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排序方式: 共有230条查询结果,搜索用时 31 毫秒
31.
Seok Su Sohn Alisson Kwiatkowski da Silva Yuji Ikeda Fritz Krmann Wenjun Lu Won Seok Choi Baptiste Gault Dirk Ponge Jrg Neugebauer Dierk Raabe 《Advanced materials (Deerfield Beach, Fla.)》2019,31(8)
Severe lattice distortion is a core effect in the design of multiprincipal element alloys with the aim to enhance yield strength, a key indicator in structural engineering. Yet, the yield strength values of medium‐ and high‐entropy alloys investigated so far do not substantially exceed those of conventional alloys owing to the insufficient utilization of lattice distortion. Here it is shown that a simple VCoNi equiatomic medium‐entropy alloy exhibits a near 1 GPa yield strength and good ductility, outperforming conventional solid‐solution alloys. It is demonstrated that a wide fluctuation of the atomic bond distances in such alloys, i.e., severe lattice distortion, improves both yield stress and its sensitivity to grain size. In addition, the dislocation‐mediated plasticity effectively enhances the strength–ductility relationship by generating nanosized dislocation substructures due to massive pinning. The results demonstrate that severe lattice distortion is a key property for identifying extra‐strong materials for structural engineering applications. 相似文献
32.
Jing Huang Nairveen Ali Elsie Quansah Shuxia Guo Michel Noutsias Tobias Meyer-Zedler Thomas Bocklitz Jürgen Popp Ute Neugebauer Anuradha Ramoji 《International journal of molecular sciences》2021,22(4)
In recent decades, vibrational spectroscopic methods such as Raman and FT-IR spectroscopy are widely applied to investigate plasma and serum samples. These methods are combined with drop coating deposition techniques to pre-concentrate the biomolecules in the dried droplet to improve the detected vibrational signal. However, most often encountered challenge is the inhomogeneous redistribution of biomolecules due to the coffee-ring effect. In this study, the variation in biomolecule distribution within the dried-sample droplet has been investigated using Raman and FT-IR spectroscopy and fluorescence lifetime imaging method. The plasma-sample from healthy donors were investigated to show the spectral differences between the inner and outer-ring region of the dried-sample droplet. Further, the preferred location of deposition of the most abundant protein albumin in the blood during the drying process of the plasma has been illustrated by using deuterated albumin. Subsequently, two patients with different cardiac-related diseases were investigated exemplarily to illustrate the variation in the pattern of plasma and serum biomolecule distribution during the drying process and its impact on patient-stratification. The study shows that a uniform sampling position of the droplet, both at the inner and the outer ring, is necessary for thorough clinical characterization of the patient’s plasma and serum sample using vibrational spectroscopy. 相似文献
33.
OR Spectrum - For online retailers with attended home delivery business models, the decisive factor for promising dynamic time slot pricing decisions is the quality of the opportunity cost... 相似文献
34.
Ziyuan Rao Biswanath Dutta Fritz Körmann Wenjun Lu Xuyang Zhou Chang Liu Alisson Kwiatkowski da Silva Ulf Wiedwald Marina Spasova Michael Farle Dirk Ponge Baptiste Gault Jörg Neugebauer Dierk Raabe Zhiming Li 《Advanced functional materials》2021,31(7):2007668
Since its first emergence in 2004, the high-entropy alloy (HEA) concept has aimed at stabilizing single- or dual-phase multi-element solid solutions through high mixing entropy. Here, this strategy is changed and renders such massive solid solutions metastable, to trigger spinodal decomposition for improving the alloys’ magnetic properties. The motivation for starting from a HEA for this approach is to provide the chemical degrees of freedom required to tailor spinodal behavior using multiple components. The key idea is to form Fe-Co enriched regions which have an expanded volume (relative to unconstrained Fe-Co), due to coherency constraints imposed by the surrounding HEA matrix. As demonstrated by theory and experiments, this leads to improved magnetic properties of the decomposed alloy relative to the original solid solution matrix. In a prototype magnetic FeCoNiMnCu HEA, it is shown that the modulated structures, achieved by spinodal decomposition, lead to an increase of the Curie temperature by 48% and a simultaneous increase of magnetization by 70% at ambient temperature as compared to the homogenized single-phase reference alloy. The findings thus open a pathway for the development of advanced functional HEAs. 相似文献
35.
Smith AR Yang R Yang H Dick A Neugebauer J Lambrecht WR 《Microscopy research and technique》2005,66(2-3):72-84
The Mn3N2 (010) surface has been studied using spin-polarized scanning tunneling microscopy at the atomic scale. The principle objective of this work is to elucidate the properties and potential of this technique to measure atomic-scale magnetic structures. The experimental approach involves the use of a combined molecular beam epitaxy/scanning tunneling microscopy system that allows the study of atomically clean magnetic surfaces. Several key findings have been obtained. First, both magnetic and non-magnetic atomic-scale information has been obtained in a single spin-polarized image. Magnetic modulation of the height profile having an antiferromagnetic super-period of c = 12.14 A (6 atomic rows) together with a non-magnetic superstructure having a period of c/2 = 6.07 A (3 atomic rows) was observed. Methods of separation of magnetic and non-magnetic profiles are presented. Second, bias voltage-dependent spin-polarized images show a reversal of the magnetic modulation at a particular voltage. This reversal is clearly due to a change in the sign of the magnetic term in the tunnel current. Since this term depends on both the tip's as well as the sample's magnetic local density of states, the reversal can be caused by either the sample or the tip. Third, the shape of the line profile was found to vary with the bias voltage, which is related to the energy-dependent spin contribution from the 2 chemically inequivalent Mn sites on the surface. Overall, the results shown here expand the application of the method of spin-polarized scanning tunneling microscopy to measure atomic-scale magnetic structures. 相似文献
36.
Conjugated polymer-based organic solar cells 总被引:3,自引:0,他引:3
37.
Research and development towards high efficiency plastic solar cells have been accelerating in recent years. Polymer-based bulk heterojunction solar cells are offering an attractive and inexpensive concept for large scale production by solution processing as well as advantageous flexible and aesthetic form factors. The thin film nano-morphology of bulk-heterojunction solar cells has been shown to dramatically influence the photovoltaic performance of the devices. This article reviews the different methods used to control the film nano-morphology of bulk-heterojunction solar cells focussing on the chemical additives during solution processing. All power conversion efficiency limiting mechanisms of bulk-heterojunction solar cells are discussed in detail. It is shown, how the formation of optimal percolation pathways between donor and acceptor influences the photovoltaic device performance. It is explained how the film nano-morphology relates to light absorption, free charge carrier generation as well as charge transport to the electrodes. 相似文献
38.
Duancheng Ma Martin Friák Johann von Pezold Dierk Raabe J?rg Neugebauer 《Science and Technology of Advanced Materials》2013,14(2)
AbstractSolid-solution strengthening in six Al–X binary systems is investigated using first-principle methods. The volumetric mismatch parameter and the solubility enthalpy per solute were calculated. We derive three rules for designing solid-solution strengthened alloys: (i) the solubility enthalpy per solute is related to the volumetric mismatch by a power law; (ii) for each annealing temperature, there exists an optimal solute–volume mismatch to achieve maximum strength; and (iii) the strengthening potential of high volumetric mismatch solutes is severely limited by their low solubility. Our results thus show that the thermodynamic properties of the system (here Al–X alloys) set clear upper bounds to the achievable strengthening effects owing to the reduced solubility with increasing volume mismatch. 相似文献
39.
Uciechowska U Schemies J Neugebauer RC Huda EM Schmitt ML Meier R Verdin E Jung M Sippl W 《ChemMedChem》2008,3(12):1965-1976
NAD+-dependent histone deacetylases (sirtuins) are enzymes that cleave acetyl groups from lysine residues in histones and other proteins. Potent selective sirtuin inhibitors are interesting tools for the investigation of the biological functions of these enzymes and may be future drugs for the treatment of cancer or neurodegenerative diseases. Herein we present the results from a protein-based virtual screen of a commercial database with subsequent biological testing of the most promising compounds. The combination of docking and in vitro experimental testing resulted in the identification of novel sirtuin inhibitors with thiobarbiturate structure. To rationalize the experimental results, free-energy calculations were carried out by molecular mechanics Poisson-Boltzmann/surface area (MM-PBSA) calculations. A significant correlation between calculated binding free energies and measured Sirt2 inhibitory activities was observed. The analyses suggested a molecular basis for the interaction of the identified thiobarbiturate derivatives with human Sirt2. Based on the docking and MM-PBSA calculations we synthesized and tested five further thiobarbiturates. The MM-PBSA method correctly predicted the activity of the novel thiobarbiturates. The identified compounds will be used to further explore the therapeutic potential of sirtuin inhibitors. 相似文献
40.
Frank Uwe Renner Gerald Andreas Eckstein Liverios Lymperakis Andrea Dakkouri-Baldauf Michael Rohwerder Jörg Neugebauer Martin Stratmann 《Electrochimica acta》2011,(4):1694
We present an electrochemical study of Au3Cu (0 0 1) single crystal surfaces in 0.1 mol dm−3 H2SO4 and 0.1 mol dm−3 H2SO4 + 0.1 mmol dm−3 HCl, and of Cu3Au (0 0 1) in 0.1 mol dm−3 H2SO4. The focus is on in situ scanning tunneling microscopy experiments. The changes of the surface morphology, which are time- and potential-dependent, have been observed, clearly resolving single atomic steps and mono-atomic islands and pits. Chloride additives enhance the surface diffusion and respective morphologies are observed earlier. All surfaces have shown considerable roughening already in the passive region far below the critical potential. 相似文献