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101.
Ballmann J Yeo A MacKay BA van Rijt S Patrick BO Fryzuk MD 《Chemical communications (Cambridge, England)》2010,46(46):8794-8796
The side-on end-on dinitrogen complex [PhP(CH(2)SiMe(2)NPh)(2)Ta](μ-H)(2)(μ-η(2):η(1)-N(2)) reacts with CS(2) with complete cleavage of both C=S double bonds and the formation of [PhP(CH(2)SiMe(2)NPh)(2)Ta](μ-S)(2)(μ-CH(2)), which has two bridging sulfides and a bridging methylene unit. Further reaction with H(2) produces CH(4) and the disulfide complex. 相似文献
102.
103.
A digraph obtained by replacing each edge of a complete multipartite graph by an arc or a pair of mutually opposite arcs
with the same end vertices is called a semicomplete multipartite digraph. L. Volkmann conjectured that l≤2c−1, where l (c, respectively) is the number of vertices in a longest path (longest cycle) of a strong semicomplete multipartite digraph.
The bound on l is sharp. We settle this conjecture in affirmative.
Received: October 26, 1998?Final version received: August 16, 1999 相似文献
104.
105.
Using a suitable orientation, we give a short proof of a strengthening of a result of Czumaj and Strothmann 4 : Every 2‐edge‐connected graph G contains a spanning tree T with the property that for every vertex v. As an analogue of this result in the directed case, we prove that every 2‐arc‐strong digraph D has an out‐branching B such that . A corollary of this is that every k‐arc‐strong digraph D has an out‐branching B such that , where . We conjecture that in this case would be the right (and best possible) answer. If true, this would again imply a strengthening of a result from 4 concerning spanning trees with small degrees in k‐connected graphs when k ≥ 2. We prove that for acyclic digraphs the existence of an out‐branching satisfying prescribed bounds on the out‐degrees of each vertex can be checked in polynomial time. A corollary of this is that the existence of arc‐disjoint branchings , , where the first is an out‐branching rooted at s and the second an in‐branching rooted at t, can be checked in polynomial time for the class of acyclic digraphs © 2003 Wiley Periodicals, Inc. J Graph Theory 42: 297–307, 2003 相似文献
106.
Pt(2)(mu-Se)(2)(PPh(3))(4) reacts with PtCl(2)(cod) to give (Pt(2)(mu(3)-Se)(2)(PPh(3))(4)[Pt(cod)])(2+) and an unexpected cod-rich product that arises from metal scrambling, viz. (Pt(mu(3)-Se)(2)(PPh(3))(2)[Pt(cod)](2))(2+). The formation of these species was detected and followed by electrospray mass spectrometry (ESMS) and subsequently verified by batch synthesis and crystallographic characterization. Other metal-scrambled aggregate products were successfully detected. 相似文献
107.
R. Graham Cooks Adrian N. H. Yeo Dudley H. Williams 《Journal of mass spectrometry : JMS》1969,2(10):985-995
An investigation of competing metastable transitions in the mass spectra of ethylene ketals RSRLC(OCH2)2 (where RL is a larger n-alkyl group than RS) has established that in most cases RS is lost with a lower activation energy than RL. This technique has also been applied to ketones RSRLC?O, to show again that RS is usually lost with the lower activation energy (thus supporting earlier data based on relative daughter ion abundances at the threshold). In the classes of compounds so far investigated, although [M+ ? RS] ions are formed with lower activation energies than [M+ ? RL] ions, the ion yield of [M+ ? RS] ions is anomalously low from ions of high internal energy. Factors which may influence the [M+ ? RS]/[M+ ? RL] ratio of daughter ion intensities are examined. It is suggested that at the threshold [M+ ? RS] and [M+ ? RL] ions may be formed with rearrangement, or from an electronic state that cannot be effectively populated from molecular ions of high internal energies. 相似文献
108.
S. H. Goh S. Y. Lee Y. T. Yeo X. Zhou K. L. Tan 《Macromolecular rapid communications》1999,20(3):148-151
A rare miscible polyacrylonitrile (PAN) blend system is reported. PAN is miscible with poly(p‐vinylphenol) (PVPh) as shown by thermal and spectroscopic studies. A single glass transition temperature was found in each blend. Infrared spectroscopic studies showed that the hydroxyl band of PVPh and the cyano band of PAN shifted to lower frequencies upon blending, showing the existence of specific interactions between the two polymers. The involvement of cyano groups in specific interactions was further evidenced by the development of a high‐binding‐energy N1s peak in each blend from X‐ray photoelectron spectroscopic studies. 相似文献
109.
Anders Yeo 《Journal of Graph Theory》1997,24(2):175-185
The problem of finding necessary and sufficient conditions for a semicomplete multipartite digraph (SMD) to be Hamiltonian, seems to be both very interesting and difficult. Bang-Jensen, Gutin and Huang ( Discrete Math to appear) proved a sufficient condition for a SMD to be Hamiltonian. A strengthening of this condition, shown in this paper, allows us to prove the following three results. We prove that every k-strong SMD with at most k-vertices in each color class is Hamiltonian and every k-strong SMD has a cycle through any set of k vertices. These two statements were stated as conjectures by Volkmann (L. Volkmann, a talk at the second Krakw Conference of Graph Theory (1994)) and Bang-Jensen, Gutin, and Yeo (J. Bang-Jensen, G. Gutin, and A. Yeo, On k-strong and k-cyclic digraphs, submitted), respectively. We also prove that every diregular SMD is Hamiltonian, which was conjectured in a weaker form by Zhang (C.-Q. Zhang, Hamilton paths in multipartite oriented graphs, Ann Discrete Math. 41 (1989), 499–581). © 1997 John Wiley & Sons, Inc. 相似文献
110.