首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   142篇
  免费   37篇
  20篇
综合类   16篇
农作物   1篇
水产渔业   1篇
畜牧兽医   135篇
植物保护   6篇
  2021年   2篇
  2020年   2篇
  2019年   1篇
  2018年   9篇
  2017年   15篇
  2016年   7篇
  2015年   8篇
  2014年   15篇
  2013年   13篇
  2012年   11篇
  2011年   15篇
  2010年   15篇
  2009年   6篇
  2008年   2篇
  2007年   2篇
  2006年   5篇
  2005年   2篇
  2004年   1篇
  2003年   4篇
  2002年   2篇
  2001年   2篇
  1999年   5篇
  1998年   3篇
  1997年   6篇
  1996年   1篇
  1995年   2篇
  1994年   1篇
  1993年   4篇
  1992年   1篇
  1990年   1篇
  1989年   1篇
  1987年   1篇
  1986年   1篇
  1982年   1篇
  1979年   2篇
  1977年   1篇
  1974年   1篇
  1973年   1篇
  1969年   1篇
  1968年   1篇
  1945年   1篇
  1934年   1篇
  1927年   1篇
  1923年   1篇
  1909年   1篇
排序方式: 共有179条查询结果,搜索用时 78 毫秒
51.
Phenol antioxidant quantity and quality in foods: fruits.   总被引:1,自引:0,他引:1  
The free and bound phenols have been measured in 20 fruits commonly consumed in the American diet. Phenols were measured colorimetrically using the Folin-Ciocalteu reagent with catechin as the standard after correction for ascorbic acid contribution. On a fresh weight basis, cranberry had the highest total phenols, and was distantly followed by red grape. Free and total phenol quality in the fruits was analyzed by using the inhibition of lower density lipoprotein oxidation promoted by cupric ion. Ascorbate had only a minor contribution to the antioxidants in fruits with the exception of melon, nectarine, orange, white grape, and strawberry. The fruit extracts' antioxidant quality was better than the vitamin antioxidants and most pure phenols, suggesting synergism among the antioxidants in the mixture. Using our assay, fruits had significantly better quantity and quality of phenol antioxidants than vegetables. Fruits, specifically apples and cranberries, have phenol antioxidants that can enrich lower density lipoproteins and protect them from oxidation. The average per capita consumption of fruit phenols in the U.S. is estimated to be 255 mg/day of catechin equivalents.  相似文献   
52.
This study evaluates the antioxidant capacity of 14 herbs/spices from Cameroon. Freeze-dried samples extracted in methanol (free or unconjugated polyphenol) and in 1.2 M hydrochloric acid (HCl) in methanol (total antioxidant that is both unconjugated and conjugated) were analyzed using two different antioxidant assay methods [Folin-Ciocalteu reagent (Folin) and the ferric reducing antioxidant power (FRAP)]. The 1.2 M HCl in methanol extracts had significantly higher (P < 0.001) antioxidant capacities than the methanolic extract. Generally, the FRAP antioxidant values were significantly (P < 0.001) higher than the Folin antioxidant values. Although a significant correlation (P < 0.05) was obtained between the Folin phenol and the FRAP antioxidant, the trends of the antioxidant capacity of the samples were different for the Folin and FRAP methods. The leaves of the Piper species top the total antioxidant tables in both Folin and FRAP assay methods, respectively. Irvingia gabonensis tops the FRAP free antioxidant list, while Piper umbellatum leads the Folin free antioxidant followed by Thymus vulgaris. Thus, the antioxidant capacity of plant samples determined by different methods should be interpreted with caution. However, irrespective of the assay method used, the samples were rich in antioxidants.  相似文献   
53.
History of veterinary education in Australia · Neurological diseases following bacterial and protozoal infections · Lameness model in sheep · Effects of barefoot trimming · EGFR and HER‐2 as prognostic makers in mammary tumours · Bacteria in semen fractions in dogs  相似文献   
54.
Lomustine‐associated toxicity · Iliopsoas fibrotic myopathy · Porcine circovirus‐associated disease in weaner pigs · Measures of welfare in Bos indicus heifers · eFSH for superovulation in mares · Recurrent Actinobacillus peritonitis in a horse  相似文献   
55.
56.
Summary A cat with weight loss, pyrexia and recurrent lethargy and depression was found to have pleural and peritoneal eosinophilic effusions, peripheral eosinophilia, eosinophilic lymphadenitis and a massively enlarged mesenteric lymph node. Visceral mast cell neoplasia was diagnosed after histopathological examination of a biopsy of the mass. Palliative chemotherapy was attempted unsuccessfully and the cat was euthanased.  相似文献   
57.
Public pressure to reduce or eliminate antimicrobials as ingredients of feed for poultry and other agricultural animals is mounting, primarily due to the fear of multidrug-resistant bacteria in clinical infections in both animals and humans. Exploration of the occurrence of antibiotic resistance in the gut flora of wildlife avian flocks that presumptively do not receive antimicrobials will determine the rate of resistance in a na?ve population. Fecal samples collected from a healthy population of the yellow-headed blackbirds (YHB) (Xanthocephalus xanthocephalus) in North Dakota were cultured to determine what genera and species of gram-negative facultative anaerobic bacteria these wild birds carry in their intestinal flora and to evaluate the antimicrobial susceptibility profiles. Isolates of Escherichia coli were further characterized for the presence of putative virulence factors and for pathogenic potential using the chicken embryo lethality assay (ELA). The ELA was performed in chicken embryos with challenges at both 12 days and 16 days of incubation to determine whether the 16-day-old embryos were better able to fight the infection and subsequent disease and also to determine whether the ELA could distinguish between primary and secondary avian Escherichia coli pathogens. After screening 33 isolates from the 21 fecal samples, only two E. coli isolates were identified. The predominant genus and species of bacterium identified was Pantoea agglomerans. Collectively, 12 of the 33 isolates (36%) exhibited no resistance to any antimicrobial tested. However, several multidrug-resistant isolates of varying genera were identified. Among the antimicrobial resistances observed, the most common was to ampicillin (60%), followed by cephalothin (33%). Neither E. coli isolate belonged to serogroups that are notorious for causing major outbreaks of colibacillosis in poultry, and only one E. coli isolate retained resistance to any antibiotics; nevertheless, the ELA results indicate that at least one of these E. coli may be a primary pathogen of chickens. This study demonstrates that antibiotic resistance occurs in the gut flora of natural populations of YHB despite the absence of antibiotic pressure. In addition, these results indicate that YHB will harbor E. coli isolates that are potentially pathogenic in poultry. However, these E. coli isolates are not a significant reservoir for multiple antibiotic resistances nor are they widespread in the population of YHB surveyed in North Dakota.  相似文献   
58.
The circumpolar boreal biomes coverca. 2 109 ha of the northern hemisphere and containca. 800 Pg C in biomass, detritus, soil, and peat C pools. Current estimates indicate that the biomes are presently a net C sink of 0.54 Pg C yr?1. Biomass, detritus and soil of forest ecosystems (includingca. 419 Pg peat) containca. 709 Pg C and sequester an estimated 0.7 Pg C yr?1. Tundra and polar regions store 60–100 Pg C and may recently have become a net source of 0.17 Pg C yr?1. Forest product C pools, including landfill C derived from forest biomass, store less than 3 Pg C but increase by 0.06 Pg C yr?1. The mechanisms responsible for the present boreal forest net sink are believed to be continuing responses to past changes in the environment, notably recovery from the little ice-age, changes in forest disturbance regimes, and in some regions, nutrient inputs from air pollution. Even in the absence of climate change, the C sink strength will likely be reduced and the biome could switch to a C source. The transient response of terrestrial C storage to climate change over the next century will likely be accompanied by large C exchanges with the atmosphere, although the long-term (equilibrium) changes in terrestrial C storage in future vegetation complexes remains uncertain. This transient response results from the interaction of many (often non-linear) processes whose impacts on future C cycles remain poorly quantified. Only a small part of the boreal biome is directly affected by forest management and options for mitigating climate change impacts on C storage are therefore limited but the potential for accelerating the atmospheric C release are high.  相似文献   
59.
Anthracnose is the main fungal disease on cashew orchards in Brazil, occurring on both vegetative and reproductive organs of cultivated and noncultivated host plants. Understanding the effect of physical and chemical exogenous factors on the biological traits of Colletotrichum spp. and determining their host range are key to developing appropriate anthracnose control measures. The present study aimed to estimate the optimum temperatures for mycelial growth, sporulation, and conidial germination of seven Colletotrichum species (C. chrysophilum, C. fragariae, C. fructicola, C. gloeosporioides, C. queenslandicum, C. siamense, and C. tropicale) associated with cashew anthracnose in Brazil. Their aggressiveness on cashew leaves and six alternative host fruits, and their sensitivity to three fungicides were also investigated. The optimum temperatures for mycelial growth, sporulation, and conidial germination ranged from about 25 to about 33°C. All Colletotrichum species induced anthracnose symptoms on wounded cashew leaves, but none of them caused lesions on intact leaf surfaces. The Colletotrichum species, except for C. fragariae and C. fructicola, were pathogenic to wounded fruits of avocado, banana, guava, mango, and papaya, and some isolates also produced lesions on nonwounded fruit tissues. No symptoms were observed on passion fruits, regardless of the inoculation method. Mycelial growth, sporulation, conidial germination, and/or appressorial formation of the seven Colletotrichum species were inhibited by azoxystrobin, difenoconazole, and thiophanate-methyl to varying degrees. The present study will contribute to the development of forecasting models based on prevailing weather of cashew cropping zones and improve cashew anthracnose management in Brazil.  相似文献   
60.
European Journal of Plant Pathology - Bauhinia forficata is an important plant commonly used in traditional medicine, and as an ornamental plant in parks and gardens. Its use as an ornamental plant...  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号