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排序方式: 共有476条查询结果,搜索用时 15 毫秒
191.
Elizabeth A. King Emily M. Peairs Diya M. Uthappa Jordan K. Villa Cameron M. Goff Naya K. Burrow Rebecca T. Deitch Anna K. Martin Douglas D. Young 《Molecules (Basel, Switzerland)》2021,26(16)
Protein methyltransferases are vital to the epigenetic modification of gene expression. Thus, obtaining a better understanding of and control over the regulation of these crucial proteins has significant implications for the study and treatment of numerous diseases. One ideal mechanism of protein regulation is the specific installation of a photolabile-protecting group through the use of photocaged non-canonical amino acids. Consequently, PRMT1 was caged at a key tyrosine residue with a nitrobenzyl-protected Schultz amino acid to modulate protein function. Subsequent irradiation with UV light removes the caging group and restores normal methyltransferase activity, facilitating the spatial and temporal control of PRMT1 activity. Ultimately, this caged PRMT1 affords the ability to better understand the protein’s mechanism of action and potentially regulate the epigenetic impacts of this vital protein. 相似文献
192.
We report on the interplay between creep and residual stresses in a carbopol microgel. When a constant shear stress σ is applied below the yield stress σ y, the strain is shown to increase as a power law of time, γ(t) = γ 0 + (t/τ) α , with an exponent α = 0.39 ± 0.04 that is strongly reminiscent of Andrade creep in hard solids. For applied shear stresses lower than some typical value σ c ? 0.2σ y, the microgel experiences a more complex, anomalous creep behavior, characterized by an initial decrease of the strain, that we attribute to the existence of residual stresses of the order of σ c that persist after a rest time under a zero shear rate following preshear. The influence of gel concentration on creep and residual stresses are investigated as well as possible aging effects. We discuss our results in light of previous works on colloidal glasses and other soft glassy systems. 相似文献
193.
This paper illustrates from a phenomenological point of view why the study of superionic conductors is essentially a study of disorders. Crystals that are good ionic conductors lack a long-range order in their mobile-ion sublattice. Moreover, low-temperature anomalies typical of amorphous materials appear to be rather common in superionic crystals. In several solid electrolytes the coupling between “disorder modes” typical of glasses and translational degrees of freedom of the ions can be shown to enhance ionic diffusion. The observed, or expected, properties of these superionic conductors are briefly discussed. The hypothesis that disorder may often play a dynamic role in ion transport in solids suggests ways to synthesize materials of technological interest. 相似文献
194.
The paper is concerned with a problem in the theory of congruence function fields which is analogous to a conjecture of Gross in Iwasawa Theory. Zp-extensions K∞/K0 of congruence function fields K0 of characteristic p≠2 involving no new constants are considered such that the set S of ramified primes is finite and these primes are fully ramified. Is the set of S-classes invariant under Gal(K∞/K0) finite ? Gross' conjecture asserts that a similar question has an affirmative answer for the class of cyclotomic Zp- extensions of CM-type if S is the set of p-primes and the classes considered are minus S-classes. Using a formula of Witt for the norm residue symbol in cyclic p-extensions of local fields of characteristic p, a necessary and sufficient condition for the validity of the analogue of Gross' conjecture is given for a class of extensions K∞/K0. It is shown by examples that the analogue of Gross' conjecture is not always true. 相似文献
195.
196.
Oliver Villa 《Archiv der Mathematik》2003,81(1):1-4
Let $\frak n$ be the anisotropic norm of a Cayley algebra $\frak C$
over a field F of characteristic
different from 2 where -1 is a square. Let Spin$(\frak C, \frak n)$ be the
spin group of the quadratic form $\frak n$.
We prove that every element in Spin$(\frak C, \frak n)$ is a product of two
involutory elements, i.e. Spin$(\frak C, \frak n)$
is birefiectional.
Received: 28 February 2002 相似文献
197.
Summary A simple relationship has been thought to exist between the dynamics of water in heterogeneous (liquid-solid) systems and
the NMR response. This relationship is usually expressed by the Bloembergen-Purcell-Pound (BPP) equations for relaxation and
the phase model. However, a requirement for the use of the BPP theory is that motions take place in an isotropic, infinite
and three-dimensional space. It is shown that the mere presence of solid surfaces causes the appearance of solidlike features
in the NMR response of the liquid even if its dynamics is directly affected by the surfaces. Some of these ?topological? or
?indirect? surface effects are of the same kind as the low-dimensionality effects. Their order of magnitude is estimated for
simple geometries and by treating the liquid motion in a hydrodynamic approximation. Comparison with the experiment is carried
on in a companion paper.
To speed up publication, the authors of this paper have agreed to not receive the proofs for correction. 相似文献
198.
Marini A. Berbenni V. Moioli S. Bruni G. Cofrancesco P. Margheritis C. Villa M. 《Journal of Thermal Analysis and Calorimetry》2003,73(2):529-545
This work exemplifies a general method of studying the drug excipient interactions, with the aim of predicting rapidly and inexpensively the long term stability of their mixtures. We study the physico-chemical properties of a drug (indomethacin) in the solid state and in different combinations with several excipients (PVP=polyvinylpyrrolidone, MGST=magnesium stearate, Avicel©). We compare the properties of pure compounds (untreated, or moisture/temperature conditioned) with those of binary mixtures drug:excipient which underwent the same treatment. The purpose is to find indications of interactions within the mixtures, which means a potential incompatibility of the excipient. Both morphological and thermal properties are sensitive to interactions which leave mostly unmodified the IR spectra and the X-rays patterns. In particular, we find that indomethacin does interact with PVP and MGST, but is certainly compatible with Avicel©. 相似文献
199.
Scalable molecular dynamics with NAMD 总被引:21,自引:0,他引:21
Phillips JC Braun R Wang W Gumbart J Tajkhorshid E Villa E Chipot C Skeel RD Kalé L Schulten K 《Journal of computational chemistry》2005,26(16):1781-1802
200.
A. S. Ahmad MD N. Hoda M. Ahmad F. Islam S. Z. Qureshi 《Journal of Analytical Chemistry》2006,61(9):870-874
A simple, sensitive, and selective kinetic spectrophotometric method for the determination of kanamycin in pure form and pharmaceutical
formulations is described. The method is based on the measurement of the intensity of the yellow chromogen formed by the reaction
between kanamycin and acetylacetone-formaldehyde reagent in a N,N′-dimethyl formamide medium. The variable-time method was used to evaluate the rate of reaction of the colored chromogen formed
at 410 nm. The reaction conditions were optimized and the calibration graph was found to be linear in the range 60–160 μg/mL.
The results obtained by the developed and reference methods are in good agreement. Various statistical parameters were evaluated
to establish the precision, accuracy, repeatability, and reproducibility of the proposed method.
The text was submitted by the authors in English. 相似文献