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81.
Philip J. Bailey Dr. Laura Budd Dr. Filipa A. Cavaco Simon Parsons Prof. Felix Rudolphi Alejandro Sanchez‐Perucha Dr. Fraser J. White Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(9):2819-2829
The dimethylamine in the adducts [(HNMe2)B(azolyl)3] (azolyl=methimazolyl, pyrazolyl), obtained by reaction of the azole with B(NMe2)3, can readily be substituted with a range of nitrogen donors to provide new charge‐neutral, tripodal ligands in high yield. This observation has led to a revision of an earlier interpretation of the mechanism of the formation of these species. The donor properties of the ligands [(nmi)B(azolyl)3] (nmi=N‐methylimidazole) have been compared with their anionic analogues [HB(azolyl)3]? by synthesis of their manganese(I)–tricarbonyl complexes and comparison of their infrared νCO energies. This comparison indicates that the new neutral ligands are only marginally weaker donors than the corresponding anionic hydrotris(azolyl)borate ligands. This may be explained by the ability of the attached nmi ring to stabilize a positive charge remotely from the coordinated metal, which may also account for the fact that the [(nmi)B(pyrazolyl)3] ligand is a substantially stronger donor than the similarly neutral tris(pyrazolyl)methane ligand. 相似文献
82.
Güneş Y Polat MF Sahin E Fleming FF Altundas R 《The Journal of organic chemistry》2010,75(21):7092-7098
Quaternary oxonitriles are stereoselectively generated from the union of five-, six-, and seven-membered 2-chloroalkenecarbonitriles with chiral alcohols via a Claisen rearrangement. The strategy rests on a new conjugate addition-elimination of allylic alkoxides to 2-chlorocycloalkenecarbonitriles to afford substituted 2-alkoxyalkenenitriles. Subsequent thermolysis unmasks a cyclic oxonitrile while selectively forming a new quaternary center with enantiomeric ratios typically greater than 9:1. The overall alkylation strategy addresses the challenge of enantioselectively generating hindered, quaternary centers while simultaneously installing ketone, nitrile, and olefin functionalities. 相似文献
83.
The setting of analytical quality specifications in laboratory medicine has attracted attention for many years. Over time,
many strategies were advocated and all had advantages and disadvantages. In the final decade of the last millennium, considerable
confusion existed on how to define analytical quality specifications correctly and how to apply them in everyday practice.
This led to wide professional interest. In 1999, a consensus conference sponsored by IUPAC, IFCC and WHO was held in Stockholm
on “Strategies to Set Global Analytical Quality Specifications in Laboratory Medicine”. The consensus set useful and well-documented
strategies for the setting of analytical quality specifications into a hierarchy with the best strategy at the highest level,
namely, (1) Evaluation of the effect of analytical performance on clinical outcomes in specific clinical situations, (2) Evaluation
of the effect of analytical performance on clinical decisions in general, (3) Published professional recommendations, (4)
Performance goals set by regulatory bodies and EQAS organisers, and (5) Goals based on the current state of the art. Much success has been achieved since the promulgation of the statement with the approach being adopted by many in laboratory
medicine for a very wide variety of purposes, particularly in quality management. However, there is a requirement for additional
investigation of, inter alia, quality specifications for examinations done on measurements performed on ordinal and nominal scales, pre-analytical factors
and matrix effects, examinations done as POCT, target values of control materials, and ways in which analytical quality specifications
can be used both to set what is the optimum performance and as a tool for assessment of everyday practice. 相似文献
84.
Rapeseed, soybean and sunflower seeds are used for a comparison of solvent extractions by SFE, ASE, fexIKA and Soxtherm apparatus
with the official standard method B-I 5 (87) by the DGF. The optimal extraction parameters for each method are evaluated.
The extracts are analysed regarding the composition of tocopherols, as a parameter for mild extraction conditions and the
content of free fatty acids and diglycerides, as a parameter for the recovery of more polar lipids. The obtained results for
oil content using the optimised methods agree well with the standard method. Differences occur in the results of tocopherol
composition and free fatty acid and diglyceride contents. The SFE method shows the highest recovery regarding the tocopherol
content. The extraction period by SFE is reduced to about 40 min in contrast to 4 h of the DGF standard method. The other
methods also provide considerable time reductions, but showed lower tocopherols and free fatty acid contents.
Received: 25 September 1998 / Revised: 18 January 1999 / Accepted: 21 January 1999 相似文献
85.
86.
Background
Stargazin (γ2) and the closely related γ3, and γ4 transmembrane proteins are part of a family of proteins that may act as both neuronal voltage-dependent calcium channel (VDCC) γ subunits and transmembrane α-amino-3-hydroxy-5-methyl-4-isoxazoleproponinc (AMPA) receptor regulatory proteins (TARPs). In this investigation, we examined the distribution patterns of the stargazin-like proteins γ2, γ3, and γ4 in the human central nervous system (CNS). In addition, we investigated whether human γ2 or γ4 could modulate the electrophysiological properties of a neuronal VDCC complex transiently expressed in Xenopus oocytes. 相似文献87.
88.
89.
Horizontal turbulent water vapour (steam) jets were discharged into ambient air from a circular convergent nozzle under unchoked/choked
and saturated/superheated nozzle exit conditions, resulting in two-phase (liquid and vapour), two-fluid (air and water) condensing
free jets. Flow properties and mixing characteristics have been measured with the aid of an isokinetic sampling probe arrangement.
Radial and axial profiles of air and steam mass flow rates and mass fractions were measured from which entrainment, centreline
decay and half-width spreading rates were calculated and compared with data from the literature. Overall, the mixing characteristics
of the condensing jets are very similar to those of non-condensing jets extensively reported in the literature.
Received: 30 September 1996 / Accepted: 19 May 1997 相似文献
90.
An LDV system for making spatial correlation measurements of velocity fluctuations in turbulent nonreacting and reacting flows is presented. The LDV system is the dual beam type and consists of an elongated probe volume and a two-point optical fiber detector. Results are presented of the integral length scale measured in a nonreacting grid generated turbulent flow.A version of this paper was presented at the ASME Winter Annual Meeting of 1984 and printed in AMD, Vol. 66 相似文献