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排序方式: 共有230条查询结果,搜索用时 187 毫秒
31.
Every mode of a single-mode or multimode helical fibre is always leaky but, for practical purposes, can be treated as being bound with an effective cut-off wavelength. The leakage loss for each mode is quantified, showing that, for fixed core offset and source wavelength, the cut-off pitch increases with increasing mode order. The value of the cut-off pitch for each mode is in agreement with experimental measurements. 相似文献
32.
In this paper, we report the efficient and regioselective synthesis of 2-aminopyrrole-4-carboxylates as derivatives of conformationally restricted analogues of γ-amino butyrates (GABA) via a zinc perchlorate catalyzed amination-annulation of α-cyanomethyl-β-ketoesters under mild reaction conditions in water. 相似文献
33.
EPR Studies of the Binding Properties,Guest Dynamics,and Inner‐Space Dimensions of a Water‐Soluble Resorcinarene Capsule 下载免费PDF全文
Dr. Mehmet Menaf Ayhan Dr. Gilles Casano Dr. Hakim Karoui Prof. Antal Rockenbauer Dr. Valérie Monnier Dr. Micaël Hardy Prof. Paul Tordo Dr. David Bardelang Dr. Olivier Ouari 《Chemistry (Weinheim an der Bergstrasse, Germany)》2015,21(46):16404-16410
Nitroxide free radicals have been used to study the inner space of one of Rebek’s water‐soluble capsules. EPR and 1H NMR spectroscopy, ESI‐MS, and DFT calculations showed a preference for the formation of 1:2 complexes. EPR titrations allowed us to determine binding constants (Ka) in the order of 107 M ?2. EPR spectral‐shape analysis provided information on the guest rotational dynamics within the capsule. The interplay between optimum hydrogen bonding upon capsule formation and steric strain for guest accommodation highlights some degree of flexibility for guest inclusion, particularly at the center of the capsule where the hydrogen bond seam can be barely distorted or slightly disturbed. 相似文献
34.
Frontispiece: EPR Studies of the Binding Properties,Guest Dynamics,and Inner‐Space Dimensions of a Water‐Soluble Resorcinarene Capsule 下载免费PDF全文
35.
Mustafa İlhan Ayhan Mergen Cevat Sarıoğlu Cemalettin Yaman 《Journal of Thermal Analysis and Calorimetry》2017,128(2):707-711
Heat capacity measurements of barium tantalate (BaTa2O6) were carried out by using a differential scanning calorimeter at temperatures between 323 and 1323 K. From the heat capacity values of BaTa2O6, other thermodynamic functions (enthalpy and entropy increments) were derived between 298.15 and 1323 K. The C p,m (298.15) value of BaTa2O6 was computed as 184.857 J mol?1 K?1. Moreover, fitted heat capacities exhibited good agreement with Neumann–Kopp rule at the temperatures between 298.15 and 1300 K. 相似文献
36.
37.
High-throughput screening of cytochrome P450CAM libraries, for their ability to oxidise indole to indigo and indirubin, has resulted in the identification of variants with activity towards the structurally unrelated substrate diphenylmethane. 相似文献
38.
Celik A Roberts GA White JH Chapman SK Turner NJ Flitsch SL 《Chemical communications (Cambridge, England)》2006,(43):4492-4494
Analysis of the substrate specificity of the self-sufficient cytochrome P450 RhF revealed that the enzyme tends to catalyse the dealkylation of substituted alkyl-aryl ethers with shorter alkyl moieties more readily than equivalent compounds with longer alkyl groups. 相似文献
39.
In this paper we introduce some certain new sequence spaces via ideal convergence, λ-sequence and an Orlicz function in n-normed spaces and study different properties of these spaces and also establish some inclusion results among them. 相似文献
40.
Sultan Akhtar Şeyda Tuğba Günday B. Rabindran Jermy M.A. Almessiere Ayhan Bozkurt 《Journal of Saudi Chemical Society》2019,23(4):477-485
In this work, we report an efficient method to produce pure hollow silica spheres (HSS) using phenyltrimethoxysilane (PTMS) compound. The production of HSS was carried out via hydrolysis of PTMS in the aqueous media and followed by a condensation reaction to form silica spheres with phenyl groups. The product was then calcined to remove phenyl groups and obtain pure silica spheres with >95% fine structure. The chemical nature of pure silica was confirmed by Fourier transforms infrared spectroscopy. The calcined HSS were stable beyond the temperature of 900 °C as confirmed by thermal gravimetric analysis (TGA). The calcined spheres preserved their spherical appearance and hollow core as shown by SEM and TEM micrographs. Interestingly, the average size of the spheres was reduced significantly after calcination from 760 to 510 nm, confirming further the removal of phenyl groups. The calcined HSS offered much higher surface area (As) when analysed by BET; As for calcined product was ~406 and mere ~4.8 m2/g for uncalcined HSS. Finally, drug release study of cisplatin/HSS showed over 45% of steady cumulative release for 72 h. The prepared HSS can be dispersed in water opening the possibility of many novel bio/non-bio applications. 相似文献