全文获取类型
收费全文 | 136249篇 |
免费 | 10394篇 |
国内免费 | 3217篇 |
专业分类
林业 | 6798篇 |
农学 | 4901篇 |
基础科学 | 2288篇 |
17509篇 | |
综合类 | 30602篇 |
农作物 | 5946篇 |
水产渔业 | 8347篇 |
畜牧兽医 | 60774篇 |
园艺 | 3509篇 |
植物保护 | 9186篇 |
出版年
2023年 | 1108篇 |
2022年 | 2187篇 |
2021年 | 2514篇 |
2020年 | 2675篇 |
2019年 | 3220篇 |
2018年 | 3406篇 |
2017年 | 4040篇 |
2016年 | 3525篇 |
2015年 | 3634篇 |
2014年 | 4029篇 |
2013年 | 6711篇 |
2012年 | 6282篇 |
2011年 | 6852篇 |
2010年 | 5301篇 |
2009年 | 4847篇 |
2008年 | 6051篇 |
2007年 | 5476篇 |
2006年 | 4887篇 |
2005年 | 4381篇 |
2004年 | 3638篇 |
2003年 | 3311篇 |
2002年 | 3088篇 |
2001年 | 3554篇 |
2000年 | 3662篇 |
1999年 | 2586篇 |
1998年 | 940篇 |
1997年 | 933篇 |
1995年 | 1104篇 |
1994年 | 957篇 |
1992年 | 2063篇 |
1991年 | 2178篇 |
1990年 | 2028篇 |
1989年 | 2036篇 |
1988年 | 1907篇 |
1987年 | 2005篇 |
1986年 | 2055篇 |
1985年 | 1959篇 |
1984年 | 1547篇 |
1983年 | 1364篇 |
1979年 | 1427篇 |
1978年 | 1166篇 |
1977年 | 1007篇 |
1976年 | 959篇 |
1975年 | 1005篇 |
1974年 | 1323篇 |
1973年 | 1357篇 |
1972年 | 1274篇 |
1971年 | 1187篇 |
1970年 | 1117篇 |
1969年 | 996篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
Hege Kippenes DVM Patrick R. Gavin DVM PhD Susan L. Kraft DVM PhD Ronald D. Sande DVM MS PhD Russell L. Tucker DVM 《Veterinary radiology & ultrasound》2001,42(2):130-133
The pituitary gland was measured from transverse magnetic resonance T1-weighted images after Gadolinium administration in 96 dogs weighing from 13 to 45 kg. The measurements were done by hand with calipers. The mean (+/- standard deviation) pituitary gland height was 5.1 mm (+/-0.9 mm). The mean width was 6.4 mm (+/- 1.1 mm). The correlation coefficient between pituitary and brain measurements, between pituitary measurement and body weight, and brain measurements and body weight was 0.0 to 0.3. A hyperintense region was present on T1-weighted images in the center of the pituitary gland in 64% of the dogs. At necropsy the pituitary glands were grossly and histologically normal. No pituitary gland measurements were performed at necropsy. 相似文献
62.
比格犬人工感染埃立克体病的临床研究 总被引:2,自引:0,他引:2
为了表述比格犬感染埃立克体(Ehrlichia)后的临床表现,用已确证为E.platys和E.canis混合感染的犬血对5条比格犬进行了人工感染,并对临床和血液学变化进行了观察。埃立克体病的潜伏期为6-29天,其后的临床表现为急性发热、眼结膜苍白、厌食、精神沉郁、体重严重减轻、腹泻带血、多处有淤血斑点出现、6-45天内全部死亡。血液学变化显示血红蛋白和白细胞明显减少(P<0.01,P<0.05)。由此可见,比格犬对2种埃立克体(E.canis和E.platys)混合感染的性很高,严重的临床表现与美国学者普遍认为的亚临床状态相左,这可能是中国Gzh981株(E.platys)和Gzh982株(E.casnis)与国外株在毒力上的差异所致。 相似文献
63.
64.
65.
Various combinations of reoviruses and coccidia were studied to see if interactions would occur. Two reoviruses were used: virus 2035, a moderate to low pathogen, and virus 2177, a nonpathogen. Coccidia used were Eimeria acervulina, E. mitis, and E. maxima at dosages of 10(3) or 10(4) sporulated oocysts/chick and E. brunetti at 10(4) sporulated oocysts/chick. In Hubbard-Hubbard cockerels, a combination of virus 2035 and E. acervulina (10(4) oocysts/chick) or E. maxima (10(3) oocysts/chick) significantly (P less than or equal to 0.05) increased the frequency of stunting (% of chicks with body weight less than 80% of controls) and further depressed weight gain over that seen with either virus or coccidia alone. Conversely, virus 2177 ameliorated the same effects in Shaver-Arbor Acre cockerels given 10(4) oocysts/chick of E. mitis or E. maxima. The interaction could not be attributed to changes in the degree of coccidial infection based on oocyst production. Reovirus did not generally change the effect of coccidia on levels of plasma pigment and plasma protein. In Hubbard-Hubbard cockerels, coccidia-induced effects were not ameliorated by virus 2177, suggesting that breed difference in interaction can be expected. 相似文献
66.
G. L. RICHARDSON dvm T. R. O'BRIEN dvm PhD Diplomateacvr J. R. PASCOE bvsc D. M. MEAGHER dvm PhD Dipiomateacvs 《Veterinary surgery : VS》1986,15(2):156-160
The medical records of 38 horses with puncture wounds of the navicular bursa were reviewed. Only 12 horses had a satisfactory outcome (breeding or riding). Of the remaining 26 horses, 19 were euthanized, five were sold due to persistent severe lameness, one died, and one was lost to long-term follow-up. Different combinations of conservative management prior to surgical debridement and drainage of the navicular bursa were unsuccessful in resolving the condition. Horses that were treated surgically within 1 week of the injury and had a hind leg affected had the best chance of a satisfactory outcome. Additional wound debridement was necessary in 15 horses after initial surgical treatment. The most common complications encountered were navicular bone osteomyelitis and sepsis of the deep digital flexor tendon. Thirteen of 14 horses that had rupture of the deep digital flexor tendon and subluxation of the distal interphalangeal joint had an unsatisfactory outcome. One mare subsequently developed ankylosis of the distal interphalangeal joint and was a useful brood mare. Two horses that had biaxial palmar digital neurectomy because of persistent lameness were later euthanized because of navicular bone fracture and rupture of the deep digital flexor tendon. Results from limited numbers of bacterial cultures and antibiotic sensitivities suggest that penicillin and an aminoglycoside antibiotic should be used as initial antibiotic therapy. Immediate surgical debridement and appropriate antibiotic treatment are recommended as the minimum therapy for penetrating wounds of the navicular bursa in horses. 相似文献
67.
马明慧 《农业环境科学学报》2004,(2)
68.
Thirteen mixed-breed beef bulls, 1 to 4 years old, were used to determine the effect of live and dead filarial nematodes, Setaria labiatopapillosa, placed in the vaginal cavity of the testes. When dead worms were used, granulomatous lesions developed on the tunica vaginalis parietalis in 7 of 8 testes. The lesions were similar to those seen in some clinical cases of periorchitis. Similar lesions developed in 5 of 6 testes after live worms were implanted in the vaginal cavity of the testes and tetramisole (8 mg/kg) was injected subcutaneously 6 days after implantation. When live worms were implanted and tetramisole was not given, lesions developed in 3 of 6 testes. It was concluded that the granulomatous reaction was a local response to dead or killed S labiatopapillosa. 相似文献
69.
笔者对苹果施用沼肥后的生物性状进行了长达4a的对比试验研究,采取对比设计法,在叶、枝、花、果等器官的相关指标取得了极为明显的效果,在果业生产上有极好的推广价值。 相似文献
70.