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1.
Hong Ming ZHANG Xian Hong WANG Xiao Jiang ZHAO Ji LI Fo Song WANG 《中国化学快报》2006,17(4):437-440
A novel method for the preparation of oligothiophene molecular wires is described via a bi-directional solid-phase synthesis. Using an alternating sequence of bromination and Stille coupling reactions, oligomers were obtained up to the heptamer in excellent yield and purity. 相似文献
2.
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4.
G. A. Van Fo Fy 《Mechanics of Composite Materials》1965,1(2):49-53
The basic relations of the theory of anisotropic creep of unidirectional glass-reinforced plastics (GRPs) in a three-dimensional stress state are found using a model of a material with inhomogeneous structure and the rheological properties of the resin. These relations are suitable for investigating the stress state of GRPs for resin stresses not exceeding certain values. The phenomena of simple creep and stress relaxation are studied with reference to a unidirectional GRP with an epoxy-maleic resin matrix.Mekhanika Polimerov, Vol. 1, No. 2, pp. 64–69, 1965 相似文献
5.
Let R be a ring with involution *. We consider R as a ring equipped with a new product r s = rs + sr*. The relationship between (ordinary) ideals of R and right ideals of R with respect to the product is studied.AMS Subject Classification (2000): 16W10, 16D25 相似文献
6.
A new radiochemical scheme for the quantitative isolation of Ga, Sc, Hf and La, based on ion exchange and extraction chromatography,
was devised, Ga and Sc were selectively retained on a Dowex 50WX2 [H+] column from 10 M HBr at 50°C. Ga was then eluted with ethyl acetate 0.25M in HBr, and scandium with 4M HBr. Hf was separated
from 10M HBr at 75°C on a Kel-F column impregnated with tri-n-octylphosphine oxide (TOPO). The lanthamm fraction, after evaporation
to dryness, was purified by ion-exchange chromatography in the system: Dowex 50WX8 [H+]−HCl. The effect of accompanying elements, and also the differences in the mechanism of uptake by the resin of various elements
from concentrated HBr solution are briefly discussed. The scheme has been used for the determination of these four elements
in refractory materials by activation analysis. As this procedure assured practically quantitative isolation of Ga, Sc, Hf
and La, the addition of carriers and determination of chemical yield were unnecessary. The radiochemical purities of the respective
fractions were as a rule high, and the measurements were performed by NaI(Tl) spectrometry. The detection limits were of the
order of fractions of ppm, and could be considerably improved if necessary by increasing the counting time and sample weight. 相似文献
7.
[RhIII(Cp*)]‐Catalyzed ortho‐Selective Direct C(sp2)H Bond Amidation/Amination of Benzoic Acids by N‐Chlorocarbamates and N‐Chloromorpholines. A Versatile Synthesis of Functionalized Anthranilic Acids 下载免费PDF全文
Fo‐Ning Ng Prof. Dr. Zhongyuan Zhou Prof. Dr. Wing‐Yiu Yu 《Chemistry (Weinheim an der Bergstrasse, Germany)》2014,20(15):4474-4480
A RhIII‐catalyzed direct ortho‐C?H amidation/amination of benzoic acids with N‐chlorocarbamates/N‐chloromorpholines was achieved, giving anthranilic acids in up to 85 % yields with excellent ortho‐selectivity and functional‐group tolerance. Successful benzoic acid aminations were achieved with carbamates bearing various amide groups including NHCO2Me, NHCbz, and NHTroc (Cbz=carbobenzyloxy; Troc=trichloroethylchloroformate), as well as secondary amines, such as morpholines, piperizines, and piperidines, furnishing highly functionalized anthranilic acids. A stoichiometric reaction of a cyclometallated rhodium(III) complex of benzo[h]quinoline with a silver salt of N‐chlorocarbamate afforded an amido–rhodium(III) complex, which was isolated and structurally characterized by X‐ray crystallography. This finding confirmed that the C?N bond formation results from the cross‐coupling of N‐chlorocarbamate with the aryl–rhodium(III) complex. Yet, the mechanistic details regarding the C?N bond formation remain unclear; pathways involving 1,2‐aryl migration and rhodium(V)– nitrene are plausible. 相似文献
8.
Ferrocene-terminated trans-Ru(dppm)2 (dppm=Ph2PCH2pph2)-containing molecular wires with alligator clips were prepared.They are suitable for self-assembly on gold electrode to investigate the influence of metal incorporation on the electron transportation property of the molecular wires. 相似文献
9.
The main purpose of this paper is to prove the following result. Let R be a prime ring of characteristic different from two and let T : R → R be an additive mapping satisfying the relation T(x
3) = T(x)x
2 − xT(x)x + x
2
T(x) for all x ∈ R. In this case T is of the form 4T(x) = qx + xq, where q is some fixed element from the symmetric Martindale ring of quotients. This result makes it possible to solve some functional
equations in prime rings with involution which are related to bicircular projections. 相似文献
10.
An alternative approach to the study of Jordan ideals in associative algebras is considered. The same method can be used when analogous questions in graded algebras are treated. 相似文献