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51.
A wavefunction used in an earlier calculation of the nuclear shielding of the hydrogen molecule has been tested by comparing the calculated magnetic susceptibility against that of Kolos and Wolniewicz. Good agreement is obtained. The procedure of Herman and Short for averaging over the nuclear motion has also been tested by comparing the predicted susceptibilities of H2, Hd and D2 with those obtained from averages of the Rydberg-Klein-Rees potential curves by Jain and Sahni. Again, good agreement is found.For the first time calculated values have been obtained for the susceptibilities of the isoropomers of hydrogen which contain tritium. It is predicted that accurate susceptibility measurements should not only be able to distinguish between all the various isotopomers but should also detect the temperature dependence of the susceptibility of any one isotopomer. 相似文献
52.
53.
Free convection from a horizontal line source of heat 总被引:1,自引:0,他引:1
Norman Riley 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1974,25(6):817-828
Summary In this paper a study is made of finite Grashof number effects upon the flow, in an unbounded domain, in the buoyant plume which forms over a horizontal line source of heat. The consequences of introducing a plane boundary into the domain are also assessed for two particular configurations.
Zusammenfassung In dieser Arbeit wird der Effekt der endlichen Grashof-Zahl auf die Strömung untersucht, in einem unbegrenzten Medium mit natürlicher Konvektion, die durch eine horizontale linienförmige Quelle erzeugt wird. Die Folgen einer ebenen Begrenzungsfläche werden für zwei besondere Konfigurationen untersucht.相似文献
54.
An apparatus and a procedure are described for the preconcentration of nanogram amounts of trace elements. Co-precipitation and pressure filtration confine the precipitate to a 1.27 mm diameter spot on a filter membrane. Trace elements in the 10-100 ng range are collected reproducibly and detected with high sensitivity by X-ray fluorescence, by use of a milliprobe instrument. Advantages of the technique for quantitative applications are discussed. 相似文献
55.
56.
Adam NE Alexander JP Berkelman K Cassel DG Crede V Duboscq JE Ecklund KM Ehrlich R Fields L Galik RS Gibbons L Gittelman B Gray R Gray SW Hartill DL Heltsley BK Hertz D Hsu L Jones CD Kandaswamy J Kreinick DL Kuznetsov VE Mahlke-Krüger H Meyer TO Onyisi PU Patterson JR Peterson D Phillips EA Pivarski J Riley D Ryd A Sadoff AJ Schwarthoff H Shepherd MR Stroiney S Sun WM Urner D Wilksen T Weinberger M Athar SB Avery P Breva-Newell L Patel R Potlia V Stoeck H Yelton J Rubin P Cawlfield C 《Physical review letters》2005,94(23):232002
We describe new measurements of the inclusive and exclusive branching fractions for psi(2S) transitions to J/psi using e(+)e(-) collision data collected with the CLEO detector operating at CESR. All branching fractions and ratios of branching fractions reported here represent either the most precise measurements to date or the first direct measurements. Indirectly and in combination with other CLEO measurements, we determine B(chi(cJ) --> gamma(J/psi)) and B[psi(2S) --> light hadrons]. 相似文献
57.
Wiedeking M Tabor SL Pavan J Volya A Aguilar AL Calderin IJ Campbell DB Cluff WT Diffenderfer E Fridmann J Hoffman CR Kemper KW Lee S Riley MA Roeder BT Teal C Tripathi V Wiedenhöver I 《Physical review letters》2005,94(13):132501
Excited states in 20O were populated in the reaction 10Be(14C,alpha) at Florida State University (FSU). Charged particles were detected with a particle telescope consisting of 4 annularly segmented Si surface barrier detectors and gamma radiation was detected with the FSU gamma detector array. Five new states were observed below 6 MeV from the alpha-gamma and alpha-gamma-gamma coincidence data. Shell model calculations suggest that most of the newly observed states are core-excited 1p-1h excitations across the N=Z=8 shell gap. Comparisons between experimental data and calculations for the neutron-rich O and F isotopes imply a steady reduction of the p-sd shell gap as neutrons are added. 相似文献
58.
Gade A Bazin D Brown BA Campbell CM Church JA Dinca DC Enders J Glasmacher T Hansen PG Hu Z Kemper KW Mueller WF Olliver H Perry BC Riley LA Roeder BT Sherrill BM Terry JR Tostevin JA Yurkewicz KL 《Physical review letters》2004,93(4):042501
The 9Be(32Ar, 31Ar)X reaction, leading to the 5/2+ ground state of a nucleus at the proton drip line, has a cross section of 10.4(13) mb at a beam energy of 65.1 MeV/nucleon. This translates into a spectroscopic factor that is only 24(3)% of that predicted by the many-body shell-model theory. We introduce refinements to the eikonal reaction theory used to extract the spectroscopic factor to clarify that this very strong reduction represents an effect of nuclear structure. We suggest that it reflects correlation effects linked to the high neutron separation energy (22.0 MeV) for this state. 相似文献
59.
Mills SJ Riley AM Liu C Mahon MF Potter BV 《Chemistry (Weinheim an der Bergstrasse, Germany)》2003,9(24):6207-6214
New and rapid syntheses of the enantiomeric intracellular signalling molecules d-myo-inositol 1,4,5,6-tetrakisphosphate (1 a) and D-myo-inositol 3,4,5,6-tetrakisphosphate (1 b) are described. The synthetic strategy employs the novel butane-2,3-diacetal-protected (BDA-protected) myo-inositol (+/-)-3 ab, directly accessible from myo-inositol on a large scale, and an optical resolution with diastereoisomeric (R)-(-)-acetylmandelate esters. The X-ray crystal structure of (+/-)-4, an unusual side product of acid-catalysed reaction of myo-inositol with butanedione is also presented, and the absolute configurations of 1 a and 1 b are definitively assigned by conversion of key precursors into (+)-bornesitol and L-iditol hexaacetate, respectively. Biological activity of synthetic 1 b was confirmed in comparison with the natural polyphosphate. 相似文献
60.
Enzymatic and chemical oxidation of 4-(4-N,N-dialkylaminobutyl)catechols leads to formation of 1,1-dialkyl-pyrrolidinium salts in good yield. It is proposed that these products are formed by tautomerism of the initially formed ortho-quinones to para-quinomethanes. The corresponding secondary amines do not form para-quinomethanes but cyclise giving tetrahydro-1H-benzo[b]azepine-7,8-diones. The failure of the dialkylaminobutyl derivatives to cyclise to bicyclic betaines, in a manner analogous to lower homologues and monoalkylaminobutyl derivatives, is attributed to steric hindrance. This proposal is supported by evidence that the sterically hindered N-tert-butylaminobutyl derivative, in contrast to other secondary amines, does not cyclise but gives a para-quinomethane-derived product. Based on pulse radiolysis and spectrophotometric evidence, para-quinomethane formation appears to be much slower than cyclisation and only occurs when cyclisation is unfavourable. The ortho-quinones formed from 5-aminopentylcatechols neither cyclise nor tautomerise suggesting that the chain length in these derivatives is too long for both cyclisation and intramolecular deprotonation. 相似文献