全文获取类型
收费全文 | 252篇 |
免费 | 16篇 |
专业分类
林业 | 7篇 |
农学 | 4篇 |
基础科学 | 1篇 |
35篇 | |
综合类 | 75篇 |
农作物 | 10篇 |
水产渔业 | 10篇 |
畜牧兽医 | 115篇 |
园艺 | 4篇 |
植物保护 | 7篇 |
出版年
2022年 | 2篇 |
2021年 | 6篇 |
2020年 | 8篇 |
2019年 | 2篇 |
2018年 | 3篇 |
2017年 | 3篇 |
2016年 | 6篇 |
2015年 | 4篇 |
2014年 | 11篇 |
2013年 | 6篇 |
2012年 | 13篇 |
2011年 | 13篇 |
2010年 | 7篇 |
2009年 | 2篇 |
2008年 | 6篇 |
2007年 | 16篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 14篇 |
2003年 | 13篇 |
2002年 | 14篇 |
2001年 | 7篇 |
2000年 | 3篇 |
1999年 | 6篇 |
1997年 | 3篇 |
1996年 | 2篇 |
1994年 | 2篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1987年 | 6篇 |
1986年 | 4篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1969年 | 2篇 |
1967年 | 3篇 |
1963年 | 1篇 |
1955年 | 1篇 |
1947年 | 1篇 |
1944年 | 1篇 |
1941年 | 1篇 |
1937年 | 1篇 |
1930年 | 1篇 |
1929年 | 1篇 |
1928年 | 1篇 |
1916年 | 2篇 |
1914年 | 1篇 |
1913年 | 1篇 |
1911年 | 1篇 |
排序方式: 共有268条查询结果,搜索用时 15 毫秒
1.
2.
Initial analytic quality assessment and method comparison of an immunoassay for adrenocorticotropic hormone measurement in equine samples 下载免费PDF全文
3.
[目的]新鲜精液在离开生殖腺后存活时间很短.相关研究表明副睾液为精子的存活提供了特殊的环境.试验探讨和研究牛附睾精子在体外模拟附睾液中的存活试验的各因素的影响.[方法]试验对公牛附睾头部和尾部的摩尔渗透压和蛋白质浓度进行了分析,牛附睾尾部精子在不同蛋白浓度的CEP-2溶液中,在4℃条件下孵育120h.每24h做一次精子活力检测.[结果]5 d后精子活力仍然超过60;.附睾头、尾部的渗透压分别为(287.0±13.7)mOsm和(310.8±17.0)mOsm.蛋白浓度分别为(37.43±12.55)mg/mL和(50.58±11.08)mg/mL.[结论]附睾尾精子在蛋白浓度为40mg/mL,渗透压为345 mOsm时,精子存活率最高. 相似文献
4.
DNA methylation is an epigenetic modification in which a methyl group is added usually to the fifth carbon position of a cytosine residue. Dysregulation of this process is an important molecular event which has been shown to be associated with neoplastic transformation and tumour progression in humans and mice. Features of methylation dysregulation in many different types of neoplasms include general genomic hypomethylation, focal hypermethylation, and altered expression of genes which encode a series of DNA (cytosine-5) methyltransferases. Interestingly, many types of neoplasia that are recognised in humans also develop spontaneously in the dog. By comparing the restriction patterns of MspI and HpaII, this study demonstrates that as in human, genomic hypomethylation is a feature of neoplastic cells in the majority of canine lymphoma cases and approximately one-third of canine leukemia cases confirming that dysregulation of the DNA methylating machinery is implicated in malignant transformation of lymphoid cells in some dogs. 相似文献
5.
6.
7.
AIM: To describe the gross and histological lesions of a neurological disease in Borderdale sheep characterised clinically by blindness and circling, as a basis to its classification. METHODS: Formalin-fixed tissues were processed into paraffin wax and epoxy resin for light and electron microscopy of variously stained sections. RESULTS: Lesions were those of a lysosomal storage disease with severe neurodegeneration of the cerebral cortex. The staining reactions, autofluorescence and ultrastructure of storage material allowed the diagnosis of neuronal ceroid-lipofuscinosis associated with the accumulation of subunit-c of mitochondrial ATP synthase. CONCLUSIONS: The severity of neurodegeneration and minor differences in the ultrastructure of storage material implied that this was a different disease from other forms of ovine ceroid-lipofuscinosis that accumulate subunit-c of mitochondrial ATP synthase. An autosomal recessive mode of inheritance is considered probable. Although of only minor economic importance, this disease may be important to research into the group of ceroid-lipofuscinoses as a whole. 相似文献
8.
9.
Martin Furr Mary Kay Tinker Lucy Edens 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1997,11(3):183-188
This study was conducted to develop an equation for the prediction of outcome in neonatal foals undergoing treatment in an intensive care unit (ICU). Fifty-three physical examination, historical, and clinicopathologic variables were analyzed from the records of 99 neonatal foals (<14 days of age) treated in the neonatal ICU of the Equine Medical Center. The outcome was recorded and the results were categorized into either surviving or nonsurviving groups. The mean values for the 2 groups were compared, and variables that differed significantly between the two groups were retained and used to construct a logistic regression equation. Retained variables were heart rate, temperature, and neutron phil count. The predictive equation then was tested prospectively in 2 additional groups of foals from 2 separate ICUs. The predicted outcome was compared to the actual outcome, and performance variables were calculated. Sensitivity (.83), specificity (.87), negative predictive value (.72), and positive predictive value (.93) were determined for foals from one neonatal ICU; the sensitivity (.83), specificity (.44), negative predictive value (.44), and positive predictive value (.83) were lower for foals at a second, separate ICU. 相似文献
10.