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Forward-backward multiplicity correlations in σ+,K + p andpp collisions at 250 GeV/c ( \(\sqrt s \) =22 GeV) are given for all charges and for the different charge combinations. The correlations are found to be caused predominantly by centrally produced particles. It is demonstrated that this result is an agreement with observations at the ISR and the CERNp \(\bar p\) -Collider. The results are compared to expectations from LUND, DPM and FRITIOF Monte Carlo models and a geometrical picture relating correlations in hadron-hadron collisions toe + e ? data in terms of impact parameters is tested.  相似文献   
4.
We present the search for a new model of -factor XIIa, a blood coagulation enzyme, with an unknown experimental 3D-structure. We decided to build not one but three different models using different homologous proteins as well as different techniques and different modellers. Additional studies, including extensive molecular dynamics simulations on the solvated state, allowed us to draw several conclusions concerning homology modelling, in general, and -factor XIIa, in particular.  相似文献   
5.
Practically all the conventional chromatographic techniques are used in the characterization of the highly complex mixtures of organic compounds occurring in fuels, heavy fractions, and crude oils. This paper surveys the techniques employed for class determination, preparative fractionation of the main classes, and determination of subgroups after class fractionation.  相似文献   
6.
We present a series of new inhibitors of the association between nuclear factor kappa B (NF-B) and the corresponding B site in DNA. They were designed using the lead compound 15-deoxy-12,14 -prostaglandin J2 (PGJ2), which is a natural product with demonstrated inhibitory efficiency for this system. First, the binding mode of PGJ2 to NF-B was unraveled by GOLD docking calculation. Subsequently, substitutions were made to PGJ2 to optimize its association with NF-B. Care was taken not to strongly increase the reactivity of the new compounds, and to keep the overall shape, size and hydrophilicity of the lead compound, which should render them a similar bioavailability. Molecular mechanics calculations were performed to decide on the suitability of the substitutions, and to evaluate the energies of association with NF-B. Density functional theory calculations were performed also to study the overall reactivity of the substituted drugs towards NF-B. Important general conclusions were obtained, concerning the improvement of these natural inhibitors; namely, a set of rational methodologies were deduced to improve the association between the PGJ2 derivatives and NF-B, and their efficiency demonstrated by generating a set of substituted complexes, some of them with a very much increased affinity for NF-B, opening new doors to enlarge the therapeutic capabilities of this class of drugs.  相似文献   
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Summary The heterocyclic compounds ClMS2 (CH2)2 (M = As, Sb) are tested by first time as source of starting materials in the synthesis of complexes. The preparation and characterization of heterocyclic dithiocarbamatesR 2NCS2 MS2 (CH2)2, (M = As, Sb;R =Me,Et,i-Pr) is reported. Spectroscopic and analytical data suggest a bidentate behavior of the dithiocarbamate entity and the presence of aMS4 core.
Die Koordinationsfähigkeit der Heterocyclen 1,3-Dithia-2-arsa- und-stiba-cyclopentan gegenüber Schwefel enthaltenden Liganden, I. Dialkyldithiocarbamat-Komplexe
Zusammenfassung Die heterocyclischen Verbindungen ClMS2 (CH2)2 (M = As, Sb) werden erstmals als Quelle für Ausgangsmaterial zur Synthese von Komplexen herangezogen. Es wird über die Herstellung und Charakterisierung der heterocyclischen DithiocarbamateR 2NCS2 MS2 (CH2)2 (M = As, Sb;R =Me,Et,i-Pr) berichtet. Spektroskopische und analytische Daten sprechen für ein bidentates Verhalten der Dithiocarbamat-Einheit und der Präsenz einerMS4-Anordnung im Komplex.
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8.
[structure: see text] Dicobalt-beta-pinene hybrids of types I and II have been prepared using a Nicholas reaction between propargyl derivatives, obtained from commercial (1R)-(-)-myrtenal, and different aromatic nucleophiles. The method is suitable for the preparation of densely functionalized bio-organometallic natural product-based hybrids, as demonstrated by the preparation of a beta-pinene-neoclerodane hybrid.  相似文献   
9.
In order to detect small variations in 13C isotopomers concentrations, high sensitivity, accuracy and precision have to be achieved. To assess such criteria, when using 13C NMR, 13C bi-labelled ethanol has been proposed as a molecular probe. Advantage has been taken of the pre-established structural relationship between the peak areas of the 13C NMR spectrum of this molecule, i.e. the ratio of signal areas is set to a fixed value. It is shown that the quality performance, required by quantitative 13C NMR spectroscopy, is not affected by a large reduction of the repetition delay using relaxation reagents.  相似文献   
10.
The effects of addition of alkanols (ethanol, n-hexanol, and 3-ethyl-3-pentanol) on the micropolarity and microviscosity of the head group region in reverse micelles of AOT-heptane-water have been investigated by fluorescence probing methods (ANS fluorescence yield and TMADPH fluorescence anisotropy), complemented by the use of the solvatochromic probe E(T)(30) in absorption spectroscopy. For all the alkanols considered, ANS fluorescence in AOT reverse micelles (at W=3) is quenched by additive incorporation, being the effect elicited almost independent of the alkanol chain length and topology. As sensed by the E(T)(30) parameter, the micropolarity of the micelle surface increases, remains unmodified, and decreases upon addition of ethanol, 3-ethyl-3-pentanol, and hexanol, respectively. While ethanol barely modifies the fluorescence anisotropy of TMADPH, 3-ethyl-3-pentanol and n-hexanol addition strongly decrease it. The similarity of the tendencies of ANS data to TMADPH anisotropies and the differences between ANS data and E(T)(30) values would indicate that, at least for 3-ethyl-3-pentanol and n-hexanol, microviscosity, rather than micropolarity, must be considered to interpret the effect of the alkanols upon the fluorescent behavior of ANS.  相似文献   
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