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排序方式: 共有1441条查询结果,搜索用时 31 毫秒
961.
962.
Chiara Guarino Fabio Fuselli Alessandro La Mantia Lucia Longo Angelo Faberi Rosa Maria Marianella 《Rapid communications in mass spectrometry : RCM》2010,24(6):705-713
A common fraud in the dairy field is the addition of sheep's milk to goat's cheeses, because it has a very similar taste to goat's milk, but is more available, and is commonly considered to have a better capacity to curdle. For similar reasons, and due to economic convenience, sheep's cheeses may also contain fraudulent cow's milk. In order to detect this fraud, an EU official method may be used, but it is only a qualitative method (presence/absence of cow's milk). A method able to quantify the presence of sheep's milk during cheese production in goat's and cow's cheeses was developed. The method is based on liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) analysis of peptides of a casein extract from the cheese. By a simple procedure, caseins are extracted from cheeses, solubilized, digested with plasmin, and subsequently analyzed by LC/ESI‐MS/MS. A typical sheep's peptide produced by plasmin hydrolysis (m/z = 860) was accurately selected and analyzed to understand if, and by how much, a declared pure goat's cheese contains sheep's milk. By analyzing the same peptide it is also possible to detect if, and by how much, a declared pure sheep's milk contains, or not, cow's milk. The method was applied to several goat's and cow's cheese samples. Quantitation was performed with a calibration curve obtained by analyzing curd cheeses containing different percentages of sheep's milk. The method detection limit and method quantitation limit were evaluated. This method appears accurate and suitable for detecting up to 2% of sheep's milk in cheeses. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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965.
Renato M. Angelo 《Foundations of Physics》2009,39(2):109-119
The polemical term “interaction-free measurement” (IFM) is analyzed in its interpretative nature. Two seminal works proposing
the term are revisited and their underlying interpretations are assessed. The role played by nonlocal quantum correlations
(entanglement) is formally discussed and some controversial conceptions in the original treatments are identified. As a result
the term IFM is shown to be consistent neither with the standard interpretation of quantum mechanics nor with the lessons
provided by the EPR debate. 相似文献
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Motivated by a renewed interest in generalizations of classical almost periodicity (originally due to Harald Bohr), we develop
a theorem of Bochner within the framework of almost periodic functions in the sense of Stepanov. As a result we establish
some conditions that guarantee the existence of Stepanov almost periodic solutions to differential equations with Stepanov
almost periodic coefficients. Finally, we extend a now classic theorem of Favard originally stated for classical almost periodic
functions to the Stepanov almost periodic case.
相似文献
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B. Gawlik Martine Druges Michele Bianchi Angelo Bortoli Antonius Kettrup Herbert Muntau 《Analytical and bioanalytical chemistry》1997,358(3):441-445
The quality of the aquatic and marine environment can be monitored by the determination of pollutants in organisms living in this environment. Certified reference materials and well-organised proficiency tests are powerful means of ensuring a constant level of quality and verifying the correct application of standardised methods. The preparation of a tuna fish proficiency testing material for the evaluation of quality of As and Hg monitoring in seafood is described. Preparation and characterisation of the material as well as studies on its homogeneity and stability are described. Concentrations of 3.4 ± 0.2 mg/kg total arsenic and 2.91 ± 0.09 mg/kg total mercury have been determined as target values. Moreover indicative values for some trace elements (Cd, Cu, Ni, Pb, Sr) and some major constituents (Al, Br, C, Ca, Cl, Fe, H, K, Mg, N, Na, P, S, Si, Zn) have also been measured. 相似文献