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151.
Lemos Maurício Ferrapontoff Mendes Luis Claudio Bohn Manfred Keicher Thomas 《Journal of Thermal Analysis and Calorimetry》2019,137(2):411-419
Journal of Thermal Analysis and Calorimetry - Hydroxyl-terminated polybutadiene (HTPB) has been widely modified and copolymerized with azide substances to be applicable as an elastomer binder in a... 相似文献
152.
Luana A. Pachechne Vinicius F. Pereira Guilherme M. Martins Edmar Martendal Fernando R. Xavier Samuel R. Mendes 《Tetrahedron letters》2019,60(38):151043
A general method for the synthesis of 1,2,3,4-tetrasubstituted pyrroles by [NMPH]CH3SO3 is reported. A full factorial design was performed in order to obtain a more robust and statistically correct optimum condition. The products were obtained in moderate to excellent yields. The developed methodology is very simple, cost-effective, and applicable for tri- and tetra-component reactions. 相似文献
153.
154.
L. C. Mendes D. F. Silva L. J. F. Araujo A. S. Lino 《Journal of Thermal Analysis and Calorimetry》2014,116(3):1461-1469
The applicability of thermogravimetry (TG) coupled to single photon ionization time-of-flight mass spectrometry (TG-SPI-TOFMS) for evolved gas analysis (EGA) of coffee is demonstrated in this study. Coffee is a chemically well-known complex food product of large scientific and commercial interest. The roasting process of single green coffee beans (Arabica, Robusta) was simulated in the TG-SPI-TOFMS device, and the chemical composition of the evolved roasting gases was monitored on-line. Additionally, roasted and ground coffee powders of different types and brands as well as instant coffee were successfully investigated. For example, the diterpenes cafestol and kahweol can be detected among many other roasting products. These compounds can be of particular interest for quality control of coffee. It is shown that kahweol can be used as a tracer compound to discriminate arabica coffee species from robusta species. 相似文献
155.
Rosilene S. Nascimento Nilton O.C. e Silva Denise B.C. Mendes José Bento B. Silva 《Talanta》2010,80(3):1102-1109
In this study we compared the use of ordinary least squares and weighted least squares in the calibration of the method for analyzing essential and toxic metals present in human milk by ICP-OES, in order to avoid systematic errors in the measurements used. Human milk samples were provided by maternity clinic Odete Valadares and digested by means of a high-performance microwave (MW) oven. Evaluation of plasma short and long-term stability was made using a solution of digested milk (1:50) with 2.0 mg L−1 Mg in HNO3 2% (v/v). The detection power resulted to be at or below the μg L−1 level, whilst the precision expressed as relative standard deviation R.S.D. was almost always equal to or better than 3.3%. Certified reference material Infant Formula (NIST SRM 1846) was used to assess the accuracy of the proposed method, which proved to be accurate and precise. Recovery rates were in the range of 83-117%. Aqueous calibration was carried out for each element under study. 相似文献
156.
Margarida Mendes Lopes Rita Pardini Sofia Tirabassi 《Mathematische Nachrichten》2023,296(10):4739-4744
Kawamata has shown that the quasi-Albanese map of a quasi-projective variety with log-irregularity equal to the dimension and log-Kodaira dimension 0 is birational. In this note, we show that under these hypotheses the quasi-Albanese map is proper in codimension 1 as conjectured by Iitaka. 相似文献
157.
158.
159.
Vítor Mendes Ana Maranha Pedro Lamosa Milton S da Costa Nuno Empadinhas 《BMC biochemistry》2010,11(1):21
Background
Maltose-1-phosphate was detected in Mycobacterium bovis BCG extracts in the 1960's but a maltose-1-phosphate synthetase (maltokinase, Mak) was only much later purified from Actinoplanes missouriensis, allowing the identification of the mak gene. Recently, this metabolite was proposed to be the intermediate in a pathway linking trehalose with the synthesis of glycogen in M. smegmatis. Although the M. tuberculosis H37Rv mak gene (Rv0127) was considered essential for growth, no mycobacterial Mak has, to date, been characterized. 相似文献160.
C. Luz‐Lima G. D. Saraiva A. G. Souza Filho W. Paraguassu P. T. C. Freire J. Mendes Filho 《Journal of Raman spectroscopy : JRS》2010,41(5):576-581
Raman spectroscopy measurements of polycrystalline Na2MoO4·2H2O (NMHO) and Na2MoO4 (NM) under hydrostatic pressure (from 0 to 10 GPa) were performed. This study allowed us to monitor the stretching and bending vibrations of MoO4 ions as well as the translational modes as a function of pressure. The pressure dependence of the wavenumbers of the modes indicates that the Na2MoO4·2H2O undergoes two phase transitions at about ∼3 and ∼4 GPa. When releasing pressure, we have observed that the original spectrum is recovered, thereby pointing to a reversible process. The Na2MoO4 (NM) starting phase was found to be stable up to 10 GPa. The pressure‐dependent Raman data for NM did not reveal any structural modification. The influence of the pressure‐transmitting medium on the phase transitions is also discussed. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献