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排序方式: 共有221条查询结果,搜索用时 15 毫秒
181.
182.
M. Nekipelov M. Bü scher W. Cassing M. Hartmann V. Hejny V. Kleber H. R. Koch V. Koptev Y. Maeda R. Maier S. Merzliakov S. Mikirtychiants H. Ohm A. Petrus D. Prasuhn F. Rathmann Z. Rudy R. Schleichert H. Schneider K. Sistemich H. J. Stein H. Str her K. -H. Watzlawik C. Wilkin 《Physics letters. [Part B]》2002,540(3-4):207-212
The ratio of forward K+ production on copper, silver and gold targets to that on carbon has been measured at proton beam energies between 1.5 and 2.3 GeV as a function of the kaon momentum pK using the ANKE spectrometer at COSY-Jülich. The strong suppression in the ratios observed for pK<200–250 MeV/c may be ascribed to a combination of Coulomb and nuclear repulsion in the K+A system. This opens a new way to investigate the interaction of K+-mesons in the nuclear medium. Our data are consistent with a K+A nuclear potential of VK0≈20 MeV at low kaon momenta and normal nuclear density. Given the sensitivity of the data to the kaon potential, the current experimental precision might allow one to determine VK0 to better than 3 MeV. 相似文献
183.
Kovács A Konings RJ Raab J Gagliardi L 《Physical chemistry chemical physics : PCCP》2008,10(8):1114-1117
Americium and curium oxides AmOn and CmOn (n = 1, 2) were studied using state-of-the-art multiconfigurational, relativistic, quantum chemical methods. Spectroscopic properties for the ground state and several excited states of the four target compounds were determined. The computed dissociation energy of AmO (4.6 eV) agrees fairly well with estimates derived from experimental studies (5.73 +/- 0.37 eV) while the computed dissociation energy of CmO (7.1 eV) agrees well with the experimental value (7.5 eV). The computed ionization energy of AmO (6.3 eV) is in good agreement with the current experimental value (5.9 +/- 0.2 eV). 相似文献
184.
Naproxen (NAP) and ibuprofen (IBU) are poor water soluble anti-inflammatory drugs. A water-soluble epichlorohydrin-β-cyclodextrin polymer (β-CDEPI) was synthesized in a highly basic aqueous solution and at a molar ratio β-CD/EPI of 1:12. Drug solubility and kinetic release of NAP and IBU from the inclusion complexes they form with β-CDEPI as host was studied. Water solubility for both drugs in the presence of this polymer increased (NAP 0.28 mmol and IBU 0.40 mmol per gram of β-CDEPI). The apparent inclusion constants for both drugs in β-CDEPI were calculated from the solubility-phase diagrams with Kincl values of 4300 ± 100 L.mol? 1 for NAP and 5100 ± 300 L.mol? 1 for IBU. Kinetic release of Ibuprofen gave a pure Fick trend (t1/2) behavior. However, for Naproxen a zero order was obtained (t). These results indicate that the nature and bulkiness of the drugs are ruling these kinetic behaviors in the environment of a highly branched polymer. 相似文献
185.
John S. Maass Rudy L. Luck Matthias Zeller 《Acta Crystallographica. Section C, Structural Chemistry》2012,68(8):m233-m234
The title compound, [Co2(C2H4NO)2(OH)2(C5H5N)4](ClO4)2·2C2H3N, consists of two octahedral CoIII centers arranged around an inversion point in which two cis hydroxide and two trans acetylamidate ligands link the two centers together, forming a dimeric cationic complex. Each CoIII center has two cis pyridine ligands which coordinate in the same plane as the cis hydroxide ligands. Two acetonitrile solvent molecules and two perchlorate anions are hydrogen bonded to the H atoms on the bridging hydroxide and acetylamidate (N atom) ligands, respectively. 相似文献
186.
The preparation and structural characterization of two trinuclear vanadium complexes, (V(3)(μ(3)-O)O(2))(μ(2)-O(2)P(CH(2)C(6)H(5))(2))(6)(H(2)O), 1, and (V(3)(μ(3)-O)O(2))(μ(2)-O(2)P(CH(2)C(6)H(5))(2))(6)(py), 2, are reported. In these nonclassical structures, the planar central core consists of the three vanadium atoms arranged in the form of an acute quasi-isosceles triangle with the central oxygen atom multiply bonded to the vanadium atom at the center of the vertex angle and weakly interacting with the two other vanadium atoms on the base sites, each of which contain one external multiply bonded oxygen atom. Reacting VO(acac)(2)in the presence of diphenylphosphinic acid affords (VO(O(2)PPh(2))(2))(∞), 3, while 2-hydroxyisophosphindoline-2-oxide at room temperature in CH(2)Cl(2) affords ((H(2)O)VO(O(2)Po-(CH(2))(2)C(6)H(4))(2))(∞), 4, and at 120 °C in EtOH yields (VO(O(2)P(o-(CH(2))(2)(C(6)H(4)))(∞), 5 on the basis of elemental analyses. The thermal and chemical stability of the complexes were assessed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) measurements. The bond strengths of the vanadium atoms to the OH(2) ligand in 1 and to the NC(5)H(5) ligand in 2 were assessed at 10.7 and 42.0 kJ/mol respectively. Room temperature magnetic susceptibility measurements reveal magnetic moments for trinuclear 1 and 2 at 3.02(1) and 3.05(1) μ(B/mol), and also close to spin only values (1.73 μ(B)) values for 3, 4, and 5 at 1.77(2), 1.758(7), and 1.77(3) μ(B), respectively. Variable-temperature, solid-state magnetic susceptibility measurements were conducted on complex 2 in the temperature range of 2.0-298 K and at an applied field of 0.5 T. Magnetization measurements at 2 and 4 K confirmed a very weak magnetic interaction between the vanadyl centers. 相似文献
187.
Craig A. Bayse Ampa Jimtaisong Anil K. Kandalam Rudy L. Luck Ravindra Pandey Mark J. Stevens 《Journal of Molecular Structure》2005,754(1-3):96-99
The crystal structure of MoO(O2)2(H2O)(hmpa), hmpa=hexamethylphosphoramide, has been reassessed and corrected as one of the axial parameters (namely the c-axis) was reported incorrectly. This resulted in significant differences in the internal geometry of the molecule, notably an decreased O–O atom distance (≈0.03 Å) in the metal-bonded peroxo ligands. Crystal packing forces and a flat bending potential of the Mo–O–P angle accounts for discrepancies between theory and experimental structures. 相似文献
188.
Hormoz Azizian Rudy Luck Robert H. Morris Hector Wong 《Journal of organometallic chemistry》1982,238(3):C24-C26
High yield syntheses and properties of the new complexes Mo(η6-C6H5-PMePh)(PMePh2)2(L), L PMePh2 and P(OMe)3, are reported along with new direct preparations of Mo(N2)2 (PMePh2)4 and Mo(η6-C6H6)(PMePh2)3. 相似文献
189.
Dr. Peter Rogl Subhash K. Naik Erwin Rudy 《Monatshefte für Chemie / Chemical Monthly》1977,108(6):1325-1337
The system TiC–HfC–MoC was investigated by means of melting point, differentiothermoanalytical, X-ray diffraction and metallographic techniques on hotpressed as well as melted alloy specimens. A constitutional diagram from 1500°C through the melting range was established.Investigation of the (Hf, Mo)C system (isopleth: HfC0.98–MoC1.0) showed a small miscibility gap within the cubic monocarbide solution () [Tc=1630°C, (HfC)0.45(MoC)0.55]. The miscibility gap interacts with the solvus curve with a monotectoid-like decomposition reaction at 1575°C, (HfC)0.35(MoC)0.65.At temperatures below 1630°C, phase equilibria within TiC–HfC–MoC are characterized by a large miscibility gap connecting the TiC–HfC and HfC–MoC boundary systems. Additions of MoC to TiC–HfC alloys decrease the critical temperature (1780°C); additions of TiC to HfC–MoC alloys raise the critical temperature (1630°C). No maximum type ternary critical point or saddle point was found to occur.Isothermal sections were prepared at 1500°C and 1650°C. At temperatures above 1960°C (-MoC+C-MoC) a complete solid solution (-B 1) is formed within TiC–HfC–MoC. The melting behaviour (liquidus projection of TiC–HfC–MoC) shows flat melting temperatures in the MoC corner but extremely heterogeneous melting near the TiC–HfC boundary.Isothermal sections have been calculated assuming regular solutions.With 5 Figures 相似文献
190.
H. Nowotny R. Kieffer F. Benesovsky C. Brukl E. Rudy 《Monatshefte für Chemie / Chemical Monthly》1959,90(5):669-679
Zusammenfassung In Übereinstimmung mit der Volumregel sind die isotypen Monokarbide von Ti, Zr, Nb und Ta mit HfC lückenlos mischbar. HfC und Cr3C2 zeigen keinerlei gegenseitige Löslichkeit, dagegen löst HfC in sehr starkem Maße Mo2C bzw. MoC (über 80 Mol%). WC wird von HfC unter den gewählten Bedingungen bis gegen 40 Mol% aufgenommen. HfC und UC lösen sich weitgehend, entgegen der Erwartung jedoch nicht lückenlos. Ein vollkommener Übergang dürfte erst bei hohen Temperaturen (etwa 2500°C) bestehen, aber es genügen 10 Mol% ZrC, um die bei tiefen Temperaturen bestehende Mischungslücke zu schließen.Mit 6 Abbildungen 相似文献