全文获取类型
收费全文 | 140030篇 |
免费 | 19981篇 |
国内免费 | 31812篇 |
专业分类
林业 | 16202篇 |
农学 | 18490篇 |
基础科学 | 13894篇 |
40788篇 | |
综合类 | 51617篇 |
农作物 | 9759篇 |
水产渔业 | 8594篇 |
畜牧兽医 | 18040篇 |
园艺 | 4497篇 |
植物保护 | 9942篇 |
出版年
2024年 | 1124篇 |
2023年 | 1845篇 |
2022年 | 3436篇 |
2021年 | 4181篇 |
2020年 | 5438篇 |
2019年 | 8449篇 |
2018年 | 7432篇 |
2017年 | 8819篇 |
2016年 | 9224篇 |
2015年 | 9926篇 |
2014年 | 9187篇 |
2013年 | 10337篇 |
2012年 | 10871篇 |
2011年 | 10457篇 |
2010年 | 9263篇 |
2009年 | 8430篇 |
2008年 | 7339篇 |
2007年 | 7399篇 |
2006年 | 6916篇 |
2005年 | 6134篇 |
2004年 | 4115篇 |
2003年 | 3717篇 |
2002年 | 3201篇 |
2001年 | 2938篇 |
2000年 | 2956篇 |
1999年 | 3111篇 |
1998年 | 2915篇 |
1997年 | 2638篇 |
1996年 | 2349篇 |
1995年 | 2368篇 |
1994年 | 2200篇 |
1993年 | 1893篇 |
1992年 | 1751篇 |
1991年 | 1470篇 |
1990年 | 1195篇 |
1989年 | 1103篇 |
1988年 | 896篇 |
1987年 | 607篇 |
1986年 | 521篇 |
1985年 | 274篇 |
1984年 | 250篇 |
1983年 | 227篇 |
1982年 | 221篇 |
1981年 | 255篇 |
1980年 | 203篇 |
1979年 | 159篇 |
1978年 | 136篇 |
1975年 | 111篇 |
1965年 | 139篇 |
1964年 | 147篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
961.
962.
963.
964.
965.
S Oikawa N Katoh H Itoh T Miyamoto M Konno T Kajita 《Canadian journal of veterinary research》1997,61(3):182-186
Serum apolipoprotein A-I concentrations in cows infected with Salmonella Typhimurium were evaluated to assess its relevance in salmonellosis. Apolipoprotein A-I has been shown in rats to be secreted by the intestine as well as the liver. Clinical symptoms such as diarrhea revealed an outbreak of salmonellosis in 22 cows on a farm, and sera were obtained at 6 (acute phase), 16, 28 (convalescent period) and 42 d (postconvalescent period) after the outbreak. Apolipoprotein A-I concentrations (mean +/- SD, mg/mL), determined by ELISA, were 0.598 +/- 0.497 (day 6), 0.111 +/- 0.060 (day 16), 0.432 +/- 0.311 (day 28) and 0.727 +/- 0.516 (day 42). Compared with the concentration at day 42, those at 16 and 28 d were significantly (P < 0.01, P < 0.05) lower, but that at day 6 was not. The serum concentration of apolipoprotein B-100 (of liver origin in cattle) was unaltered during the course of salmonellosis. The concentration of apolipoprotein A-I was positively correlated with those of serum total cholesterol (r = 0.589, P < 0.01) and phospholipids (r = 0.590, P < 0.01). These results suggest that apolipoprotein A-I in cattle is in part of intestinal origin, and also that its decreased serum concentration in salmonellosis can be attributed to the reduced intestinal synthesis or secretion of this apolipoprotein. Moreover, as a potential carrier for dietary lipids such as cholesterol, determination of serum apolipoprotein A-I concentration is suggested to be useful when assessing the nutritional status of the affected cows. 相似文献
966.
967.
968.
K Rogers G M Barrington S M Parish 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(10):643-644
A nonhealing wound associated with a laceration in a 12-year-old llama was evaluated. Initial attempts at closure were unsuccessful and biopsy revealed scar tissue. Subsequent biopsies, 18 mo later, revealed squamous cell carcinoma with regional metastasis. This report describes squamous cell carcinoma, secondary to a traumatic wound in a llama. 相似文献
969.
The Canadian Cooperative Wildlife Health Centre and surveillance of wild animal diseases in Canada. 下载免费PDF全文
F A Leighton G A Wobeser I K Barker P Y Daoust D Martineau 《The Canadian veterinary journal. La revue veterinaire canadienne》1997,38(5):279-284
The Canadian Cooperative Wildlife Health Centre (CCWHC) was established in 1992 as an organization among Canada's 4 veterinary colleges, with a mandate to apply veterinary medicine to wildlife management and conservation in Canada. A major function of the CCWHC is nation-wide surveillance of wild animal diseases. Disease surveillance is conceived as consisting of 4 different activities: detection, diagnosis, information management, and use of information. In the CCWHC surveillance program, detection of disease is carried out by a wide range of professional and avocational field personnel, and much effort is expended to stimulate and support this activity. Diagnosis is done by personnel of provincial and federal veterinary laboratories and the CCWHC. Information management is achieved through a national database of wildlife disease incidents developed and maintained by the CCWHC. Use of information is enabled through established channels for distribution of information derived from the surveillance program to persons responsible for wildlife programs and policies, and to the public. There has been a high demand for the services of the CCWHC since its establishment. The CCWHC responds to approximately 2000 requests for information annually, distributes its newsletter to over 1700 recipients, examines approximately 1200 wild animal submissions each year, and has accumulated records of over 5000 disease incidents in its database. Technical information from the CCWHC has benefited federal, provincial/territorial, and nongovernment wildlife agencies; endangered species recovery programs; federal and provincial veterinary services; and federal and provincial public health programs. 相似文献
970.
经三年防治桑瘿蚊农药筛选试验和家蚕残毒测定结果表明,5%喹硫磷粉剂是取代有机氯农药防治桑瘿蚊的有效土壤处理剂.得出:(1)5%喹硫磷粉剂对防治桑瘿蚊有良好的效果.1983年小区试验校正防效为95.7%,1984年和1985年大田试验为89.14—91.56%,与有机氯农药相似.(2)施用安全,采用施药区内桑叶养蚕均无急性中毒现象发生.(3)越冬代桑瘿蚊的生活力,休眠体最强,蛹最弱,在5月中旬对越冬代桑瘿蚊的蛹期施药效果最好.但是,喹硫磷对桑瘿蚊的各个发育阶段都有良好的毒杀作用. 相似文献