全文获取类型
收费全文 | 299篇 |
免费 | 12篇 |
国内免费 | 1篇 |
专业分类
林业 | 10篇 |
农学 | 11篇 |
34篇 | |
综合类 | 37篇 |
农作物 | 2篇 |
水产渔业 | 10篇 |
畜牧兽医 | 201篇 |
园艺 | 2篇 |
植物保护 | 5篇 |
出版年
2022年 | 2篇 |
2021年 | 4篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2017年 | 6篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 8篇 |
2011年 | 17篇 |
2010年 | 7篇 |
2009年 | 5篇 |
2008年 | 16篇 |
2007年 | 17篇 |
2006年 | 27篇 |
2005年 | 13篇 |
2004年 | 12篇 |
2003年 | 6篇 |
2002年 | 12篇 |
2001年 | 12篇 |
2000年 | 16篇 |
1999年 | 16篇 |
1998年 | 5篇 |
1997年 | 5篇 |
1995年 | 4篇 |
1994年 | 2篇 |
1992年 | 3篇 |
1991年 | 2篇 |
1990年 | 4篇 |
1989年 | 5篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1980年 | 3篇 |
1972年 | 2篇 |
1971年 | 4篇 |
1970年 | 4篇 |
1969年 | 5篇 |
1968年 | 4篇 |
1967年 | 4篇 |
1966年 | 2篇 |
1965年 | 1篇 |
1963年 | 2篇 |
1956年 | 1篇 |
1954年 | 1篇 |
1953年 | 1篇 |
1951年 | 1篇 |
1948年 | 1篇 |
1942年 | 1篇 |
1939年 | 2篇 |
排序方式: 共有312条查询结果,搜索用时 15 毫秒
221.
Reports of clinical scrapie in Great Britain between January 1, 1993 and December 31, 2002 were reviewed. Scrapie was confirmed in 4142 sheep on 1099 holdings. The cumulative case and holding incidence risks decreased in 2001, probably owing to the outbreak of foot-and-mouth disease, although there were regional variations. Sheep aged between three and four years old constituted the largest affected group. In the period between 1998 and 2002, 51.3 per cent of the cases had the genotype ARQ/VRQ, 19.3 per cent were ARQ/ARQ and 18.9 per cent were VRQ/VRQ; Swaledale, Shetland and Welsh mountain sheep were the most common pure breeds reported. The areas at highest risk were the Shetland Islands, followed by the south and east of England. 相似文献
222.
Imbschweiler I Kummerfeld M Gerhard M Pfeiffer I Wohlsein P 《Veterinary journal (London, England : 1997)》2009,182(3):481-483
A case of animal sexual abuse and sadism in a female sheep is described. The animal suffered severe genital tract injury most likely caused by the insertion and manipulation of a branch of wood and by penile penetration by a human male. Postmortem examination revealed multiple perforations of the vagina with massive haemorrhages. Animal sexual abuse is a complex diagnostic problem in veterinary medicine. Reported cases are often linked to sadism and often lead to the animal's death. Veterinarians should keep in mind animal sexual abuse as a differential diagnosis in cases of anogenital injuries of unknown origin. 相似文献
223.
Multivariate analysis of management and biosecurity practices in smallholder pig farms in Madagascar 总被引:1,自引:0,他引:1
S. Costard V. Porphyre S. Messad S. Rakotondrahanta H. Vidon F. Roger D.U. Pfeiffer 《Preventive veterinary medicine》2009,92(3):199
A cross-sectional study was carried out in 2005 and 2006 in three geographical areas of Madagascar to investigate and differentiate swine farm management and biosecurity practices in smallholder farming communities. Questionnaire data from a total of 709 pig farms were analysed using multiple factor analysis (MFA) and hierarchical cluster analysis (HCA). Variables describing management and biosecurity practices were organised into five groups: structure of the farm, animal-contacts, person- and vehicle-contacts, feeding, and sanitary aspects. In general, few biosecurity measures were implemented in the pig farms included in the study. Regional differences in management and biosecurity practices emerged from the MFA and were mainly due to, in order of decreasing importance: structure of the farm, sanitary aspects, feeding and animal-contacts and, to a lesser extent, person- and vehicle-contacts. HCA resulted in the differentiation of four distinct types of farms in each of two study areas, Arivonimamo and Marovoay, while no grouping could be identified amongst farms in Ambatondrazaka area. The characterisation of the different types of smallholder pig farms will allow adapting recommendations on husbandry practices and control measures in pig farms of these regions of Madagascar. The development of tailored recommendations is essential for Malagasy smallholders who have limited resources and need to make evidence-based management changes to reduce the risk of contagious diseases in their herds. 相似文献
224.
S. Schmid A. Hodshon S. Olin I. Pfeiffer S. Hecht 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》2017,31(2):545-549
Familial narcolepsy secondary to breed‐specific mutations in the hypocretin receptor 2 gene and sporadic narcolepsy associated with hypocretin ligand deficiencies occur in dogs. In this report, a pituitary mass is described as a unique cause of narcolepsy‐cataplexy in a dog. A 6‐year‐old male neutered Dachshund had presented for acute onset of feeding‐induced cataplexy and was found to have a pituitary macrotumor on magnetic resonance imaging (MRI). Cerebral spinal fluid hypocretin‐1 levels were normal, indicating that tumor effect on the ventral lateral nucleus of the hypothalamus was not the cause of the dog's narcolepsy‐cataplexy. The dog was also negative for the hypocretin receptor 2 gene mutation associated with narcolepsy in Dachshunds, ruling out familial narcolepsy. The Dachshund underwent stereotactic radiotherapy (SRT), which resulted in reduction in the mass and coincident resolution of the cataplectic attacks. Nine months after SRT, the dog developed clinical hyperadrenocorticism, which was successfully managed with trilostane. These findings suggest that disruptions in downstream signaling of hypocretin secondary to an intracranial mass effect might result in narcolepsy‐cataplexy in dogs and that brain MRI should be strongly considered in sporadic cases of narcolepsy‐cataplexy. 相似文献
225.
Susanne Menzel Eva-Maria Nordstr?m Matthias Buchecker Alexandra Marques Heli Saarikoski Annika Kangas 《European Journal of Forest Research》2012,131(5):1367-1379
Participatory approaches and computerised tools such as decision support systems (DSS) represent conflicting tendencies in state-of the-art sustainable forest management. As a result, there may be considerable tension between these two developments in practice. The objective of this paper is to explore how participatory approaches and DSS could be brought together to improve planning processes and to explore how DSS could be adapted in their use or combined with other tools to enable successful participatory planning. From a review of the literature, we identified criteria related to successful participatory planning. From these criteria, we selected those a DSS can influence and created a short list of the criteria that could be used to evaluate participatory processes where DSS are applied. The evaluation criteria with particular relevance for DSS that we identified are as follows: fairness, opportunity to influence outcome, quality and selection of information, cost-effectiveness, challenging status quo and fostering creative thinking, structured decision-making process, transparency, and independence and neutrality of process. We also scrutinised existing forest DSS and identified features that may enable DSS to address these criteria. The features of DSS we identified that may support participatory processes are as follows: group decision support, possibilities to include other values than timber production, flexibility of system to include non-traditional forest data and management options, and multi-criteria decision analysis tools. We argue that the DSS to be used should be assessed to clarify, how it can be used in the specific planning situation and how it should be complemented with other available and non-computerised tools. 相似文献
226.
Principles and practical application of the receiver-operating characteristic analysis for diagnostic tests 总被引:1,自引:0,他引:1
We review the principles and practical application of receiver-operating characteristic (ROC) analysis for diagnostic tests. ROC analysis can be used for diagnostic tests with outcomes measured on ordinal, interval or ratio scales. The dependence of the diagnostic sensitivity and specificity on the selected cut-off value must be considered for a full test evaluation and for test comparison. All possible combinations of sensitivity and specificity that can be achieved by changing the test's cut-off value can be summarised using a single parameter; the area under the ROC curve. The ROC technique can also be used to optimise cut-off values with regard to a given prevalence in the target population and cost ratio of false-positive and false-negative results. However, plots of optimisation parameters against the selected cut-off value provide a more-direct method for cut-off selection. Candidates for such optimisation parameters are linear combinations of sensitivity and specificity (with weights selected to reflect the decision-making situation), odds ratio, chance-corrected measures of association (e. g. kappa) and likelihood ratios. We discuss some recent developments in ROC analysis, including meta-analysis of diagnostic tests, correlated ROC curves (paired-sample design) and chance- and prevalence-corrected ROC curves. 相似文献
227.
This investigation examined primarily epidermal specializations of the adult horse tongue by light, scanning and transmission electron microscopy. Samples were collected from seven regions of the normal tongue of various breeds of horse. The filiform papillae, present on the dorsal and lateral aspects but not the ventral aspect of the tongue, were short, slender and finger-like structures with variable-shaped terminae. The epidermal thickness and height of dermal ridges were reduced on fungiform and vallate papillae, but tissue architecture and keratinocyte ultrastructure of most of the lingual epidermis corresponded to the common mammalian epidermal paradigm. One unique finding was the highly localized clustering of epidermal cells with exceptionally high content of PAS-negative trichohyalin cytoplasmic granules at a location atop the dermal ridges and beneath the base of filiform papillae. These granular cells were immediately subjacent to clusters of clear, non-granulated epidermal cells. It is believed that this integumentary specialization may enhance the structural strength at this localized site of the tissue architecture, in relationship to the mechanical papillae. 相似文献
228.
229.
230.