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排序方式: 共有865条查询结果,搜索用时 15 毫秒
821.
Matrix metalloproteinase-7 facilitates immune access to the CNS in experimental autoimmune encephalomyelitis 总被引:1,自引:0,他引:1
Lillian A Buhler Ramsey Samara Esther Guzman Carole L Wilson Liljana Krizanac-Bengez Damir Janigro Douglas W Ethell 《BMC neuroscience》2009,10(1):17
Background
Metalloproteinase inhibitors can protect mice against experimental autoimmune encephalomyelitis (EAE), an animal model for multiple sclerosis (MS). Matrix metalloproteinase-9 (MMP-9) has been implicated, but it is not clear if other MMPs are also involved, including matrilysin/MMP-7 – an enzyme capable of cleaving proteins that are essential for blood brain barrier integrity and immune suppression. 相似文献822.
Summary: In this paper we report the synthesis, characterisation and photopatterning of polydisperse fluorene oligomers. The oligomers were synthesised using the Yamamoto coupling. The molecular weights of the oligomers and as a consequence the nematic-isotropic transition temperatures were tailored by an endcapping reaction. With the endcapping species we introduced reactive acrylate functionalities. Subsequent photocrosslinking through a test mask led to the formation of fluorescent microstructures with a resolution of 1 µm. 相似文献
823.
824.
Chromatography in authenticity and traceability tests of vegetable oils and dairy products: a review 总被引:1,自引:0,他引:1
The new applications of various chromatographic techniques such as gas-liquid chromatography, high-performance liquid chromatography and electrophoretic methods employed for the analysis in macro- and micro-components in vegetable oils and dairy products are compiled and critically evaluated. The employment of these methods for authenticity tests and traceability is discussed. 相似文献
825.
Fraga MF Uriol E Borja Diego L Berdasco M Esteller M Cañal MJ Rodríguez R 《Electrophoresis》2002,23(11):1677-1681
A new approach to the evaluation of the relative degree of genomic DNA methylation through the quantification of 2'-deoxynucleosides is proposed. Detection and quantification of 5-methyl 2'-deoxycytidine in genomic DNA has been performed using micellar high-performance capillary electrophoresis (HPCE) with UV-Vis detection. This approach has been demonstrated to be more sensitive and specific than other HPCE methods for the quantification of DNA methylation degree and also to be faster than other HPLC-based methods. The detection and quantification of nucleosides through enzymatic hydrolyses notably increases the specificity of the technique and allows its exploitation in the analysis of poorly purified and/or concentrated DNA samples such as those obtained from meristematic plant regions and paraffin-embedded tissues. 相似文献
826.
Cserháti T Forgács E Darwish Y Morais H Mota T Ramos AC 《Journal of chromatography. A》2002,949(1-2):269-273
Multiwavelength spectrometry and reversed-phase high-performance liquid chromatography have been employed for the study of the effect of reduced glutathione and storage time on the pigments of paprika powders. The evaluation of the data by principal component analysis and cluster analysis proved that the storage time exerts the highest effect of the decomposition rate of pigments. The stability of some pigment fractions was modified in the presence of reduced glutathione. However, the effect was of secondary importance. Multiwavelength spectrometry combined with HPLC can be successfully used for the study of the stability of pigments of paprika powder. 相似文献
827.
Bröring M Tejero EC Pfister A Brandt CD Pérez Torrente JJ 《Chemical communications (Cambridge, England)》2002,(24):3058-3059
The metalation reactions of the 2,2'-bidipyrrin 4 with different rhodium(I) precursors yield the complexes 5 and 6 and the unusual corrinoid 7, depending only on the type of the ancillary ligand employed. 相似文献
828.
829.
The proper characterization of a commercial qualitative method for determining aflatoxin B1 in some nuts is described. A qualitative method that provides binary responses of the yes/no type means that the performance parameters have been properly adapted and defined. Performance characteristics such as the cut-off limit, the detection limit, sensitivity, specificity, false-positive and negative rates, and the unreliability or uncertainty region are defined and then estimated by means of the performance characteristic curves. The commercial test kit showed the cut-off limit at 1.6 ng/g, with a sensitivity rate of 95% and a false-negative rate of zero. A modification can be performed to shift the cut-off to 2.0 ng/g, keeping the same values for the sensitivity and false-negative rate. 相似文献
830.
Barrena E Palacios-Lidón E Munuera C Torrelles X Ferrer S Jonas U Salmeron M Ocal C 《Journal of the American Chemical Society》2004,126(1):385-395
The structure and stability of alkanethiols self-assembled on Au(111) have been studied as a function of the molecular chain length by means of atomic force microscopy (AFM) and grazing incidence X-ray diffraction (GIXD). Below saturation, phases consisting of molecules with different tilt angles and periodicities are formed. Differences in the mechanical stability of these phases are revealed by AFM experiments and discussed in terms of the competition between intermolecular and molecule-substrate interactions as a function of chain length. For long molecules, intermolecular interactions play a dominant role which stabilizes the formation of closed packed 30 degrees tilted ( radical 3x radical 3)R30 degrees structures. For short molecules, the van der Waals interaction with the gold substrate favors the formation of a 50 degrees tilted phase in which the molecules are arranged in a rectangular configuration. 相似文献