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41.
The strain energies and through-space distances between the two bridgehead E atoms of a selection of 1,3-dimethyl-1,3-ditetrelbicyclo[1.1.1]pentanes
(tetrel E = Si, Ge or Sn) were examined by quantum chemical calculations at MP2 and B3LYP levels. The aim is to identify which
bridges lead to short through-space E,E distances, and simultaneously, to as low strain as possible. A short E,E distance
should improve through-space interaction, and a low strain should promote the thermal stability and possibly also facilitate
their synthesis. The bridges examined included CH2, CMe2, CtBu2, C(CH2)n (n = 2–4), O, NMe, S, PMe, SiMe2, GeMe2, and SnMe2. The calculations indicate that the phospha bridge is a good compromise providing reasonably low strain as well as E,E through-space
distances which are only longer than normal E–E single bonds by factors of 1.06–1.10.
This paper is dedicated to Professor Mitsuo Kira in recognition of his stimulating Si chemistry and his 2005 Wacker Award. 相似文献
42.
Margareta H. Häggström Charles L. Cooney 《Applied biochemistry and biotechnology》1984,9(5-6):475-481
Glucose prevents maltose utilization bySaccharomyces cerevisiae in batch culture, whereas in a mixed carbohydrate-limited chemostat, maltose and glucose were consumed simultaneously. The specific activity of α-glucosidase was dependent on the dilution rate as well as the proportion of maltose in the mixture. Maximum specific activities in the batch and chemostat cultures on mixtures of maltose and glucose were lower than corresponding values observed on maltose alone. 相似文献
43.
A. Varinlioĝlu A. Köse U. Çevik A. I. Kopya M. Altunbaş H. Karal 《Journal of Radioanalytical and Nuclear Chemistry》1995,201(1):31-37
Sediment samples collected from the Eastern Black Sea in 1993 from 15 sampling stations of different depths have been analyzed. Natural and artifical radionuclide activity levels in offshore sediment samples from the Eastern Black Sea in Turkey are reported about seven years after the Chernobyl accident. The purpose of this paper is to follow up the earlier study and present results for the distributions of radionuclides in sediments of the Black Sea. 相似文献
44.
45.
Spin density redistribution between the paramagnetic centers Cu2+, N-O, and N’-O’ of bischelate complexes CuL2 of the copper ion with enaminoketone 3-imidazoline nitroxides (L) are investigated using an ab initio RHF (restricted Hartree-Fock)
approach. The most important channels of unpaired electron delocalization over the systems of π- and Σ-bonds in such complexes
are revealed. The conformation dependence of spin density localized on paramagnetic centers and delocalized due to a distortion
of the structure of the environment of the Cu2+ ion from square planar to tetrahedral is analyzed and explained.
Translated fromZhurnal Strukturnoi Khimii, Vol. 38, No. 5, pp. 840–849, September-October, 1997. 相似文献
46.
An immobiline DryStrip application method enabling high-capacity two-dimensional gel electrophoresis 总被引:5,自引:0,他引:5
Sabounchi-Schütt F Aström J Olsson I Eklund A Grunewald J Bjellqvist B 《Electrophoresis》2000,21(17):3649-3656
In the field of proteomics the need to detect low-abundance cellular components, such as regulatory proteins, is of critical importance. Two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) is one of the most commonly used separation tools for these biological investigations. In this paper we report an alternative micropreparative 2-D PAGE sample application method, called the "paper bridge loading" method. This method makes it possible to apply a larger sample volume to commercially available immobilized pH gradient (IPG) strips. The Vh products required for focusing are only marginally longer than those used in analytical experiments. The method was compared to traditional cup loading and in-gel rehydration. With 18 cm long narrow-range Immobiline DryStrip pH 4.5-5.5, the "paper bridge" method allowed the application of 10 mg human plasma proteins compared to 3 mg with traditional loading methods. The corresponding figures using Escherichia coli sample was found to be 6 mg and less than 2 mg, respectively. The paper bridge method also showed the best results in terms of spot resolution and separation of high molecular weight proteins. 相似文献
47.
L. Adiels G. Backenstoss I. Bergström S. Carius S. Charalambous M. D. Cooper Ch. Findeisen D. Hatzifotiadou M. Hugi A. Kerek H. O. Meyer P. Pavlopoulos J. Repond L. Tauscher D. Tröster M. C. S. Williams K. Zioutas 《Zeitschrift fur Physik C Particles and Fields》1987,35(1):15-19
The branching ratios of \(p\bar p\) annihilations into the neutral final states 2π0, π0γ, and 2γ are measured by stopping antiprotons in liquid hydrogen. They are \(B_{2\pi ^0 } = \left( {2.06 \pm 0.14} \right) \times 10^{ - 4} \) , \(B_{\pi ^0 \gamma } = \left( {1.74 \pm 0.22} \right) \times 10^{ - 5} \) , andB γγ<1.7×10?6 (95% c.l.). 相似文献
48.
P. Alstrøm 《Communications in Mathematical Physics》1986,104(4):581-589
Every orientation preserving circle mapg with inflection points, including the maps proposed to describe the transition to chaos in phase-locking systems, gives occasion for a canonical fractal dimensionD, namely that of the associated set of for whichf
=+g has irrational rotation number. We discuss how this dimension depends on the orderr of the inflection points. In particular, in the smooth case we find numerically thatD(r)=D(r
–1)=r
–1/8. 相似文献
49.
Kimmo Smolander Risto J?rnstr?m Annika Sajalinna 《Fresenius' Journal of Analytical Chemistry》1989,335(4):392-394
Summary The matric effect of boric acid was investigated in the determination of iron in the primary circuit coolant water of nuclear power plants by furnace atomic absorption spectrometry. The effect of boric acid was of particular interest. The method was applied during refuelling and maintenance periods and the results were used to interpret the chemical changes in the water.
Einfluß von Borsäure auf die Bestimmung von Eisen in Reaktorkühlwasser durch GF-AAS相似文献
50.
V. Barci H. El-Samman A. Gizon J. Gizon R. Kossakowski B. M. Nyako T. Vertse S. Elfström D. Jerrestam W. Klamra Th. Lindblad T. Bengtsson 《Zeitschrift für Physik A Hadrons and Nuclei》1986,325(4):399-404
The effective moment of inertiaI eff (2) of132Ce,134Nd and136Nd produced in40Ar induced reactions has been deduced from continuumγ-ray spectra measured by sum spectrometer methods. Results concerning the deformation of these nuclei are obtained by comparison of the experimental data and calculations in the frame of a cranking Nilsson — Strutinsky model. 相似文献