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51.
Dr. W. Hill Harman Dr. Tzu‐Pin Lin Prof. Dr. Jonas C. Peters 《Angewandte Chemie (International ed. in English)》2014,53(4):1081-1086
Bifunctional E? H activation offers a promising approach for the design of two‐electron‐reduction catalysts with late first‐row metals, such as Ni. To this end, we have been pursuing H2 activation reactions at late‐metal boratranes and herein describe a diphosphine–borane‐supported Ni—(H2) complex, [(PhDPBiPr)Ni(H2)], which has been characterized in solution. 1H NMR spectroscopy confirms the presence of an intact H2 ligand. A range of data, including electronic‐structure calculations, suggests a d10 configuration for [(PhDPBiPr)Ni(H2)] as most appropriate. Such a configuration is highly unusual among transition‐metal H2 adducts. The nonclassical H2 adduct is an intermediate in the complete activation of H2 across the Ni? B interaction. Reaction‐coordinate analysis suggests synergistic activation of the H2 ligand by both the Ni and B centers of the nickel boratrane subunit, thus highlighting an important role of the borane ligand both in stabilizing the d10 Ni—(H2) interaction and in the H—H cleavage step. 相似文献
52.
Let an be an increasing sequence of positive reals with an as n . Necessary and sufficient conditions are obtained foreach of the sequences to take on infinitely many prime values for almost all > rß.For example, the sequence an is infinitely often prime for almostall > 0 if and only if there is a subsequence of the an,say bn, with bn + 1 > bn + 1 and with the series divergent. Asymptotic formulae areobtained when the sequences considered are lacunary. An earlierresult of the author reduces the problem to estimating the measureof overlaps of certain sets, and sieve methods are used to obtainthe correct order upper bounds. 1991 Mathematics Subject Classification:primary 11N05; secondary 11K99, 11N36. 相似文献
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Interband magnetoreflection experiments on Hg0.84Cd0.16 Te give a valence band effective mass of 0.3 m0 appropriate to the (100) plane. The Γ6 - Γ8 separation is slightly negative at 4°K and slightly positive at 77°K. About twenty magnetooptical transitions are seen and indicate a high level of homogeneity for this material. 相似文献
56.
Trichoderma is one of the most promising biocontrol agents against plant fungal diseases. In this study, a transgenic strain of Trichoderma atroviride was characterized. The transgenic strain contains an endochitinase gene (ThEn-42) driven by the cellulase promoter cbh1 of T. reesei for overexpression of ThEn-42. The culture filtrates of the transformant and the parental strain grown in eight different media were evaluated for chitinase
and antifungal enzyme production based on activity gels, protein profiles, and antifungal activities. Results demonstrated
that chitinases are important components and synergistic interactions play a key role in the antagonistic action of T. atroviride. Moreover, altering medium nutrient concentration and composition led to enhanced production of antifungal enzymes, a potential
strategy for mass production. Two of the culture filtrates contained almost pure endochitinase, and could be excellent commercial
sources for this enzyme. Several culture filtrates were highly antifungal. Two filtrates were so effective in biocontrol of
a fungal pathogen, Penicillium digitatum, that they not only inhibited spore germination but destroyed the spores completely when 20 μl of culture filtrate (corresponding
to approximately 104 μg of total protein) was applied in a total volume of 150 μl (approximately 0.7 mg protein ml−1). 相似文献
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We define a q-deformation of the classical ring of integer-valued polynomials which we call the ring of quantum integer-valued polynomials. We show that this ring has a remarkable combinatorial structure and enjoys many positivity properties: For instance, the structure constants for this ring with respect to its basis of q-binomial coefficient polynomials belong to \(\mathbb {N}[q]\). We then classify all maps from this ring into a field, extending a known classification in the classical case where \(q=1\). 相似文献
59.
Tunable diode laser measurements of water vapour lines in the 5 μm region have been extended to include oxygen as well as nitrogen broadening. Positive pressure shifts of line positions have been observed for the first time in the v 2 band. Absolute calibration of a line position using the CO laser as a reference has also been carried out. 相似文献
60.
Orts RS Harman Z López-Urrutia JR Artemyev AN Bruhns H Martínez AJ Jentschura UD Keitel CH Lapierre A Mironov V Shabaev VM Tawara H Tupitsyn II Ullrich J Volotka AV 《Physical review letters》2006,97(10):103002
The relativistic recoil effect has been the object of experimental investigations using highly charged ions at the Heidelberg electron beam ion trap. Its scaling with the nuclear charge Z boosts its contribution to a measurable level in the magnetic-dipole (M1) transitions of B- and Be-like Ar ions. The isotope shifts of 36Ar versus 40Ar have been detected with sub-ppm accuracy, and the recoil effect contribution was extracted from the 1s(2)2s(2)2p 2P(1/2) - 2P(3/2) transition in Ar13+ and the 1s(2)2s2p 3P1-3P2 transition in Ar14+. The experimental isotope shifts of 0.00123(6) nm (Ar13+) and 0.00120(10) nm (Ar14+) are in agreement with our present predictions of 0.00123(5) nm (Ar13+) and 0.00122(5) nm (Ar14+) based on the total relativistic recoil operator, confirming that a thorough understanding of correlated relativistic electron dynamics is necessary even in a region of intermediate nuclear charges. 相似文献