全文获取类型
收费全文 | 360篇 |
免费 | 15篇 |
专业分类
林业 | 29篇 |
农学 | 6篇 |
81篇 | |
综合类 | 18篇 |
农作物 | 17篇 |
水产渔业 | 16篇 |
畜牧兽医 | 172篇 |
园艺 | 9篇 |
植物保护 | 27篇 |
出版年
2023年 | 6篇 |
2022年 | 8篇 |
2021年 | 10篇 |
2020年 | 17篇 |
2019年 | 22篇 |
2018年 | 15篇 |
2017年 | 11篇 |
2016年 | 9篇 |
2015年 | 5篇 |
2014年 | 11篇 |
2013年 | 25篇 |
2012年 | 32篇 |
2011年 | 22篇 |
2010年 | 22篇 |
2009年 | 15篇 |
2008年 | 25篇 |
2007年 | 12篇 |
2006年 | 19篇 |
2005年 | 22篇 |
2004年 | 13篇 |
2003年 | 11篇 |
2002年 | 5篇 |
2001年 | 1篇 |
1999年 | 1篇 |
1998年 | 2篇 |
1997年 | 3篇 |
1996年 | 3篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1984年 | 1篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1954年 | 1篇 |
1941年 | 1篇 |
1939年 | 1篇 |
1938年 | 1篇 |
1937年 | 1篇 |
排序方式: 共有375条查询结果,搜索用时 15 毫秒
181.
van Hemert S Hoekman AJ Smits MA Rebel JM 《Veterinary immunology and immunopathology》2006,114(3-4):247-258
Poultry products are an important source of Salmonella enterica. An effective way to reduce food poisoning due to Salmonella would be to breed chickens more resistant to Salmonella. Unfortunately host responses to Salmonella are complex with many factors involved. To learn more about responses to Salmonella in young chickens, a cDNA microarray analysis was performed to compare gene expression profiles between two chicken lines under control and Salmonella infected conditions. Newly hatched chickens were orally infected with S. enterica serovar Enteritidis. Since the intestine is the first barrier the bacteria encounter after oral inoculation, intestinal gene expression was investigated at different timepoints. Differences in gene expression between the two chicken lines were found in control as well as Salmonella infected conditions. In response to the Salmonella infection a fast growing chicken broiler line induced genes that affect T-cell activation, whereas in a slow growing broiler line genes involved in macrophage activation seemed to be more affected at day 1 post-infection. At days 7 and 9 most gene expression differences between the two chicken lines were identified under control conditions, indicating a difference in the intestinal development between the two chicken lines which might be linked to the difference in Salmonella susceptibility. The findings in this study have lead to the identification of novel genes and possible cellular pathways, which are host dependent. 相似文献
182.
Knuuttila A Uzcátegui N Kankkonen J Vapalahti O Kinnunen P 《Veterinary microbiology》2009,133(3):229-238
Aleutian mink disease virus (AMDV) is a parvovirus that causes an immune complex-mediated disease in minks. To gain a more detailed view of the molecular epidemiology of mink AMDV in Finland, we phylogenetically analysed 14 new Finnish strains from 5 farms and all 40 strains with corresponding sequences available in GenBank. A part of the major non-structural (NS1) protein gene was amplified and analysed phylogenetically. A rooted nucleotide tree was constructed using the maximum parsimony method. The strains described in this study showed 86-100% nucleotide identity and were nearly identical on each farm. The ratio of synonymous to non-synonymous substitutions was approximately 2.7, indicating a mild purifying selection. Phylogenetic analysis confirmed that AMDV strains form three groups (I-III), all of which contained Finnish strains. The tree inferred that the three lineages of AMDV have been introduced to Finland independently. The analysis suggested that AMDV strains do not cluster into genotypes based on geographical origin, year of isolation or pathogenicity. Based on these data, the molecular clock is not applicable to AMDV, and within this gene area no recombination was detected. 相似文献
183.
184.
Johanna P. Pierre Edward R. Abraham John Cleal Nathan A. Walker 《Biological conservation》2010,143(11):2779-2788
Seabird bycatch in trawl fisheries is driven by the attraction of birds to foraging opportunities, i.e., the discharge of catch processing waste and the contents of trawl nets. The risk of seabird captures increases with seabird abundance and exposure to fishing gear. We investigated (1) how quickly seabirds responded to discharges of trawl catch processing waste and (2) whether decreasing numbers of seabirds attended trawlers during processing waste discharge events as the time interval between these events increased. Waste was retained onboard the vessel for four different holding periods (30 min, 2 h, 4 h, 8 h), one of which was applied each day using a randomised block design. We determined seabird responses to batch discharge events after the prescribed holding periods using the abundance of large (albatrossses and giant petrels Macronectes spp.) and small (all other petrels except cape petrels Daption capense, shearwaters and prions) seabirds in a semi-circle of 40 m radius, centred on the stern of the experimental trawler. Seabird responses reflected the type of discharge released: birds moved from the air to the water, as the amount of food available increased from no discharge, through sump discharge to batch discharge. When discharge occurred, seabird abundance increased faster than could be resolved with the 5 min sampling period. However, abundance decreased more slowly over a 10-15 min period after the discharge event. The number of large seabirds attending the vessel during discharge events decreased significantly when waste was held for 4 h. For small birds, significant decrease occurred after 8 h. Such holding periods emphasise the tenacity of foraging seabirds, although we have not evaluated any long-term habituation to a particular discharge regime. While holding waste for less than 4 h may not reduce seabird attendance during discharge events, holding for shorter intervals can still reduce bycatch risk, e.g., prior to and during net shooting and hauling. 相似文献
185.
Johanna R. Frank Felicia B. Nutter rew E. Kyles Clarke E. Atkins Ranee K. Sellon DVM Phd 《Journal of veterinary internal medicine / American College of Veterinary Internal Medicine》1997,11(3):189-194
Systemic arterial dirofilariasis is an unusual manifestation of heartworm disease of dogs that results from aberrant migration of Dirofilaria immitis into the peripheral arterial circulation. To expand the clinical characterization of systemic arterial dirofilariasis, 5 dogs evaluated at the North Carolina State University's College of Veterinary Medicine were reviewed. Common clinical presentations included hindlimb lameness, paresthesia of hindlimbs, and interdigital ischemic necrosis resulting from thromboembolic disease. Visualization of heartworms with angiography or ultrasonography confirmed the diagnosis in all cases. All 5 dogs were treated with an adulticide; 3 dogs were treated with thiacetarsamide sodium and 2 with melarsomine dihydrochloride. Four of the 5 dogs survived the initial treatment period; 1 dog died of severe thromboembolic complications after thiacetarsamide sodium therapy. The treatment of systemic arterial dirofilariasis creates a therapeutic challenge because of multiple potential complications resulting from thromboembolic disease. 相似文献
186.
Johanna L. F. Erstad 《Euphytica》1996,88(3):201-206
Summary Clones of Ribes spp. from 6 regions in Norway and from Denmark, together with a commercial variety, had shown differences in phenological and morphological characters. However, some crossing between wild and cultivated material was suspected to have occurred. A cluster analysis was performed in order to regroup the clones. The results for both vegetative and generative characters showed that most of the clones had a common origin. Some differentiation had occurred between wild and cultivated types and also between northern and southern types (north and south of 61° N resp.). These may be considered to be different ecotypes. The pattern is compared with that of other species. 相似文献
187.
Stability of black tea polyphenol, theaflavin, and identification of theanaphthoquinone as its major radical reaction product 总被引:1,自引:0,他引:1
Jhoo JW Lo CY Li S Sang S Ang CY Heinze TM Ho CT 《Journal of agricultural and food chemistry》2005,53(15):6146-6150
In the current study, we have focused on isolation and detection of major radical oxidation products from theaflavin in order to better understand antioxidation mechanisms of this compound. Theanaphthoquinone was identified as a major oxidation product of theaflavin from two different oxidant model systems: DPPH and peroxidase/hydrogen peroxide. This result indicated that the benzotropolone moiety in theaflavin may play an important role in its antioxidant properties. The stability of theaflavin was studied in varying pH solutions: simulated gastric juice and buffer solutions of pH 5.5, pH 7.4, and pH 8.5. The results indicated that theaflavin is unstable in alkaline conditions, while it was stable in acidic conditions. Theanaphthoquinone was identified as an autoxidation product of theaflavin during its stability study in alkaline conditions. 相似文献
188.
Michael Starr Carl Johan Westman Johanna Ala-Reini 《Water, air, and soil pollution》1996,89(1-2):147-157
Batch acid addition experiments were carried out to determine the acid buffer capacities (amount of acid required to lower soil pH by one unit) of forest soils. Samples of O, E, B (or BC), and C horizons taken from 29 podzolic profiles in southern Finland were used in the experiments. Subsamples of soil were equilibrated for 24 h with NaCl solution containing additions of HCl acid. Cation exchange, mineral dissolution (weathering), and the protonation of organic matter all appeared to have been involved in the buffering of the acid additions. For the O horizon samples, most of the cations released in response to the acid additions were base cations. For the mineral soil samples, most of the cations released were Al3+ ions. With the exception of a few samples, the added acid was not fully neutralised and pH was lowered even with the lowest addition treatment. However, the acid addition treatments corresponded to many times the regional annual acid deposition load (1.6–2.0 cmol(c) m?2). Calculated acid buffer capacities (cmol(c) kg?1 pH?1) ranged from 9.8 to 40.8 for O horizon soil samples and from 0.1 (C horizon) to 5.2 (E horizon) for the mineral soil samples. Total acid buffer capacities for a profile (to a depth of 50 cm) ranged from 500 to 2349, with a mean value of 1091 cmol(c) m?2 pH?1. It is concluded that, in addition to CEC and base saturation, acid buffer capacity is a useful measure to describe the ecological effects of acid deposition on soil. 相似文献
189.
OBJECTIVES: To assess the prevalence and identify the predictors of food insecurity among households in Los Angeles County with incomes below 300% of the federal poverty level. METHODS: The Six-Item Short Form of the US Department of Agriculture's Household Food Security Scale was used as part of a 1999 county-wide, population-based, telephone survey. RESULTS: The prevalence of food insecurity was 24.4% and was inversely associated with household income. Other independent predictors of food insecurity included the presence of children in the household (odds ratio (OR) 1.7, 95% confidence interval (CI) 1.2-2.3) and a history of homelessness in the past five years (OR 5.6, 95% CI 3.4-9.4). CONCLUSION: Food insecurity is a significant public health problem among low-income households in Los Angeles County. Food assistance programmes should focus efforts on households living in and near poverty, those with children, and those with a history of homelessness. 相似文献
190.