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排序方式: 共有619条查询结果,搜索用时 15 毫秒
1.
Background
The aim of the present study was to characterize the activation profiles of 15 opioid ligands in transfected human embryonic kidney cells expressing only δ opioid receptors. Activation profiles of most of these ligands at δ opioid receptors had not been previously characterized in vitro. Receptor activation was assessed by measuring the inhibition of forskolin-stimulated cAMP production. 相似文献2.
Here we present a theoretical analysis of the effect of inelastic electron scattering on spin-dependent transport characteristics (conductance, current–voltage dependence, magnetoresistance, shot noise spectrum, Fano factor) for magnetic nanojunction. Such device is composed of molecular quantum dot (with discrete energy levels) connected to ferromagnetic electrodes (treated within the wide-band approximation), where molecular vibrations are modeled as dispersionless phonons. Non-perturbative computational scheme, used in this work, is based on the Green's function theory within the framework of mapping technique (GFT–MT), which transforms the many-body electron–phonon interaction problem into a single-electron multi-channel scattering problem. The consequence of the localized electron–phonon coupling is polaron formation. It is shown that polaron shift and additional peaks in the transmission function completely change the shape of considered transport characteristics. 相似文献
3.
Kamil Walczak 《Central European Journal of Physics》2006,4(1):8-19
The rate-equation approach is used to describe sequential tunneling through a molecular junction in the Coulomb blockade regime.
Such device is composed of molecular quantum dot (with discrete energy levels) coupled with two metallic electrodes via potential
barriers. Based on this model, we calculate nonlinear transport characteristics (conductance-voltage and current-voltage dependences)
and compare them with the results obtained within a self-consistent field approach. It is shown that the shape of transport
characteristics is determined by the combined effect of the electronic structure of molecular quantum dots and by the Coulomb
blockade. In particular, the following phenomena are discussed in detail: the suppression of the current at higher voltages,
the charging-induced rectification effect, the charging-generated changes of conductance gap and the temperature-induced as
well as broadening-generated smoothing of current steps. 相似文献
4.
Sulaiman Wadi Harun Nizam Tamchek Mohd Kamil Abd-Rahman Prabakaran Poopalan Harith Ahmad 《Optical Review》2003,10(3):133-135
A multiwavelength Brillouin/erbium fibre laser (BEFL) which operates in the long wavelength (L-band) region is demonstrated for potential applications in an L-band wavelength division multiplexing (WDM) communication system. The laser configuration consists of a long erbium-doped fibre to enable L-band amplification where two 3-dB couplers take a portion of the generated BEFL signal and re-inject it into the single mode fibre to seed a cascaded BEFL line in the same direction as the first BEFL line. A stable and strong laser comb of up to five lines with 10-GHz spacing has been obtained with a Brillouin pump (BP) of 9.2 mW and a 980 nm pump of 92 mW. The BEFL has shown a broad tuning range with a tuning characteristic for line #1 which is flat over a range greater than 9.9 nm. 相似文献
5.
Kamil John 《Mathematische Annalen》1990,287(1):509-514
6.
K. H. C. Baser H. R. Nuriddinov T. Ozek B. Demirci N. Azcan A. M. Nigmatullaev 《Chemistry of Natural Compounds》2002,38(1):51-53
The herbal parts of Arischrada korolkowii (Regel et Schmalh.) Pobed. (Lamiaceae) growing in Uzbekistan were hydrodistillated to yield 1.1% of essential oil. The essential oil was analyzed by GC/MS. Eighty eight compounds were characterized representing 98% of the essential oil with 1,8-cineole (29.3%), camphor (9.8%), -caryophyllene (8.5%), bornyl acetate (7.7%), caryophyllene oxide (7.2%), and borneol (5.6%) as the main constituents. 相似文献
7.
H. Saglam T. Gozler B. Kivcak B. Demirci K. H. C. Baser 《Chemistry of Natural Compounds》2001,37(5):439-441
The chemical composition of the essential oil ofHaplophyllum myrtifoliumBoiss., endemic to Turkey, was examined by GC/MS. Ninety-seven compounds were characterized with linalool (12.8%), -caryophyllene (10.3 %), and methyleugenol (5.9 %) as the main constituents. 相似文献
8.
The red complex formed by copper (II) and phenanthraquinone monothiosemicarbazone has an absorption maximum at 530 nm with a molar absorptivity of 14000 cm?1 mole?1. The pH range for the determination is 1.1–6.6. Optimum range of concentration for accurate determination is 0.50–3.47 ppm of copper (II) in 50% methanol medium. The limits of interference due to foreign ions have been studied. The method has been successfully employed for the determination of copper in various samples of milk. 相似文献
9.
Fiammengo R Wojciechowski K Crego-Calama M Timmerman P Figoli A Wessling M Reinhoudt DN 《Organic letters》2003,5(19):3367-3370
[structure: see text] Water-soluble models of heme-protein active sites are obtained via the self-assembly of cationic porphyrins 1 and tetrasulfonato calix[4]arene 2 (K(1.2)() = 10(5) M(-)(1)). Selective binding of ligands either outside or inside the cavity of assemblies 1.2 via coordination to the zinc center has been observed. Small ligands such as 4-methylpyridine and 1-methylimidazole are encapsulated, while the bulkier caffeine is bound outside. Assemblies Co-1.2, in which the Zn porphyrin moiety has been replaced by a Co(II) porphyrin, can act as O(2) carriers. 相似文献
10.
Direct and selective catalytic arylation of alpha-C-H bond in pyridine with iodobenzene was achieved in up to 70% yield. Phosphido-bridged bisruthenium complexes 6a and 6b arising from Ru3(CO)12 and PPh3 were identified as active catalysts. The formation of complexes 6a and 6b was investigated, a sequence of C-H and C-P bond cleavage, cluster fragmentation, and disproportionation was established, and the intermediate ruthenium complexes lying on this pathway were isolated and fully characterized. 相似文献