全文获取类型
收费全文 | 251974篇 |
免费 | 15338篇 |
国内免费 | 669篇 |
专业分类
林业 | 23403篇 |
农学 | 13981篇 |
基础科学 | 2958篇 |
42315篇 | |
综合类 | 23959篇 |
农作物 | 17054篇 |
水产渔业 | 16490篇 |
畜牧兽医 | 97916篇 |
园艺 | 6268篇 |
植物保护 | 23637篇 |
出版年
2021年 | 2449篇 |
2020年 | 2842篇 |
2019年 | 3630篇 |
2018年 | 3924篇 |
2017年 | 4297篇 |
2016年 | 4726篇 |
2015年 | 4279篇 |
2014年 | 5644篇 |
2013年 | 16158篇 |
2012年 | 6018篇 |
2011年 | 7935篇 |
2010年 | 7219篇 |
2009年 | 7828篇 |
2008年 | 7321篇 |
2007年 | 6278篇 |
2006年 | 7075篇 |
2005年 | 6246篇 |
2004年 | 6100篇 |
2003年 | 5890篇 |
2002年 | 5261篇 |
2001年 | 6012篇 |
2000年 | 5775篇 |
1999年 | 5370篇 |
1998年 | 4134篇 |
1997年 | 4210篇 |
1996年 | 3939篇 |
1995年 | 4550篇 |
1994年 | 3967篇 |
1993年 | 3639篇 |
1992年 | 4498篇 |
1991年 | 4709篇 |
1990年 | 4341篇 |
1989年 | 4291篇 |
1988年 | 3837篇 |
1987年 | 4000篇 |
1986年 | 3940篇 |
1985年 | 4166篇 |
1984年 | 3777篇 |
1983年 | 3575篇 |
1982年 | 2912篇 |
1981年 | 2770篇 |
1980年 | 2774篇 |
1979年 | 3280篇 |
1978年 | 2990篇 |
1977年 | 2739篇 |
1976年 | 2544篇 |
1975年 | 2391篇 |
1974年 | 2630篇 |
1973年 | 2646篇 |
1972年 | 2382篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
971.
972.
973.
Physiopathologie et thérapeutique de l'utérus en période puerpérale chez la vache laitière: revue 下载免费PDF全文
Accurate diagnosis and effective therapeutics of uterine pathologies in cattle represent some of the daily preoccupations for the veterinarians involved in herd health medicine. A rational approach requires a competence based on fundamental and clinical knowledge.
The physiological aspects of the uterine involution in cattle are reviewed with emphasis about the in utero bacteriological dynamic and the endocrinological evolution during this period. The pathogenesis of uterine pathologies is discussed following new research results and new knowledge on the mechanisms of uterine defense. The value and limitations of the clinical diagnosis is briefly reviewed. The therapeutics of uterine pathologies is debated in relation with the pathophysiology of the uterine involution and with the rational of the traditional and new concepts of the treatment of the postpartum uterine pathologies.
相似文献974.
Denicourt M Gradel D Martineau GP 《The Canadian veterinary journal. La revue veterinaire canadienne》1987,28(6):346-354
Environment is of primary importance to animal health and development. Ventilation is a problem in establishing an adequate environment, particularly in swine housing. In order for veterinarians to deal with this problem, a fundamental understanding of the building is necessary. The present article describes a clinical approach to ventilation diagnosis problems in the piggery. 相似文献
975.
976.
977.
A case of selenium poisoning was suspected following the administration of 325 micromol selenium a day as sodium selenate (25 mg Se) for five consecutive days. The main signs were confined to changes in the integument which were loss of hair from the mane and tail, disintegration of the skin of the anus, lips, prepuce and scrotum, and separation of the hooves from the coronary corium. Periodic analyses of blood, hair and hoof parings from the sole correlated strongly with blood and identified horn and hair as important additional routes of excretion. 相似文献
978.
A single, artificially-induced fly-strike with Lucilia sericata larvae was associated with a rapid (decline in food intake in sheep, with a consequent reduction in liveweight. Loss of weight ranged from 0.5 to 5.5 kg over four to six days and recovery to pre-infestation liveweight took three to 36 days. Pair-fed, uninfested partners of these sheep also showed a reduction in liveweight, whereas uninfested sheep in some experiments fed ad libitum showed either little change or a gain in liveweight over the same period. In general, maggot infested sheep took less time to regain weight than did their pair-fed partners although the weight lost as a proportion of initial weight was similar in both groups. Loss of appetite alone would appear to account for these events. 相似文献
979.
Hampson DJ 《New Zealand veterinary journal》1987,35(3):35-36
Pigs weaned for five days had caecal contents with significantly lower osmolalities than those of unweaned animals of the same age. Supplementation of a standard weaning diet with therapeutic levels of oxytetracycline to suppress the normal large intestinal microbial flora did not significantly further reduce osmolarity of caecal contents after weaning. This observation suggests that microbial activity in the large intestine may not be sufficiently developed by five days after weaning to have a major influence on absorptive processes at that site. Incomplete development of the large intestinal microflora may be one more factor which acts to predispose the young pig to diarrhoea after weaning. 相似文献
980.
Canfield PJ Watson AD Ratcliffe RC 《Veterinary clinical pathology / American Society for Veterinary Clinical Pathology》1987,16(1):21-28
Dyserythropoiesis characterized by enhanced intramedullary destruction, pathologic sideroblasts and siderocytes, and hemoglobin crystallization was detected in a female Cocker Spaniel presented for poor exercise tolerance. Examination of peripheral blood revealed intraerythrocytic crystals, granulation of erythrocytes, nucleated erythroid cells, reticulocytosis and marked variation in erythrocyte morphology in the absence of anemia. Bone marrow examination revealed sideroblasts, a low M:E ratio and evidence of enhanced intramedullary destruction of erythroid cells. Electron microscopy of peripheral blood and bone marrow confirmed pathologic mitochondrial iron accumulation in erythroid cells and the presence of intraerythrocytic hemoglobin crystals. A cause for the hematologic changes was not identified. After the animal became clinically normal, siderocytes disappeared from peripheral blood but intraerythrocytic crystals and reticulocytosis persisted. 相似文献