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882.
Summary Principles are proposed to select solvents for the coating of glass capillary columns with medium-polar and polar stationary phases applying the free-release static-coating technique, practical examples are given, demonstrating that this technique is suitable to coat stationary phases like OV-1701 and Carbowaxes. 相似文献
883.
In the crystal structure of N,N′-dimethylurea, there is one molecule in the asymmetric unit, but with two halves related by
an axis of pseudosymmetry. All nonhydrogen atoms of each molecule lie on a plane. In the crystal the molecules are held together
by hydrogen bonds in the direction of the “a” axis. They form parallel rows with the same sense orientation, so that the crystal has a polar structure. 相似文献
884.
IstvÁn Talata 《Geometriae Dedicata》1999,74(1):61-71
For a collection C of convex bodies let h(C) be the minimum number m with the property that every element K of C can be covered by m or fewer smaller homothetic copies of K. Denote by C
d
*
the collection of all duals of cyclic d-polytopes, d 2. We show that h(C
2k
*
)=(k +1)2 for any k 2. We also prove the inequalities (d+1) (d+3)/4 h(C
d
*
) (d+1) 2/2$ for any d 2. 相似文献
885.
Klaus Metsch 《Designs, Codes and Cryptography》1999,17(1-3):219-224
In bose&burton, Bose and Burton determined the smallest point sets of PG(d, q) that meet every subspace of PG(d, q) of a given dimension c. In this paper an equivalent result for quadrics of elliptic type is obtained. It states the folloing. For 0 c n - 1 the smallest point set of the elliptic quadric Q
-(2n + 1, q) that meets every singular subspace of dimension c of Q
-(2n + 1, q) has cardinality (q
n+1 + q
c
)(q
n-c
- 1)/(q - 1). Furthermore, the point sets of the smallest cardinality are classified. 相似文献
886.
A submillisecond response, wide view and single-cell-gap transflective (TR) display employing a blue-phase liquid crystal is proposed. The device employs polar opposite in-plane switching (IPS) electrodes. To balance the optical phase retardation between transmissive (T) and reflective (R) regions, the IPS electrodes are formed with unequal gaps in the two regions. This display exhibits reasonably high optical efficiency and well-matched voltage-dependent transmittance and reflectance curves. 相似文献
887.
Adéla Jagerová Petr Malinský Romana Mikšová Pavla Nekvindová Jakub Cajzl Petr Ryšánek Anna Macková 《Surface and interface analysis : SIA》2020,52(12):1083-1088
The paper presents a study of 5-MeV energy Au+ ion implantation in polar c-plane (0001), nonpolar a-plane (11-20) and m-plane (10–10) ZnO crystallographic cuts using fluences of 5 × 1014 and 1 × 1015 cm−2. The implanted samples were subsequently annealed in O2 atmosphere at 600°C. It was shown that a-plane ZnO exhibited a lowest level of Zn sublattice disorder evidenced by Rutherford backscattering spectroscopy in channelling mode (RBS-C); in contrast, m-plane ZnO showed the highest disorder. The disorder in the Zn sublattice grew progressively in the subsurface as well as in the implanted layer in c-plane and m-plane ZnO, while a-plane has shown slight increase of disorder just in the implanted layer. Angular scans provided using RBS-C have shown the preservation of channelling effect in the subsurface layer in a-plane ZnO. On the contrary, the narrowed and shallow angular scan dips were seen in m-plane ZnO. Raman spectroscopy has shown significant O-sublattice disorder and O rearrangement mainly in a-plane and m-plane ZnO compared to c-plane. After ion implantation, the exciton-related luminescence band at 375 nm vanished almost completely, and the defect-related band ‘shifted’ to shorter wavelengths. Annealing has beneficial influence on near-band-edge (NBE) luminescence recovery, whereas deep-level-emission (DLE) luminesce has been shifted to lower wavelengths than appeared after implantation. 相似文献
888.
889.
890.
Yi-Ming Zhang Xin-Yang Wang Jian-Peng Wang Wei Shao Shao-Qiu Xiao 《Molecular physics》2014,112(12):1724-1730
ReaxFF molecular dynamics (MD) simulations are performed to study high-temperature pyrolysis of toluene under microwave heating. It is observed that the temperature of the reaction system under microwave heating has a rapidly rising stage, which is similar to the phenomenon of thermal runaway often appeared in reactions under microwave heating. Simulations indicate that the consumption rate of toluene and generating rates of H2 and CH4 obtained under microwave heating are always lower than those obtained under conventional heating at the early stage. Analyses of the pyrolysis of toluene show that ReaxFF MD simulations can provide an efficient way to study chemical reactions under microwave heating. 相似文献