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We show how the mapping of the magnetic field vector components can be achieved in a fountain clock by measuring the Larmor transition frequency in atoms that are used as a spatial probe. We control two vector components of the magnetic field and apply audio frequency magnetic pulses to localize and measure the field vector through Zeeman spectroscopy. 相似文献
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Mathieu Renouf Philippe A. Guy Cynthia Marmet Anne‐Lise Fraering Karin Longet Julie Moulin Marc Enslen Denis Barron Fabiola Dionisi Christophe Cavin Gary Williamson Heike Steiling 《Molecular nutrition & food research》2010,54(6):760-766
Previous studies on coffee examined absorption of phenolic acids (PA) in the small intestine, but not the contribution of the colon to absorption. Nine healthy volunteers ingested instant soluble coffee (~335 mg total chlorogenic acids (CGAs)) in water. Blood samples were taken over 12 h, and at 24 h to assess return to baseline. Many previous studies, which used glucuronidase and sulfatase, measured only PA and did not rigorously assess CGAs. To improve this, plasma samples were analyzed after full hydrolysis by chlorogenate esterase, glucuronidase and sulfatase to release aglycone equivalents of PA followed by liquid–liquid extraction and ESI‐LC‐ESI‐MS/MS detection. Ferulic, caffeic and isoferulic acid equivalents appeared rapidly in plasma, peaking at 1–2 h. Dihydrocaffeic and dihydroferulic acids appeared in plasma 6–8 h after ingestion (Tmax=8–12 h). Substantial variability in maximum plasma concentration and Tmax was also observed between individuals. This study confirms that the small intestine is a significant site for absorption of PA, but shows for the first time that the colon/microflora play the major role in absorption and metabolism of CGAs and PA from coffee. 相似文献
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Marmet P 《The Review of scientific instruments》1979,50(1):79
The extremely simple mathematical technique called 'straightening through smoothing,' which is a numerical frequency filter, is generalized in order to provide a transmission function having any shape. This frequency filter requires such a small memory that it can be performed using a minicomputer or even a programmable hand held calculator and the number of channels used is not limited to a power of 2, as in the case of the fast Fourier transform. For some filtering functions the number of operations required is smaller than with the fast Fourier transform. 相似文献
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Marmet L. Madej A.A. Siemsen K.J. Bernard J.E. Whitford B.G. 《IEEE transactions on instrumentation and measurement》1997,46(2):169-173
We have measured the frequency of the 5s 2S1/2 -4d 2D5/2 clock transition of a single Sr ion confined in a Paul trap. A diode laser locked to an ultrastable Fabry-Perot (F-P) cavity was used to probe the transition with a resolution of 3.5 kHz. The absolute frequency was determined from heterodyne measurements referenced to an iodine stabilized HeNe laser and a CO2 laser yielding a value for the S-D transition of (444 779 043 963±30) kHz. This work could lead to the development of a new optical frequency standard at 674 nm 相似文献
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Francesca Giuffrida Isabelle Masserey Elmelegy Sagar K. Thakkar Cynthia Marmet Frédéric Destaillats 《Lipids》2014,49(10):997-1004
It has been reported that dietary gangliosides may have an important role in preventing infections and in brain development during early infancy. However, data related to the evolution of their concentration over the different stages of lactation are scarce. Liquid chromatography coupled with electrospray ionization high resolution mass spectrometer (LC/ESI‐HR‐MS) has been optimized to quantify the two major ganglioside classes, i.e., aNeu5Ac(2‐8)aNeu5Ac(2‐3)bDGalp(1‐4)bDGlcp(1‐1)Cer (GD3) and aNeu5Ac(2‐3)bDGalp(1‐4)bDGlcp(1‐1)Cer (GM3) in human milk. Gangliosides were extracted using chloroform and methanol, further purified by solid‐phase extraction and separated by reversed‐phase liquid chromatography. Repeatability, intermediate reproducibility, and recovery values were assessed to validate the method. In human milk, GD3 and GM3 could be quantified at the level of 0.1 and 0.2 μg/mL, respectively, with relative standard deviation of repeatability [CV(r)] and intermediate reproducibility [CV(iR)] values ranging from 1.9 to 15.0 % and 1.9 to 22.5 %, respectively. The described method was used to quantify GD3 and GM3 in human milk samples collected from 450 volunteers between 0 and 11 days and at 30, 60 and 120 days postpartum, providing for the first time the concentration of these minor lipids in a large cohort. The content of total gangliosides ranged from 8.1 and 10.7 μg/mL and the mean intake of gangliosides in infants 30, 60 and 120 days postpartum could be estimated at about 5.5, 7.0 and 8.6 mg of total gangliosides per day, respectively, when infants were exclusively breastfed. 相似文献
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