全文获取类型
收费全文 | 5072篇 |
免费 | 489篇 |
专业分类
林业 | 2篇 |
农学 | 3篇 |
基础科学 | 2篇 |
9篇 | |
综合类 | 6篇 |
农作物 | 2篇 |
水产渔业 | 4篇 |
畜牧兽医 | 5521篇 |
园艺 | 2篇 |
植物保护 | 10篇 |
出版年
2024年 | 6篇 |
2023年 | 93篇 |
2022年 | 1篇 |
2021年 | 3篇 |
2020年 | 170篇 |
2019年 | 7篇 |
2018年 | 123篇 |
2017年 | 139篇 |
2016年 | 89篇 |
2015年 | 140篇 |
2014年 | 226篇 |
2013年 | 246篇 |
2012年 | 188篇 |
2011年 | 223篇 |
2010年 | 172篇 |
2009年 | 249篇 |
2008年 | 157篇 |
2007年 | 100篇 |
2006年 | 84篇 |
2005年 | 86篇 |
2004年 | 145篇 |
2003年 | 147篇 |
2002年 | 166篇 |
2001年 | 159篇 |
2000年 | 122篇 |
1999年 | 118篇 |
1998年 | 171篇 |
1997年 | 180篇 |
1996年 | 158篇 |
1995年 | 159篇 |
1994年 | 138篇 |
1993年 | 150篇 |
1992年 | 175篇 |
1991年 | 147篇 |
1990年 | 186篇 |
1989年 | 131篇 |
1988年 | 113篇 |
1987年 | 145篇 |
1986年 | 54篇 |
1985年 | 78篇 |
1984年 | 82篇 |
1983年 | 79篇 |
1982年 | 35篇 |
1981年 | 11篇 |
1980年 | 5篇 |
1977年 | 3篇 |
1962年 | 1篇 |
1961年 | 1篇 |
排序方式: 共有5561条查询结果,搜索用时 843 毫秒
161.
162.
163.
164.
165.
166.
杨智满 《国外畜牧学(猪与禽)》2007,27(3):42-43,70
毫无疑问,应激是影响肉食品动物生产一个重要因素。处于应激的动物对疾病更敏感,生产低质量的肉类产品,生长速度和生产性能很可能达不到其正常的指标。避免非必要的应激并不是仅仅对动物福利有利:它也能确保养猪场取得良好的商业利润。 相似文献
167.
Landscape Ecology - The response of rare species to human land use is poorly known because rarity is difficult to study; however, it is also important because rare species compose most of... 相似文献
168.
169.
A. Raoofi DVM DVSc M.Gh. Nadalian DVM D. Sharifi MVSc PhD 《Journal of Equine Veterinary Science》1996,16(12):574-575
A 25-year-old mule was showing signs of colic. Clinical examination revealed acute pain, bilateral abdominal distention, stretching out and standing in this position. Rectal palpation revealed a hardened mass in the ventral region of the pelvic inlet. Surgical intervention was accomplished and faecaliths removed by colotomy. The mule died unexpectedly and postmortem examination revealed sand masses within the right ventral and right dorsal colon which caused obstruction of the intestinal tract in sternal and diaphragmatic flexures, respectively. This appears to be the first report of sand colic in a mule in Iran. 相似文献
170.
T.L. Blanchard DVM MS Dip ACT J.B. Jorgensen BS D.D. Varner DVM MS Dip ACT D.W. Forrest MS PhD J.W. Evans MS PhD 《Journal of Equine Veterinary Science》1996,16(5):195-201
To investigate effects of thermally-induced testicular degeneration on hormonal and seminal parameters in stallions, the scrotum was insulated for 36 hours in two mature (5-year-old mixed breed and 11-year-old Throughbred) stallions. Semen was collected daily for 10 days (DSO) prior to, and at intervals after, scrotal insulation. When DSO determinations were not being made, semen was collected 3 times weekly. Jugular blood samples were collected at 15-minute intervals for 6 hours from each stallion prior to, and at intervals after, scrotal insulation. A mouse interstitial cell testosterone assay was modified to quantify biologic activity of equine luteinizing hormone (BLH) in plasma samples. Immunoactive luteinizing hormone (ILH) and testosterone (T) concentrations were determined in plasma samples by routine RIA procedures. Percentages of progressively motile and morphologically normal spermatozoa began to decrease by 1 to 2 weeks postinsulation, reached nadir values at 3 to 3-1/2 weeks postinsulation, and returned to preinsulation values by 7 weeks postinsulation. Total number of spermatozoa and total number of progressively motile, morphologically normal spermatozoa in ejaculates at DSO returned to normal by 8 weeks postinsulation in stallion 2 and 12 weeks postinsulation in stallion 1. Concentrations of BLH and ILH increased, and while T concentrations decreased, immediately postinsulation. The increase in ILH concentrations was greater than the increase in BLH concentrations, resulting in a decrease in the BLH:ILH (B:I) ratio. Following the peak in LH secretion immediately postinsulation, LH concentrations gradually decreased while T concentrations increased. The B:I ratio was elevated from 1 to 13 weeks postinsulation compared to immediately postinsulation. In addition to changes in spermatozoal quality in ejaculates, stallion response to scrotal insulation included increased secretion of luteinizing hormone and impaired Leydig cell function (as determined by reduced testosterone concentration in circulating plasma). The proportion of biologically active LH secreted in response to thermal testicular injury increased during the recovery phase. 相似文献