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排序方式: 共有619条查询结果,搜索用时 15 毫秒
131.
Leila Peraro Assoc. Prof. Joshua A. Kritzer 《Angewandte Chemie (International ed. in English)》2018,57(37):11868-11881
Biomolecules such as antibodies, proteins, and peptides are important tools for chemical biology and leads for drug development. They have been used to inhibit a variety of extracellular proteins, but accessing intracellular proteins has been much more challenging. In this review, we discuss diverse chemical approaches that have yielded cell‐penetrant peptides and identify three distinct strategies: masking backbone amides, guanidinium group patterning, and amphipathic patterning. We summarize a growing number of large data sets, which are starting to reveal more specific design guidelines for each strategy. We also discuss advantages and disadvantages of current methods for quantifying cell penetration. Finally, we provide an overview of best‐odds approaches for applying these new methods and design principles to optimize cytosolic penetration for a given bioactive peptide. 相似文献
132.
Alain Valtz Leila Gicquel Christophe Coquelet Dominique Richon 《Fluid Phase Equilibria》2005,230(1-2):184-191
Isothermal vapour–liquid equilibrium data have been measured for the binary system R134a + DME at five temperatures between 293.18 and 358.15 K, and pressures between 0.4899 and 2.9442 MPa. The peculiarity of this system is the existence of an azeotrope with a minimum pressure, which disappears at 358.15 K. The experimental method used in this work is of the static-analytic type, taking advantage of two pneumatic capillary samplers (Rolsi™, Armines’ patent) developed in the CENERG/TEP Laboratory. The data were obtained with uncertainties within ±0.02 K, ±0.0001 MPa and ±1% for molar compositions.
The isothermal P, x, y data are well represented with the Redlich and Kwong equation of state using the Mathias–Copeman alpha function and the Huron–Vidal mixing rules involving the NRTL model. 相似文献
133.
Novel sulfate ion-selective polymeric membrane electrode based on a derivative of pyrilium perchlorate 总被引:1,自引:0,他引:1
Ganjali MR Naji L Poursaberi T Taghizadeh M Pirelahi H Yousefi M Yeganeh-Faal A Shamsipur M 《Talanta》2002,58(2):359-366
A sulfate ion-selective PVC membrane sensor based on 4-(4-bromophenyl)-2,6-diphenylpyrilium perchlorate (BDPP) as a novel sensing material is successfully developed. The electrode shows a good selectivity for sulfate ion with respect to common organic and inorganic anions. The sensor exhibits a good linear response with slope of -28.9+/-0.5 mV per decade over the concentration range of 1.0x10(-6)-1.0x10(-2) M, and a detection limit of 8.0x10(-7) M of SO(4)(2-) ions. The electrode response is independent of pH in the range of 4.0-9.0. The proposed sensor was applied as an indicator electrode in potentiometric titration of sulfate and barium ions, and to the determination of zinc in zinc sulfate tablets. 相似文献
134.
Reger DL Gardinier JR Gemmill WR Smith MD Shahin AM Long GJ Rebbouh L Grandjean F 《Journal of the American Chemical Society》2005,127(7):2303-2316
Sonogashira coupling reactions of terminal alkynes with Fe[(p-IC6H4)B(3-Mepz)3]2 (pz = pyrazolyl ring) yield Fe[(p-PhC2C6H4)B(3-Mepz)3]2 (2), Fe[(p-Me3SiC2C6H4)B(3-Rpz)3]2 (R = H, 3a, R = Me, 3b), and Fe[(p-HC2C6H4)B(3-Mepz)3]2 (R = H, 4a, R = Me, 4b), a series of new complexes containing "third generation" poly(pyrazolyl)borate ligands. Complex 2 undergoes a fairly gradual iron(II) electronic spin-state crossover with a 30 K hysteresis, whereas complex 3b is an unusual example of a complex with equivalent iron(II) sites in the high-spin form that shows an abrupt 50% spin crossover. For complex 4b, 50% of the iron(II) sites undergo a gradual spin-state transition between 185 and 350 K with an activation energy of 1590 +/- 30 cm(-1) and a T(1/2) = 280 K and, for the remaining iron(II) sites, an abrupt cooperative spin-state crossover between 106 and 114 K. The crystal structures of 4b obtained for each of the three distinct electronic spin states reveal two crystallographically different iron(II) sites, and analysis of the molecular/supramolecular structures indicates that the difference in the degree of pyrazolyl ring tilting in the ligands between the two sites, rather than the strength of the intermolecular forces, play a prominent role in determining the temperature of the spin-state crossover. 相似文献
135.
Christopher Brenig Leila Mosberger Katja Baumann Olivier Blacque Felix Zelder 《Helvetica chimica acta》2021,104(8):e2100067
This publication describes the straightforward and redox-neutral synthesis of 10-bromophenylethynylcobalamin and its facile conversion to 10-bromoaquacobalamin. In this approach, the phenylethynyl ligand acts as convenient light-stable protecting group that is removed in quantitative yield under acidic conditions. The proteolytic cleavage at pH 2.0 was studied under pseudo-first-order conditions and is 1.5 times slower than that of phenylethynylcobalamin with a hydrogen instead of a bromine at C(10). Preliminary electrochemical studies of organometallic ethynyl-Cbls (Cbl=cobalamin) are reported for the first time. A reduction potential of −0.94 V vs. Ag/AgCl was determined for the CoIII/CoI reduction of 10-bromophenylethynylcobalamin. The positive potential shift of 180 mV compared to phenylethynylcobalamin is in agreement with earlier electrochemical studies of related cyanocobalamins. 相似文献
136.
Ganjali MR Pourjavid MR Haji-Agha Babaei L Salavati-Niasari M 《Annali di chimica》2004,94(5-6):447-456
A simple and fast method for the extraction and determination of ppt level of Pb2+ and Cu2+ ions using octadecyl-bonded silica membrane disks modified by a new tetradentates Schiffs base [Bis(2,4-dimethoxy benzaldehyde) ethylen diimine](TDSB) and inductively coupled plasma atomic emission spectrometry is described. Extraction efficiency, and influence of flow rate, pH, type and the least amount of acid for stripping of Cu2+ and Pb2+ from the modified disks and break through volume were evaluated. The maximum capacity of the membrane disks modified by 5 mg of TDSB used was found to be 347 +/- 7 and 470 +/- 6 microg of copper and lead, respectively. The concentration factor is 500 (for 2500 mL water sample and flow rate of 20 mL min(-1)) and detection limit of the proposed method is 12.5 and 150.5 pg/ml for Cu2+ and Pb2+, respectively. The method was applied to the determination of Cu2+ and Pb2+ ions from various water, wastewater, black tea, and hot pepper samples. 相似文献
137.
Faezeh Farzaneh Leila Tayebi Mehdi Ghandi 《Reaction Kinetics and Catalysis Letters》2007,91(2):333-340
Vit-B12/ Al-MCM-41 catalyzed successfully the epoxidation either of cis or trans — stilbene with O2 as oxidant and isobutyraldehyde as co-reductant with 86–98% reactivity and 97–100% selectivity. Other olefins such as norbornene
and styrene undergo epoxidation reaction under similar conditions with good to fair selectivity. Details of the reactions
will be presented in this article. 相似文献
138.
Mona H. N. Arsanious Leila S. Boulos 《Monatshefte für Chemie / Chemical Monthly》2006,137(9):1177-1184
Summary. The reaction of dibenzoyldiazine with phosphorus ylides afforded the new 2-[(benzoylhydrazono)phenylalkyl]but-2-enedioic acid
dialkylesters. Moreover, ethyl-2(triphenylphosphoranylidene)propionate reacts with dibenzoyldiazine to give the olefinic compound
and triphenylphosphine oxide. On the other hand, oxovinylidene-triphenylphosphorane reacts with dibenzoyldiazine to give a
new phosphorane adduct. Trialkyl phosphites react with dibenzoyldiazine to yield the dialkyl phosphonate products. The reaction
of dibenzoylhydrazide with Wittig reagents gave rise to the new 3,7-diphenylpyrazolo[1,2-α]pyrazole-1,5-diones. Possible reaction mechanisms are considered,
and the structural assignments are based on analytical and spectroscopic results. 相似文献
139.
Leila Rahmani 《Comptes Rendus Mathematique》2014,352(3):223-227
We consider a multi-structure consisting of a plate reinforced by a thin stiffener on a portion of its boundary. The model we consider for this structure (viewed as a heterogeneous plate) is nonlinear and takes into account the transverse shear effects. Our aim is to model this junction and reproduce the effect of the thin stiffener by means of approximate boundary conditions on the junction region. 相似文献