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241.
G Bender T Wiegand H Eckert R Fröhlich CG Daniliuc C Mück-Lichtenfeld S Ndambuki T Ziegler G Kehr G Erker 《Angewandte Chemie (International ed. in English)》2012,51(35):8846-8849
An enyne-zirconium complex stabilizes molecular magnesium hydride (MgH(2) ) and even a molecular hydride, nC(4) H(9) MgH. These systems feature magnesium olefin π?complexation. 相似文献
242.
N-Alkenyl carboxamides undergo gold-catalyzed intramolecular exo-hydroamination to form nitrogen heterocycles in excellent yield. 相似文献
243.
[Structure: see text] Treatment of an N-4-pentenyl or N-5-hexenyl urea with a catalytic 1:1 mixture of a gold(I) N,N-diaryl imidazol-2-ylidine complex and AgOTf at or near room temperature leads to intramolecular exo-hydroamination to form the corresponding nitrogen heterocycle in excellent yield. 相似文献
244.
Surface chemistry of zirconium 总被引:1,自引:0,他引:1
This article presents an overview of the surface chemistry of zirconium, focusing on the relationship of what is known from model studies and how this connects to current and future applications of Zr-based materials. The discussion includes the synergistic nature of adsorbate interactions in this system, the role of impurities and alloying elements, and temperature-dependent surface–subsurface transport. Finally, some potential uses of zirconium and its alloys for biomedical and nanolithographic applications are presented. 相似文献
245.
246.
Hyperfine Interactions - A sample from the Great Nile (near Khartoum) has been investigated by Mössbauer spectroscopy, infrared spectroscopy, analytical electron transmission microscopy, and... 相似文献
247.
Michael A. Bender Ziyang Duan John Iacono Jing Wu 《Journal of Algorithms in Cognition, Informatics and Logic》2004,53(2):1448
This paper presents a simple dictionary structure designed for a hierarchical memory. The proposed data structure is cache-oblivious and locality-preserving. A cache-oblivious data structure has memory performance optimized for all levels of the memory hierarchy even though it has no memory-hierarchy-specific parameterization. A locality-preserving dictionary maintains elements of similar key values stored close together for fast access to ranges of data with consecutive keys.The data structure presented here is a simplification of the cache-oblivious B-tree of Bender, Demaine, and Farach-Colton. The structure supports search operations on N data items using O(logBN+1) block transfers at a level of the memory hierarchy with block size B. Insertion and deletion operations use O(logBN+log2N/B+1) amortized block transfers. Finally, the data structure returns all k data items in a given search range using O(logBN+k/B+1) block transfers.This data structure was implemented and its performance was evaluated on a simulated memory hierarchy. This paper presents the results of this simulation for various combinations of block and memory sizes. 相似文献
248.
Fire-induced mineral transformations have been investigated in composite mineral grains separated from the coarse sand fractions (400–2,000 μm) from Ultisols developed in the Chittagong Hill Tracts (Bangladesh). Magnetic and colour based separation (into light brown, dark red, and magnetic, dark red classes) were used to select the grains that were studied by Mössbauer spectroscopy. Aluminium substituted goethite (α-FeOOH) dominates the light brown particles. Fire transform the goethite into a poorly crystalline hematite (α-Fe2O3) dominating in the dark red particles. In the dark red, magnetic grains a recrystallized hematite dominates, but small amounts of maghemite (γ-Fe2O3) are also present. The latter is indicated by comparing the line intensities in spectra measurement with and without an external magnetic field. 相似文献
249.
We introduce a forward scheme for simulating backward SDEs. Compared to existing schemes, ours avoids high order nestings of conditional expectations backwards in time. In this way the error, when approximating the conditional expectation, depending on the time partition, is significantly reduced. Besides this generic result, we present an implementable algorithm and prove its convergence. Finally, we demonstrate the strength of the new algorithm by solving a financial problem numerically. 相似文献
250.
Tõnsuaadu K. Peld M. Bender V. Veiderma M. 《Journal of Thermal Analysis and Calorimetry》1999,56(1):35-42
The reaction of SO2 with synthetic apatites was studied by TG, XRD and IR analyses at 400-1000°C. Due to an interaction of apatite with SO2, destruction of apatite and formation of CaSO4 and diphosphate up to 750°C takes place. The further calcination leads to the formation of β-Ca3(PO4)2 and a part of the SO2 bound is lost again. The amount of SO2 bound with apatite at calcination depends on the substitution ((F- ↔ OH-, PO4
3- ↔ CO3
2-, Ca2+ ↔ Mg2+) in its structure.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献