全文获取类型
收费全文 | 365篇 |
免费 | 27篇 |
专业分类
林业 | 4篇 |
农学 | 2篇 |
63篇 | |
综合类 | 48篇 |
农作物 | 4篇 |
水产渔业 | 5篇 |
畜牧兽医 | 257篇 |
园艺 | 2篇 |
植物保护 | 7篇 |
出版年
2020年 | 4篇 |
2019年 | 5篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 7篇 |
2015年 | 5篇 |
2014年 | 16篇 |
2013年 | 16篇 |
2012年 | 13篇 |
2011年 | 15篇 |
2010年 | 4篇 |
2009年 | 7篇 |
2008年 | 14篇 |
2007年 | 24篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 10篇 |
2002年 | 12篇 |
2001年 | 14篇 |
2000年 | 11篇 |
1999年 | 15篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1993年 | 2篇 |
1992年 | 5篇 |
1991年 | 5篇 |
1990年 | 11篇 |
1989年 | 6篇 |
1988年 | 4篇 |
1987年 | 7篇 |
1986年 | 9篇 |
1985年 | 8篇 |
1984年 | 7篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 2篇 |
1979年 | 7篇 |
1978年 | 5篇 |
1976年 | 2篇 |
1974年 | 3篇 |
1973年 | 2篇 |
1971年 | 3篇 |
1970年 | 5篇 |
1969年 | 2篇 |
1968年 | 6篇 |
1966年 | 3篇 |
1944年 | 2篇 |
1928年 | 2篇 |
1923年 | 2篇 |
排序方式: 共有392条查询结果,搜索用时 15 毫秒
101.
AMJ McFadden GF Mackereth MI Avery RR Clough I Bolotovski J Fitzmaurice 《New Zealand veterinary journal》2013,61(1):63-68
AIM: To determine the aetiology of a syndrome characterised by facial paralysis in calves (facial paralysis syndrome; FPS); describe the epidemiology of the syndrome on an affected case farm; and define the intra-farm prevalence of affected calves, and inter-farm prevalence of affected dairy farms, in the Franklin district of New Zealand. CASE HISTORY AND CLINICAL FINDINGS: An investigation was carried out on a town-supply dairy farm experiencing an outbreak of FPS in calves during the autumn of 2007, following a previous outbreak during the spring of 2006; 21 calves were affected in both outbreaks. Post-mortem examinations of three affected calves revealed no infectious aetiological agent in neurological tissues despite tests for viruses, bacteria and Mycoplasma species. Tests on hepatic tissues for vanadium toxicity were inconclusive. SURVEY OF DAIRY FARMS: Results from a postal survey of 177/325 (54%) farms established the yearly prevalence of affected farms, based on farmer diagnosis, was 11%, and there was a median two (range 1–25) affected calves on those farms. There was no evidence of spatial clustering of affected farms after accounting for the underlying farm density, or of an increase in the number of affected farms between 2003 and 2007. CLINICAL RELEVANCE: Facial paralysis syndrome is an unusual condition that has not been reported in other districts of New Zealand or in other countries. It is probable that this syndrome will continue to occur at a low to moderate prevalence, and have a significant impact on a small number of farms. 相似文献
102.
103.
Mitigation of greenhouse gas emissions from soil under silage production by use of organic manures or slow-release fertilizer 总被引:4,自引:0,他引:4
Abstract. Grassland is a major source of nitrous oxide (N2 O) and methane (CH4 ) emissions in the UK, resulting from high rates of fertilizer application. We studied the effects of substituting mineral fertilizer by organic manures and a slow-release fertilizer in silage grass production on greenhouse gas emissions and soil mineral N content in a three-year field experiment. The organic manures investigated were sewage sludge pellets and composted sewage sludge (dry materials), and digested sewage sludge and cattle slurry (liquid materials). The organic manures produced N2 O and carbon dioxide (CO2 ) consistently from time of application up to harvest. However, they mitigated N2 O emissions by around 90% when aggregate emissions of 15.7 kg N ha−1 from NPK fertilizer were caused by a flux of up to 4.9 kg N ha−1 d−1 during the first 4 days after heavy rainfall subsequent to the NPK fertilizer application. CH4 was emitted only for 2 or 3 days after application of the liquid manures. CH4 and CO2 fluxes were not significantly mitigated. Composting and dried pellets were useful methods of conserving nutrients in organic wastes, enabling slow and sustained release of nitrogen. NPK slow-release fertilizer also maintained grass yields and was the most effective substitute for the conventional NPK fertilizer for mitigation of N2 O fluxes. 相似文献
104.
The effect of soil texture and soil drainage on emissions of nitric oxide and nitrous oxide 总被引:7,自引:0,他引:7
Abstract. Agricultural soils are important sources of the tropospheric ozone precursor NO and the greenhouse gas N2 O. Emissions are controlled primarily by parameters that vary the soil mineral N supply, temperature and soil aeration. In this field experiment, the importance of soil physical properties on emissions of NO and N2 O are identified. Fluxes were measured from 13 soils which belonged to 11 different soil series, ranging from poorly drained silty clay loams to freely drained sandy loams. All soils were under the same soil management regime and crop type (winter barley) and in the same maritime climate zone. Despite this, emissions of NO and N2 O ranged over two orders of magnitude on all three measurement occasions, in spring before and after fertilizer application, and in autumn after harvest. NO emissions ranged from 0.3 to 215 μg NO-N m–2 h–1 , with maximum emissions always from the most sandy, freely drained soil. Nitrous oxide emissions ranged from 0 to 193 μg N2 O-N m–2 h–1 . Seasonal shifts in soil aeration caused maximum N2 O emissions to switch from freely drained sandy soils in spring to imperfectly drained soils with high clay contents in autumn. Although effects of soil type on emissions were not consistent, N2 O emission was best related to a combination of bulk density and clay content and the NO/N2 O ratio decreased logarithmically with increasing water filled pore space. 相似文献
105.
Soil compaction can affect crop growth and greenhouse gas emission and information is required of how both these aspects are affected by compaction intensity and weather. In this paper we describe treatments of compaction intensity and their effects on soil physical conditions and crop growth in loam to sandy loam cambisol soils. Soil conditions and crop performance were measured over three seasons in a field experiment on soil compacted by wheels on freshly ploughed seedbeds. Ploughing buried the chopped residues of the previous crop. After ploughing, traffic was controlled such that the experimental plots received wheel traffic only as treatments. The overall objective was to discover how the intensity and distribution of soil compaction just before sowing influenced crop performance, soil conditions and emissions of nitrous oxide. Compaction treatments were zero, light compaction by roller (up to 1 Mg m−1) and heavy compaction by loaded tractor, (up to 4.2 Mg). The experiment was located at Boghall, near Edinburgh (860 mm average annual rainfall) for the first two seasons under spring and winter barley (Hordeum vulgare L.) and in a drier area at North Berwick (610 mm average annual rainfall) for the third season under winter oil-seed rape (Brassica napus L.). Heavy compaction in dry soil conditions had little effect on crop growth. However, in wet conditions heavy compaction reduced air porosity, air permeability and gas diffusivity, increased cone resistance and limited winter barley growth and grain yield. Heavy compaction in wet conditions reduced winter barley yields to 7.1 Mg ha−1, in comparison to 8.8 Mg ha−1 in the zero compaction treatment. The compaction status of the top 15 cm of soil seemed to be particularly important. Loosening of the top 10 cm of soil immediately after heavy compaction restored soil conditions for crop growth. However, zero seed bed compaction gave patchy and uneven crop emergence in dry conditions. Both zero and light compaction to a target depth of 10 cm gave similar crop productivity. Maintenance of a correct compaction level near the soil surface is particularly important for establishment and overwintering of barley and oil seed rape. 相似文献
106.
Barry A. Ball Alan J. Conley Juliana Almeida Alejandro Esteller-Vico James Crabtree Coralie Munro Irwin K.M. Liu 《Journal of Equine Veterinary Science》2014
Endocrine diagnoses of granulosa cell tumors (GCTs) in the mare are frequently based upon determination of serum concentrations of inhibin, testosterone, and progesterone (GCT panel). In the present study, we examined results from 2,253 samples submitted for determination of GCT panel. In an additional subset of samples (n = 75), diagnosis of GCT was confirmed based upon surgery or necropsy. The objective of the current study was to examine the agreement between serum inhibin and testosterone concentrations in mares with serum progesterone concentrations less than or ≥1 ng/mL. Across all samples, elevations in serum inhibin or testosterone were noted in 15.2% or 17.3% of samples, respectively. For samples with progesterone <1 ng/mL, more (P = .001) samples had elevated inhibin than elevated testosterone, whereas for samples with progesterone ≥1 ng/mL, more (P < .0001) samples had elevated testosterone than elevated inhibin. For samples with progesterone <1 ng/mL, the agreement between elevated inhibin and testosterone was greater than that for samples with progesterone ≥1 ng/mL. In a subset of 53 samples with progesterone ≥1 ng/mL, 28 samples had endocrine evidence of a granulosa cell tumors based upon elevations of serum anti-Müllerian hormone, and 4 of these samples had endocrine evidence of pregnancy based upon estrone sulfate concentrations. For samples from mares with confirmed GCTs, 85% and 55% had elevated inhibin or testosterone, respectively. Based upon endocrine diagnosis, GCTs occur in mares with elevated progesterone and/or estrone sulfate, albeit at a low rate. 相似文献
107.
Histamine: effect on self-stimulation 总被引:5,自引:0,他引:5
When injected discretely into the lateral hypothalamus of rats, histamine inhibited electrical self-stimulation at the injection site without affecting self-stimulation in the contralateral lateral hypothalamus. This effect was blocked by prior treatment with antihistaminics. Histidine, the amino acid precursor of histamine, produced a similar effect after a delay of 6 to 10 minutes. 相似文献
108.
OBJECTIVE: To examine associations between shopping, food preparation, meal and eating behaviours and fruit and vegetable intake among women. DESIGN: Cross-sectional survey. SETTING: Community-based sample from metropolitan Melbourne, Australia. SUBJECTS: A sample of 1136 women aged 18-65 years, randomly selected from the electoral roll. RESULTS: Food-related behaviours reflecting organisation and forward-planning, as well as enjoyment of and high perceived value of meal shopping, preparation and consumption were associated with healthier intakes of fruits and vegetables. For example, women who more frequently planned meals before they went shopping, wrote a shopping list, enjoyed food shopping, planned in the morning what they will eat for dinner that night, planned what they will eat for lunch, reported they enjoy cooking, liked trying new recipes and who reported they sometimes prepare dishes ahead of time were more likely to consume two or more servings of vegetables daily. Conversely, women who frequently found cooking a chore, spent less than 15 minutes preparing dinner, decided on the night what they will eat for dinner, ate in a fast-food restaurant, ate takeaway meals from a fast-food restaurant, ate dinner and snacks while watching television and who frequently ate on the run were less likely to eat two or more servings of vegetables daily. CONCLUSIONS: Practical strategies based on these behavioural characteristics could be trialled in interventions aimed at promoting fruit and vegetable consumption among women. 相似文献
109.
110.
Daniels MJ Ball N Hutchings MR Greig A 《Veterinary journal (London, England : 1997)》2001,161(3):306-313
Transmission of Mycobacterium avium subspecies paratuberculosis, the organism responsible for paratuberculosis (or Johne's disease) in ruminants, occurs through the faecal-oral route. As M. a. paratuberculosis has been isolated from rabbit faeces, cattle grazing rabbit faecal contaminated pasture may thus be at risk.A herd of 57 beef cattle was monitored on a farm in Perthshire, throughout the 1999 'grazing year', to investigate whether the cattle avoided rabbit faecal contaminated pasture and thus the potential for disease transmission. Grazing was measured every two days over eight rotations by sward heights on 40 marked treatment plots (0.5 m x 0.5 m) to which 0, 10, 50 and 250 rabbit faecal pellets were added. Cattle were also monitored by an active transponder system which enabled individual animals contacting two plots per field rotation (one control and one contaminated) to be recorded. During the monitored grazing year, grazing pressure was low with a net mean sward offtake of 18% of sward height per rotation. There were no significant differences between rabbit faecal treatments (0, 10, 50 and 250 pellets) with respect to the height or proportion of sward removed, or between the numbers of contacts made by cattle on contaminated and uncontaminated plots. Over 90% of all the cattle contacted contaminated plots, indicating that the potential for disease transmission was widespread among the herd.To our knowledge, this is the first reported instance of a lack of avoidance by grazing cattle towards swards contaminated with faeces, and implies that the potential for transmission of paratuberculosis from rabbit contaminated pasture is high. 相似文献