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51.
针对智能电网(SG)中电力线通信(PLC)网络中负载均衡的问题,提出了一个自适应机会路由协议——负载均衡的机会路由协议(LBORP)。在LBORP中,所有收到数据包的候选转发节点都有机会参与到数据包的转发中,不再局限于一条路由路径,避免了流量仅从一条链路经过导致的负载不均衡现象;而且候选转发节点的转发优先级不仅考虑到转发节点到目的节点的距离,还考虑到了PLC链路的不稳定性以及流量的变化。除此之外,在LBORP中采用一种隐式确认方案,进一步减少协议的端到端时延。在仿真实验中,与基于有序树的PLC路由协议(PLC-TR)和PLC机会路由协议(PLC-OR)相比,LBORP在时延上分别降低了19.7%和45.8%,在丢包率上分别降低了23.4%和32.5%。实验结果表明,LBORP能够实现网络的负载均衡,提升网络的可靠性并减小端到端时延。  相似文献   
52.
Enhancing evacuee safety is a key factor in reducing the number of injuries and deaths that result from earthquakes. One way this can be achieved is by training occupants. Virtual Reality (VR) and Serious Games (SGs), represent novel techniques that may overcome the limitations of traditional training approaches. VR and SGs have been examined in the fire emergency context; however, their application to earthquake preparedness has not yet been extensively examined.We provide a theoretical discussion of the advantages and limitations of using VR SGs to investigate how building occupants behave during earthquake evacuations and to train building occupants to cope with such emergencies. We explore key design components for developing a VR SG framework: (a) what features constitute an earthquake event; (b) which building types can be selected and represented within the VR environment; (c) how damage to the building can be determined and represented; (d) how non-player characters (NPC) can be designed; and (e) what level of interaction there can be between NPC and the human participants. We illustrate the above by presenting the Auckland City Hospital, New Zealand as a case study, and propose a possible VR SG training tool to enhance earthquake preparedness in public buildings.  相似文献   
53.
The current power grid confronts severe challenges in satisfying customers' demands. Fast transition to the much more flexible power grid enriched with renewable energies, micro-grid, and distributed energy resources has been considered as a straightforward solution to the customers’ high demand. Using smart equipment and renewable energies, electric power generation and storage through the power grid domains will be facilitated, which enables bi-directional energy and information flows. The power grid with such enhanced features is called Smart Grid (SG). Controlling and managing the diverse sets of variables in the SG requires precise measuring, monitoring, communicating, and analytic systems which increase the complexity of the grid. This complexity is the main barrier to the realization of the SG up to now. The emergence of the Internet of Things (IoT) simplifies monitoring, communications, and data processing among smart things to connect to anything in the world. This motivates the SG stakeholders and researchers to proceed with the best way to exploit the IoT technologies in the SG. In this survey paper, we summarize various efforts in this regard to highlight the advantages of the IoT-enabled SG and its probable gaps. To this end, a comprehensive layered approach has been proposed in this paper to classify various applications of the IoT technologies in the SG. Investigating IoT opportunities in each architecture layer facilitates the role of each technology and its relationship with other technologies. Also, open issues and future measures for the realization of IoT-enabled SG have been discussed in the paper.  相似文献   
54.
This paper presents some of the main technical features and insights of the Kozloduy nuclear power plant (NPP) units 5 and 6 probabilistic safety analysis (PSA) level 1. Probabilistic analyses and their applications in Bulgaria were given further impetus in recent years. More than 17 years after the first PSA study in Bulgaria in 1992 today probabilistic analyses receive increasing attention and application than ever before. The Bulgarian regulatory body (BNRA) is also interested in expanding their capability of reviewing and using PSA in plant safety assessments. In November 2008 within the framework of the program financed by European Union (PHARE), a project for assisting the BNRA in establishing the regulatory requirements on the base of PSA was completed. One of the objectives of this project was performance of the independent review of Kozloduy NPP units 5 and 6 PSA. This review was a new impulse for the authors to present in more details of Kozloduy NPP probabilistic assessment studies in the present paper.  相似文献   
55.
Sterol glycosides (SG) are known to cause filter blocking problems in biodiesel use. The extraction and quantitative analysis of SG is difficult due to its low problematic concentration and its compatibility with biodiesel. The purpose of this study is to develop a method to quantify SG in FAME and biodiesel using gas chromatography and other equipment found in laboratories performing routine biodiesel analyses. SG was isolated from FAME using n‐dodecane, acidification and cold soaking, followed by cold centrifugation at ?8 to ?15 °C. The solids obtained were further separated by phase partition with a Folch wash, followed by a final n‐dodecane rinse. This solution was analyzed by GC‐FID using the operating conditions outlined in ASTM D6584. A calibration curve for SG was produced and a first order fit gave a value of r2 = 0.992. Reproducibility tests were performed on soybean FAME and B100 canola biodiesel samples spiked with SG. The recovery of SG by the new method was found to be 99 % for soy FAME with a standard deviation of 0.7 and 100 % for B100 canola with a standard deviation of 3.5 %. The reproducibility based on two standard deviations of the predicted concentration for all 12 spiked samples studied in this work was 2.4 ppm.  相似文献   
56.
Syngas produced by gasification process of biomass fuels is an environmental friendly alternative to conventional petrochemical fuels for the production of electricity, hydrogen, synthetic transportation biofuels and other chemicals. However, the advanced utilization of syngas is significantly limited due to the contaminants which can seriously deactivate the catalysts used for downstream reaction such as steam reforming methane, Fischer-Tropsch synthesis and corrosion of downstream equipments such as a gas turbine. Among the contaminants, sulphur compounds produced in the gasification process, which are mainly H2S with small amounts of COS, CS2 and thiophenes depending on process conditions, must be removed. For biomass feedstock advances are required in the cleanup technologies and processes to upgrade the raw product gas with minimal impact on the overall process efficiency. Hot gas desulphurization (HGD) can improve the overall thermal efficiency due to the elimination of fuel gas cooling and associated heat exchangers. With this aim, the present review paper highlights currently developed methods used for desulphurization of hot gas produced from gasification process of solid fuels. The methods presented here are for both in situ and downstream sulphur capture. Also, the attention is paid to the regeneration of the used materials. In situ sulphur capture is mainly done by using calcium-based sorbents such as limestone and dolomite, whereas downstream sulphur capture is mainly focused on the use of regenerable single, mixed, and supported metal oxides. A comparison is indicated at the end to show the sulphur loading of various materials.  相似文献   
57.
Early on, crystallography was a domain of mineralogy and mathematics and dealt mostly with symmetry properties and imaginary crystal lattices. This changed when Wilhelm Conrad Röntgen discovered X-rays in 1895, and in 1912, Max von Laue and his associates discovered that X-ray irradiated salt crystals would produce diffraction patterns that could reveal the internal atomic periodicity of the crystals. In the same year, the father-and-son team, Henry and Lawrence Bragg successfully solved the first crystal structure of sodium chloride and the era of modern crystallography began. Protein crystallography (PX) started some 20 years later with the pioneering work of British crystallographers. In the past 50–60 years, the achievements of modern crystallography and particularly those in PX have been due to breakthroughs in theoretical and technical advancements such as phasing and direct methods; to more powerful X-ray sources such as synchrotron radiation; to more sensitive and efficient X-ray detectors; to ever faster computers and to improvements in software. The exponential development of PX has been accelerated by the invention and applications of recombinant DNA technology that can yield nearly any protein of interest in large amounts and with relative ease. Novel methods, informatics platforms and technologies for automation and high-throughput have allowed the development of large-scale, high-efficiency macromolecular crystallography efforts in the field of structural genomics. Very recently, the X-ray free-electron laser sources and its applications in PX have shown great potential for revolutionizing the whole field again in the near future.  相似文献   
58.
Abstract

This paper presents a thermomicrostructural model for the simulation of the solidification process of an eutectic ductile cast iron. The thermal balance is written at a macroscopic level and takes into account both the structural component being cast and its mould. Models of nucleation and growth represent the evolution of the microstructure, and the microsegregation of silicon is also considered. The resulting formulation is solved using a finite element discretisation of the macrodomain, in which the evolution of the microstructure is taken into account at the Gauss integration points. The numerical results are presented in terms of cooling curves and are compared with available experimental values. Furthermore, the sensitivity of the response with respect to changes in the cooling rate and nucleation parameters are investigated. The agreement between experimental and computational values is acceptable in both quantitative and qualitative aspects. Ways to improve the computational model are suggested.  相似文献   
59.
太阳能电动车电源控制系统的研究   总被引:1,自引:0,他引:1  
分析了太阳能电动车现状,设计了一种太阳能电动车电源电路,同时,利用SG3525芯片设计了蓄电池boost电路,满足了电动车的负载需求。该系统具有效率高、响应快、稳定性好等优点,很好地满足了太阳能电动车供电需求。  相似文献   
60.
介绍一种利用C8051f系列单片机和电流控制型PWM控制器SG3525.设计并研制的一种中频感应加热电源控制线路.分析采用C8051f330单片机控制SG3525实现高压脉冲加热启停和频率测量,加热时间设定以及设计主回路过温过压等保护功能。  相似文献   
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