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排序方式: 共有931条查询结果,搜索用时 15 毫秒
831.
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833.
Wang M Simon JE Aviles IF He K Zheng QY Tadmor Y 《Journal of agricultural and food chemistry》2003,51(3):601-608
Artichoke leaf is an herbal medicine known for a long time. A systematic antioxidant activity-directed fractionation procedure was used to purify antioxidative components from the aqueous methanol extractions of artichoke heads and leaves in this study. Seven active polyphenolic compounds were purified from artichoke, and structural elucidation of each was achieved using MS and NMR. Two of these compounds, apigenin-7-rutinoside and narirutin, were found to be unique to artichoke heads, this represents the first report of these compounds in the edible portion of this plant. The contents of these antioxidants and total phenols in dried artichoke samples from leaves and immature and mature heads of three varieties, Imperial Star, Green Globe, and Violet, were then analyzed and compared by colorimetric and validated HPLC methods. Significant differences by variety and plant organ were observed. 相似文献
834.
Multiple mutations produce delta beta 0 thalassemia in Sardinia 总被引:5,自引:0,他引:5
In Sardinia the common form of beta thalassemia is a beta 0 thalassemia due to a nonsense mutation at codon 39. delta beta 0 Thalassemia is rare in Sardinia and is associated with increased production of hemoglobin F of the A gamma type. In this study we used a synthetic oligomer assay and detected the beta 39 nonsense mutation on the delta beta 0 thalassemia chromosome. Hence at least two different mutations have occurred on this chromosome; one that increases A gamma globin synthesis and another that silences the beta globin gene. 相似文献
835.
不同抚育方式杉木林效益的计量评价 总被引:2,自引:2,他引:0
在杉木不同抚育方式径流场定位观测基础上,根据不同抚育方式对杉木林的影响程度,对不同抚育方式杉木林生产效益、涵养水源效益及保持水土效益的计量结果表明:20年生扩穴连带抚育杉木林综合效益为63462.33元/hm2,比块状抚育杉木林高491.78元/hm2,但块状抚育经济效益明显高于扩穴连带抚育杉木林,今后林业经营中宜推广块状抚育. 相似文献
836.
M F Geertsma J F Nouws J L Grondel M M Aerts T B Vree C A Kan 《The Veterinary quarterly》1987,9(1):67-75
The depletion of sulphadimidine (SDM) and its N4-acetyl and hydroxy metabolites was studied in eggs laid by hens after administration of either a single or multiple oral dosages of 100 mg SDM/kg. During medication and until 1 day after the last dose, the SDM and its metabolite concentrations in the egg white exceeded those in the egg yolk and reflected the plasma levels. In the period starting 2 days after the (last) dosage, the SDM concentration in the yolk became higher than in the egg white, and the drug depletion curves ran parallel. The mean maximum amount of SDM found in the whole egg was 1500 micrograms after a single and 1280 micrograms after multiple dosage. In eggs, traces of the N4-acetyl and 6-methylhydroxy metabolites could be detected (mainly in the egg white), and their concentrations were approximately 40 times lower than those of the parent drug. A highly significant correlation (P less than 0.005) was found between the development stage of the oocyte at the time of (last) medication and the amount of SDM found in the egg that developed from it. A period of 7 or 8 days after the (last) dosage of 100 mg SDM/kg/day is required to obtain SDM levels below 0.1 micrograms/g egg. 相似文献
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840.
Miyamoto T Takahashi Y Oohashi T Sato K Oikawa S 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2005,67(3):243-248
Paraoxonase 1 (PON1) is an enzyme associated with high-density lipoprotein (HDL) and has a protective effect against oxidation of lipoproteins in mammals. We investigated PON1 enzyme activities in bovine serum and its distribution among bovine serum lipoproteins. Paraoxonase activity and arylesterase activity in serum (152 Holstein cows and 42 Japanese Blacks) were 275 +/- 55 U/ml and 130 +/- 27 U/ml (mean +/- SD), respectively. There was a high correlation (r=0.962) between the two enzyme activities, and the activity ratio of paraoxonase/arylesterase did not exhibit individual variation. More than 85% of both paraoxonase and arylesterase activities were detected in the HDL fraction separated by ultracentrifugation. The 43-kDa protein in the HDL fraction was identified as bovine PON1 by N-terminal amino acid sequence analysis. Bovine PON1 was purified by ultracentrifugation and preparative sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and an anti-bovine PON1 antiserum was developed. The concentration of PON1 protein determined by immunoblotting was closely correlated (r=0.976) with paraoxonase activity in serum. Bovine HDL was further fractionated into subpopulations, and the distribution of PON1 was examined. Paraoxonase activity and PON1 protein increased with decreasing HDL size and approximately 60% of total paraoxonase activity was distributed in the heavy HDL fraction. The different distributions of PON1 among HDL subpopulations might be concerned to the function and metabolism of bovine HDL. 相似文献