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561.
Significant attention has been given to advancing cyber-infrastructures to support virtual engineering and science communities based on the proposition that virtual organizations can more effectively create and leverage knowledge due to diverse information, skills, and resources to enhance capacity to innovate. Yet, relatively little is known about desirable organizing processes in virtual open science communities. To this end, a simulation-based exploratory study is conducted to better understand the conditions that confer increased rates of innovation in such socio-technical systems. Three types of open science communities are identified and simulated using agent simulation as a method of inquiry. Simulation results show that centrality, as a measure of degree of connectedness, correlates with innovation output in exploratory and service communities up to a point. Also, utility-oriented communities have social network structures with low density and high centrality, which suggest high potential for innovation. 相似文献
562.
This paper describes a GC–MS method for the determination of naproxen in human plasma. Naproxen and internal standard ibuprofen were extracted from plasma using a liquid–liquid extraction method. Derivatization was carried out using N‐methyl‐N‐(trimethylsilyl)trifluoroacetamide. The calibration curve was linear between the concentration range of 0.10–5.0 μg/mL. Intra‐ and interday precision values for naproxen in plasma were <5.14, and accuracy (relative error) was better than 4.67%. The extraction recoveries of naproxen from human plasma were between 93.0 and 98.9%. The LOD and LOQ of naproxen were 0.03 and 0.10 μg/mL, respectively. Also, this assay was applied to determine the pharmacokinetic parameters of naproxen in six healthy Turkish volunteers who had been given 220 mg naproxen. 相似文献
563.
A new series of 1,3-benzoxazol-2(3H)-one hybrid compounds, including coumarin, isatin 1,3,4-triazole and 1,3,4-thiadiazole moieties, were synthesized and biologically evaluated for their antioxidant capacities and anti-urease properties. The synthesized benzoxazole-coumarin ( 6a–e ) and benzoxazole-isatin ( 10a–c ) hybrids showed remarkable urease inhibitory activities with IC50 (μM), ranging from 0.0306 ± 0.0030 to 0.0402 ± 0.0030, while IC50 of standard thiourea is 0.5027 ± 0.0293. The synthesized benzoxazole-triazole ( 8a–c ) and benzoxazole-thiadiazole ( 9a–c ) hybrids showed similar urease inhibitory activities with IC50 (μM), ranging from 0.3861 ± 0.0379 to 0.5126 ± 0.0345. The antioxidant activity of the synthesized compounds was evaluated for their antioxidant activities, such as reducing power and ABTS (2,2′-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt) radical scavenging. The results of ABTS radical scavenging activities of some of the synthesized molecules showed higher activities than standard Trolox, SC50 (μM) = 213.04 ± 18.12. One benzoxazole-coumarin ( 6f ), two benzoxazole-isothiocyanate ( 7b, 7c ), and two benzoxazole-triazole ( 8b, 8c ) derivatives showed higher activities (SC50 (μM) values, 82.07 ± 10.34, 120.19 ± 7.30, 104.58 ± 10.55, 153.26 ± 7.14, and 144.82 ± 10.68, respectively) than standard Trolox, (SC50 (μM) = 213.04 ± 18.12). 相似文献
564.
An efficient and general method for the synthesis of spiro-1,4-oxazepines and 3,3-dimethyl-1,4-oxazepines is reported. When treated with ZnI2 and AgSbF6 in refluxing DCE, cyclohexane-embedded N-propargylic β-enaminones underwent 7-exo-dig cyclization to afford spiro-1,4-oxazepines, specifically 12-methylene-11-oxa-7-azaspiro[5.6]dodeca-7,9-dienes, in good to high yields. Accordingly, N-(1,1-dimethyl)propargylic β-enaminones produced 3,3-dimethyl-1,4-oxazepines. Cyclization was found to be general for a diverse range of N-propargylic β-enaminones with high efficiency and broad functional group tolerance. This operationally easy method might provide quick access to a library of functionalized spiro and gem-dimethyl-substituted 1,4-oxazepine derivatives of pharmacological interest. 相似文献
565.
566.
A new macrocyclic ligand, 1,3,5-triaza-2,4:7,8:,14,15-tribenzo-9,13-dioxacyclohexadeca-1,5-diene (L) was synthesized by reaction
of 2,6-diaminopyridine and 1,3-bis(2-carboxyaldehyde phenoxy)propane. Then, its CuII, NiII, PbII, CoIII and LaIII complexes were synthesized by a template effect by reaction of 2,6-diaminopyridine and 1,3-bis (2-carboxyaldehyde phenoxy)propane
and Cu
O, Ni
O, Co
O, La
O, respectively. The ligand and its metal complexes have been characterized by elemental analysis, IR, 1H- and 13C-NMR-, UV-vis spectra, magnetic susceptibility, conductivity measurements, mass spectra and cyclic voltammetry. All complexes
are diamagnetic and the CuII complex is binuclear. The diamagnetic behaviour of the binuclear complex may be explained by a very strong anti-ferromagnetic
interaction in the Cu–Cu pair. The CoII was oxidised to CoIII. 相似文献
567.
Recently, Srivastava et al. introduced a new generalization of the Bernoulli, Euler and Genocchi polynomials (see [H.M. Srivastava, M. Garg, S. Choudhary, Russian J. Math. Phys. 17 (2010) 251-261] and [H.M. Srivastava, M. Garg, S. Choudhary, Taiwanese J. Math. 15 (2011) 283-305]). They established several interesting properties of these general polynomials, the generalized Hurwitz-Lerch zeta functions and also in series involving the familiar Gaussian hypergeometric function. By the same motivation of Srivastava’s et al. [11] and [12], we introduce and derive multiplication formula and some identities related to the generalized Bernoulli type polynomials of higher order associated with positive real parameters a, b and c. We also establish multiple alternating sums in terms of these polynomials. Moreover, by differentiating the generating function of these polynomials, we give a interpolation function of these polynomials. 相似文献
568.
The aim of this paper is to study and discuss the action of the Hecke operators to not only the generalized the Weber-type functions, but also the kth derivative of the Weierstrass-type functions. Furthermore, relations related to the Weierstrass-type functions and Riemann zeta and theta function are found. 相似文献
569.
Serkan Sayin Gülderen Uysal Akkuş Radek Cibulka Ivan Stibor Mustafa Yilmaz 《Helvetica chimica acta》2011,94(3):481-486
The synthesis of two new flavin substituted calix[4]arene derivatives, 9 and 10 , is described. The first flavin substituted calix[4]arene derivative 9 was synthesized by the reaction of 3‐methylalloxazine ( 5 ) with 25,27‐bis(3‐bromopropoxy)‐26,28‐dihydroxy‐5,11,17,23‐tetra(tert‐butyl)calix[4]arene ( 4 ) in high yield (92%). The other derivative 10 was prepared from 3‐methylalloxazine‐1‐acetic acid ( 7 ) and 25,27‐bis(3‐cyanopropoxy)calix[4]arene ( 3 ). All new compounds were characterized by a combination of FT‐IR and 1H‐NMR spectroscopy, and elemental‐analysis techniques. 相似文献
570.
Ozlem Akpinar Okan Levent Şeyda Bostanci Ufuk Bakir Levent Yilmaz 《Applied biochemistry and biotechnology》2011,163(2):313-325
Cotton stalk, a lignocellulosic waste material, is composed of xylose that can be used as a raw material for production of
xylitol, a high-value product. There is a growing interest in the use of lignocellulosic wastes for conversion into various
chemicals because of their low cost and the fact that they are renewable and abundant. The objective of the study was to determine
the effects of H2SO4 concentration, temperature, and reaction time on the production of sugars (xylose, glucose, and arabinose) and on the reaction
by-products (furfural and acetic acid). Response surface methodology was used to optimize the hydrolysis process in order
to obtain high xylose yield and selectivity. The optimum reaction temperature, reaction time, and acid concentration were
140 °C, 15 min, and 6%, respectively. Under these conditions, xylose yield and selectivity were found to be 47.88% and 2.26 g
g−1, respectively. 相似文献