme care and in face of strong "at risk" situations. 相似文献
996.
997.
998.
999.
1000.
Pepsin: hydrochloric acid digestion and histological examination of the myocardium of 51 hearts from five to nine month-old lambs from the southern half of the North Island, showed that 47 (92%) were infected with microscopic sarcocysts that are presumed to be dog-derived. Of 157 sarcocysts detected histologically, 32 corresponded morphologically with Sarcocystis ovicanis and 120 with Sarcocystis tenella (Syn. S. arieticanis). The remainder could not be identified as to type. 相似文献