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61.
Ding S Chen J Jiang H He J Shi W Zhao W Shen J 《Journal of agricultural and food chemistry》2006,54(17):6139-6142
A new indirect competitive fluorescence-linked immunosorbent assay (cFLISA) method for the detection of sulfamethazine (SM2) in chicken muscle tissue was demonstrated using quantum dots (QDs) as the fluorescence label coupled with secondary antibody. The sensitivity of the cFLISA was compared with that of the HPLC method. The 50% inhibition value (IC50) and the limit of detection (LOD) of the cFLISA were 7.7 and 1.0 ng/mL, respectively. When SM2 was spiked at levels of 50, 100, and 200 ng/g, recoveries ranged from 80.6% to 117.4%, with a coefficient of variation of 6.9-9.6%. In the incurred sample analysis, the amounts of SM2 quantified by cFLISA were similar to the results obtained by the HPLC method. This study shows that cFLISA could be used as a screening method in practice. 相似文献
62.
Stereoselectivity of the generation of 3-mercaptohexanal and 3-mercaptohexanol by lipase-catalyzed hydrolysis of 3-acetylthioesters 总被引:1,自引:0,他引:1
Wakabayashi H Wakabayashi M Eisenreich W Engel KH 《Journal of agricultural and food chemistry》2003,51(15):4349-4355
The enantioselectivity of the generation of 3-mercaptohexanal and 3-mercaptohexanol, two potent sulfur-containing aroma compounds, by lipase-catalyzed hydrolysis of the corresponding 3-acetylthioesters was investigated. The stereochemical course of the kinetic resolutions was followed by capillary gas chromatography using modified cyclodextrins as chiral stationary phases. The enzyme preparations tested varied significantly in terms of activity and enantioselectivity (E). The highest E value (E = 36) was observed for the hydrolysis of 3-acetylthiohexanal catalyzed by lipase B from Candida antarctica resulting in (S)-configured thiol products. Immobilization of the enzyme (E = 85) and the use of tert-butyl alcohol as cosolvent (E = 49) improved the enantioselectivity. Modification of the acyl moiety of the substrate (3-benzoylthiohexanal) had no significant impact. The sulfur-containing compounds investigated possess attractive odor properties, and only one of the enantiomers exhibits the pleasant citrus type note. 相似文献
63.
安徽省土壤微量元素状况与地质背景的关系 总被引:6,自引:0,他引:6
根据不同地质背景特点将安徽全境分为5个地质背景区,分别从不同背景地质体(区域)和土壤类型集土样分析,并对结果进行统计处理,通过其差异性对, 出不同地质背景下发育的土壤中微量元素的丰缺(分为高,中,低,贪4级)及其对作物的适宜性,以此为基础对地质背景,特别是背景地质体与土壤微量元素的相关性进行了探讨。 相似文献
64.
Zhang S Lai X Liu X Li Y Li B Huang X Zhang Q Chen W Lin L Yang G 《Journal of agricultural and food chemistry》2012,60(14):3580-3585
The proliferation of fake and inferior edible bird's nest (EBN) products has recently become an increasingly serious concern. To identify and classify EBN products, a competitive enzyme-linked immunoassay (ELISA) was developed to quantitate sialoglycoprotein in EBN used in food and cosmetic applications. The characteristic sialoglycoprotein in EBN was found, extracted, purified, and analyzed. Sialoglycoprotein, considered the main carrier of sialic acid in EBN, consisted of 106 and 128 kDa proteins. A monoclonal antibody that could recognize both proteins was prepared. The heat-treated process did not change the affinity of sialoglycoprotein with the antibody. An optimized ELISA method was established with a cross-reactivity of less than 0.1% and an IC(50) of 3.3 μg/mL. On the basis of different food and cosmetic samples, the limits of detection (LOD) were 10-18 μg/g. Recoveries of fortified samples at levels of 20 and 80 μg/g ranged from 81.5 to 96.5%, respectively. The coefficients of variation were less than 8.0%. 相似文献
65.
Synchronizing rock clocks of Earth history 总被引:8,自引:0,他引:8
Kuiper KF Deino A Hilgen FJ Krijgsman W Renne PR Wijbrans JR 《Science (New York, N.Y.)》2008,320(5875):500-504
Calibration of the geological time scale is achieved by independent radioisotopic and astronomical dating, but these techniques yield discrepancies of approximately 1.0% or more, limiting our ability to reconstruct Earth history. To overcome this fundamental setback, we compared astronomical and 40Ar/39Ar ages of tephras in marine deposits in Morocco to calibrate the age of Fish Canyon sanidine, the most widely used standard in 40Ar/39Ar geochronology. This calibration results in a more precise older age of 28.201 +/- 0.046 million years ago (Ma) and reduces the 40Ar/39Ar method's absolute uncertainty from approximately 2.5 to 0.25%. In addition, this calibration provides tight constraints for the astronomical tuning of pre-Neogene successions, resulting in a mutually consistent age of approximately 65.95 Ma for the Cretaceous/Tertiary boundary. 相似文献
66.
The present research developed a bioeconomic model for control of Californian thistle (Cirsium arvense L. Scop.) in intensive, lowland sheep pastures in New Zealand. Production costs included two control methods: herbicides and defoliation, with defoliation encompassing both physical means and biocontrol measures. The model was used to examine the economic value of a research programme into biological control of the weed, given several different future scenarios. These scenarios were high herbicide prices, a price premium for lamb raised without chemical herbicides, and development of herbicide resistance. The model results were used to estimate national impacts. If the only change in the agricultural sector was the cost of the biocontrol to the nation's farmers, the research programme to find an effective biocontrol agent had little economic impact. If other factors changed, such as the price of petroleum or levels of herbicide resistance in the weed. the model's results suggested that intensive sheep farming could grow or shrink by as much as NZ$219 million dollars over five years. In the latter case, having an alternative control method reduced potential losses and increased potential gains, resulting in a net benefit of between NZ$81 million and NZ$153 million. This work extended prior research in several ways. First. Californian thistle reproduces via root buds, which affected the modelling of weed behaviour. Secondly, the model allowed optimistation over continuous levels of weed control for two different methods. Thirdly, the model accounted for both weed control and damage to nitrogen-fixing clover from herbicide use. Finally, the research investigated optimal weed control in several different alternative future states. 相似文献
67.
为了获得性状优良的水稻种质资源,采用EMS方法对缙恢21进行诱变,M4代获得不同类型的稳定突变材料,选取36份性状明显不同的突变材料进行SSR分子标记分析。从覆盖水稻12对染色体的200对SSR引物中筛选出15对扩增产物具有稳定多态性的引物,检测到59个等位基因,有效等位基因数为46.2574,有效等位基因百分数为78.40%,每对引物检测出3~5个等位基因,平均为3.9333个;遗传多样性指数在0.9951~1.3849之间,平均为1.2071;每个位点的多态性信息量变化于0.8285~0.9794之间,平均为0.9134。聚类分析得出,36份材料的遗传相似系数变幅为0.515~1.000,并在遗传相似系数0.63处将36份材料分为两大类群。 相似文献
68.
基于多目标决策的贵州地方稻种资源综合评价 总被引:1,自引:0,他引:1
为探索多目标决策在水稻资源和育种上的应用,为贵州水稻遗传研究和种质创新提供参考,同时也为稻种资源的综合评价和水稻育种工作提供新的方法,采用多目标决策方法对50份贵州地方稻种资源进行综合评价研究。结果表明:1)大糯表现最优,其次是野芒禾、白糯谷和野马糯稻。2)通过聚类分析将50份贵州地方稻种资源分为5类,第Ⅰ类早熟大粒型,第Ⅱ类表现一般,第Ⅲ类高秆、多穗、低结实率、小粒型,第Ⅳ类为高秆、高结实率、大穗型,第Ⅴ类为早熟、矮秆、多穗、高结实率型。其中,前3类表现为低产类型,后2类表现为高产类型。应用多目标决策综合评价最优的稻种资源正好在第Ⅳ类和第Ⅴ类中,表明,多目标决策在对稻种资源的综合评价中是简单有效的。 相似文献
69.
70.
Lucia T Corrêa MN Deschamps JC Bianchi I Donin MA Machado AC Meincke W Matheus JE 《Preventive veterinary medicine》2002,53(4):57-292
We evaluated stillbirth risk factors in two commercial swine farms of the Rio Grande do Sul State (south of Brazil). The study was conducted during 1 month in Farm A and during 2 months in Farm B, both during 1999. Data for all farrowings that occurred during the study period were recorded (101 for Farm A and 373 for Farm B), without interference in the farm management. In Farm A, 39% of all litters born during the period of interest had stillborn piglets and the stillborn risk for piglets was 12%. In Farm B, 25% of all litters had stillborn piglets whereas the stillborn risk was 2%. Variables considered as potential risk factors for stillbirths were: parity (1, 2–3, 4+); breed (purebred or crossbred); sow body-condition (normal or fat); use of oxytocin during parturition (yes or no); obstetric intervention through vaginal palpation (yes or no); farrowing duration (<4 or ≥4 h); mummified fetuses (yes or no); total litter size (<12 or ≥12 piglets); and litter birth weight (<11 or ≥11 kg). All stillborn piglets had their classification validated by necropsy. In multivariable logistic-regressions, the cases were the litters having at least one stillborn piglet. In Farm A, litters having at least 12 pigs and in which oxytocin was used during the parturition had 20.8-times-higher odds of stillborn occurrence. In Farm B, litters from sows having parity ≥4 had 2.2-times-higher odds of stillborn occurrence than litters from parity 2 to 3 females, litters having ≥12 pigs had 2.0-times-higher odds of a stillborn piglet than smaller litters and farrowings in which vaginal palpation was performed had 8.0-times-higher odds. Farrowing room management to minimize stillborn risk should target higher-parity females, large litters and optimization of practices of obstetric interventions. 相似文献