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排序方式: 共有209条查询结果,搜索用时 218 毫秒
101.
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Mushtaq Sajid Choi Mi Hee Yang Jung Eun Shim Ha Eun Song Lee Song Ha Yeon Choi Yong Jun Jeon Jongho 《Journal of Radioanalytical and Nuclear Chemistry》2018,317(2):997-1003
Journal of Radioanalytical and Nuclear Chemistry - We herein report a convenient radiolabeling method capable of real-time in vivo imaging and biodistribution of bacteria in a living subject.... 相似文献
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Bashir S Giannakopulos AE Derrick PJ Critchley P Bottrill A Padley HJ 《European journal of mass spectrometry (Chichester, England)》2004,10(1):109-120
In the first part of this study fragmentation patterns from a range of dextran oligomers (containing 4-20 anhydroglucose units) were compared in three different methods of analysis coupled with matrix-assisted laser desorption/ionisation (MALDI) mass spectrometry. Collision-induced-dissociation (CID), prompt in-source decay (ISD) and post-source decay (PSD) all caused cleavage of the glycosidic bonds. Both CID and to a lesser extent ISD caused further cleavage of pyranose rings of the individual sugar residues. There was very little cleavage of pyranose rings detected in the PSD spectrum. Derivatisation of the reducing end-groups of the oligodextrans with 1-phenyl-3-methyl-5-pyrazolone (PMP) restricted cleavage in the MALDI mass spectrometer to the non-reducing end, and further it enabled the saccharides to be separated by HPLC so that a single chain length could be examined as a standard. Maltoheptaose was also used as a standard. In the second part of the study prompt ISD-MALDI mass spectrometry was used to compare the fragmentation of three oligoglucans, dextran, maltodextrin and gamma cyclodextrin, that have different linkages and different secondary structure. The results showed that the degree of fragmentation correlated with the degree of freedom in the saccharide chains in solution determined by NMR. Dextran the most random conformation was fragmented most whereas there was little evidence of any fragments, not even glycosidic bond breakage from cyclodextrin, even when the laser power was increased considerably. The fragmentation pattern of maltodextrin was intermediate. The patterns of fragmentation produced by MALDI mass spectrometry, particularly where standards are available to calibrate the spectrum and the energy of the laser is controlled, can be used to predict the type of linkage present. 相似文献
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Ahmad Z Mehmood S Fatima I Malik A Ifzal R Afza N Iqbal L Latif M Nizami TA 《Magnetic resonance in chemistry : MRC》2008,46(1):94-98
Salsolins A (1) and B (2), the new triterpenes, have been isolated from the chloroform soluble fraction of Salsola baryosma along with 2alpha,3beta,23,24-tetrahydroxyurs-12-en-28-oic acid (3) reported for the first time from this species. Their structures have been assigned from 1H and 13C NMR spectra, DEPT and by 2D COSY, NOESY, HMQC and HMBC experiments. The compounds 1-3 showed significant antioxidant activity. 相似文献
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KABIR-UD-DIN ALI Mohd. Sajid KHAN Zaheer 《物理化学学报》2008,24(5):810-816
Kinetics of D-mannose oxidation by cerium (IV) was studied in a sulfuric acid medium at 40℃ both in absence and presence of ionic micelles. In both cases, the rate of the reaction was first-order in D-mannose and in cerium(Ⅳ), which decreased with increasing [H2SO4]. This suggested that the redox reaction followed the same mechanism. The reaction proceeded through formation of an intermediate complex, which was proved by kinetic method. The complex underwent slow unimolecular decomposition to a free radical that reacted with cerium (Ⅳ) to afford the product. The catalytic role of cationic cetyltrimethylammonium bromide (CTAB) micelles was best explained by the Menger-Portnoy model. The study of the effect of CTAB also indicated that a negatively charged species was reactive form of cerium (Ⅳ). From the kinetic data, micelle-cerium (Ⅳ) binding and rate constants in micellar medium were evaluated.The anionic micelle of sodium dodecyl sulfate plays no catalytic role. The oxidation has the rate expression --d[Ce(Ⅳ)]= k1Kcl[D-mannose] [Ce(Ⅳ)]dt Different activation parameters for micelle catalyzed and uncatalyzed paths were also calculated and discussed. 相似文献
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Muhammad Aamir Sajid Sohail Anjum Shahzad Fatima Hussain W. G. Skene Muhammad Yar 《合成通讯》2018,48(15):1893-1908
Chitin and chitosan are well-thought-out multipurpose biopolymers. Chitosan which is deacetylated chitin is useful than chitin and is biomaterial of great interest. Regardless of its biodegradability, chemical modifications suggest due to the amino side reactivity, helps to impart it other great qualities. Herein, we discuss the preparative methods of synthetically modified derivatives, some are commercially available. This review shields the literature from last few decades. 相似文献
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Iqbal Muhammad Sajid Inc Mustafa Safdar Samreen Tarar Muhammad Akhtar ahmed Muhammad Ozair Shahid Naveed 《Optical and Quantum Electronics》2022,54(9):1-16
Optical and Quantum Electronics - In the current paper, we try to engineer the refractive index profile in a one-dimensional photonic crystal as a powerful tool to manage the electromagnetic wave... 相似文献