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51.
We have presented a model-based approach for human gait recognition, which is based on analyzing the leg and arm movements. An initial model is created based on anatomical proportions, and a posterior model is constructed upon the movements of the articulated parts of the body, using active contour models and the Hough transform. Fourier analysis is used to describe the motion patterns of the moving parts. The k-nearest neighbor rule applied to the phase-weighted Fourier magnitude of each segment’s spectrum is used for classification. In contrast to the existing approaches, the main focus of this paper is on increasing the discrimination capability of the model through extra features produced from the motion of the arms. Experimental results indicate good performance of the proposed method. The technique has also proved to be able to reduce the adverse effects of self-occlusion, which is a common incident in human walking.  相似文献   
52.
一种新型双凸极单相永磁电动机--工作原理与参数计算   总被引:3,自引:13,他引:3  
介绍了1种双凸极单相永磁电动机.电机有4个定子极和6个转子极,转子上无绕组及永磁体,定子上放置绕组和永磁体.定子极采用阶梯形结构,使电机可以起动.电机结构控制简单,可双向运转,适合于调速控制系统.研究了该电机的工作原理及其参数的计算,为电机的控制及系统仿真奠定了基础并提供了依据.  相似文献   
53.
一种新型双凸极单相永磁电动机的工作原理与参数计算   总被引:2,自引:6,他引:2  
介绍了1种双凸极单相永磁电动机。电机有4个定子极和6个转子极,转子上无绕组及永磁体,定子上放置绕组和永磁体。定子极采用阶梯形结构,使电机可以起动。电机结构控制简单,可双向运转,适合于调速控制系统。研究了该电机的工作原理及其参数的计算,为电机的控制及系统仿真奠定了基础并提供了依据。  相似文献   
54.
Zirconia (ZrO2) with the thickness of about 1.5 μm were prepared onto mechanically polished and electrochemically prepared surfaces of 316L stainless steel by direct and pulse current electrodeposition followed by annealing. The ZrO2 coatings were nanocrystalline with a tetragonal crystallographic structure. The coatings produced by direct current showed a heterogeneous structure in “cracked-mud” appearance. Pulse current produced a more uniform and dense coating with a strong mechanical barrier property. It also revealed a passive behavior on the Tafel polarization plot. The ZrO2 coatings produced on electrochemically prepared surfaces showed a very small passive region on Tafel polarization curves.  相似文献   
55.
Finely ground titanium slag (–400 mesh) dissolves slowly in dilute H2SO4 (2–10 mol/L) in the temperature range 70–110°C, but attrition ground slag dissolves much faster under similar conditions. The process is strongly dependent on the speed of agitation in the region 345–1035 rpm, and has an activation energy of 28 kJ/mole TiO2, thus suggesting that the dissolution is controlled by diffusion through the boundary layer.  相似文献   
56.
Triphenylmethane dyes react at ambient conditions with chrysotile asbestos to form homogeneously coloured fibres. Formation of the chelates on the fibre varies: for Basic Fuchsin, Malachite Green and Methyl Blue equilibrium is reached in 1 h, the concentration on the fibre is 1% to 2.4%, and increases slightly on boiling. For Brilliant Blue R, Crystal Violet, and Methyl Violet equilibrium is reached after 16 to 24 h, the concentration on the fibre is 8% to 10%, and increases greatly on boiling reaching 10% to 31%. No precipitates were observed on the coloured fibre under the scanning electron microscope indicating a chelate formation. This was also supported by X-ray diffraction and infrared analysis.  相似文献   
57.
Heavy metal concentrations were measured in airborne dust collected at three sites with different traffic densities from August 2001 to July 2002 in the Frankfurt am Main area. Bulk samples of particulate matter (PM) with an aerodynamic equivalent diameter of <22 microm were collected on cellulose nitrate filters using air filtration devices. Fractionated samples of PM with an aerodynamic equivalent diameter of <10 microm were collected using an eight-stage Andersen impactor. Pb, Cd, Mn, Ni, Zn, V, As, Sb, Cu, Cr, Co, and Ce were determined by inductively coupled plasma sector field mass spectrometry, Pt and Rh were determined by adsorptive voltammetry, and Pd was determined by total reflection X-ray fluorescence analysis. The results show that the highest airborne heavy metal concentrations occurred at the main street with a large volume of traffic. With the exception of Co, V, Ce, and Mn, the heavy metals had an elevated enrichment factor compared to their concentrations in the continental crust. The main street site was especially contaminated with Sb, Zn, Cu, V, and Ni. Motor vehicles are the likely source of emissions. With the exception of Cr, Cu, and Zn, most of the airborne heavy metal concentrations determined for impactor samples deviate slightly from the results for total airborne dust. Heavy metal particle size distributions can be divided into three groups. For metals such as As, Cd, Pb, and V, the main fraction can be found in fine particles with a diameter of <2.1 microm, whereas Ce, Cr, Co, and Ni occur mainly in coarse particles with a diameter of >2.1 microm. Cu, Mn, Sb, Zn, Pt, Pd, and Rh occur in high concentrations in the medium range of the impactor stages (particle diameters of 1.1-4.7 microm). Metal concentrations in fine dust particles are needed to assess the human health risks of their inhalation.  相似文献   
58.
The Journal of Supercomputing - Technology scaling has exacerbated the aging impact on the performance and reliability of integrated circuits. By entering into nanotechnology era in recent years,...  相似文献   
59.
Solid oxide cell electrodes need to display a wide range of combined properties, for example, electronic and ionic conductivities, catalytic activity, chemical compatibility with other parts, thermal expansion match, phase stability, and tolerance to foreign species/contaminants. It is extremely challenging for a single material to meet all these features required. Surface decoration is a remarkably adaptive strategy to provide needed features to the electrodes by introducing functioning materials through various target-guided methods. This review provides an overview of typical and novel techniques to create surface decoration on the electrodes to abruptly improve the drawbacks of the electrodes of solid oxide cells, including performance enhancement, stability of long-term operation, and tolerance to poisoning foreign species. It starts with the introduction of surface decoration experimental procedure, proceeds to crucial characterization methods that are particularly effective in identifying the properties of the surface coating, continues with target-oriented practice in terms of surface decoration materials choice and microstructure manipulation, and ends with the explorations of functioning mechanisms for the resultant behavior. With hope, the review will spark more novel utilizations of surface decoration practice to promote the technical status of the solid oxide cells for widespread commercialization in the future.  相似文献   
60.
Unmanned aerial vehicles (UAVs), also known as drones, communicate, collaborate, and form flying ad hoc networks (FANETs) to perform many different missions, ranging from delivery tasks to agriculture applications. Recently, FANETs have been integrated with different technologies, such as artificial intelligence (AI), virtual reality, and Internet of Things. Such new avenues for the use of UAVs directly impact the research on FANETs and cause some major challenges, such as security and physical layer issues, resource management, and UAV positioning issues that need to be addressed. Several researchers have been working for the last few years to propose AI and machine learning (ML)-based solutions for different use cases in UAV-based networks. They present the limitations of the existing research work and highlight some possible future works on FANETs. However, exhibiting the trends in the UAV research papers in a quantitative manner is still required to motivate researchers to rethink the research on FANETs. Therefore, this study covers more than 170 scientific publications extracted from five trusted academic databases published from 2013 to 2021 to provide a thorough overview of the main research and development statistics in the area of FANETs, the open challenges existing in this area and the ML-based solutions to solve these challenges. In addition, the investigation of emerging technologies integrated with FANETs, as well as the simulation tools employed for evaluating FANETs' performance are discussed. Moreover, the future research directions in the area of FANETs are considered within a prospective vision discussion.  相似文献   
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