全文获取类型
收费全文 | 1052篇 |
免费 | 53篇 |
专业分类
林业 | 36篇 |
农学 | 35篇 |
基础科学 | 21篇 |
148篇 | |
综合类 | 88篇 |
农作物 | 37篇 |
水产渔业 | 72篇 |
畜牧兽医 | 595篇 |
园艺 | 11篇 |
植物保护 | 62篇 |
出版年
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 25篇 |
2018年 | 13篇 |
2017年 | 13篇 |
2016年 | 20篇 |
2015年 | 18篇 |
2014年 | 19篇 |
2013年 | 54篇 |
2012年 | 28篇 |
2011年 | 47篇 |
2010年 | 26篇 |
2009年 | 32篇 |
2008年 | 55篇 |
2007年 | 58篇 |
2006年 | 38篇 |
2005年 | 44篇 |
2004年 | 38篇 |
2003年 | 32篇 |
2002年 | 39篇 |
2001年 | 30篇 |
2000年 | 30篇 |
1999年 | 33篇 |
1998年 | 13篇 |
1997年 | 15篇 |
1996年 | 9篇 |
1995年 | 13篇 |
1994年 | 10篇 |
1993年 | 12篇 |
1992年 | 21篇 |
1991年 | 19篇 |
1990年 | 11篇 |
1989年 | 16篇 |
1988年 | 16篇 |
1987年 | 12篇 |
1986年 | 11篇 |
1985年 | 19篇 |
1984年 | 10篇 |
1983年 | 11篇 |
1982年 | 10篇 |
1981年 | 7篇 |
1979年 | 12篇 |
1978年 | 10篇 |
1977年 | 7篇 |
1975年 | 14篇 |
1974年 | 12篇 |
1973年 | 10篇 |
1971年 | 11篇 |
1969年 | 11篇 |
1967年 | 8篇 |
排序方式: 共有1105条查询结果,搜索用时 349 毫秒
131.
Kirk RK Svensmark B Ellegaard LP Jensen HE 《Journal of veterinary medicine. A, Physiology, pathology, clinical medicine》2005,52(8):423-428
Given the increase in sow mortality in Danish pig herds over the last 10 years, we have investigated the causes of spontaneous death and killing of sows, especially those due to locomotive disorders. A total of 265 culled sows (93 spontaneously dead sows and 172 killed sows) from 10 different herds were sent for complete necropsy, and grouped according to primary diagnoses. From 35 of these sows, tissue for histological evaluation and samples for bacteriological cultivation were also collected, and secondary diagnoses and body condition were recorded. The main causes for killing were related to the locomotive system (72%), arthritis (24%) and fractures (16%) being the most frequent lesions. The main causes of spontaneous death were related to the gastrointestinal system and spleen (45%) and the reproductive system (24%). Arthrosis was a secondary diagnosis in 88% of the killed sows and in 92.5% of the spontaneously dead sows. Arcanobacterium pyogenes was the main cause of arthritis. The killed sows had significantly lower body condition compared with spontaneously dead sows. The first two parities and the time around farrowing were associated with the highest mortality in both groups. Hopefully, these observations can guide breeding units attempting to monitor, control and reduce sow mortality. 相似文献
132.
133.
A bullet shaped virus presumably belonging to the Rhabdoviridae was isolated from a pool of 7 cods (Gadus morhua) with the ulcus-syndrome. This virus measured 55 x 175 nm. The virus caused CPE in PS (pike sarcoma) cells, but not in a number of other cell lines. From the same pool another virus was isolated in EPC (epithelia carp) cells. This virus was an icosahedron of 145 nm and most likely to be placed in the family Iridoviridae. Electronmicroscopic examination of papules from another 13 cods with the ulcus-syndrome failed to reveal any virus. Attempts to isolate virus from 33 individual cases of the ulcus-syndrome were successful in one single case only. The two viruses have not consistently been isolated from cods with the ulcus symdrome, but on the other hand they have never been isolated from cods without the ulcus-syndrome. 相似文献
134.
135.
136.
137.
R Jensen A C Pier C C Kaltenbach W J Murdoch V M Becerra K W Mills J L Robinson 《American journal of veterinary research》1989,50(2):285-289
Premature calving, typified by early expulsion (17 to 43 days) of weak or dead calves and accompanied by retained placentas, was induced in 8 of 9 pregnant cows fed a mixture of Ponderosa pine needles and alfalfa hay. Five control cows of comparable gestation age fed only alfalfa hay maintained normal pregnancies until they were euthanatized at the time the pine needle-treated cows were producing premature calves. Serum specimens from all cows were assayed for progesterone concentration and ovaries and placentomes were examined for histopathologic changes. There were no bacterial, fungal, chlamydial, or viral agents determined to be associated with the premature births. Serum progesterone concentration in the treated cows decreased progressively and were 0.4 to 1.5 ng/ml at the time of premature calving. Histopathologic changes were evident in the placenta and corpora lutea of treated cows only. The number of binucleate trophoblastic giant cells in placentomes was less than normal and the number of necrotic luteal cells in corpora lutea was greater than normal. 相似文献
138.
139.
J. Koch A. L. Jensen H. D. Pedersen P. S. Leifsson† 《The Journal of small animal practice》1994,35(1):28-31
This case report describes the clinical, imaging, clinical pathology and necropsy findings in a five-year-old male Border collie with low output cardiac failure. The heart was enlarged by infiltrative lymphosarcoma. 相似文献
140.
In a swine production herd dwarfs with extremely short limbs were observed in 3 litters sired by the same boar. Clinical, radiographical, and pathologic-anatomical examinations, showed the affected individuals to be chondrodysplastic dwarfs. Such dwarfism has not been reported previously in pigs. An inbreeding experiment conducted with a dwarf gilt and related boars indicated that the dwarfism was hereditary with a simple autosomal recessive inheritance. 相似文献