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排序方式: 共有4601条查询结果,搜索用时 31 毫秒
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Dr. Karlee P. Castro Dr. Tyler T. Clikeman Nicholas J. DeWeerd Dr. Eric V. Bukovsky Kerry C. Rippy Dr. Igor V. Kuvychko Dr. Gao‐Lei Hou Dr. Yu‐Sheng Chen Dr. Xue‐Bin Wang Dr. Steven H. Strauss Dr. Olga V. Boltalina 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(12):3930-3936
In a simple, one‐step direct trifluoromethylation of phenazine with CF3I we prepared and characterized nine (poly)trifluoromethyl derivatives with up to six CF3 groups. The electrochemical reduction potentials and gas‐phase electron affinities show a direct, strict linear relation to the number of CF3 groups, with phenazine(CF3)6 reaching a record‐high electron affinity of 3.24 eV among perfluoroalkylated polyaromatics. 相似文献
35.
An efficient approach for Cu-catalyzed thiolation of Csp2–H bonds of directing-group-containing aromatic amides with 1°, 2°, and 3° aliphatic thiols and thiophenols has been developed. This method shows excellent functional group tolerance and provides a straightforward way for the preparation of aryl thioethers. 相似文献
36.
We define a new statistic on the even hyperoctahedral groups which is a natural analogue of the odd length statistic recently defined and studied on Coxeter groups of types and . We compute the signed (by length) generating function of this statistic over the whole group and over its maximal and some other quotients and show that it always factors nicely. We also present some conjectures. 相似文献
37.
《Mathematische Nachrichten》2017,290(8-9):1381-1405
The aim of this article is to exhibit the variety of different Ricci soliton structures that a nilpotent Lie group can support when one allows for the metric tensor to be Lorentzian. In stark contrast to the Riemannian case, we show that a nilpotent Lie group can support a number of non‐isometric Lorentzian Ricci soliton structures with decidedly different qualitative behaviors and that Lorentzian Ricci solitons need not be algebraic Ricci solitons. The analysis is carried out by classifying all left invariant Lorentzian metrics on the connected, simply‐connected five‐dimensional Lie group having a Lie algebra with basis vectors and and non‐trivial bracket relations and , investigating the various curvature properties of the resulting families of metrics, and classifying all Lorentzian Ricci soliton structures. 相似文献
38.
Tobias Kildetoft 《代数通讯》2017,45(6):2325-2333
We define the position of an irreducible complex character of a finite group as an alternative to the degree. We then use this to define three classes of groups: position reducible (PR)-groups, inductively position reducible (IPR)-groups and weak IPR-groups. We show that IPR-groups and weak IPR-groups are solvable and satisfy the Taketa inequality (ie, that the derived length of the group is at most the number of degrees of irreducible complex characters of the group), and we show that any M-group is a weak IPR-group. We also show that even though PR-groups need not be solvable, they cannot be perfect. 相似文献
39.
Assume a fixed point v∈VG can be separated from zero by a homogeneous invariant f∈𝕜[V]G of degree prd, where p>0 is the characteristic of the ground field 𝕜 and p,d are coprime. We show that then v can also be separated from zero by an invariant of degree pr, which we obtain explicitly from f. It follows that the minimal degree of a homogeneous invariant separating v from zero is a p-power. 相似文献
40.
In this paper, we determine the universal central extension, derivation algebra and automorphism group of the twisted N = 1 Schrödinger–Neveu–Schwarz algebra. Furthermore, we generalize these results to the generalized twisted N = 1 Schrödinger–Neveu–Schwarz algebra in the final section. 相似文献