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   104篇
  免费   7篇
林业   4篇
农学   2篇
  35篇
农作物   11篇
水产渔业   6篇
畜牧兽医   35篇
园艺   2篇
植物保护   16篇
  2021年   6篇
  2020年   2篇
  2019年   5篇
  2018年   2篇
  2017年   4篇
  2016年   3篇
  2015年   3篇
  2014年   9篇
  2013年   7篇
  2012年   14篇
  2011年   18篇
  2010年   6篇
  2009年   6篇
  2008年   2篇
  2007年   3篇
  2006年   3篇
  2005年   2篇
  2004年   6篇
  2003年   2篇
  2002年   4篇
  2000年   1篇
  1999年   1篇
  1995年   1篇
  1988年   1篇
排序方式: 共有111条查询结果,搜索用时 31 毫秒
1.
The risk of undesirable by-products from chlorine disinfection in fresh-cut industries, together with its limited efficacy, has led to a search for alternative agents. The aim of this study was to test several alternative putative antimicrobial substances to reduce Escherichia coli O157:H7, Salmonella spp. and Listeria spp. populations on fresh-cut apple. Carvacrol, vanillin, peroxyacetic acid, hydrogen peroxide, N-acetyl-l-cysteine and Citrox were selected for their results in in vitro assays against E. coli O157:H7 and Listeria spp., to be tested on fresh-cut apple plugs. Apple flesh was inoculated by dipping in a suspension of a mix of the studied pathogens at 106 cfu mL?1, and then treated with the antimicrobial substances. All treatments were compared to deionized water and a standard sodium hypochlorite treatment (SH, 100 mg L?1, pH 6.5). Pathogen population on apple plugs was monitored for up to 6 days at 10 °C. Bacterial reductions obtained by peroxyacetic acid (80 and 120 mg L?1), vanillin (12 g L?1), hydrogen peroxide (5, 10, 20 mL L?1) and N-acetyl-l-cysteine (5 and 10 g L?1) were similar or higher than reduction obtained by SH. In addition, bacterial populations were maintained at low levels throughout storage. No cells of any of the pathogens were detected in the peroxyacetic acid, hydrogen peroxide, Citrox and SH washing solutions after apple treatment. Peroxyacetic acid, hydrogen peroxide and N-acetyl-l-cysteine could be potential disinfectants for the fresh-cut industry as an alternative to chlorine disinfection. However, their effect on sensory quality and effectiveness under commercial processing conditions should be evaluated.  相似文献   
2.
Twenty-four hour urinary excretion, fractional excretion and the filtered load of calcium and phosphorus were monitored as hyperparathyroidism evolved in a model of progressive canine renal failure. Thirteen beagles of both sexes aged four and a half months were used. Nine of them were subjected to a renal damaging schedule (neomycine, 60 mg/kg/48 h, IM, 32 weeks) in order to induce chronic renal failure leading to secondary hyperparathyroidism (2HPT group). The remaining four were kept as the control group. The experiment was conducted over 32 weeks. Blood and 24 h urine were collected every four weeks. Calcium, phosphorus and creatinine were analyzed. Plasma parathormone and calcitonin were determined at weeks 0, 12, 24 and 32. The level of renal function in the 2HPT animals was reduced to 25% of that of the controls (endogenous creatinine clearance was 0.45 +/- 0.22 mL/min/kg as opposed to 1.81 +/- 0.54 mL/min/kg). Hyperparathyroidism was confirmed by a progressive increase in the levels of the parathyroid hormone. Calcitonin levels were not modified. A tendency to hypocalcaemia was observed, reaching statistically significant levels from the twenty-eighth week of the study, when hyperphosphataemia also became significant. Daily urinary excretion of calcium and phosphorus remained at values considered normal throughout the experiment with no alteration imputable to the impaired renal function. This is explained by the decrease in the filtered load of these elements (in both cases statistically significant from the 24th week on) being associated with an increase in their fractional excretion. Thus, calcium and phosphorus urinary excretion values could be maintained in a normal range up to the end of the experiment, showing that renal calcium handling in dogs with experimentally induced renal failure seems to differ from that observed in human patients.  相似文献   
3.

The effects of a thinning treatment on soil respiration (Rs) were analysed in two dryland forest types with a Mediterranean climate in east Spain: a dry subhumid holm oak forest (Quercus ilex subsp. ballota) in La Hunde; a semiarid postfire regenerated Aleppo pine (Pinus halepensis) forest in Sierra Calderona. Two twin plots were established at each site: one was thinned and the other was the control. Rs, soil humidity and temperature were measured regularly in the field at nine points per plot distributed into three blocks along the slope for 3 years at HU and for 2 years at CA after forest treatment. Soil heterotrophic activity was measured in laboratory on soil samples obtained bimonthly from December 2012 to June 2013 at the HU site. Seasonal Rs distribution gave low values in winter, began to increase in spring before lowering as soil dried in summer. This scenario indicates that with a semiarid climate, soil respiration is controlled by both soil humidity and soil temperature. Throughout the study period, the mean Rs value in the HU C plot was 13% higher than at HU T, and was 26% higher at CA C than the corresponding CA T plot value, being the differences significantly higher in control plots during active growing periods. Soil microclimatic variables explain the biggest proportion of variability for Rs: soil temperature explained 24.1% of total variability for Rs in the dry subhumid forest; soil humidity accounted for 24.6% of total variability for Rs in the semiarid forest. As Mediterranean climates are characterised by wide interannual variability, Rs showed considerable variability over the years, which can mask the effect caused by thinning treatment.

  相似文献   
4.
An outbreak of human leishmaniosis was confirmed in the southwest of the province of Madrid, Spain, between July 2009 and December 2012. Incidence of Leishmania infection in dogs was unchanged in this period, prompting a search for alternative sylvatic infection reservoirs. We evaluated exposure to Leishmania in serum samples from animals in the area with an indirect immunofluorescence test (IFAT). Using promastigotes from six culture passages and a 1/25 threshold titer, we found anti-Leishmania infantum seroreactivity in 9.3% of cats (4 of 43), 45.7% of rabbits (16/35) and 74.1% of hares (63/85). Use of promastigotes from >10 in vitro passages resulted in a notably IFAT lower titer, suggesting antigenic changes during extended culture. Postmortem inspection of seropositive animals showed no clinical signs of infection. The results clearly suggest that asymptomatic hares were the main reservoir in the outbreak, and corroborate IFAT as a sensitive serological surveillance method to detect such cryptic Leishmania infections.  相似文献   
5.
The aim of this study was to evaluate the effects of rapid cooling prior to freezing on frozen-thawed canine sperm quality. In experiment 1, centrifuged ejaculates from 6 dogs were pooled, split into 4 aliquots and cryopreserved by the Uppsala procedure using different cooling rates (control, cooling speed 18 C/90 min and average cooling rate 0.2 C/min; rapid, cooling speed 18 C/8 min and average cooling rate 2.25 C/min) in combination with 2 glycerol addition protocols (fractionated or unfractionated). In experiment 2, centrifuged ejaculates from 4 dogs were processed individually using the same cooling rates described in experiment 1 in combination with an unfractionated glycerol addition protocol. Each of the experiments was replicated 5 times. Sperm quality was evaluated after 30 and 150 min of post-thawing incubation at 38 C. Total motility (TM), progressive motility (PM) and quality of movement parameters were assessed using a computerized system, and sperm viability (spermatozoa with intact plasma and acrosome membranes) was assessed using flow cytometry (H-42/PI/FITC-PNA). Values for TM, PM, viable spermatozoa and the quality of movement parameters after thawing were not significantly affected by the cooling rate. The interaction between the cooling rate and the added glycerol protocol was not significant. There were significant differences among the males (P<0.01) in the sperm quality parameters evaluated after thawing. The interaction between the males and the cooling rate was not significant. In conclusion, canine spermatozoa can be cryopreserved using the Uppsala method at an average cooling rate of 2.25 C/min prior to freezing together with addition of fractionated or unfractionated glycerol.  相似文献   
6.
The high content of amino acids of the quinoa, especially essential amino acids (higher than other cereals) makes a food increasingly demanded by consumers. A total of twelve amino acids (arginine, cystine, isoleucine, leucine, lysine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine) were analyzed in quinoa samples from Chile by near infrared spectroscopy (NIR) with direct application to the samples of a remote fiber-optic reflectance probe. The calibration results using modified partial least squares (MPLS) regression satisfactorily allowed the determination of the concentrations of this amino acid group with high multiple correlation coefficients (RSQ = 0.97–0.71) and low standard prediction errors (SEPC = 0.07–0.20). The prediction capacity (RPD) for the arginine, the cystine, the isoleucine, the lysine, the serine, the threonine, the tryptophan, the tyrosine and the valine ranged between 2.6 and 5.2, for the rest of amino acids were higher to 1.8, indicating that the NIRS equations obtained were applicable to unknown samples. It has confirmed that NIRS technology is a method that may be useful to replace the traditional methods for routine analysis of some amino acids.  相似文献   
7.
Byproducts generated from food industries, such as olive oil mills, have been studied to decrease harmful pollution and their environmental consequences. In this work, a new thermal pretreatment and saprobic fungal incubation to detoxify alperujo (two-phase olive mill waste) have been evaluated in view of its use as fertilizer in agriculture. The sequential use of both methods simplifies the thermal conditions and incubation times of the fungal treatment. Optimization of the thermal treatment from 150 to 170 °C for 45 and 15 min, respectively, reduced the incubation time with Coriolpsis rigida from 20 to 10 weeks needed to reduce phytotoxic effects on tomato plants. Therefore, the combination of thermal and biological treatments will allow the development of the potential benefits of alperujo to improve nutrients in agricultural soil.  相似文献   
8.
Ocular lesions associated with Trypanosoma spp. infection have been described in man and many animal species. However, loss of vision has not been demonstrated in humans presenting Chagas disease or in animals affected by different trypanosome species. In order to assess the possible ocular disorders caused by Trypanosoma evansi infection, six goats were inoculated with 1 x 10(5) T. evansi and maintained for 12 months and four goats were used as control. The inoculated animals became positive at serological and parasitological tests at 1-month post-inoculation and showed a subclinical course of the disease. Unilateral superficial corneal ulceration and retinochoroiditis were observed in two inoculated animals. Data from ocular neurologic examination and electroretinography showed no significant differences between inoculated and non-inoculated goats. It could be concluded that Trypanosoma evansi can produce ocular lesion but without apparent loss of vision in goats.  相似文献   
9.
Bluetongue viruses (BTVs) could invade N-W Europe similar to BTV serotype 8 (BTV8/net06), since the source and route of introduction of this virus has not been solved. Therefore, the Dutch survey for Bluetongue by PCR testing was extended by further analysis of PCR positives to identify the involved BTV. In late August 2008, BTV was reported with 12 nucleotide differences in the S10 amplicon (S10 genotyping). This virus was identified as serotype 6, here named BTV6/net08. Promptly, serotype specific real-time PCR tests were developed for serotypes 1, 6, and 8 (S2 genotyping). Agreement was found between results by S10- and S2 genotyping. Further, BTV1 was identified by both S10- and S2 genotyping in one imported animal. After initial discovery of BTV6 in the Netherlands, animals from 18 holdings tested PCR positive for BTV6/net08 in 2008. Remarkably only one or two PCR positive animals per holding were found. Serum neutralization tests did not result in the discovery of more BTV6 infected animals. Retrospective studies indicated no evidence for infections by BTV6/net08 prior to the first discovery. Experimental infections with BTV6/net08 did not cause clinical disease in sheep, calves and cattle, except for a very short fever in some animals. This clearly showed that the vaccine-related BTV6/net08 is not virulent. BTV6/net08 was not found by passive and active surveys in the years after its discovery. Apparently, BTV6/net08 was not efficiently transmitted by endemic species of Culicoides in N-W Europe, and disappeared without the need of any control measure.  相似文献   
10.
Veterinary Research Communications - The emergence of virulent strains of porcine reproductive and respiratory syndrome virus (PRRSV), causing atypical and severe outbreaks, has been notified...  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