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921.
922.
    
We fabricate thin epitaxial crystal silicon solar cells on display glass and fused silica substrates overcoated with a silicon seed layer. To confirm the quality of hot‐wire chemical vapor deposition epitaxy, we grow a 2‐µm‐thick absorber on a (100) monocrystalline Si layer transfer seed on display glass and achieve 6.5% efficiency with an open circuit voltage (VOC) of 586 mV without light‐trapping features. This device enables the evaluation of seed layers on display glass. Using polycrystalline seeds formed from amorphous silicon by laser‐induced mixed phase solidification (MPS) and electron beam crystallization, we demonstrate 2.9%, 476 mV (MPS) and 4.1%, 551 mV (electron beam crystallization) solar cells. Grain boundaries likely limit the solar cell grown on the MPS seed layer, and we establish an upper bound for the grain boundary recombination velocity (SGB) of 1.6x104 cm/s. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
923.
    
The gallium gradient in Cu(In,Ga)Se2 (CIGS) layers, which forms during the two industrially relevant deposition routes, the sequential and co‐evaporation processes, plays a key role in the device performance of CIGS thin‐film modules. In this contribution, we present a comprehensive study on the formation, nature, and consequences of gallium gradients in CIGS solar cells. The formation of gallium gradients is analyzed in real time during a rapid selenization process by in situ X‐ray measurements. In addition, the gallium grading of a CIGS layer grown with an in‐line co‐evaporation process is analyzed by means of depth profiling with mass spectrometry. This gallium gradient of a real solar cell served as input data for device simulations. Depth‐dependent occurrence of lateral inhomogeneities on the µm scale in CIGS deposited by the co‐evaporation process was investigated by highly spatially resolved luminescence measurements on etched CIGS samples, which revealed a dependence of the optical bandgap, the quasi‐Fermi level splitting, transition levels, and the vertical gallium gradient. Transmission electron microscopy analyses of CIGS cross‐sections point to a difference in gallium content in the near surface region of neighboring grains. Migration barriers for a copper‐vacancy‐mediated indium and gallium diffusion in CuInSe2 and CuGaSe2 were calculated using density functional theory. The migration barrier for the InCu antisite in CuGaSe2 is significantly lower compared with the GaCu antisite in CuInSe2, which is in accordance with the experimentally observed Ga gradients in CIGS layers grown by co‐evaporation and selenization processes. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   
924.
    
Thermal oxides are commonly used for the surface passivation of high‐efficiency silicon solar cells from mono‐ and multicrystalline silicon and have led to the highest conversion efficiencies reported so far. In order to improve the cost‐effectiveness of the oxidation process, a wet oxidation in steam ambience is applied and experimentally compared to a standard dry oxidation. The processes yield identical physical properties of the oxide. The front contact is created using a screen‐printing process of a hotmelt silver paste in combination with light‐induced silver plating. The contact formation on the front requires a short high‐temperature firing process, therefore the thermal stability of the rear surface passivation is very important. The surface recombination velocity of the fired oxide is experimentally determined to be below S ≤ 38 cm/s after annealing with a thin layer of evaporated aluminium on top. Monocrystalline solar cells are produced and 19·3% efficiency is obtained as best value on 4 cm2 cell area. Simulations show the potential of the developed process to approach 20% efficiency. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
925.
    
Organic fluorescent molecules are infiltrated in the channels of zeolite L nanocrystals, thus creating organic–inorganic fluorescent nanoparticles. Combined with dielectric matrices, these fluorescent nanopigments open the way to the realization of novel optical devices. In this paper, the optical measurement of the quantum yield of fluorescent zeolites by means of a precise and reliable diffuse reflectance technique is presented. Several possible factors that may affect the fluorescence quantum yield are also investigated.  相似文献   
926.
    
Here, a new series of crosslinkable heteroleptic iridium (III) complexes for use in solution processed phosphorescent organic light emitting diodes (OLEDs) is reported. These iridium compounds have the general formula of (PPZ‐VB)2Ir(CˆN), where PPZ‐VB is phenylpyrazole (PPZ) vinyl benzyl (VB) ether; and the CˆN ligands represent a family of four different cyclometallating ligands including 1‐phenylpyrazolyl (PPZ) (1), 2‐(4,6‐difluorophenyl)pyridyl (DFPPY) (2), 2‐(p‐tolyl)pyridyl (TPY) (3), and 2‐phenylquinolyl (PQ) (4). With the incorporation of two crosslinkable VB ether groups, these compounds can be fully crosslinked after heating at 180 °C for 30 min. The crosslinked films exhibit excellent solvent resistance and film smoothness which enables fabrication of high‐performance multilayer OLEDs by sequential solution processing of multiple layers. Furthermore, the photophysical properties of these compounds can be easily controlled by simply changing the cyclometallating CˆN ligand in order to tune the triplet energy within the range of 3.0–2.2 eV. This diversity makes these materials not only suitable for use in hole transporting and electron blocking but also as emissive layers of several colors. Therefore, these compounds are applied as effective materials for all‐solution processed OLEDs with (PPZ‐VB)2IrPPZ (1) acting as hole transporting and electron blocking layer and host material, as well as three other compounds, (PPZ‐VB)2IrDFPPY ( 2 ), (PPZ‐VB)2IrTPY(3), and (PPZ‐VB)2IrPQ( 4 ), used as crosslinkable phosphorescent emitters.  相似文献   
927.
    
This paper describes a structure–property study using two dithieno[3,2‐b;2′,3′‐d]phosphole building blocks for the generation of white light emission and the incorporation of these units in a single polystyrene material. The emission of one of the light‐emitting organophosphorus building blocks can efficiently be switched from orange to green by simple protonation of the amino functional groups that are part of the π‐conjugated scaffold. The resulting three components (blue, green, and orange) exhibit photophysical properties that allow for an efficient fluorescence resonance energy transfer (FRET) in the mixture/polymer and provide intense white fluorescence upon excitation of the blue component; the fluorescence is close to pure white in solution and similar to the emission of an incandescent light bulb in the thin film. The results nicely illustrate the intriguing features that can be obtained by exclusively using organophosphorus‐based organic electronic materials.  相似文献   
928.
    
This paper presents the application of the analytical model for locally contacted rear sides recently published by Fischer to the determination of recombination losses of solar cells with fixed metallization fraction, but varying contact pitch. After the successful experimental validation of the model on oxide‐passivated solar cells with ohmic contacts, the model was used for a detailed investigation of rear sides prepared by the laser‐fired contacts (LFC) method. In this way the surface recombination velocity (SRV) at the very contact areas was extracted for a broad base doping range. The determined parameterization allows the calculation of the SRV of any LFC rear side concerning base doping and contact pitch. The excellent passivation quality of the alnealed oxide with LFC contacts is shown: on 1 (100) Ω cm FZ an effective SRV of only 35 (4·3) cm/s could be measured with 1000 µm contact pitch. Copyright © 2006 John Wiley & Sons, Ltd.  相似文献   
929.
    
Molecular visualization is often challenged with rendering of large molecular structures in real time. We introduce a novel approach that enables us to show even large protein complexes. Our method is based on the level‐of‐detail concept, where we exploit three different abstractions combined in one visualization. Firstly, molecular surface abstraction exploits three different surfaces, solvent‐excluded surface (SES), Gaussian kernels and van der Waals spheres, combined as one surface by linear interpolation. Secondly, we introduce three shading abstraction levels and a method for creating seamless transitions between these representations. The SES representation with full shading and added contours stands in focus while on the other side a sphere representation of a cluster of atoms with constant shading and without contours provide the context. Thirdly, we propose a hierarchical abstraction based on a set of clusters formed on molecular atoms. All three abstraction models are driven by one importance function classifying the scene into the near‐, mid‐ and far‐field. Moreover, we introduce a methodology to render the entire molecule directly using the A‐buffer technique, which further improves the performance. The rendering performance is evaluated on series of molecules of varying atom counts.  相似文献   
930.
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