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排序方式: 共有470条查询结果,搜索用时 93 毫秒
461.
Nader Saemian Gholamhossein Shirvani Sayed Sajad Oliyaee Mohsen Javaheri 《Journal of Radioanalytical and Nuclear Chemistry》2012,292(1):237-241
The key synthetic intermediate, (2-mercapto-1-(4-nitrobenzyl)-1H-imidazol-5-yl)methanol-[2-14C], has been synthesized by using one pot procedure from potassium[14C]-thiocyanate. It was converted to two nonpeptide angiotensin II receptor antagonists, 2-methylthio-1-[4-N-α-ethoxycarbonyl
benzyl)-aminobenzyl]-5-hydroxymethyl-1H-imidazole-[2-14C] and 1-[4-N-α-ethoxy-carbonylbenzyl)-aminobenzyl]-5-hydroxymethyl-1H-imidazole-[2-14C] via a 3-step sequence synthetic pathway. 相似文献
462.
High yielding synthesis of six- and five-membered N-substituted iminosugar glycosides and of five-membered iminosugar thioglycosides by nucleophilic opening of both new and previously described N-diethoxycarbonylvinyl anhydroiminosugar derivatives (glycosyl donors) with primary alcohols, primary thiols, and thiophenol (glycosyl acceptors) is reported. The reactions are highly stereoselective, with anomeric ratios better than 4:1. 相似文献
463.
Nader M. A. Mohamed Asmaa G. Abo El-Nor Mohamed Soliman Ahmed A. Abdel Aal M. K. Shaat 《Journal of Radioanalytical and Nuclear Chemistry》2010,285(2):321-329
Participation in inter-comparison programs is an important process to enhance the accuracy and precision of the analytical
techniques. The Instrumental Neutron Activation Analysis laboratory (INAA) at Egypt Second Research Reactor (ETRR-2), ETRR-2
INAA Laboratory, was participated in three inter-comparison tests organized by AFRA Research Reactor Project for Socio-economic
development. AFRAIV-12 Inter-laboratory Analysis Test 2007 is the third inter-laboratory analysis test within that project.
The laboratories were asked to analyze for 43 essential and toxic elements using nuclear and related analytical techniques,
with neutron activation analysis as the common technique. Five materials were distributed to the participants representing
foodstuff, medicinal plants and aquatic biomonitors according to the focus of the AFRA IV-12 2006–2010 project. In this paper
the ETRR-2 INAA Laboratory results is evaluated. 相似文献
464.
In this paper, a linear controller based on the Lyapunov stability theorem is designed and implemented on a smart beam. This smart beam consists of a steel beam with a piezoactuator bonded to it. The controller is used to attentuate the vibrations of the smart beam while exciting it by it's first eigenmode. A super element (SE) model of the same beam is firstly derived, and the controller is implemented on the SE and results are shown. (© 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
465.
Inspired by its analog from classic optics, we introduce one-atom-thick reflectors for infrared (IR) surface plasmon polaritons (SPP) surface waves based on graphene. Using numerical simulations, we first present the simple case of one-atom-thick straight-line mirror and then show how a one-atom-thick parabolic reflector (mirror) can be envisioned for focusing guided SPP waves on the graphene. 相似文献
466.
We deal with consistent first order non-relativistic corrections (i.e. in the small parameter , where c is the speed of light) of the Dirac–Maxwell system. We discuss a selfconsistent modeling of the Pauli equation as the O(ɛ) approximation of the Dirac equation. We suggest a coupling to the “magnetostatic”O(ɛ) approximation of the Maxwell equations consisting of Poisson equations for the four components of the potential. We sketch the semiclassical/nonrelativistic limits of this model. 相似文献
467.
A series of rhodamine B (RhB) encapsulated zeolitic imidazolate framework-8 (RhB@ZIF-8) composite nanomaterials with different concentrations of guest loadings have been synthesized and characterized in order to investigate their applicability to solid-state white-light-emitting diodes (WLEDs). The nanoconfinement of the rhodamine B dye (guest) in the sodalite cages of ZIF-8 (host) is supported by fluorescence spectroscopic and photodynamic lifetime data. The quantum yield (QY) of the luminescent RhB@ZIF-8 material approaches unity when the guest loading is controlled at a low level: 1 RhB guest per ~7250 cages. We show that the hybrid (luminescent guest) LG@MOF material, obtained by mechanically mixing a suitably high-QY RhB@ZIF-8 red emitter with a green-emitting fluorescein@ZIF-8 “phosphor” with a comparably high QY, could yield a stable, intensity tunable, near-white light emission under specific test conditions described. Our results demonstrate a novel LG@MOF composite system exhibiting a good combination of photophysical properties and photostability, for potential applications in WLEDs, photoswitches, bioimaging and fluorescent sensors. 相似文献
468.
469.
Mansooreh MOVAHEDI Nader ZABARJAD SHIRAZ Ali EZABADI Marjaneh SAMADIZADEH Mohamad Reza TALEI BAVIL OLYAI 《Turkish Journal of Chemistry》2021,45(5):1609
The mechanism as well the stereochemistry of cascade cycloisomerization of 15–membered triazatriacetylenic macrocycle was investigated theoretically by using M062X/6–31+G(d,p) and M062X/LANL2DZ calculations. The results showed that the mechanism and outcome of the reaction depended on the absence and presence of a transition metal catalyst. So that, in thermal-induced condition, the reaction had to experience several suprafacial concerted reactions including Ene-reaction (DG#=35.38 kcal/mol), Diels–Alder cycloaddition (DG# = 17.16 kcal/mol), and sigmatropic H-shift rearrangement (DG# = 56.21 kcal/mol) to produce diastereoselective fused cis–tetracyclic aromatic bearing a pyrrole moiety by following kinetic considerations. Also, the [2+2+2] cycloaddition mechanism was neglected in thermal–induced conditions because of high activation free Gibbs energy (DG# = 63.90 kcal/mol). In the presence of palladium catalyst, Pd(0) formed an adduct by coordinating to C = C bonds and decreased the DG# of the process to 29.58 kcal/mol, and consequently provided a facilitated media for the reaction to follow the [2+2+2] to produce more stable fused tetracyclic benzenoid aromatic by passing through the lower energy barrier. 相似文献
470.
We prove the instability of the Couette flow if the disturbances is less smooth than the Gevrey space of class 2. This shows that this is the critical regularity for this problem since it was proved in [5] that stability and inviscid damping hold for disturbances which are smoother than the Gevrey space of class 2. A big novelty is that this critical space is due to an instability mechanism which is completely nonlinear and is due to some energy cascade. © 2023 The Authors. Communications on Pure and Applied Mathematics published by Wiley Periodicals LLC. 相似文献