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排序方式: 共有180条查询结果,搜索用时 15 毫秒
1.
Nadir Arada Paulo Correia Adélia Sequeira 《Numerical Methods for Partial Differential Equations》2007,23(6):1468-1500
This article is concerned with the equations governing the steady motion of a viscoelastic incompressible second‐order fluid in a bounded domain. A new proof of existence and uniqueness of strong solutions is given. In addition, using appropriate finite element methods to approximate a coupled equivalent problem, sharp error estimates are obtained using a fixed point argument. The method is applied to the two‐dimensional lid‐driven cavity problem, at low Reynolds number and in a certain range of values of the viscoelastic parameters, to analyze the combined effects of inertia and viscoelasticity on the flow. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
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Attempts to cyclise o-chlorophenyl benzyl ether, sulphide, sulphoxide and sulphone by treatment with KNH2/NH3 were unsuccessful. Similar reaction of 1-(o-chlorophenyl)-2,2-diphenylethane led to amination whereas α-(o-chlorobenzyl)phenylacetic acid gave a dihydrocoumarin. Reaction of 4- and 2-(o-chlorophenethyl)-pyridines, however, afforded products comprising benzisoquinolines and 1-pyridylbenzocyclobutenes. 相似文献
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5.
H. Yücel H. Karadeniz M. A. Çetiner H. Demirel Ş. Turhan 《Journal of Radioanalytical and Nuclear Chemistry》2003,258(2):445-447
The sorption behavior of 235U fission fission products 99Mo and 132Te was studied through batch and dynamic experiments when they were dissolved in 1 to 7M HNO3 solutions. It was found that 99Mo is always totally adsorbed on hydrated SnO2, while 132Te is rather weakly adsorbed, therefore they can be separated from each other although 132Te in the solution still remains contaminated with other radionuclides as well as 99Mo does in the solid. 相似文献
6.
Ibrahim Isildak Murat Yolcu Omer Isildak Nadir Demirel Giray Topal Halil Hosgoren 《Mikrochimica acta》2004,144(1-3):177-181
Two diaza-crown ether compounds were synthesized and evaluated as Ag+-selective carriers in polyvinylchloride (PVC) membrane electrodes of solid-state type. The all-solid-state PVC membrane electrode based on N,N-Dibenzyl-dibenzo-diaza-18-crown-6 exhibited a super-Nernstian response (75±10mV per decade) over the concentration range of 1×10–1 to 7×10–6M of Ag+ ion and a detection limit of 3×10–6M, at a wide range of pH (pH 4–7). The response time of the electrode was fast (less than 10s), and it can be used for three months without any significant deviation in potential. The proposed all-solid-state PVC membrane electrodes revealed high selectivity toward Ag+ ion with respect to alkali, alkaline earth, heavy and transition metal ions. A flow-through cell of all-solid-state PVC membrane Ag+-selective electrode based on N,N-Dibenzyl-dibenzo-diaza-18-crown-6 has also been prepared and applied for flow-injection analysis of Ag+ ion in solution. 相似文献
7.
P. Arikan O. Acar R. Acar G. A. Aycik M. A. Cetiner H. Demirel N. Efe T. Golge R. Gurellier R. Kirmaz S. Tulumen H. Yucel A. Zararsiz Y. Agus 《Journal of Radioanalytical and Nuclear Chemistry》2004,259(3):391-394
Comprehensive Quality Control (QC) and Quality Assurance (QA) Program is stated on the quality policy, organization, methods
and records for nuclear analytical laboratories which are necessary for improvement of productivity, to upgrade the performance,
credibility and reputation. The proper and complete identification of quality elements for management and technical requirements
are being written in Quality Manual as well as analytical and organizational procedures and working instructions according
to ISO 17025 standard. Technical ability of gamma, X-ray and a/b laboratories in the Center has been checked by participation
in proficiency test, critical technical variables, and quality results. Performance of quality system has been controlled
by external audit inspection, progress reports and service to clients. The present study is a framework of the model project
of IAEA, coded RER/2/004, which has resulted self-sustainable accreditation from the national body, TURKAK.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
8.
John Quigley Lesley Walls Güven Demirel Bart L. MacCarthy Mahdi Parsa 《European Journal of Operational Research》2018,264(3):932-947
We consider supplier development decisions for prime manufacturers with extensive supply bases producing complex, highly engineered products. We propose a novel modelling approach to support supply chain managers decide the optimal level of investment to improve quality performance under uncertainty. We develop a Poisson–Gamma model within a Bayesian framework, representing both the epistemic and aleatory uncertainties in non-conformance rates. Estimates are obtained to value a supplier quality improvement activity and assess if it is worth gaining more information to reduce epistemic uncertainty. The theoretical properties of our model provide new insights about the relationship between the degree of epistemic uncertainty, the effectiveness of development programmes, and the levels of investment. We find that the optimal level of investment does not have a monotonic relationship with the rate of effectiveness. If investment is deferred until epistemic uncertainty is removed then the expected optimal investment monotonically decreases as prior variance increases but only if the prior mean is above a critical threshold. We develop methods to facilitate practical application of the model to industrial decisions by a) enabling use of the model with typical data available to major companies and b) developing computationally efficient approximations that can be implemented easily. Application to a real industry context illustrates the use of the model to support practical planning decisions to learn more about supplier quality and to invest in improving supplier capability. 相似文献
9.
Prof. Gökçen Birlik Demirel 《Chemphyschem》2014,15(8):1693-1699
A simple strategy for the immobilization of Cy3‐labeled single strand DNA (Cy3‐ssDNA) on a Si(001) surface and its release under control of both light and pH stimuli is presented. In order to prepare a dual pH/light‐triggered surface, positively chargeable azobenzene molecules are self‐assembled on the Si(001) surface. The surface wettability of this substrate can be changed under influence of both light and pH conditions. The substrates can be positively charged under mildly acidic conditions. The pH‐sensitive behavior of the film allows binding of Cy3‐ssDNA on the functionalized Si(001) surface through e?ective electrostatic interactions with the negatively charged polynucleotide backbone. Moreover, irradiation of the film with UVA light induces trans–cis isomerization of the azobenzene units on the surface. As a result, the binding a?nity for DNA decreases due to the changing surface hydrophilicity. In order to understand and control the reversible photoswitchable mechanism of this surface, water contact angles are measured after UVA and visible light irradiation. The release of DNA from a dual pH/light‐sensitive sample is performed using fluorescence microscopy. The results show that irradiation of the film with UVA light induces trans–cis isomerization of the photoresponsive azobenzene units; this leads to significant changes in the surface hydrophilicity and reduces the binding affinity for DNA. 相似文献
10.
Mehmet Atilla Tasdelen Selim Beyazit Deniz Gunes Niyazi Bicak Pinar Tatar A. Levent Demirel Yusuf Yagci 《Journal of polymer science. Part A, Polymer chemistry》2011,49(18):4021-4026
The synthesis of poly(p‐phenylene methylene) (PPM)‐based block copolymers such as poly(p‐phenylene methylene)‐b‐poly(ε‐caprolactone) and poly(p‐phenylene methylene)‐b‐polytetrahydrofuran by mechanistic transformation was described. First, precursor PPM was synthesized by acid‐catalyzed polymerization of tribenzylborate at 16 °C. Then, this polymer was used as macroinitiators in either ring‐opening polymerization of ε‐caprolactone or cationic ring‐opening polymerization of tetrahydrofuran to yield respective block copolymers. The structures of the prepolymer and block copolymers were characterized by GPC and 1H NMR investigations. The composition of block copolymers as determined by 1H NMR and TGA analysis was found to be in very good agreement. The thermal behavior and surface morphology of the copolymers were also investigated, respectively, by differential scanning calorimetry and atomic force microscopy measurements, and the contribution of the major soft segment has been observed. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献