共查询到20条相似文献,搜索用时 31 毫秒
1.
ABSTRACT2,5- and 2,4-disubstituted 1,3-thiazoles have been incorporated as core units in thermotropic liquid crystalline materials. However, synthetic approaches to these systems have been somewhat limited, and this is reflected in the relatively few reports of these mesogenic systems. This paper highlights both recent and well-established synthetic approaches to these systems using ring closure (Gabriel- and Hantzsch-type approaches) methodology and modifications of an intact 1,3-thiazole ring. The scope and limitations of each of these approaches are discussed. 相似文献
2.
This article reviews recent forays in theoretical modeling of the double layer structure at electrode/electrolyte interfaces by current atomistic and continuum approaches. We will briefly discuss progress in both approaches and present a perspective on how to better describe the electric double layer by combining the unique advantages of each method. First-principles atomistic approaches provide the most detailed insights into the electronic and geometric structure of electrode/electrolyte interfaces. However, they are numerically too demanding to allow for a systematic investigation of the electric double layers over a wide range of electrochemical conditions. Yet, they can provide valuable input for continuum approaches that can capture the influence of the electrochemical environment on a larger length and time scale due to their numerical efficiency. However, continuum approaches rely on reliable input parameters. Conversely, continuum methods can provide a preselection of interface structures and conditions to be further studied on the atomistic level. 相似文献
3.
Computational identification of microRNAs and their targets 总被引:1,自引:0,他引:1
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Kennedy J 《Natural product reports》2008,25(1):25-34
The combination of biological and chemical approaches for the generation of new and diverse natural products holds much promise. While mutasynthesis based approaches are still very relevant, more recent approaches have utilised genetic and metabolic engineering to generate key intermediates for chemical syntheses. This new semi-synthetic approach exploits the ability of biological systems to efficiently generate complex chiral molecules and of synthetic chemistry to elaborate these into new, or difficult to source, molecules. 相似文献
6.
Patel Prajay Kuntz David M. Jones Michael R. Brooks Bernard R. Wilson Angela K. 《Journal of computer-aided molecular design》2020,34(5):495-510
Journal of Computer-Aided Molecular Design - Two different types of approaches: (a) approaches that combine quantitative structure activity relationships, quantum mechanical electronic structure... 相似文献
7.
Three new approaches for automated structure elucidations of organic molecules using NMR spectroscopic data were introduced recently. These approaches apply a neural network 13C NMR chemical shift prediction method to rank the results of structure generators by their agreement of the predicted and experimental chemical shifts. These three existing implementations are compared using realistic example molecules. The applicability and reliability of such approaches is addressed. 相似文献
8.
Michael Fritzsche Carl-Fredrik Mandenius 《Analytical and bioanalytical chemistry》2010,398(1):181-191
Fluorimetric cell-based sensing methods have attracted increasing interest in toxicity testing of pharmaceuticals, pathogens,
environmental pollutants, and other chemicals. The objective of this review is to summarise the variety of approaches reported
up to now and to present recent developments in this area. The different approaches are described in relation to their underlying
mechanism and, especially, to the role of the fluorophore involved. The methods discussed include the use of fluorescent or
fluorogenic indicators, fluorescence-based testing for membrane integrity, approaches based on fluorescence labelling, inducible
fluorescent protein expression, and analysis of cellular autofluorescence. Several of these approaches have been shown to
be advantageous in comparison with non-fluorescence methods and have potential in high-throughput screening, for example in
drug discovery and safety pharmacology. 相似文献
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10.
Kenneth D. M. Harris 《中国化学会会志》1999,46(1):5-22
This article reviews some of the fundamental scientific issues associated with solid inclusion compounds, and describes the approaches and strategies that may be used to investigate the structural, dynamic and chemical properties of these systems. Two particular families of solid organic inclusion compounds - the urea and thiourea inclusion compounds - are highlighted. In order to understand the fundamental nature of these solids, it has been necessary to apply a wide range of experimental, computational and theoretical approaches. Each technique provides information on a different aspect of the solid, and the combined information obtained from these complementary approaches allows a comprehensive understanding to be established. Several issues of contemporary interest for urea and thiourea inclusion compounds are described, and the approaches that have been taken towards a fundamental understanding of these systems are explained. 相似文献
11.
Garcia J Mata EG Tice CM Hormann RE Nicolas E Albericio F Michelotti EL 《Journal of combinatorial chemistry》2005,7(6):843-863
Solid phase, solution, and hybrid approaches to the synthesis of small focused libraries of alpha,alpha-disubstituted-alpha-acylaminoketones have been explored. Solution and hybrid approaches that used support-bound reagents and scavenger resins were the most productive. 相似文献
12.
Ricardo J. N. B. da Silva Júlia R. Santos M. F. G. F. C. Camões 《Accreditation and quality assurance》2006,10(12):664-671
A new terminology for the approaches to the quantification of the measurement uncertainty is presented, with a view to a better understanding of the available methodologies for the estimation of the measurement quality and differences among them. The knowledge of the merits, disadvantages and differences in the estimation process, of the available approaches, is essential for the production of metrologically correct and fit-to-purpose uncertainty estimations. The presented terminology is based on the level of the analytical information used to estimate the measurement uncertainty (e.g., supralaboratory or intralaboratory information), instead of the direction of information flow (“bottom-up” or “top-down”) towards the level of information where the test is performed, avoiding the use of the same designation for significantly different approaches. The proposed terminology is applied to the approaches considered on 19 examples of the quantification of the measurement uncertainty presented at the Eurachem/CITAC CG4 Guide, Eurolab Technical Report 1/2002 and Nordtest Technical Report 537. Additionally, differences of magnitude in the measurement uncertainty estimated by various approaches are discussed. 相似文献
13.
Meshcheryakova I. N. Shavyrin A. S. Cherkasov A. V. Piskunov A. V. 《Russian Chemical Bulletin》2019,68(7):1414-1423
Russian Chemical Bulletin - Two synthetic approaches were used for the synthesis of 3,6-di-tert-butylcatecholate derivatives of titanium(iv). These approaches are based on the exchange reaction... 相似文献
14.
Taniya Olga S. Kopchuk Dmitry S. Khasanov Albert F. Kovalev Igor S. Zyryanov Grigory V. Charushin Valery N. Chupakhin Oleg N. 《Chemistry of Heterocyclic Compounds》2019,55(6):505-507
Chemistry of Heterocyclic Compounds - Microreview focuses on the main modern synthetic approaches toward 2-azaanthracene and its derivatives. These approaches are: inverse electron-demand... 相似文献
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John C. Berridge 《Trends in analytical chemistry : TRAC》1984,3(1):5-10
The availability of computer controlled HPLC instrumentation has enabled more systematic approaches to be taken to the optimization of chromatographic separations. Many of these approaches are suitable for automated applications. 相似文献
16.
Danese PN 《Chemistry & biology》2002,9(8):873-880
Bacteria frequently attach to medical devices such as intravascular catheters by forming sessile multicellular communities known as biofilms, which can be the source of persistent infections that are recalcitrant to systemic antibiotic therapy. As a result of this persistence, a number of technologies have been developed to prevent catheter-associated biofilm formation. Whereas the most straightforward approaches focus on impregnating catheter material with classical antimicrobial agents, these approaches are not universally effective, thereby underscoring the need for more potent and more sophisticated approaches to the prevention of catheter-related biofilm infections. 相似文献
17.
Bermúdez-Saldaña JM Escuder-Gilabert L Villanueva-Camañas RM Medina-Hernández MJ Sagrado S 《Journal of chromatography. A》2005,1094(1-2):24-33
The retention factor is one of the most universally used parameters in chromatography. The errors associated with the conventional ways to determine the retention factor of compounds in liquid chromatography are studied and compared with those corresponding to new approaches. The later avoid the use of extra-column time and hold-up time values, which have proven to be tedious and ambiguous. Simulations and real data, used to examine the accuracy of four different approaches (two classic and two new), suggest that the new approaches could be considered more satisfactory than the classic ones. 相似文献
18.
The limit of detection is one of the fundamental metrological characteristics of any chemical measurement systems but, even now, it is a highly controversial matter because of the existing differences in terminology, formulations and understanding. Even when limiting the analysis to those operational approaches that, because of their simplicity, are often suggested by the guidelines of some international bodies, the available approaches can return appreciably different estimates. In this paper, the matter is critically reconsidered, and the different approaches compared with the aid of some case studies. 相似文献
19.
Mathematical modeling and simulation of dynamic biochemical systems are receiving considerable attention due to the increasing availability of experimental knowledge of complex intracellular functions. In addition to deterministic approaches, several stochastic approaches have been developed for simulating the time-series behavior of biochemical systems. The problem with stochastic approaches, however, is the larger computational time compared to deterministic approaches. It is therefore necessary to study alternative ways to incorporate stochasticity and to seek approaches that reduce the computational time needed for simulations, yet preserve the characteristic behavior of the system in question. In this work, we develop a computational framework based on the It? stochastic differential equations for neuronal signal transduction networks. There are several different ways to incorporate stochasticity into deterministic differential equation models and to obtain It? stochastic differential equations. Two of the developed models are found most suitable for stochastic modeling of neuronal signal transduction. The best models give stable responses which means that the variances of the responses with time are not increasing and negative concentrations are avoided. We also make a comparative analysis of different kinds of stochastic approaches, that is the It? stochastic differential equations, the chemical Langevin equation, and the Gillespie stochastic simulation algorithm. Different kinds of stochastic approaches can be used to produce similar responses for the neuronal protein kinase C signal transduction pathway. The fine details of the responses vary slightly, depending on the approach and the parameter values. However, when simulating great numbers of chemical species, the Gillespie algorithm is computationally several orders of magnitude slower than the It? stochastic differential equations and the chemical Langevin equation. Furthermore, the chemical Langevin equation produces negative concentrations. The It? stochastic differential equations developed in this work are shown to overcome the problem of obtaining negative values. 相似文献
20.
An advanced intermediate in the Nakatsuka synthesis of 0231B was prepared using a fluoride-mediated indole formation in the key step. Both palladium-based approaches and hydride-based approaches failed to generate the indole. 相似文献