排序方式: 共有93条查询结果,搜索用时 15 毫秒
61.
1-Aryl-3-phenethylamino-1-propanone hydrochlorides 1-10, which are potentialpotent cytotoxic agents, were synthesized via Mannich reactions using paraformaldehyde,phenethylamine hydrochloride as the amine component and acetophenone, 4'-methyl-, 4'-methoxy-, 4'-chloro-, 4'-fluoro-, 4'-bromo-, 2',4'-dichloro-, 4'-nitro-, 4'-hydroxyacetophenone or 2-acetylthiophene as the ketone component. Yields were in the87-98 % range. Of the compounds synthesized, compounds 2, 6-8 and 10 were new. Theoptimum reaction conditions were investigated by changing the mol ratios of the reactants,the solvents and the acidity levels using 1 and 10 as representative targets. It was observedthat the best mol ratio of the ketone, paraformaldehyde and phenethylamine hydrochloridewas 1:1.2:1 (compared with a 2:2.1 ratio), and the most suitable reaction medium wasethanol containing concentrated hydrochloric acid (compared with only ethanol or nosolvent). This study may serve as a guide for the conditions of the reactions to synthesizecompounds having similar chemical structures. 相似文献
62.
Ebru Ucakturk Chao Cai Lingyun Li Guoyun Li Fuming Zhang Robert J. Linhardt 《Analytical and bioanalytical chemistry》2014,406(19):4617-4626
A capillary zone electrophoresis–laser-induced fluorescence detection (CZE-LIF) method was developed for the simultaneous analysis of disaccharides derived from heparan sulfate, chondroitin sulfate/dermatan sulfate, hyaluronan, and keratan sulfate. Glycosaminoglycans (GAGs) were first depolymerized with the mixture of GAG lyases (heparinase I, II, III and chondroitinase ABC and chondroitinase AC II) and GAG endohydrolase (keratinase II) and the resulting disaccharides were derivatized by reductive amination with 2-aminoacridone. Nineteen fluorescently labeled disaccharides were separated using 50 mM phosphate buffer (pH 3.3) under reversed polarity at 25 kV. Using these conditions, all the disaccharides examined were baseline separated in less then 25 min. This CZE-LIF method gave good reproducibility for both migration time (≤1.03 % for intraday and ≤4.4 % for interday) and the peak area values (≤5.6 % for intra- and ≤8.69 % for interday). This CZE-LIF method was used for profiling and quantification of GAG derivative disaccharides in bovine cornea. The results show that the current CZE-LIF method offers fast, simple, sensitive, reproducible determination of disaccharides derived from total GAGs in a single run. Figure
Separation of 19 glycosaminoglycan-derived disaccharides using CZE. These disaccharides are HA (pink), HS (blue), CS (green) and KS (red). Residual AMAC tag is shown in orange. 相似文献
63.
An experimental study exploring colour ranges corresponding to different colour names has been conducted. Available colour terms in Turkish language have been identified and the most frequently known or used colour terms have been attained. Using the Munsell Color System, colour ranges reflecting the colour naming and colour perception of Turkish people, have been constructed for each colour term. The discussion of the findings and observations during the research are also included. 相似文献
64.
This article presents a semigroup approach for the mathematical analysis of the inverse coefficient problems of identifying the unknown coefficient k(u(x,t)) in the quasi‐linear parabolic equation ut(x,t)=(k(u(x,t))ux(x,t))x, with Dirichlet boundary conditions u(0,t)=ψ0, u(1,t)=ψ1. The main purpose of this paper is to investigate the distinguishability of the input–output mappings Φ[?]:?? →C1[0,T], Ψ[?]:??→C1[0,T] via semigroup theory. In this paper, it is shown that if the null space of the semigroup T(t) consists of only zero function, then the input–output mappings Φ[?] and Ψ[?] have the distinguishability property. It is also shown that the types of the boundary conditions and the region on which the problem is defined play an important role in the distinguishability property of these mappings. Moreover, under the light of measured output data (boundary observations) f(t):=k(u(0,t))ux(0,t) or/and h(t):=k(u(1,t))ux(1,t), the values k(ψ0) and k(ψ1) of the unknown diffusion coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, can be determined explicitly. In addition to these, the values ku(ψ0) and ku(ψ1) of the unknown coefficient k(u(x,t)) at (x,t)=(0,0) and (x,t)=(1,0), respectively, are also determined via the input data. Furthermore, it is shown that measured output data f(t) and h(t) can be determined analytically by an integral representation. Hence the input–output mappings Φ[?]:??→ C1[0,T], Ψ[?]:??→C1[0,T] are given explicitly in terms of the semigroup. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
65.
Ebru Ozbilge 《Mathematical Methods in the Applied Sciences》2008,31(11):1333-1344
In this article, a semigroup approach is presented for the mathematical analysis of the inverse coefficient problems of identifying the unknown diffusion coefficient k(u(x, t)) in the quasi‐linear parabolic equation ut(x, t)=(k(u(x, t))ux(x, t))x, with Dirichlet boundary conditions ux(0, t)=ψ0, u(1, t)=ψ1. The main purpose of this work is to analyze the distinguishability of the input–output mappings Φ[·] : ??→C1[0, T], Ψ[·] : ??→C1[0, T] using semigroup theory. In this article, it is shown that if the null space of semigroups T(t) and S(t) consists of only a zero function, then the input–output mappings Φ[·] and Ψ[·] have the distinguishability property. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
66.
This article presents a semigroup approach to the mathematical analysis of the inverse parameter problems of identifying the unknown parameters p(t) and q in the linear parabolic equation ut(x, t) = uxx + qux(x, t) + p(t)u(x, t), with Dirichlet boundary conditions u(0, t) = ψ0, u(1, t) = ψ1. The main purpose of this paper is to investigate the distinguishability of the input-output mapping Φ[·]:P→H1,2[0,T], via semigroup theory. In this paper, it is shown that if the nullspace of the semigroup T(t) consists of only zero function, then the input-output mapping Φ[·] has the distinguishability property. It is also shown that the types of the boundary conditions and the region on which the problem is defined play an important role in the distinguishability property of the mapping. Moreover, under the light of the measured output data ux(0, t) = f(t) the unknown parameter p(t) at (x, t) = (0, 0) and the unknown coefficient q are determined via the input data. Furthermore, it is shown that measured output data f(t) can be determined analytically by an integral representation. Hence the input-output mapping Φ[·]:P→H1,2[0,T] is given explicitly interms of the semigroup. 相似文献
67.
In this study, essential oil compositions of two Hypericum L. taxa (Hypericum triquetrifolium Turra. and Hypericum aviculariifolium Jaub. et Spach subsp. depilatum var. depilatum (Freyn et Bornm.) Robson) naturally grown in Turkey were determined using gas chromatography and gas chromatography-mass spectrometry systems. The essential oils were obtained by hydrodistillation from the aerial parts of plants. A total of 45 compounds were identified in the essential oils of H. triquetrifolium; 1-hexanal (18.8%), 3-methylnonane (12.5%) and α-pinene (12.3%). In this study, 41 components were identified in H. aviculariifolium subsp. depilatum var. depilatum oil; α-pinene (52.1%), germacrene D (8.5%) and β-pinene (3.6%) were the predominant constituents. The essential oil analysis showed that monoterpene concentrations were higher than that of the sesquiterpenes in both oils. The results were discussed in the meaning of the usefulness of these plants and their chemicals as natural products and potential usage in chemotaxonomy. 相似文献
68.
Uçaktürk E 《Journal of separation science》2012,35(3):341-350
Therapeutic monoclonal antibodies (mAbs), immunoglobulins, have been efficiently used in the treatment of many diseases, such as cancer, inflammatory and cardiovascular diseases, and organ transplantation. mAbs are glycoprotein molecules undergoing posttranslational modifications. Glycosylation is one of the posttranslational modifications. Different glycoforms that are important for maintaining the potency of mAb drugs show various biological activities. Therefore, the profile of the glycans and glycosylation sites should be determined to produce safe, good quality, consistent mAb drugs for human use. For this reason, simple, robust, accurate, and reproducible analytical methods need to be developed. In this article, chromatographic methods for the analysis of the glycoforms on the glycosylation site and the glycans in mAb biopharmaceuticals have been evaluated. 相似文献
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70.
A project scheduling model tailored specifically for software development projects is proposed in this study. The model incorporates uncertainties related to activity durations and network topology. The first type of uncertainty exists due to error-prone coding which might result in elongated task durations caused by validation and debugging sessions. Furthermore, in practice, macro-activities represent groups of sub-tasks in order to simplify the planning and monitoring of the project. Due to the aggregation, it is more difficult to be precise on the duration of a macro-activity.The uncertainty related to the network topology is due to common database design issues or program modules shared among parallel tasks in the project network. These tasks become associated with each other through uncertain Start-to-Start (SS) precedence relationships. On the other hand, SS lags may also be the outcome of technological precedence relationships among pairs of activities. However, the imprecision underlying the work content of a predecessor activity leads to uncertain SS lags.Software development projects are human-intensive projects and hence, the duration of a task depends on the skill of the person assigned to the job as well as his/her learning rate. Thus, a task may be realized by alternative staff members which results in different expected task durations. Hence, a realistic model proposed for software development projects should incorporate staff assignment features under the uncertainties discussed above. In this study, we develop a mathematical model for software development projects and propose heuristic solution methods to be used by the project co-ordinator in preparing the project plan. The heuristic algorithms developed here are tested on real data provided by a consulting firm undertaking software development projects from manufacturing companies in Turkey. 相似文献