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排序方式: 共有1401条查询结果,搜索用时 15 毫秒
941.
Paweł Góralski Małgorzata Rogalińska Jerzy Z. Błoński Edyta Pytel Tadeusz Robak Zofia M. Kiliańska Henryk Piekarski 《Journal of Thermal Analysis and Calorimetry》2014,118(2):1339-1344
Chronic lymphocytic leukemia (CLL) is a heterogenous disease with an imbalance between apoptosis and cell proliferation. Therefore, the main goal in CLL therapy is to induce apoptosis and effectively support this process in transformed B lymphocytes. In the current study, we have compared differential scanning calorimetry (DSC) profiles of nuclei isolated from CLL cells and normal mononuclear cells exposed to cladribine or fludarabine combined with mafosfamide (CM; FM), and additionally to CM combined with monoclonal antibody—rituximab (RCM) for 48 h, as well as in culture medium only (controls). Under current study, the mononuclear cells from peripheral blood (PBMCs) of healthy individuals have been included. The obtained results have shown the presence of thermal transition at 95 ± 5 °C in most of nuclear preparations (92.2 %) isolated from blood of CLL patients. This thermal characteristic parameter was changed after drug exposure, however, to a different extent. These thermal changes were accompanied by the decrease of cell viability, an elevation of apoptosis rate and the changes in expression/proteolysis of poly(ADP-ribose)polymerase-1—main marker of apoptosis. Importantly, in DSC profiles of nuclear preparations of PBMCs from blood of healthy donors exposed to investigated drug combinations and control CLL cells, the lack of such changes was observed. Our results confirmed that DSC technique complemented with other biological approaches could be helpful in tailoring therapy for CLL patients. 相似文献
942.
Correlations in commodity markets 总被引:1,自引:0,他引:1
Pawe? Sieczka 《Physica A》2009,388(8):1621-1630
In this paper we analyzed dependencies in commodity markets, investigating correlations of future contracts for commodities over the period 1998.09.01-2007.12.14. We constructed a minimal spanning tree based on the correlation matrix. The tree provides evidence for sector clusterization of investigated contracts. We also studied dynamical properties of commodity dependencies. It turned out that the market was constantly getting more correlated within the investigated period, although the increase of correlation was distributed non-uniformly among all contracts, and depended on contracts branches. 相似文献
943.
Anna Kisiel Maciej Mazur Sylwia Kuśnieruk Krystyna Kijewska Paweł Krysiński Agata Michalska 《Electrochemistry communications》2010,12(11):1568-1571
Polypyrrole microcapsules filled with different electrolytes were prepared using novel photopolymerization method. The obtained microstructurized material was applied as a transducer for ion-selective potentiometric sensors. In contrary to typical conducting polymer transducer, microcapsules result in introduction of significantly higher amount of exchangeable ions. Depending on the choice of electrolyte encapsulated, the resulting sensors were characterized with different analytical and electrical parameters. 相似文献
944.
945.
Paulina Majewska Marek Doskocz Barbara Lejczak Paweł Kafarski 《Tetrahedron: Asymmetry》2009,20(13):1568-1574
The use of quinine as a chiral solvating agent allows us to determine a tentative absolute configuration at the phosphorus atom of hydroxyphosphinates with two stereogenic centres (at the phosphorus and α-carbon atoms). Two ethyl butyryloxyalkane(P-phenyl)phosphinates were hydrolysed using various lipases. In all cases isomers possessing α-carbon atom with an (S)-configuration were hydrolysed preferentially. The absolute configuration of both chiral centres of obtained α-hydroxyphosphinates was determined by using (S)-(+)-MTPA-Cl and quinine. The mode of chiral discrimination of α-hydroxyphosphinates by quinine was studied by means of computational chemistry, which confirmed the experimental findings that the signals in 31P NMR spectra of compounds with an (RP)-configuration are situated upfield when compared with the respective (SP) isomers. 相似文献
946.
Ewa Rudzińska Łukasz Berlicki Paweł Kafarski Michael Lämmerhofer Artur Mucha 《Tetrahedron: Asymmetry》2009,20(23):2709-2714
A series of chiral amines of increasing structural complexity, such as 1-(1-naphthyl)ethylamine, ephedrine, quinine, quinidine, 9-O-tert-butylcarbamoylquinine, and 9-O-tert-butylcarbamoylquinidine were studied as chiral solvating agents for the enantiodifferentiation of N-benzyloxycarbonyl derivatives of 1-aminoalkanephosphonic and phosphinic acids by means of 31P NMR spectroscopy. Among the cinchona alkaloids, that induced the most significant chemical shift non-equivalences, non-substituted quinidine exhibited the best effectiveness, excellent for analytical purposes (for example Δδ = 0.348 up to 1.008 ppm for phosphinic acid analogs). The signal separation of the diionic phosphonic acid enantiomers could be further optimized by the addition of an excess of the solvating agents. The newly obtained results appeared better when compared to the data set previously reported for the same analytes with the application of cyclodextrins. 相似文献
947.
Joseph??Zaccai 《Pramana》2008,71(4):739-743
The short review concentrates on recent work performed at the neutrons in biology laboratories of the Institut Laue Langevin
and Institut de Biologie Structurale in Grenoble. Extremophile organisms have been discovered that require extreme conditions
of temperature, pressure or solvent environment for survival. The existence of such organisms poses a significant challenge
in understanding the physical chemistry of their proteins, in view of the great sensitivity of protein structure and stability
to the aqueous environment and to external conditions in general. Results of neutron scattering measurements on the dynamics
of proteins from extremophile organisms, in vitro as well as in vivo, indicated remarkably how adaptation to extreme conditions involves forces and fluctuation amplitudes that have been selected
specifically, suggesting that evolutionary macromolecular selection proceeded via dynamics. The experiments were performed
on a halophilic protein, and membrane adapted to high salt, a thermophilic enzyme adapted to high temperature and its mesophilic
(adapted to 37°C) homologue; and in vivo for psychrophilic, mesophilic, thermophilic and hyperthermophilic bacteria, adapted respectively to temperatures of 4°C,
37°C, 75°C and 85°C. Further work demonstrated the existence of a water component of exceptionally low mobility in an extreme
halophile from the Dead Sea, which is not present in mesophile bacterial cells.
相似文献
948.
Pawe? Wo?ny 《Applied mathematics and computation》2009,215(4):1622-1645
A new method of summation of slowly convergent series is proposed. It may be successfully applied to the summation of generalized and basic hypergeometric series, as well as some classical orthogonal polynomial series expansions. In some special cases, our algorithm is equivalent to Wynn’s epsilon algorithm, Weniger transformation [E.J. Weniger, Nonlinear sequence transformations for the acceleration of convergence and the summation of divergent series, Computer Physics Reports 10 (1989) 189-371] or the technique recently introduced by ?í?ek et al. [J. ?í?ek, J. Zamastil, L. Skála, New summation technique for rapidly divergent perturbation series. Hydrogen atom in magnetic field, Journal of Mathematical Physics 44 (3) (2003) 962-968]. In the case of trigonometric series, our method is very similar to the Homeier’s H transformation, while in the case of orthogonal series — to the K transformation. Two iterated methods related to the proposed method are considered. Some theoretical results and several illustrative numerical examples are given. 相似文献
949.
950.
It is proved that if a K?the space λ1(A) is distinguished and E is an arbitrary Fréchet space then every reflexive map T: λ1(A)→E (i.e., T maps bounded sets into relatively weakly compact ones) factorizes through a reflexive Fréchet space. An analogous result
is proved for Montel maps (i.e., which map bounded sets into relatively compact ones). The result is a consequence of the
fact proved also in this paper that, for a distinguished λ1(A) space, the spaces of reflexive maps R(λ1(A), C(K)) and of Montel maps M(λ1(A), C(K)) are the Mackey completions of the spaces of weakly compact and compact maps, respectively. Consequences for spaces of vector-valued
(weakly) continuous functions are also obtained.
Received: 24 November 1997 / Revised version: 14 May 1998 相似文献