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21.
J. L. Gels J. T. Elliston J. W. Talnagi S. E. Glover H. B. Spitz 《Journal of Radioanalytical and Nuclear Chemistry》2008,277(1):217-221
A revized method for determining 232Th using a pre-concentration neutron activation analysis (PCNAA) procedure was developed to accommodate irradiation in a dry
irradiation tube environment. 232Th extracted by ion-exchange from a sample was electrodeposited onto 5/8″ diameter vanadium planchets, which are arranged
in a stack and irradiated in the dry tube central irradiation facility (CIF) of the reactor. The higher neutron fluence of
this facility improved sensitivity by approximately 37%, however, the higher temperatures required modifications to the irradiation
procedure. Because the heat in the CIF would melt the plastic spacers used in the original method, a tube of high-purity quartz
was used to contain samples, and high purity quartz spacers were used to separate the vanadium planchets during the irradiation.
Test irradiations have determined that no significant transfer occurred from the disks to the silica disks and no significant
variation in the neutron flux was observed. Finally, a thin film barrier was tested for its ability to reduce recoil contamination
from 229Th onto the detector during alpha spectroscopy. The film was shown to reduce contamination to levels indistinguishable from
normal background. 相似文献
22.
Keggin type heteropolyacids was found to be an efficient and reusable catalyst for the synthesis of biologically active quinoxaline derivatives from the condensation of 1,2-diamine with 1,2-dicarbonyl compounds in excellent yields in water.This method provides a new and efficient protocol in terms of small quantity of catalyst,a wide scope of substrates,and simple work-up procedure. 相似文献
23.
A synthesis of methyl 2-hydroxy-4-oxo-4-(substituted phenyl)butanoates has been accomplished using Friedel-Crafts acylation of substituted benzenes with 2-acetoxybutanoyl chloride.The key feature of this strategy is that various 4-arylbutanoates can be obtained conveniently,which are important intermediates for the synthesis of biologically active compounds including ACE inhibitors. 相似文献
24.
Under mild conditions, conversion of a variety of ketoximes and aldoximes to their corresponding amides and nitriles proceeded in the presence of PEG-SO3H with high yields. 相似文献
25.
Methane gas sensor was fabricated based on electrocatalytic properties of the Pd/MWNT nanocomposites on indium tin oxide (ITO)glass substrates.A linear response for methane was obtained in the range of 0-16%(v/v)with a detection limit of 0.167%(v/ v)and R.S.D.of 4.1%.After 100 times sensing or stable stored more than 12 months in atmosphere,unconspicuous measurable decrease was observed.The response time was less than 60s at room temperature and ambient pressure.Some common potential interferents in samp... 相似文献
26.
Citrinal A(1),a novel tricyclic compound with a rare tetrahydro-2H-benzofuro[7-b][1,4]dioxin-9(3H)-one skeleton,along with two known related compounds,citrinin(2) and 2,3,4-trimethyl-5,7-dihydroxy-2,3-dihydrobenzofuran(3) were isolated from an algicolous fungus Penicillium sp.i-1-1.The structure and stereochemistry of 1 were determined by comprehensive spectral and biogenic analysis.Its cytotoxic effects on the A-549 and HL-60 cell lines were evaluated. 相似文献
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28.
A new 3,4-seco-lanostane triterpenoid,schisanlactone G (1),was isolated from the fruits of Schisandra sphenanthera.Its structure was established on the basis of extensive spectroscopic analysis.2009 Rong Tao Li.Published by Elsevier B.V.on behalf of Chinese Chemical Society.All fights reserved. 相似文献
29.
Under mild condition,using FeCl3 as catalyst,a series of functionalized diarylmethanes were prepared efficiently from the reactions of arenes with paraformaldehyde.This catalytic system is not sensitive to air and moisture. 相似文献
30.
Triangular silver nanoprisms were prepared and applied to make colorimetric detection of cysteine based on our findings that cysteine could lead to the blue shift of the dipole plasmon resonance absorption,but other 19 kinds of natural amino acids could not.Cysteine with a concentration 160 nmol/L can result in a color change that can be discerned with naked eyes. 相似文献