全文获取类型
收费全文 | 3707篇 |
免费 | 90篇 |
国内免费 | 1篇 |
专业分类
林业 | 2265篇 |
农学 | 27篇 |
基础科学 | 7篇 |
186篇 | |
综合类 | 15篇 |
农作物 | 176篇 |
水产渔业 | 54篇 |
畜牧兽医 | 852篇 |
园艺 | 42篇 |
植物保护 | 174篇 |
出版年
2014年 | 34篇 |
2013年 | 112篇 |
2012年 | 31篇 |
2011年 | 32篇 |
2010年 | 44篇 |
2009年 | 55篇 |
2008年 | 37篇 |
2006年 | 35篇 |
2005年 | 81篇 |
2004年 | 81篇 |
2003年 | 56篇 |
2002年 | 49篇 |
2001年 | 35篇 |
1997年 | 49篇 |
1996年 | 77篇 |
1995年 | 52篇 |
1994年 | 55篇 |
1993年 | 65篇 |
1992年 | 72篇 |
1991年 | 53篇 |
1990年 | 41篇 |
1989年 | 37篇 |
1988年 | 43篇 |
1987年 | 40篇 |
1986年 | 49篇 |
1985年 | 32篇 |
1984年 | 49篇 |
1983年 | 51篇 |
1982年 | 60篇 |
1981年 | 106篇 |
1980年 | 52篇 |
1979年 | 81篇 |
1978年 | 43篇 |
1954年 | 36篇 |
1953年 | 61篇 |
1938年 | 58篇 |
1937年 | 47篇 |
1936年 | 49篇 |
1935年 | 49篇 |
1934年 | 48篇 |
1933年 | 53篇 |
1932年 | 48篇 |
1931年 | 38篇 |
1930年 | 37篇 |
1929年 | 31篇 |
1928年 | 33篇 |
1927年 | 44篇 |
1926年 | 74篇 |
1925年 | 55篇 |
1898年 | 33篇 |
排序方式: 共有3798条查询结果,搜索用时 15 毫秒
71.
72.
73.
Hanna Werhahn Engel F. HesselHerman F.A. Van den Weghe Prof Dr Ir 《Journal of Equine Veterinary Science》2012,32(1):45-52
Although welfare of animals has become more important, housing horses in systems that limit natural behavior patterns is still widespread. Single stalls are the predominant housing system in Germany, especially for competition horses. Free exercise on fields or paddocks helps to improve welfare for the animals, but allowing it is not taken for granted by many horse keepers. In the present study, three common management practices were investigated with regard to their effect on the behavior of six competition horses housed in single stalls: 2-hour turnout after training in groups of two horses (group turnout [GT]), solitary turnout (ST) after training for 2 hours, and no turnout (NT) in addition to training. The aim of the study was to determine the differences in the horses’ behavior during turnout, training, and in the stable caused by the treatments. This article focuses on the behavior and activity patterns during turnout. The horses’ behavior was observed directly by the scan sampling method (5-minute interval), and the distance covered during turnout was measured by global positioning system devices. During turnout, the horses spent most of the time eating. After 1 hour of being turned out, eating decreased, and occupation, locomotion, and social interaction increased. When turnout was allowed in groups (GT), the horses spent more time in social interactions and less time walking and trotting than in ST. Therefore, they also covered a greater distance in ST than in GT. The distance covered in ST also showed a greater deviation both within and between days compared with GT. 相似文献
74.
75.
76.
Extract “Yellow fat disease” is a disease of certain species of animals, characterized macroscopically by greyish-yellow discoloration and microscopically by inflammatory and degenerative reactions and the occurrence of a characteristic acid-fast pigment in the fat tissue. The terms “nonsuppurative panniculitis”, “pansteatitis”, or “yellow ear disease (chinchilla)” are synonyms. 相似文献
77.
Lorrie Gaschen D.V.M. Johann Lang Dr. med. vet. Hansjuerg Haeni Dr. med. vet. 《Veterinary radiology & ultrasound》1995,36(6):509-516
The herniation of intervertebral disc material into the vertebral body, known as Schmorl's nodes, is a well described disease process in man. Schmorl's nodes have not until now been described in the dog. This paper describes intravertebral disc herniation in the dog based on five patients taken from a retrospective study of dogs suspected of having cauda equina syndrome. The significance of intravertebral disc herniation in the dog at this time is that they indicate a disturbance in the vertebral endplate, they present definite radiographic signs, should be considered in patients with ostecohondrosis, and remain a possibls etiology for fibrocartilaginous emboli. Back pain is a common sign in people when Schmorl's nodes were the only pathologic findings. The common signs of palpatory pain in the lumbosacral region of the dogs in this report is noted but cannot be directly correlated at this time to the intravertebral disc herniation; however, it is suspected in two of the cases. 相似文献
78.
Gultekin Atalan Dr. Vet. Med. Frances J. Barr MA VetMB PhD MRCVS Peter E. Holt BVMS PhD CBiol MIBiol FRCVS 《Veterinary radiology & ultrasound》1999,40(4):408-412
The purposes of this study were to: 1) compare prostatic dimensions measured on radiographic and ultrasonographic images and 2) compare a subjective radiographic assessment of prostate size with a previously-described objective method. Thirty-four male dogs undergoing investigation of prostatic disorders were used. Prostate length and depth were measured from ultrasonographic and radiographic images. A subjective assessment of prostate size ('small', 'normal', or 'enlarged') was made in 29 animals by one of the authors who was unaware of radiographic or ultrasonographic measurements. In addition, the distance from sacral promontory to the pubic brim was also measured. A prostate length or depth of >70% of this distance was defined as 'enlarged' and <70% as 'normal'. After the effects of magnification on radiographic measurements were eliminated, there were no significant differences between prostatic length measured by the two methods. However, a significant difference was obtained between prostatic depth measurements. The subjective assessment agreed with a previously described objective assessment of prostatic size in 21/29 dogs for prostate length but in only 12/29 for depth. Prostatic length varied from 46.6 to 116.4% (mean 75.7%) of the distance from the pubic brim to the sacral promontory. Prostatic depth varied from 33.0% to 94.6% (mean 59.7%) of the same distance. It is recommended that prostate length, rather than depth, be used when evaluating prostate size from lateral abdominal radiographs. 相似文献
79.
80.