全文获取类型
收费全文 | 85篇 |
免费 | 10篇 |
专业分类
林业 | 3篇 |
农学 | 1篇 |
15篇 | |
综合类 | 14篇 |
农作物 | 3篇 |
水产渔业 | 16篇 |
畜牧兽医 | 33篇 |
植物保护 | 10篇 |
出版年
2023年 | 3篇 |
2022年 | 1篇 |
2021年 | 1篇 |
2020年 | 6篇 |
2019年 | 3篇 |
2018年 | 8篇 |
2017年 | 3篇 |
2016年 | 1篇 |
2014年 | 1篇 |
2013年 | 5篇 |
2012年 | 6篇 |
2011年 | 2篇 |
2010年 | 2篇 |
2008年 | 9篇 |
2006年 | 6篇 |
2005年 | 3篇 |
2004年 | 3篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 3篇 |
1999年 | 3篇 |
1998年 | 2篇 |
1997年 | 1篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1990年 | 1篇 |
1988年 | 1篇 |
1982年 | 1篇 |
1979年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1956年 | 1篇 |
1945年 | 1篇 |
1940年 | 1篇 |
排序方式: 共有95条查询结果,搜索用时 46 毫秒
61.
A phytochemical investigation of Alchornea latifolia 总被引:1,自引:0,他引:1
Setzer WN Shen X Bates RB Burns JR McClure KJ Zhang P Moriarity DM Lawton RO 《Fitoterapia》2000,71(2):195-198
A phytochemical investigation of the chloroform leaf extract of Alchornea latifolia has been undertaken. Along with the triterpenoids taraxerone, friedelin, epifriedelinol, and taraxerol, the plant also contains seco-3,4-friedelin (dihydroputranjivic acid) (1) and seco-3,4-taraxerone (2). These A-ring-opened triterpenoids show in vitro cytotoxic activity against Hep-G2 and A-431 human cancer cell lines and are potent inhibitors of topoisomerase II. 相似文献
62.
Shaughnessy RG Meade KG McGivney BA Allan B O'Farrelly C 《Veterinary immunology and immunopathology》2011,142(1-2):64-71
Campylobacter jejuni colonises the caecum of more than 90% of commercial chickens. Even though colonisation is asymptomatic, we hypothesised that it is mediated by activation of several biological pathways. We therefore used chicken-specific 20K oligonucleotide microarrays to examine global gene expression in C. jejuni-challenged birds. Microarray results demonstrate small but significant fold-changes in expression of 270 genes 20 h post-challenge, corresponding to a wide range of biological processes including cell growth, nutrient metabolism and immunological activity. Expression of NOX1 (2.3-fold) and VCAM1 (1.5-fold) were significantly increased in colonised birds (P<0.05), indicating oxidative burst and endothelial cell activation, respectively. Microarray results, supplemented by qRT-PCR analyses demonstrated increased TOPK (1.9-fold), IL17 (3.6-fold), IL21 (2.1-fold), IL7R (4-fold) and CTLA4 (2.5-fold) gene expression (P<0.05), which was suggestive of T cell mediated activity. Combined these results suggest that C. jejuni has nominal effects on global caecal gene expression in the chicken but significant changes detected are suggestive of a protective intestinal T cell response. 相似文献
63.
Kieran A. Monaghan Ana L. Machado Frederick J. Wrona Amadeu M.V.M. Soares 《水产资源保护:海洋与淡水生态系统》2020,30(4):662-674
- The increasing risk of wildfire has focused attention on the timescale of the impact and recovery of river ecosystems and methods for their bioassessment.
- An 18‐year pseudo time‐series was exploited to document patterns in benthic macroinvertebrate impact and recovery and evaluate the efficacy of alternative metrics to assess fire damage. Macroinvertebrates were surveyed by kick‐sampling and data were collected on river habitats. Details of river catchments and wildfire were collated as a GIS database.
- Macroinvertebrate richness and abundance recovered rapidly, marked by a phase of dynamic increase, followed by relative stability (0–2 years and 3–18 years, respectively). Across sites, richness and abundance were best explained by time since fire.
- A biotic index of general river quality was ineffective as an indicator of fire damage. While a metric of K‐selected taxa (Odonata richness) was generally indicative of fire‐affected assemblages, a contrasting metric of r‐selected taxa (percentage of chironomids, baetids, and simuliids) was not.
- Ordination analysis revealed time as a significant determinant of community structure across sites; however, its overall statistical importance was eclipsed by habitat characteristics (water quality, shade, altitude, and latitude) that were associated with ecological variation across both recently affected sites and the putatively recovered communities.
- These results highlight the stochastic processes – environmental and ecological – that frame the macroinvertebrate response to wildfire. This probabilistic context emphasizes the difficulties of developing indicator taxa for wildfire bioassessment and reinforces the importance of standardized survey protocols and the use of contrasting metrics in the assessment of wildfire impact on the ecological quality of rivers.
64.
65.
Lawton MP 《The Veterinary record》2005,157(15):456; discussion 456
66.
67.
AIM: To determine the resistance to antibiotics among the indictor bacteria, Escherichia coli and Enterococcus spp, isolated from the faeces of healthy pigs on three conventional pig farms and one organic farm in the North Island of New Zealand. METHODS: Faecal samples, collected at intervals between March and October 2001, were plated onto MacConkey agar and Slanetz-Bartley agar and examined after 1-3 days incubation for colonies resembling E. coli and Enterococcus spp, respectively. Typical colonies were subcultured for further identification and storage. The isolates were tested for antibiotic resistance, using disc diffusion, to ampicillin, gentamicin, streptomycin, and tetracycline. Escherichia coli isolates were also tested for resistance to ciprofloxacin, cotrimoxazole and neomycin. Enterococcus spp isolates were also tested for resistance to vancomycin, erythromycin and virginiamycin. RESULTS: A total of 296 E. coli and 273 Enterococcus spp isolates were obtained from the three conventional farms, and 79 E. coli and 80 Enterococcus spp isolates were obtained from the organic farm. All the E. coli isolates from both the conventional and organic pig farms were susceptible to ciprofloxacin, and all the Enterococcus spp isolates were susceptible to ampicillin, gentamicin and vancomycin. Isolates of E. coli from conventional pig farms were resistant to gentamicin (0.7%), neomycin (0.7%), ampicillin (2.7%), cotrimoxazole (11%), streptomycin (25%) and tetracycline (60%). Enterococcus spp isolates from the same farms were resistant to erythromycin (68%), tetracycline (66%), streptomycin (54%) and virginiamycin (49%). By contrast, for the organic pig farm 相似文献
68.
69.
BACKGROUND: Captan is an important fungicide for controlling diseases in horticultural crops. Understanding its dissipation is important for estimating dietary risks and optimising pesticide application. Field experiments were conducted on apple leaves and fruit to investigate (1) the temporal variability of captan residues, (2) the contribution of several factors to the variability in residues and (3) the relationship between residues and climatic conditions. RESULTS: Initial captan deposits and subsequent residues on fruit and leaves were closer to a lognormal than to a normal distribution. The unit-to-unit variation contributed most to the observed variability in the initial deposit and subsequent residues. Variability due to orchards or trees or tree-zone interactions was also frequently important, but there was no discernable trend in the effects. The variability in residues did not appear to decrease over time. Canopy structure affected greatly the initial deposition but had little direct effect on subsequent captan loss. Fruit and leaves on the outside of the tree canopy received more deposit than those on the inside, but these differences gradually decreased over time. Captan loss resulted mainly from the first rainfall after an application. CONCLUSIONS: Captan loss is mainly due to rain, and the loss is negligible under dry conditions. 相似文献
70.
John W. Lawton 《Cereal Chemistry》2006,83(5):565-568
Traditionally, zein is isolated and recovered from corn gluten meal (GCM) using aqueous alcohol as the solvent. Recovery of zein from this solvent is inconvenient and costly. Zein is insoluble in 100% ethanol at room temperature, but it is soluble at 120°C in ethanol. Absolute ethanol effectively extracted zein from CGM, distillers dried grains (DDG), and ground corn. Zein was extracted from CGM with absolute ethanol in a high‐pressure reactor at 130°C. After extracting at 130°C for 45 min, the solution was pumped out of the extractor and allowed to cool. Upon cooling, the zein precipitated from solution. The precipitate was removed from the solution and air‐dried, resulting in 14% recovery of the starting material. The recovered precipitate had an average protein content of >90% on a dry basis, accounting for ≈20% of the CGM protein and recovered ≈35% of its zein. No differences were seen in the amount of zein extracted from CGM samples that were hand‐collected off the dewatering screen and gently dried, versus commercial CGM samples. The commercial CGM did produce a greater amount of solubles. The extraction procedure also worked at temperatures as low as 90°C. The lower temperature did produce lower yields of extracted zein. The zein extracted at the lower temperatures was less brown, but zein extracted at either temperature was almost fully soluble in traditional zein solvents. 相似文献