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   20篇
  免费   3篇
  国内免费   1篇
  2019年   1篇
  2018年   1篇
  2017年   3篇
  2013年   3篇
  2012年   1篇
  2011年   1篇
  2009年   2篇
  2008年   1篇
  2006年   2篇
  2004年   2篇
  2003年   3篇
  1998年   1篇
  1992年   1篇
  1982年   1篇
  1979年   1篇
排序方式: 共有24条查询结果,搜索用时 15 毫秒
1.
The chromatographic analysis of carboxyl-containing mycotoxins, such as fumonisin B1, ochratoxin A, and citrinin, presents a continual challenge. Toxins must first be extracted from foods or tissues and then cleaned up before chromatographic separation and detection. Liquid–liquid extraction efficiencies for some carboxylic mycotoxins are marginal for spiked samples and uncertain for incurred residues. Immunoaffinity columns may be useful for concentrating mycotoxins from samples before chromatography. In almost every case, more than one analytical method must be used to confirm the identification of the mycotoxin. The fumonisins are especially troublesome to analyze because they are relatively insoluble in organic solvents, they are not separated easily by gas chromatography, and they do not respond to the usual absorbance or fluorescence detectors used in liquid chromatography. Fluorescence derivatization and electrospray liquid chromatography–mass spectrometry have now made it possible to detect trace levels of mycotoxins. The purity of mycotoxin standards for toxicological studies can be determined by liquid chromatography with either an evaporative light scattering detector or electrospray mass spectrometer. New developments in capillary electrophoresis, nonporous microsphere liquid chromatography, and detection methods for low-volatility compounds show promise for improving the analysis of mycotoxins in the future.  相似文献   
2.
The specific immune-reaction between the anti-citrinin antibody immobilized on the surface of magnetic/silica core–shell (MSCS) and the citrinin–Rho123–BSA conjugate brings the Rho123 fluorophore as an acceptor and the QDs as a donor in close spatial proximity and causes FRET for occurring upon photo-excitation of the QDs. The novelties of this study include: (1) immobilization of the MSCS; (2) large amount of the immobilized QDs, and (3) immobilization of a large amount of Rho123 on the BSA macromolecule. Cd/Te QDs were synthesized by the simultaneous reduction of cadmium chloride and tellurium in the presence of sodium borohydride. Magnetic nanoparticles were synthesized using FeSO4 and FeCl3. The prepared magnetic nanoparticles shelled by silica using tetraethoxysilane in the presence of ammonia. Transmission electron microscopy (TEM) analysis was used for investigating shape and monodispersity of the nanoparticles. EDC/NHS was used as a cross linking agent for immobilization of the QDs, conjugation of citrinin to amino groups of BSA, labeling of BSA with Rho123 and also for immobilization of the amino-functionalized MSCS on the immobilized QDs. Immobilization of the anti-citrinin antibody on the surface of the amino-functionalized MSCS was performed by Schiff-base mechanism. By using these three effective strategies, sensitivity of the designed nanobiosensor was incredibly enhanced as a very low limit of detection (up to 0.1 pM). The feasibility of this technique was tested by the detection of citrinin in the spiked human serum. Results showed that there was a linear correlation between the decreased fluorescence intensity of the Rho123 and increased fluorescence intensity of the QDs with increasing concentration of citrinin in the spiked samples in the range of 1–6 pM. According to obtained results, we conclude that this highly sensitive detection scheme is a easy, quick and impressive method that can be used in optical-based nanosensors.  相似文献   
3.
Abstract

Saatweizen wurde ohne vorhergchende Sterilisation mit einem Ochratoxin A und Citrinin bildenden Stamm von Penicillium verrucosum beimpft und bei Wassergehalten von 18, 20, 22, 24 und 26% bei 4 und 10°C gelagert. Die Produktion von Ergosterin, eines chemischen Indikators für die von Pilzen gebildete Biomasse, setzte innerhalb der untersuchten Lagerdauer (240 Tage) ein. Lediglich bei 18% H2O/4°C war keine Zunahme des Ergosteringehaltes zu beobachten. Ochratoxin A und Citrinin waren bei 18% H2O/4°C und 20% H2O/4°C über 240 Tage nicht zu finden (Nachweisgrenze: 10 bzw. 25 μg/kg). Bei den übrigen Kombinationen von Wassergehalt und Temperatur begann die Anhäufung der beiden Toxine etwa gleichzeitig mit der Ergosterinproduktion. Mit steigendem Wassergehalt und steigender Temperatur nahm die Zeit bis zum Beginn der Ergosterinproduktion ab, während die Geschwindigkeit der Produktion von Ergosterin, Ochratoxin A und Citrinin zunahm. Beide Toxine wurden während einer ersten Phase der Anhäufung etwa mit gleicher Rate gebildet. Bei 20–26% H2O hatten der Wassergehalt und die Temperatur keinen Einfluß auf die Beziehung zwischen dem Toxingehalt und dem gleichzeitig erreichten Ergosteringehalt. Es wird empfohlen, stark mit Penicillium verrucosum kontaminierten Weizen nicht über den Beginn der Ergosterinproduktion hinaus zu lagem.

INVESTIGATIONS ON REFRIGERATED STORAGE OF WHEAT

1. Ergosterol, ochratoxin A and citrinin after inoculation with Penicillium verrucosum

Seed wheat was innoculated without having been sterilized with an ochratoxin A and citrinin forming strain of Penicillium verrucosum and stored at moisture contents of 18, 20, 22, 24, and 26% at 10 and 4°C. The production of ergosterol, a chemical indicator of fungal biomass, started within the storage time investigated (240 days). Only at 18% H2O/4°C an increase of the ergosterol content was not observed. Ochratoxin A and Citrinin were not detected at 18% H2O/4°C and 20% H2O/4°C within 240 days (detection limit: 10 and 25 μg/kg, respectively). At the other combinations of moisture content and temperature the first detection of the two toxins approximately coincided with the onset of ergosterol production. With increasing moisture content and temperature the time up to the start of ergosterol production decreased, whereas the production rates of ergosterol, ochratoxin A and citrinin increased. Both toxins were produced with about the same rate during a first phase of accumulation. At 20–26% H2O there was no influence of moisture content and temperature on the relation between toxin content and the simultaneously reached ergosterol content. It is recommended that wheat highly contaminated with Penicillium verrucosum should not be stored beyond the start of ergosterol production.  相似文献   
4.
5.
The mycotoxins citrinin, patulin and terreic acid are absorbed by rice seedling roots and translocated to shoots. Ten day analysis of toxin treated plants showed persistence of citrinin, patulin and terreic acid. All three toxins at a concentration of 100 ppm showed phytotoxic activity indicating terreic acid in addition to citrinin and patulin as phytotoxins.  相似文献   
6.
红曲霉桔霉素的检测方法及红曲霉产桔霉素的判别方法*   总被引:13,自引:0,他引:13  
建立了红曲霉真菌毒素桔霉素的HPLC检测方法。用谷氨酸和葡萄糖为唯一氮、碳源的培养基(MSG)液态摇瓶培养及红曲米固态培养,对30多株红曲霉产桔霉素的情况进行了普查,发现大多数红曲霉菌种可产生桔霉素。红曲霉的培养状态及条件对桔霉素的产生有重大影响。红曲霉菌种是否产桔霉素,可根据MSG培养基摇瓶发酵液中是否含有桔霉素来初步定性判断,为准确判断红曲霉菌是否产桔霉素,可采用多种培养法综合判断。  相似文献   
7.
红曲菌能产生多种有益的次级代谢产物,但红曲菌也产生一种对人和哺乳动物肝和肾有毒害的毒素,即桔霉素。因此控制毒素的产生是保障红曲产品安全性所必须的。故对桔霉素的合成途径及相关的基因做深入了解。6个桔霉素合成相关的基因成簇位于21 kb的DNA片段上。克隆了一个新基因(orf7基因),其位于该基因簇的外侧。采用基因敲除技术,构建红曲菌orf7基因缺失菌株。并采用紫外分光光度法检测orf7基因缺失菌株的红曲色素产量,HPLC法检测其桔霉素产量。orf7缺失菌株产红曲色素能力与出发菌株As3.4384相比没有变化;产桔霉素培养13~19 d,桔霉素的产量与出发菌株As3.4384相比增加了 142.4%。从而证实orf7基因与桔霉素代谢相关。  相似文献   
8.
The production of red pigments and citrinin by Monascus purpureus CCT3802 was investigated in submerged batch cultures performed in two phases: in the first phase, cells were grown on glucose, at pH 4.5, 5.5 or 6.5; after glucose depletion, pH was adjusted, when necessary, to 4.5, 5.5, 6.5, 7.0, 8.0 or 8.5, for a production phase. The highest total red pigments absorbance of 11.3 U was 16 times greater than the lowest absorbance and was achieved with growth at pH 5.5, followed by production at pH 8.5, which causes an immediate reduction of the intra cellular red pigments from 75% to 17% of the total absorbance. The lowest citrinin concentration, 5.5 mg L−1, was verified in the same culture while the highest concentration, 55 mg L−1, was verified in cultures entirely carried out at pH 5.5. An alkaline medium, besides promoting intra cellular red pigments excretion, strongly represses citrinin synthesis.  相似文献   
9.
The aims of this work were to determine the effect of feeding BALB/c mice a diet containing culture materials of a citrinin producing strain of Penicillium citrinum (Thom). Changes in hematological parameters, serum chemistry and histological changes in liver, kidney and heart were determined. After 60 days, control treated (CT) mice appeared normal in all respects, whereas, the mice fed the feeds supplemented with Penicillium (CMT) showed decreased weight gain, lower hematocrits, increased serum alanine aminotransferase (ALT) and clear signs of renal and hepatotoxicity based on histological changes. Changes observed in the liver of CMT mice included portal and lobular infiltration of polymorphonuclear cells, with concomitant hepatocellular necrosis, hepatic steatosis, prominent Kupffer's cells, hemosiderin granules in the cytoplasm of periportal hepatocytes and other lipid inclusions in the surrounding mitochondria were also observed. Our findings suggest that in vivo, P. citrinum Thom metabolites, which contain citrinin, could cause illnesses such as toxic hepatitis or intravascular hemolysis.  相似文献   
10.
红曲中桔霉素的检测及控制   总被引:1,自引:0,他引:1  
潘荣华  郑立忠  姜嘉善  蒙辉  徐小丽 《生物磁学》2013,(36):7160-7164,7134
红曲是指以大米为原料,用红曲菌属(Monascusspp.)红曲霉发酵培养制得,具有红色的颗粒或用其制成的粉末。目前红曲可分为色曲、酒曲和功能性红曲。在红曲霉的发酵过程中,同时与红曲色素相伴产生一种有害的次级代谢产物一桔霉素。研究表明桔霉素具有肾毒性,可致畸、致癌和诱发基因突变。桔霉素的存在,制约了红曲在食品及药品方面的广泛应用,在一定程度上阻碍了红曲产业的发展。为此,在红曲生产中如何快速准确检测桔霉素以及有效地防控桔霉素,是我们当前迫切需要解决的问题。本文对近年来国内外红曲中桔霉素的检测方法及控制策略进展进行了综述。目前,桔霉素的检测方法主要有抑菌圈法、TLC法、酶联免疫法和HPLC法等,其中HPLC法是检测红曲中桔霉素高效且应用最广泛的方法。桔霉素的控制主要从菌种选育,发酵工艺及产品后续处理等方面进行调控。目前尚没有成熟的控制策略全部去除桔霉素,只有采用低产桔霉素的菌种,适合的生产工艺及结合后续的物理或化学处理等综合措施,生产出符合桔霉素控制标准的高品质红曲产品。  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