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排序方式: 共有743条查询结果,搜索用时 31 毫秒
711.
Mihaela Popovici Johan Swerts Kazuyuki Tomida Dunja Radisic Min‐Soo Kim Ben Kaczer Olivier Richard Hugo Bender Annelies Delabie Alain Moussa Christa Vrancken Karl Opsomer Alexis Franquet Malgorzata A. Pawlak Marc Schaekers Laith Altimime Sven Van Elshocht Jorge A. Kittl 《固体物理学:研究快报》2011,5(1):19-21
Crystalline rutile TiO2 films were grown by atomic layer deposition on oxidized Ru electrodes using a titanium methoxide as the metal precursor and O3 as the oxidant. A protective layer of ~0.3 nm TiO2 grown with H2O as the oxidant was first deposited in order to avoid etching of the Ru bottom electrode by the O3 used for the growth of the TiO2 (bulk) layer. Electrical evaluation of the capacitor stacks with TiO2 as dielectric, RuO2/Ru and Pt as the bottom and top electrodes respectively, resulted in superior characteristics of the rutile phase as compared to the anatase. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
712.
Stability is a particular problem for biopharmaceutical products because the efficacy of peptides and proteins as therapeutic or diagnostic agents can be affected during preparation, shipping, and storage. A particular formulation may have no immediately apparent effect on physical or chemical stability, and the time required for these studies at ambient temperature can be very lengthy because chemical reactions proceed relatively slowly at low temperatures. Undoubtedly, accelerated and stress testing of stability can provide useful information for future product development. The many methods used to study kinetics in aqueous solution may be experimental or computational. Experimental approaches may be isothermal or non-isothermal. Non-linear and linear regression methods can be used to analyze data from these experimental approaches, and the Monte Carlo method could be useful to obtain information about uncertainties in experimental data.The purpose of this review is to describe and to discuss options for the accelerated study of peptide and protein drugs. These options are not necessarily the same as those used for regulatory testing to set expiration dates. We also review statistical techniques to estimate kinetic parameters (rate constant, activation energy, and pre-exponential factor). Further, we establish the advantages and the limitations of both thermal approaches. We analyze and discuss all aspects using the most recent examples of peptide and protein stability. 相似文献
713.
Braulio Insuasty Alberto Insuasty Alexis Tigreros Jairo Quiroga Rodrigo Abonia Manuel Nogueras Justo Cobo Marcos Derita Susana Zacchino 《Journal of heterocyclic chemistry》2011,48(2):347-350
This work describes the synthesis and antifungal evaluation of 5‐arylidene‐(Z)‐2‐(1,1‐dicyanomethylene)‐1,3‐thiazol‐4‐ones 5 obtained from the reaction of 2‐(1,1‐dicyanomethylene)‐1,3‐thiazol‐4‐one 3 and benzaldehydes 4. The starting material 3 was synthesized by a condensation reaction of rhodanine 1 and malononitrile 2. The structures of the obtained products were established by IR, NMR, mass spectrometry, and elemental analysis. J. Heterocyclic Chem., (2011). 相似文献
714.
The total synthesis of enantiopure 4-epi-(+)-codonopsinine was achieved in 10 steps starting from D-ribose as a chiral building block. The key step involved a highly stereoselective nucleophilic addition of a Grignard reagent to a protected ribosylamine. Synthesis of the N-desmethyl derivative and its p-tolyl analogue was also accomplished, and the compounds were assayed against α-fucosidase. 相似文献
715.
Numbers whose continued fraction expansion contains only small digits have been extensively studied. In the real case, the Hausdorff dimension ?? M of the reals with digits in their continued fraction expansion bounded by M was considered, and estimates of ?? M for M???? were provided by Hensley (J. Number Theory 40:336?C358, 1992). In the rational case, first studies by Cusick (Mathematika 24:166?C172, 1997), Hensley (In: Proc. Int. Conference on Number Theory, Quebec, pp. 371?C385, 1987) and Vallée (J. Number Theory 72:183?C235, 1998) considered the case of a fixed bound M when the denominator N tends to ??. Later, Hensley (Pac. J. Math. 151(2):237?C255, 1991) dealt with the case of a bound M which may depend on the denominator N, and obtained a precise estimate on the cardinality of rational numbers of denominator less than N whose digits (in the continued fraction expansion) are less than M(N), provided the bound M(N) is large enough with respect to N. This paper improves this last result of Hensley towards four directions. First, it considers various continued fraction expansions; second, it deals with various probability settings (and not only the uniform probability); third, it studies the case of all possible sequences M(N), with the only restriction that M(N) is at least equal to a given constant M 0; fourth, it refines the estimates due to Hensley, in the cases that are studied by Hensley. This paper also generalises previous estimates due to Hensley (J. Number Theory 40:336?C358, 1992) about the Hausdorff dimension ?? M to the case of other continued fraction expansions. The method used in the paper combines techniques from analytic combinatorics and dynamical systems and it is an instance of the Dynamical Analysis paradigm introduced by Vallée (J. Théor. Nr. Bordx. 12:531?C570, 2000), and refined by Baladi and Vallée (J. Number Theory 110:331?C386, 2005). 相似文献
716.
Alexis Kotland Imane Hadef Jean‐Hugues Renault Mahmoud Hamzaoui Agathe Martinez Nicolas Borie Arnaud Guilleret Romain Reynaud Jane Hubert 《Journal of separation science》2013,36(8):1362-1369
Sophorolipids represent an important class of natural surfactants with a variety of environmental, cosmetic, and pharmaceutical applications. Despite their promising physicochemical and biological properties, the use of sophorolipids is hampered by the lack of information regarding their individual structure‐activity relationships. The major difficulty in isolating pure sophorolipids arises from the high complexity of crude fermentation media composition and from their strong structural similarities. In this work, a centrifugal partition chromatography method was developed in an original gradient elution mode for the separation of sophorolipids produced by the yeast Candida bombicola. Experiments were realized by using three sets of solvent systems composed of n‐heptane, ethyl acetate, n‐butanol, methanol, and water in different proportions. The separation was performed at 5 mL/min in the ascending mode by increasing progressively the polarity of the organic mobile phase. In these conditions, more than 80% of the sophorolipids present in the initial crude fermentation extract were eluted successively from the most hydrophobic lactone forms to the most hydrophilic acid forms. The structures of the isolated sophorolipids were further elucidated by HPLC and NMR analyses. 相似文献
717.
Using the Population‐Shift Mechanism to Rationally Introduce “Hill‐type” Cooperativity into a Normally Non‐Cooperative Receptor
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Anna J. Simon Prof. Dr. Alexis Vallée‐Bélisle Prof. Dr. Francesco Ricci Dr. Herschel M. Watkins Prof. Dr. Kevin W. Plaxco 《Angewandte Chemie (International ed. in English)》2014,53(36):9471-9475
Allosteric cooperativity, which nature uses to improve the sensitivity with which biomolecular receptors respond to small changes in ligand concentration, could likewise be of use in improving the responsiveness of artificial biosystems. Thus motivated, we demonstrate here the rational design of cooperative molecular beacons, a widely employed DNA sensor, using a generalizable population‐shift approach in which we engineer receptors that equilibrate between a low‐affinity state and a high‐affinity state exposing two binding sites. Doing so we achieve cooperativity within error of ideal behavior, greatly steepening the beacon’s binding curve relative to that of the parent receptor. The ability to rationally engineer cooperativity should prove useful in applications such as biosensors, synthetic biology and “smart” biomaterials, in which improved responsiveness is of value. 相似文献
718.
719.
Zalubovskis R Bouet A Fjellander E Constant S Linder D Fischer A Lacour J Privalov T Moberg C 《Journal of the American Chemical Society》2008,130(6):1845-1855
Pd(II) allyl and Pd(0) olefin complexes containing the configurationally labile ligand 1,2-bis-[4,5-dihydro-3H-dibenzo[c-e]azepino]ethane were studied as models for intermediates in Pd-catalyzed allylic alkylations. According to NMR and DFT studies, the ligand prefers C(s) conformation in both eta3-1,3-diphenylpropenyl and eta3-cyclohexenyl Pd(II) complexes, whereas in Pd(0) olefin complexes it adopts different conformations in complexes derived from the two types of allyl systems in both solution and, as verified by X-ray crystallography, in the solid state. These results demonstrate that the Pd complex is capable of adapting its structure to the reacting substrate. The different structural preferences also provide an explanation for the behavior of 1,3-diphenyl-2-propenyl acetate and 2-cyclohexenyl acetate in Pd-catalyzed allylic alkylations using pseudo-C2 and pseudo-C(s) symmetric ligands. 相似文献
720.
Kitson PJ Song YF Gamez P de Hoog P Long DL Parenty AD Reedijk J Cronin L 《Inorganic chemistry》2008,47(6):1883-1885
The formation of a pentanuclear palladium(II) complex with a phenanthridinonetriazine-based ligand system, which itself is formed by a metal-mediated rearrangement of a triazinephenanthridinium proligand, is described. 相似文献