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排序方式: 共有78条查询结果,搜索用时 31 毫秒
31.
Hongbo Yu Mustafa Ozturk Pakize Demirel Huseyin Cakmak Ekmel Ozbay 《Journal of Crystal Growth》2010,312(23):3438-3442
Non-polar a-plane GaN film with crystalline quality and anisotropy improvement is grown by use of high temperature AlN/AlGaN buffer, which is directly deposited on r-plane sapphire by pulse flows. Compared to the a-plane GaN grown on AlN buffer, X-ray rocking curve analysis reveals a remarkable reduction in the full width at half maximum, both on-axis and off-axis. Atomic force microscopy image exhibits a fully coalesced pit-free surface morphology with low root-mean-square roughness (∼1.5 nm). Photoluminescence is carried out on the a-plane GaN grown on r-plane sapphire. It is found that, at low temperature, the dominant emission at ∼3.42 eV is composed of two separate peaks with different characteristics, which provide explanations for the controversial attributions of this peak in previous studies. 相似文献
32.
A robust and scalable synthesis of a novel, cyano-substituted Danishefsky-type diene and its use in the Diels-Alder reaction with various dienophiles is reported. The diene allows for the rapid construction of highly substituted aminonaphthoquinones that occur in numerous ansamycin antibiotics. 相似文献
33.
High energy picosecond pulse generation from a two contact tapered 5 quantum well (QW) InGaAlAs/InP diode laser (1550 nm) is investigated using a passive Q-switching technique. Single peak pulses with pulse energies as high as 500 pJ and durations of typically hundreds of picoseconds are obtained from the device by applying reverse bias voltages in the range of 0 V to ?18 V to the absorber section of the device. It is also demonstrated that more symmetrical Q-switched pulses are obtained by reducing the duration of electrical pulses applied to the gain section of the laser. Such an improvement is attributed to the reduced time of the population inversion in the gain section due to shorter electrical pulse. We also show comparatively the dependence of optical spectra on the reverse bias voltage for diode lasers emitting at 1550 nm and 1350 nm, and demonstrate that better spectral output is obtained from AlGaInAs lasers emitting at a wavelength of 1550 nm. 相似文献
34.
F.M. Hashimzade A.M. Babayev S. Cakmak S. Cakmaktepe 《Physica E: Low-dimensional Systems and Nanostructures》2005,28(4):447-452
Particle penetration through a square potential and a step potential barrier are studied with the eight-band Kane Hamiltonians. It has found expressions for transmission probability and reflection coefficients of electrons for both potentials. It is shown in the Kane model that the transmission probability will have a finite value that is different from the one-band model at the state where the barrier height is infinite. The Landauer formula for resistance is applied to the Kane type semiconductor heterostructures. 相似文献
35.
Near‐IR‐Triggered,Remote‐Controlled Release of Metal Ions: A Novel Strategy for Caged Ions
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Ahmet Atilgan Dr. Esra Tanriverdi Eçik Dr. Ruslan Guliyev T. Bilal Uyar Dr. Sundus Erbas‐Cakmak Prof. Dr. Engin U. Akkaya 《Angewandte Chemie (International ed. in English)》2014,53(40):10678-10681
A ligand incorporating a dithioethenyl moiety is cleaved into fragments which have a lower metal‐ion affinity upon irradiation with low‐energy red/near‐IR light. The cleavage is a result of singlet oxygen generation which occurs on excitation of the photosensitizer modules. The method has many tunable factors that could make it a satisfactory caging strategy for metal ions. 相似文献
36.
In this study, we have coupled the real time mechano‐optical measurements with the off‐line structural characterization techniques including AFM, WAXS, and DSC to establish the quantitative relationships between the “true mechano‐optical behavior and developed morphology” as influenced by the fraction of molten phase present in the polypropylene films. Stretching PP in the solid state invariably leads to formation of fibrillar texture. The evolution of surface morphology in partially molten state was found to depend on the fraction of the molten phase present at the start of the deformation. If the samples are strained past the yielding in partially molten state, the birefringence begins a rapid rise. Concurrent with this, the equatorial zones of the spherulites begin to crack while meridional regions remaining intact. This leads to temporary reduction of crystallinity because of destruction of some of the crystals. If held in this strained state, the crystallite thickening was observed while the birefringence increases while the lost crystallinity is recovered. If the films are strained past the strain hardening point, the microfibrillar structure was found to dominate the surface morphology. When the films are stretched in the melting temperature range, they exhibit substantial nodular surface topology. These nodules that were absent in the solid state deformed samples are hard lamellae buried inside amorphous “soft matter”. The tangential lamellae increasingly become dominant as the processing temperature approaches substantially molten state leading to the observation of a* oriented crystallites in the X‐ray analysis. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 925–941, 2006 相似文献
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38.
Edna Bode Antje K. Heinrich Merle Hirschmann Desalegne Abebew Yan‐Ni Shi Tien Duy Vo Frank Wesche Yi‐Ming Shi Peter Grün Svenja Simonyi Nadine Keller Yvonne Engel Sebastian Wenski Reuel Bennet Sophie Beyer Iris Bischoff Anthony Buaya Sophie Brandt Ibrahim Cakmak Harun imen Simone Eckstein Denia Frank Robert Fürst Martin Gand Gerd Geisslinger Selcuk Hazir Marina Henke Ralf Heermann Virginie Lecaudey Wilhelm Schfer Susanne Schiffmann Anja Schüffler Rebecca Schwenk Marisa Skaljac Eckhard Thines Marco Thines Thomas Ulshfer Andreas Vilcinskas Thomas A. Wichelhaus Helge B. Bode 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(52):19288-19288
39.
Yakan Hasan Cakmak Sukriye Kutuk Halil Yenigun Semiha Ozen Tevfik 《Research on Chemical Intermediates》2020,46(5):2767-2787
Research on Chemical Intermediates - We performed a series of novel benzamide compounds which were synthesized starting from 2,3-dimethoxybenzoic acid or 3-acetoxy-2-methylbenzoic acid and amine... 相似文献
40.
This present work focuses on the surface characterization of reactor-thermoplastic-polyolefin copolymers (R-TPO) for automotive
applications to deduce an appropriate parameter as a measure of the surface stickiness behavior. Therefore, nanoindentation
experiments are performed and the well-known mechanical contact properties have been determined. Additional, it has been tried
to measure an adhesion force between the indenter tip and the material’s surface. The adhesion force has been measured as
negative force during unloading and is the tensile force needed to bring the indenter tip to the initial position. Moreover,
the verification and correction of the viscoelastic effects have been considered. 相似文献