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排序方式: 共有143条查询结果,搜索用时 15 毫秒
1.
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
2.
P. L. Trakhtenberg M. N. Zemtsova A. N. Gusarov V. P. Zvolinskii A. E. Lipkin 《Chemistry of Heterocyclic Compounds》1979,15(6):608-611
The electronic structures and reactivity indexes (RI) of 2-(4-R-2-quinolyl)thiophenes and 5-(4-R-2-quinolyl)-2,2-dithienyls (R = H, COOH, COOC2H5, and NHCOCH3) and their protonated forms were calculated by the Pariser-Parr-Pople (PPP) method. The peculiarities of the geometrical and -electron structures were established. The calculated reactivity indexes are compared with experimental data on the electrophilic substitution reactions of the investigated compounds. A qualitative agreement between the calculated values and the experimental data was established. It is shown that quinoline derivatives of thiophene are less reactive than the corresponding dithienyl compounds in electrophilic substitution reactions.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 751–754, June, 1979. 相似文献
3.
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
4.
5.
6.
2-Nitro-5-(4-carboxy-2-quinolyl)thiophene was obtained bynitration of 5-(4-carboxy-2-quinolyl) thiophene. Data from microbiological tests of the nitro-substituted thiophene and its carboxyl-group derivatives are presented.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 183–184, February, 1973. 相似文献
7.
Crotonoid condensation of 5-formyl-2,2′-dithienyl with some aromatic and heterocyclic ketones in alkaline medium is used to synthesize a number of hitherto undescribed α,β unsaturated ketones of the 2,2′-dithienyl series. All the compounds investigated give intensely colored halochromic solutions in sulfuric acid. 相似文献
8.
K. Hansen O. Dybing M. Jowett M. Marks und D. Lipkin 《Fresenius' Journal of Analytical Chemistry》1942,124(7-8):312-314
Ohne Zusammenfassung 相似文献
9.
10.
Joel Lipkin 《Experimental Mechanics》1974,14(5):177-183
An experimental method is described that has been used to determine the yield strength of 6061-T6 aluminum after extremely short times at elevated temperature. The method combines electron-beam pulse heating and onedimensional stress-wave loading. A 3.5-MeV pulsed electron-beam source (pulse width of 70 nanoseconds) is used to deposit energy uniformly through the thickness and along a limited region of a slender aluminum rod. An axial compressive stress wave, produced by projectile impact on one end of the rod, propagates into the heated region a few microseconds after energy deposition. The nanosecond electron-beam pulse increases the internal energy of the material before it can expand to equilibrium dimensions at the elevated temperature. Additional time is therefore required for the specimen to equilibrate mechanically through the propagation of radial release waves which originate at the stress-free boundary of the sample. The deformation produced by these radial relief waves is coupled with microstructural changes that also contribute to a reduction in the yield strength of the material at elevated temperature, as well as at room temperature following electron-beam heating. 相似文献