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排序方式: 共有925条查询结果,搜索用时 15 毫秒
1.
Daniel E. Lynch Gillian E. Spicer Ian Mcclenaghan 《Journal of heterocyclic chemistry》2005,42(7):1363-1368
Three α‐phenylmalonamides have been prepared by the selective nucleophilic cleavage of 5,7‐dimethyl‐2‐phenyl‐1‐oxo‐1H‐pyrazolo[1,2‐a]pyrazol‐4‐ylium‐3‐olate in solventless microwave syntheses. The three weak nucleophiles employed were aniline, p‐chloroaniline and m‐toluidine. The α‐phenylmalonamides of these three aniline derivatives could not be prepared using the previously reported solvent syntheses via 3‐oxopyrazolo[1,2‐a]pyrazol‐8‐ylium‐1‐olates. All products were characterised using, infrared spectroscopy, 1H nmr and electrospray mass spectrometry. The single crystal X‐ray structures of the starting pyrazolo‐[1,2‐a]pyrazole and α‐phenylmalon‐m‐toluidide are also reported. 相似文献
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Summary Interpretive methods are accepted to give the best possible results for selectivity optimization in HPLC. However the methods are very complex, and most work so far has been detailed academic studies. This paper describes an evaluation of a complete integrated system incorporating peak labelling, modelling of retention behaviour and calculation of response surfaces, with particular emphasis on the retention modelling. The peak labelling section has been discussed previously.A piece-wise quadratic function is investigated for the modelling of retention times across an isoeluotropic plane to effect selectivity optimization in HPLC. This requires 10 data-points on the isoeluotropic plane. The predicted global optimum and local optima are evaluated by comparison of calculated and experimental retention data, for a nine component sample. Seven interstitial points, distributed across the whole plane between the data-points, are similarly evaluated for a related sample. The typical error (in retention time) is less than 2%, often 1%, and the maximum error is 4.2%. At the global optimum the error was found be less than 1.3% for all 9 peaks. 相似文献
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Determination of the total nitrogen content of hard, semihard, and processed cheese by the Kjeldahl method: collaborative study 总被引:1,自引:0,他引:1
The objective of this collaborative study was to determine interlaboratory performance statistics for a modified and optimized version of AOAC Method 920.123 for the determination of the total nitrogen content of hard, semihard, and processed cheese by Kjeldahl analysis. Details included addressing the issues of material homogeneity, test portion size (1 g), quantitative transfer (weighing on to filter paper), ensuring system suitability (nitrogen recoveries), and using AOAC Method 991.20 as the basis for nitrogen analysis. Fifteen laboratories tested 18 pairs of blind duplicate cheese materials with a crude protein content between 18 and 36%. Materials represented hard, semihard, and processed commercial cheeses with a wide range of composition. Statistical performance parameters expressed as crude protein (nitrogen x 6.38), g/100 g, with invalid and outlier data removed were mean = 26.461, repeatability standard deviation (Sr) 0.111, reproducibility standard deviation (S(R)) = 0.153, repeatability relative standard deviation (RSDr) = 0.42%, reproducibility relative standard deviation (RSDR) = 0.58%, repeatability (r) = 0.312, and reproducibility (R) = 0.428. The interlaboratory study results were acceptable and comparable to those for the milk Kjeldahl nitrogen method on a relative nitrogen basis. The Study Directors recommend that this modified method for the determination of total nitrogen in hard, semihard, and processed cheese by Kjeldahl analysis be adopted First Action as an improved method to replace Method 920.123. 相似文献
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Sajal Sen Mark W. Perrin Adam C. Sedgwick Vincent M. Lynch Jonathan L. Sessler Jonathan F. Arambula 《Chemical science》2021,12(21):7547
Recent decades have witnessed the emergence of Au(i) bis-N-heterocyclic carbenes (NHCs) as potential anticancer agents. However, these systems exhibit little interaction with serum proteins (e.g., human serum albumin), which presumably impacts their pharmacokinetic profile and tumor exposure. Anticancer drugs bound to human serum albumin (HSA) often benefit from significant advantages, including longer circulatory half-lives, tumor targeted delivery, and easier administration relative to the drug alone. In this work, we present Au(i) bis-NHCs complexes, 7 and 9, capable of binding to HSA. Complex 7 contains a reactive maleimide moiety for covalent protein conjugation, whereas its congener 9 contains a naphthalimide fluorophore for non-covalent binding. A similar drug motif was used in both cases. Complexes 7 and 9 were prepared from a carboxylic acid functionalized Au(i) bis-NHC (complex 2) using a newly developed post-synthetic amide functionalization protocol that allows coupling to both aliphatic and aromatic amines. Analytical, and in vitro techniques were used to confirm protein binding, as well as cellular uptake and antiproliferative activity in A549 human lung cancer cells. The present findings highlight a hitherto unexplored approach to modifying Au(i) bis-NHC drug candidates for protein ligation and serve to showcase the relative benefits of covalent and non-covalent HSA binding.Au(i) bis-N-heterocyclic carbenes (NHCs) functionalized using an amide linker were found to bind to human serum albumin (HSA) in covalent and non-covalent fashion. The solubility and in vitro anti-cancer activity of these new conjugates were studied. 相似文献
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