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排序方式: 共有675条查询结果,搜索用时 218 毫秒
111.
A. Yu. Andreev B. A. Andreev M. N. Drozdov Z. F. Krasil’nik M. V. Stepikhova V. B. Shmagin V. P. Kuznetsov R. A. Rubtsova E. A. Uskova Yu. A. Karpov H. Ellmer L. Palmetshofer K. Piplits H. Hutter 《Semiconductors》1999,33(2):131-134
A study is made of the electrical, optical, and structural properties of Si:Er layers produced by sublimation molecular-beam
epitaxy. The Er and O contents in the layers, grown at 400–600°C, were as high as 5×1018 and 4×1019 cm−3, respectively. The electron concentration at 300 K was ∼10% of the total erbium concentration and the electron mobility was
as high as 550 cm2/(V·s). Intense photoluminescence at 1.537 μm was observed from all the structures up to 100–140 K. The structure of the optically
active centers associated with Er depended on the conditions under which the layers were grown.
Fiz. Tekh. Poluprovodn. 33, 156–160 (February 1999) 相似文献
112.
Max Braune Nico Scherf Claudia Heine Katja Sygnecka Thanigaimalai Pillaiyar Chiara Parravicini Bernd Heimrich Maria P. Abbracchio Christa E. Müller Heike Franke 《International journal of molecular sciences》2021,22(21)
Characterization of new pharmacological targets is a promising approach in research of neurorepair mechanisms. The G protein-coupled receptor 17 (GPR17) has recently been proposed as an interesting pharmacological target, e.g., in neuroregenerative processes. Using the well-established ex vivo model of organotypic slice co-cultures of the mesocortical dopaminergic system (prefrontal cortex (PFC) and substantia nigra/ventral tegmental area (SN/VTA) complex), the influence of GPR17 ligands on neurite outgrowth from SN/VTA to the PFC was investigated. The growth-promoting effects of Montelukast (MTK; GPR17- and cysteinyl-leukotriene receptor antagonist), the glial cell line-derived neurotrophic factor (GDNF) and of two potent, selective GPR17 agonists (PSB-16484 and PSB-16282) were characterized. Treatment with MTK resulted in a significant increase in mean neurite density, comparable with the effects of GDNF. The combination of MTK and GPR17 agonist PSB-16484 significantly inhibited neuronal growth. qPCR studies revealed an MTK-induced elevated mRNA-expression of genes relevant for neuronal growth. Immunofluorescence labelling showed a marked expression of GPR17 on NG2-positive glia. Western blot and RT-qPCR analysis of untreated cultures suggest a time-dependent, injury-induced stimulation of GPR17. In conclusion, MTK was identified as a stimulator of neurite fibre outgrowth, mediating its effects through GPR17, highlighting GPR17 as an interesting therapeutic target in neuronal regeneration. 相似文献
113.
Hellstern D Schulze K Schöpf B Petri-Fink A Steitz B Kamau S Hilbe M Koch-Schneidemann S Vaughan L Hottiger M Hofmann M Hofmann H von Rechenberg B 《Journal of nanoscience and nanotechnology》2006,6(9-10):3261-3268
PVA coated and fluorescent dye (Cy3.5) functionalized vinyl alcohol/vinyl amine copolymer coated superparamagnetic iron oxide nanoparticles (SPION) were evaluated for systemic distribution and elimination after intraarticular injection in sheep. Observation was done at 3, 24, 72, and 120 hours after injection using light microscopy, fluorescent microscopy, and confocal microscopy. No pathologic influence of SPION on the tissue harvested could be seen. A significantly increased iron content could be identified in the kidneys, lymph nodes, and spleen after injection of SPION. No particles were detected in the liver, the urinary, and the gall bladder. No positive fluorescent signal could be attributed to SPION throughout the organs. Our results indicated that the iron component of the SPION is possible to be incorporated into the physiologic iron metabolism after reabsorption in the proximal tubule system of the kidney and that concentration levels of Cy3.5 are too low to be detected throughout the body. 相似文献
114.
Kastl K Menke M Lüthgens E Faiss S Gerke V Janshoff A Steinem C 《Chembiochem : a European journal of chemical biology》2006,7(1):106-115
The kinetics of annexin A1 binding to solid-supported lipid bilayers consisting of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine (POPS; 4:1) has been investigated as a function of the calcium ion concentration in the bulk phase. Quartz crystal microbalance measurements in conjunction with scanning force microscopy, fluorescence microscopy, and computer simulations indicate that at a given Ca2+ concentration annexin A1 adsorbs irreversibly on membrane domains enriched in POPS. By contrast, annexin A1 adsorbs reversibly on the POPC-enriched phase, which is composed of single POPS molecules embedded within a POPC matrix. The overall area occupied by the POPS-enriched phase is controlled by the CaCl2 concentration. Monte Carlo simulations suggest that the area of the POPS-enriched phase increases by a factor of 7 when the Ca2+ concentration is changed from 0.01 to 1 mM. 相似文献
115.
The synthesis of amphiphilic polyaza crown ether monomers X (benzyl-substituted), Y (palmityl-substituted) and Z (cholesteryl-substituted) and their incorporation into oligonucleotides are described. Their effects on thermal duplex stability were investigated by UV melting curve analysis in different alkaline metal buffer solutions. Thermal-denaturation experiments showed remarkable stabilization of dsDNA by polyaza crown ether monomers when incorporated in opposite positions. The series of polyaza crown ether monomers (X, Y and Z) with different overall lipophilicities showed a trend of increased stability of the corresponding dsDNA with increasing lipophilicity of the polyaza crown ether monomer. Multiple incorporations of benzyl-substituted polyaza crown ether monomer X as dangling ends on both sides of dsDNA resulted in strongly increased stability of the corresponding duplex. 相似文献
116.
Fisk DG Ball CA Dolinski K Engel SR Hong EL Issel-Tarver L Schwartz K Sethuraman A Botstein D Cherry JM;Saccharomyces Genome Database Project 《Yeast (Chichester, England)》2006,23(12):857-865
The S. cerevisiae genome is the most well-characterized eukaryotic genome and one of the simplest in terms of identifying open reading frames (ORFs), yet its primary annotation has been updated continually in the decade since its initial release in 1996 (Goffeau et al., 1996). The Saccharomyces Genome Database (SGD; www.yeastgenome.org) (Hirschman et al., 2006), the community-designated repository for this reference genome, strives to ensure that the S. cerevisiae annotation is as accurate and useful as possible. At SGD, the S. cerevisiae genome sequence and annotation are treated as a working hypothesis, which must be repeatedly tested and refined. In this paper, in celebration of the tenth anniversary of the completion of the S. cerevisiae genome sequence, we discuss the ways in which the S. cerevisiae sequence and annotation have changed, consider the multiple sources of experimental and comparative data on which these changes are based, and describe our methods for evaluating, incorporating and documenting these new data. 相似文献
117.
D. Hochauer C. Mitterer M. Penoy S. Puchner C. Michotte H.P. Martinz H. Hutter M. Kathrein 《Surface & coatings technology》2012
Alumina (Al2O3) coatings deposited by chemical vapor deposition (CVD) with different modifications and dopants are widely applied as wear resistant coatings on cemented carbide cutting tools. The aim of this work was to investigate the influence of CH4 addition on the deposition of α-Al2O3 by low-pressure chemical vapor deposition (LPCVD). The coatings were deposited at 1005 °C on a TiN–TiCN base layer using a precursor gas mixture of AlCl3, CH4, CO2, HCl, H2S, and H2. Coating characterization was conducted by scanning electron microscopy (SEM), glow discharge optical emission spectroscopy (GDOES), X-ray photoelectron spectroscopy (XPS), time-of-flight secondary ion mass spectroscopy (ToF-SIMS), glancing angle X-ray diffraction (GAXRD), nanoindentation and tribological ball-on-disk tests against Al2O3 balls. Additionally, the ball-on-disk wear tracks were investigated by Raman spectroscopy. 相似文献
118.
This article focuses on the electrophoretic co-deposition of SiC and MgO, which has not been previously reported. The EPD
of SiC has been widely investigated, whilst the EPD of SiC with sintering additives is usually not taken into account since
every compound added to the suspension seriously affects the zeta-potential and the conductivity, the two main parameters
that should be optimized to achieve a good deposit. We comprehensively observed the effects of the individual compounds on
the colloidal behaviour of a suspension suitable for co-deposition to achieve good homogeneity and the highest possible green
density. The obtained green densities reached up to 1.92 g/cm3, which correspond to 60% of theoretical density, whilst after sintering in open air at 1350 °C the densities reached 2.33 g/cm3. SEM and TEM analyses revealed that the microstructure is composed of SiC grains embedded in a SiO2 matrix, whilst XRD confirmed that even though the sintering caused a partial oxidation and the appearance of an amorphous
phase, the prevailing crystalline phase is still β-SiC. In the presence of MgO, SiO2 also appears in the crystalline form as cristobalite. 相似文献
119.
We present a detailed analysis of the patient and resource scheduling problem in rehabilitation hospitals. In practice, the
predominantly therapeutical treatments and activities which are prescribed for the patients are typically scheduled manually.
This leads to rigid and inefficient schedules which can have negative effects on the quality of care and the patients’ satisfaction.
We outline the conceptual framework of a decision support system for the scheduling process that is based on formal optimization
models. To this end, we first develop a large-scale monolithic optimization model. Then we derive a numerically tractable
hierarchical model system in order to deal with problem instances of realistic sizes. We report numerical results with respect
to solution times, model sizes and solution quality. 相似文献
120.
Electron beam induced deposition (EBID) has recently been developed into a method to directly write optically active three-dimensional nanostructures. For this purpose a metal-organic precursor gas (here dimethyl-gold(III)-acetylacetonate) is introduced into the vacuum chamber of a scanning electron microscope where it is cracked by the focused electron beam. Upon cracking the aforementioned precursor gas, 3D deposits are realized, consisting of gold nanocrystals embedded in a carbonaceous matrix. The carbon content in the deposits hinders direct plasmonic applications. However, it is possible to activate the deposited nanostructures for plasmonics by coating the EBID structures with a continuous silver layer of a few nanometers thickness. Within this silver layer collective motions of the free electron gas can be excited. In this way, EBID structures with their intriguing precision at the nanoscale have been arranged in arrays of free-standing dimer antenna structures with nanometer sized gaps between the antennas that face each other with an angle of 90°. These dimer antenna ensembles can constitute a reproducibly manufacturable substrate for exploiting the surface enhanced Raman effect (SERS). The achieved SERS enhancement factors are of the order of 10? for the incident laser light polarized along the dimer axes. To prove the signal enhancement in a Raman experiment we used the dye methyl violet as a robust test molecule. In future applications the thickness of such a silver layer on the dimer antennas can easily be varied for tuning the plasmonic resonances of the SERS substrate to match the resonance structure of the analytes to be detected. 相似文献