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排序方式: 共有142条查询结果,搜索用时 327 毫秒
1.
I. M. Kolthoff S. R. Cooper V. J. Tulane F. Reimers H. A. J. Pieters K. Höppner V. H. Matula C. B. Macek W. N. Skworzow J. S. Schepelewa F. Čuta K. Kámen S. Cohen R. E. Oesper D. S. Narayanamurthi T. R. Seshadri H. M. State A. W. Kirssanow W. M. Tscherkassow D. M. Mukherjee T. Akiyama Y. Mine S. Yabe Y. Volmar M. Déribéré 《Analytical and bioanalytical chemistry》1937,111(5-6):192-197
2.
CV Tomy D Pal SS Banerjee S Ramakrishnan AK Grover S Bhattacharya MJ Higgins G Balakrishnan McK Paul 《Pramana》2002,58(5-6):925-935
The weakly pinned single crystals of the hexagonal 2H-NbSe2 compound have emerged as prototypes for determining and characterizing the phase boundaries of the possible order-disorder
transformations in the vortex matter. We present here a status report based on the ac and dc magnetization measurements of
the peak effect phenomenon in three crystals of 2H-NbSe2, in which the critical current densities vary over two orders of magnitude. We sketch the generic vortex phase diagram of
a weakly pinned superconductor, which also utilizes theoretical proposals. We also establish the connection between the metastability
effects and pinning. 相似文献
3.
T Nishi F Saito H Nagahori M Kataoka Y Morisawa Y Yabe M Sakurai S Higashida M Shoji Y Matsushita 《Chemical & pharmaceutical bulletin》1990,38(1):103-109
Syntheses and biological activities of dipeptide renin inhibitors that contain statine analogues are described. The key steps of the synthetic approach to dipeptide renin inhibitors are the asymmetric synthesis of 2(R)-substituted-3-aminocarbonylpropionic acids and the diastereoselective syntheses of (3S,4S)-statine analogues. These inhibitors (2,14-40) inhibited human renin in the 3-140 nM range. Inhibitor ES 6864 (2) was found to be a highly potent inhibitor of human renin (IC50: 4.6 x 10(-9) M) and showed high enzyme specificity. Oral administration of ES 6864 at 3 mg/kg to conscious, sodium-depleted marmosets inhibited plasma renin activity (PRA) more than 80% after 1 h. 相似文献
4.
Alberti G Brunet E Dionigi C Juanes O de La Mata MJ Rodríguez-Ubis JC Vivani R 《Angewandte Chemie (International ed. in English)》1999,38(22):3351-3353
The hydrophilic oxygen atoms of polyethylenoxide chains inserted as pillars in gamma-zirconium phosphate form hydrogen bonds with the acid groups of the host. As a result the pillars are almost perpendicular to the gamma layers. Upon changing the pH level of the supernatant solution the hydrogen bonds are broken and the pillars become almost perpendicular to the layers (shown schematically). Thus there is a reversible enlargement-shortening of the interlayer space. 相似文献
5.
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7.
Sol-gel-derived titania films were analyzed by temperature programmed desorption (TPD) and X-ray diffraction (XRD) techniques.
The relationship between the TPD curves measured for two types of titania gel films and their crystal structures was investigated.
On the basis of the analyses, a preparation process for a titania sol solution containing anatase nanocrystals was designed
and developed. Using this process, a colloidal anatase titania sol solution was prepared by heating aqueous titanium hydroxide
containing HCl at 60°C for 2 h. The nanocrystal structure of the titania films obtained by coating the sol on glass substrates
was confirmed by TPD and XRD measurements. 相似文献
8.
F Oka H Sagawa K Yabe A Okuyama M Tachibana T Noge K Torizumi S Okamoto M Yasui T Tuda 《Radioisotopes》1988,37(10):572-575
The patients receiving maintenance hemodialysis were divided into two groups in the absence and the presence of bone pain and investigated the markers of bone pain in these patients. These results suggested that the duration of receiving hemodialysis, serum concentrations of alkaline phosphatase, osteocalcin and parathyroid hormone became to be the markers of bone pain. 相似文献
9.
In the chemistry toward generating benzdiyne from five benzenetetracarboxylic dianhydride derivatives, ketene formation was exclusively observed in the photolysis of difluorobenzenetetracarboxylic dianhydride in a nitrogen matrix at 13 K. Two ketenes were formed concomitantly with difluorobenzdiyne. These ketenes were identified on the basis of good agreement between the observed and calculated (B3LYP/6-31G level) IR spectra. Neither ketene contained the five-membered-ring moiety as cyclopentadienylideneketene, which is formed by Wolff rearrangement in the benzyne chemistry. The first generated ketene was assigned to a ketene with a cyclopropene moiety, and the second, to a ketene with a butadiyne moiety. The first generated ketene was a major product in the photolysis and was formed by cleavage of the bond connecting the ketene group and the C-F carbon and not the bond connecting the ketene group and the carbene moiety. Thus the structures of these ketenes indicated that a unprecedented ring cleavage, rather than Wolff rearrangement, is the dominant process in the benzdiyne chemistry. 相似文献
10.
Density functional theory (DFT) studies were performed to investigate the effect of substituents on the properties of benzdiyne derivatives. Twelve substituted benzdiynes-C(6)X(2), where X = F, Cl, Br, Me, CF(3), CN, OH, NO(2), NH(2), OMe, NMe(2), and Ph-were considered along with the unsubstituted 1,4-benzdiyne. The structures, vibrational frequencies, and IR intensities of these benzdiynes were studied with a popular three-parameter hybrid density functional (B3LYP) combined with the split-valence 6-31G(d) basis set and Dunning's correlation-consistent polarized triple-zeta (cc-pVTZ) basis set. The relative stabilities of the substituted benzdiynes were studied with the help of reaction energies of isodesmic reactions, which showed that the electron-withdrawing groups destabilized the benzdiynes more than they did the corresponding benzenes, whereas the electron-donating groups stabilized the benzdiynes more than they did their benzene counterparts. Correlation analyses revealed that field/inductive effects played a more important role than did resonance effects. The changes in atomic charges and spin populations due to the substituents were also studied. The asymmetric nu(Ctbd1;C) stretching modes obtained were close to the 1500-cm(-)(1) mark. Reinvestigation of the experimental results supported these results; a weak IR band at 1486 cm(-)(1) was assigned to this asymmetric stretching mode in C(6)(CF(3))(2) F. Some other benzdiynes also had large IR intensity values for their asymmetric nu(Ctbd1;C) vibrational modes due to the coupling with other vibrational modes. Heats of formation for the substituted benzdiynes were obtained from the reaction energies calculated at the B3LYP/cc-pVTZ level of theory. 相似文献