全文获取类型
收费全文 | 155658篇 |
免费 | 9233篇 |
国内免费 | 82篇 |
专业分类
林业 | 6030篇 |
农学 | 5477篇 |
基础科学 | 1041篇 |
18937篇 | |
综合类 | 26854篇 |
农作物 | 6259篇 |
水产渔业 | 8110篇 |
畜牧兽医 | 80267篇 |
园艺 | 2024篇 |
植物保护 | 9974篇 |
出版年
2019年 | 1517篇 |
2018年 | 2332篇 |
2017年 | 2735篇 |
2016年 | 2529篇 |
2015年 | 2162篇 |
2014年 | 2666篇 |
2013年 | 6156篇 |
2012年 | 4698篇 |
2011年 | 5677篇 |
2010年 | 3747篇 |
2009年 | 3704篇 |
2008年 | 5513篇 |
2007年 | 5203篇 |
2006年 | 5040篇 |
2005年 | 4494篇 |
2004年 | 4312篇 |
2003年 | 4345篇 |
2002年 | 4056篇 |
2001年 | 5328篇 |
2000年 | 5193篇 |
1999年 | 4113篇 |
1998年 | 1731篇 |
1997年 | 1715篇 |
1996年 | 1494篇 |
1995年 | 1743篇 |
1994年 | 1559篇 |
1993年 | 1568篇 |
1992年 | 3202篇 |
1991年 | 3283篇 |
1990年 | 3182篇 |
1989年 | 3234篇 |
1988年 | 2826篇 |
1987年 | 2928篇 |
1986年 | 2979篇 |
1985年 | 2859篇 |
1984年 | 2281篇 |
1983年 | 1976篇 |
1982年 | 1424篇 |
1979年 | 1949篇 |
1978年 | 1550篇 |
1977年 | 1304篇 |
1976年 | 1297篇 |
1975年 | 1467篇 |
1974年 | 1727篇 |
1973年 | 1717篇 |
1972年 | 1624篇 |
1971年 | 1560篇 |
1970年 | 1529篇 |
1969年 | 1449篇 |
1967年 | 1306篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
961.
962.
963.
964.
965.
Lavigne C Smith HJ 《The Canadian veterinary journal. La revue veterinaire canadienne》1983,24(12):389-390,391
In 1982, approximately 13,000 Canadian cattle were treated once for sarcoptic mange with ivermectin at a dose of 10 mg per 45.4 kg of body weight. The results showed 100% efficacy against Sarcoptes scabiei and other ectoparasites present. All cattle showed marked improvement in general condition with new hair growth and apparent weight gains by 31 days posttreatment. Surveillance of treated herds for a year following treatment showed that one parenteral treatment with ivermectin eradicated the disease from closed herds. 相似文献
966.
A condition resembling chronic malignant catarrhal fever was seen in a 9-month-old pet sika hind (Cervus nippon). From an initial acute depression, pyrexia, and anorexia, the condition progressed to include hypopyon, keratitis, lethargy, loss of condition, sloughing of one hoof and eventually death after seven weeks. There were multiple, 5 to 8mm diameter dark-red nodules throughout the mesenteries and mediastinum, along abdominal organ ligaments, and about the uterus and kidneys. Histopathology showed the nodules to be organising vascular thrombi. Concurrent perivascular mononuclear infiltrations and intravascular thrombi in many tissues confirmed that the condition was malignant catarrhal fever. 相似文献
967.
968.
969.
Endocrine effects of heat stress in boars 总被引:1,自引:0,他引:1
K. Larsson S. Einarsson K. Lundstrm J. Hakkarainen 《Acta veterinaria Scandinavica》1983,24(3):305-314
The purpose of this study was to describe the temporal changes in peripheral plasma levels of testosterone and Cortisol in boars during and after heat stress. A total of 8 boars were utilized, 4 of them were exposed to 35°C, for 100 h in a climatic room, and 4 served as controls and were kept at 20 °C for 100 h in the climatic room.Blood samples were obtained via permanent vein catheters 3 times daily from 5 days before heat stress until 20 days after termination of heat stress. Testestorone levels were determined by radioimmunoassay and Cortisol by a competitive protein binding technique.For both hormones the pre-exposure levels were similar in both groups of boars. The control boars had significantly higher testosterone levels, while being in the climatic room, than during any other period. The experimental boars had slightly increased testosterone levels during the first day of heat stress and thereafter continuously decreased levels. In the control boars the testosterone levels returned to pre-exposure levels immediately after removal from the climatic room, whereas in the experimental boars the testosterone levels were dramatically increased during the first 5 days after exposure. The differences in Cortisol levels, between the 2 groups of boars were restricted to the period spent in the climatic room. During this period the experimental boars had significantly higher Cortisol levels.Key words: boars, heat stress, testosterone, cortisol 相似文献
970.
Latimer CA Wyman M Szymanski C Werling K 《Journal of the American Veterinary Medical Association》1983,183(9):1003-5, 965
A cyst involving the gland of the 3rd eyelid was removed from an 8-year-old dog. Clinically the circumscribed mass resembled a pigmented neoplasm. Histologically the cyst was multiloculated, with homogeneous eosinophilic periodic acid-Schiff-positive content. Melanin pigment was present in epithelial cells and cystic lumens. Protective functions of the 3rd eyelid were retained following excisional biopsy. 相似文献