全文获取类型
收费全文 | 1255篇 |
免费 | 69篇 |
国内免费 | 1篇 |
专业分类
林业 | 130篇 |
农学 | 20篇 |
基础科学 | 19篇 |
185篇 | |
综合类 | 197篇 |
农作物 | 24篇 |
水产渔业 | 35篇 |
畜牧兽医 | 633篇 |
园艺 | 9篇 |
植物保护 | 73篇 |
出版年
2021年 | 11篇 |
2019年 | 19篇 |
2018年 | 20篇 |
2017年 | 19篇 |
2016年 | 21篇 |
2015年 | 20篇 |
2014年 | 22篇 |
2013年 | 48篇 |
2012年 | 34篇 |
2011年 | 63篇 |
2010年 | 33篇 |
2009年 | 24篇 |
2008年 | 46篇 |
2007年 | 47篇 |
2006年 | 50篇 |
2005年 | 40篇 |
2004年 | 37篇 |
2003年 | 35篇 |
2002年 | 26篇 |
2001年 | 33篇 |
2000年 | 27篇 |
1999年 | 28篇 |
1997年 | 9篇 |
1995年 | 13篇 |
1994年 | 9篇 |
1992年 | 17篇 |
1991年 | 32篇 |
1990年 | 23篇 |
1989年 | 15篇 |
1988年 | 19篇 |
1987年 | 22篇 |
1986年 | 15篇 |
1985年 | 28篇 |
1984年 | 19篇 |
1983年 | 17篇 |
1982年 | 12篇 |
1981年 | 13篇 |
1980年 | 10篇 |
1979年 | 17篇 |
1978年 | 16篇 |
1977年 | 19篇 |
1974年 | 12篇 |
1973年 | 31篇 |
1972年 | 21篇 |
1971年 | 16篇 |
1970年 | 13篇 |
1969年 | 11篇 |
1967年 | 14篇 |
1966年 | 18篇 |
1930年 | 10篇 |
排序方式: 共有1325条查询结果,搜索用时 343 毫秒
1.
The study describes plumage modifications and specific feather malformations, as related to the domestication process of different poultry species. The modifications include naked necks, leg feathering, frizzle feathering, silky feathering, fat quills, and feather abnormalities caused by behavioural hypertrophies. Most of these plumage modifications correspond to the breed standard for exhibition poultry fancy. However, they impair the normal function of these animals. The negative influences comprise disorders in social behaviour, loss of typical plumage functions and disabilities of normal mobility, as well as genetic defects and pathogenic predispositions. 相似文献
2.
Red foxes ( Vulpes vulpes ) are a major pest species in Europe and Australia. Traditional methods of control such as hunting or poisoning are no longer sufficient or feasible. As with domestic dogs and cats, prolactin (PRL) in the vixen is an essential luteotropin during the second half of gestation. Hence, PRL inhibitors such as cabergoline have been used to induce abortions. Eighteen mated silver fox vixens (three groups of six foxes each) were treated orally with a placebo of paraffin oil (I), or with 15 μ g/kg cabergoline in feed once (II) or twice (III), on day 30 (I and II) or days 30 and 32 (III) post-coitum. Blood samples were taken prior to and after treatments and concentrations of PRL and progesterone (P4 ) were determined. Normal parturitions were observed in five of six, five of six and two of six vixens in groups I, II and III, respectively. In group III plasma concentrations of PRL and P4 decreased significantly but only temporarily. This drop in hormone concentrations was more pronounced in the vixens that did not carry to term. In conclusion, doses in excess of 15 μ g/kg of cabergoline are likely to prevent the development of fetuses to term in pregnant vixens. 相似文献
3.
Expression of β2-integrin on monocytes and blood polymorphonuclear leukocytes in the periparturient period in dairy cows 下载免费PDF全文
Araceli Diez-Fraile Luc Duchateau Evelyne Meyer Christian Burvenich 《Canadian journal of veterinary research》2003,67(3):235-238
The hypothesis that an altered expression of CD11/CD18 on bovine circulating monocytes, polymorphonuclear leukocytes (PMN), or both, contributes to an increased mastitis susceptibility in periparturient cows was tested. Expression of CD18 and CD11a, -b, -c on bovine monocytes and PMN were assessed in 8 Friesian-Holstein cows by flow cytometry from 2 wk before calving to 5 wk after calving. Minor changes in adhesion molecule expression levels were detected throughout the experimental period. Compared with PMN, monocytes exhibited an expression level that was similar for CD18, higher for CD11a and CD11c, but lower for CD11b. Differences in density may reflect the relative importance of these adhesion molecules on both leukocyte types. In this study, the decreased number of milk resident macrophages and PMN observed during the periparturient period could not be attributed to changes of CD11/CD18 levels on circulating leukocytes. 相似文献
4.
5.
6.
7.
Lea Middendorf Marion Schmicke Kristian Düngelhoef Erwin Sieverding Heinrich Windhaus Dieter Mischok Dimitri Radko Christian Visscher 《Journal of animal physiology and animal nutrition》2021,105(Z2):70-78
The hepatic lipidosis (HL) in fattening turkeys is a disease has been known for a long time, but the cause and pathogenesis is still not clarified. A recent study reported unexplained high levels of iron in liver tissue of fattening turkeys suffering from HL. In this study, the iron status, possible infectious or inflammatory influences in form of an acute phase reaction and the analysis of fatty acid pattern in liver tissue of turkeys affected by HL were examined. Three cases of HL on three different fattening turkey farms were investigated during the outbreak of the disease. Clinically affected and non-affected animals were subjected to a pathological examination, where the diagnosis HL or non-affected was made. In total, 70 birds were examined (40 with HL, 30 without HL) and blood and liver samples were taken. Additionally, samples from 15 slaughtered birds were taken as a further control group. In liver tissue, the iron content and the content of long-chain fatty acids were determined; in blood samples, ferritin and transferrin were measured. The iron content in liver tissue was more than three times higher for animals with HL than among non-affected animals and the control group. The transferrin levels were lowest for animals with HL, highest in the control group and in between for non-affected animals. The fatty acid pattern in liver tissue of affected animals indicated a shift from polyunsaturated fatty acids to saturated fatty acids and monounsaturated fatty acids compared to the control group and the non-affected animals. Overall, the non-affected animals of a flock affected by HL were similar to the healthy animals of the abattoir. The low acute phase protein levels for animals with HL together with high iron contents could indicate a previous malnutrition/starvation period and/or severe liver damage for those animals suffering from HL. 相似文献
8.
9.
10.
Long‐term follow‐up of renal function assessing serum cystatin C in dogs with diabetes mellitus or hyperadrenocorticism 下载免费PDF全文