首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   330篇
  免费   20篇
电工技术   5篇
化学工业   73篇
金属工艺   2篇
机械仪表   4篇
建筑科学   18篇
矿业工程   1篇
能源动力   35篇
轻工业   20篇
水利工程   8篇
无线电   41篇
一般工业技术   35篇
冶金工业   8篇
原子能技术   1篇
自动化技术   99篇
  2024年   1篇
  2023年   6篇
  2022年   16篇
  2021年   17篇
  2020年   7篇
  2019年   16篇
  2018年   15篇
  2017年   17篇
  2016年   11篇
  2015年   11篇
  2014年   11篇
  2013年   24篇
  2012年   29篇
  2011年   38篇
  2010年   19篇
  2009年   23篇
  2008年   11篇
  2007年   22篇
  2006年   9篇
  2005年   2篇
  2004年   9篇
  2003年   7篇
  2002年   4篇
  2001年   5篇
  2000年   2篇
  1999年   2篇
  1998年   3篇
  1997年   4篇
  1996年   1篇
  1995年   1篇
  1993年   1篇
  1987年   1篇
  1979年   1篇
  1976年   4篇
排序方式: 共有350条查询结果,搜索用时 31 毫秒
31.
Clustering of nodes in optical networks has been proven to be an efficient way to serve end-to-end connectivity. However, clustering requires specific topological characteristics, or alternatively the introduction of significant alterations of an existing topology to achieve the expected performance improvements. The comparison of future dynamic optical networking technologies should therefore include in the set of initial assumptions, apart from the statistical properties of the traffic load, the network topology to draw conclusions regarding the efficiency as well as feasibility and scalability of the proposed solutions. In this article, we show how node clustering under the CANON architecture can be applied in real-life core networks and provide superior performance compared to conventional burst switching techniques in terms of blocking, resource utilization and power consumption.  相似文献   
32.
In this paper we present a new location management protocol for wireless ATM networks, called LMCP (Location Management and Control Protocol). This protocol is based on the PNNI (Private Network-to-Network Interface) routing functionality to advertise the movement of mobile terminals within predefined areas. Moreover, LMCP uses specialized entities to store and retrieve the current location area of the mobile terminals. These entities are located in mobility enhanced switches that control the execution of mobility procedures (e.g., handovers).The main benefit from the application of LMCP is the establishment of connections that do not contain any misrouted segments. Furthermore, it requires minor modifications to the PNNI and enables its inter-working with other location management mechanisms. The protocol is compared with other similar mechanisms, and its efficiency is demonstrated by the results of an analytical model.  相似文献   
33.
A current premium vehicle is implemented with a variety of information, entertainment, and communication functions, which are generally referred as an infotainment system. During vehicle development, testing of the infotainment system at an overall level is conventionally carried out manually by an expert who can observe at a customer level. This approach has significant limitations with regard to test coverage and effectiveness due to the complexity of the system functions and human’s capability. Hence, it is highly demanded by car manufacturers for an automated infotainment testing system, which replicates a human expert encompassing relevant sensory modalities relating to control (i.e., touch) and observation (i.e., sight and sound) of the system under test. This paper describes the design, development, and evaluation of such a system that consists of simulation of vehicle network, vision-based inspection, automated navigation of features, random cranking waveform generation, sound detection, and test automation. The system developed is able to: stimulate a vehicle system across a wide variety of initialisation conditions, exercise each function, check for system responses, and record failure situations for post-testing analysis.  相似文献   
34.
This paper provides a concise overview of the influence of human activity within the UK society on resource consumption and the subsequent effects on the environment. The concept of the Multi Scale Integrated Analysis of Societal Metabolism (MSIASM) is applied in order to elucidate the evolution of the UK economy for the period between 1981 and 2004. Our findings highlight the transition to a service-based economy and the disproportionate increase of energy demand when compared to the overall population increase. Emergy synthesis is applied in order to understand the production and consumption patterns and the environmental support required to sustain human activity within the UK for the year 2004. Generally speaking the UK society greatly benefits from its significant natural resources with 44.3% of the total emergy used coming from home sources and 29.1% from locally renewable sources. Interestingly enough, despite its significant natural resources, the UK economy, seems to be a net emergy importer by 638.5 × 1021 seJ. Furthermore, the current economic activity is believed to have a significant impact in the environment despite the relatively low environmental load ratio of 2.44.  相似文献   
35.
Recycling of PET was examined using hydrolytic depolymerization in an alkaline solution under microwave irradiation. The reaction was carried out in a sealed microwave reactor in which the pressure and temperature were controlled and recorded. The main products were the monomers TPA and EG. The effect of reaction temperature, time, amount of PET and alkaline concentration on the degree of PET depolymerization and TPA recovery was investigated. Microwave irradiation was found to reduce the time needed to achieve a specific degradation of PET significantly, with almost complete depolymerization occurring in 30 min at 180 °C and only 46 W of microwave power. Using a phase transfer catalyst (TOMAB) resulted in the same amount of unreacted PET but at significantly lower depolymerization temperatures.

  相似文献   

36.
It has very often been stated that the difficulty and complexity of achieving green energy targets in the European Union (EU) will require strengthened measures to promote implementation of New Energy Technologies, Energy End-use Efficiency, as well as measures to support the related energy Research and Technology Development (RTD). Often forgotten is the fact, that most of all, a European-wide co-ordinated forum is needed to continuously develop and sophisticate the monitoring and methodology results, bringing together specialised statisticians, energy researchers and experts on energy socio-economics. The aim of this paper is to present the Scientific Reference System (SRS) Scorecard; a data validation platform for the sophisticated monitoring and communication of the energy technology sector. In this respect, the concept of the SRS scorecard system will be laid out, the parameters and the scoring criteria will be explained as well as the assessment system so as to provide the interested reader with the basis needed to understand the technology evaluation examples provided, as well as its critical analysis.  相似文献   
37.
38.
This paper aims at analysing the factors, which motivate communities to resist the installation of wind farms in their vicinity. To this end, the choice experiment methodology was employed in communities in two Greek Aegean Islands to assess the determinants of preferences towards different wind-farm projects. Unlike other studies, the willingness to accept welfare measure was adopted. The results of our analysis show that the conservation status of the area where the wind farms are to be installed, along with the governance characteristics of the planning procedure are the most important determinants of local community welfare in relation to wind farms. In contrast to other studies, we find that the physical attributes of wind farms appear to be of less relative importance from a local community welfare point of view. Implications for the EU's future energy policy are drawn.  相似文献   
39.
Late transition metal nanoparticles (NPs) with a favorably high surface area to volume ratio have garnered much interest for catalytic applications. Yet, these NPs are prone to aggregation in solution, which has been mitigated through attachment of surface ligands, additives or supports; unfortunately, protective ligands can severely reduce the effective surface area on the NPs available for catalyzing chemical transformations. The preparation of ‘metastable’ NPs can readily address these challenges. We report herein the first synthesis of monodisperse metastable ruthenium nanoparticles (RuNPs), having sub 5 nm size and an fcc structure, in aqueous media at room temperature, which can be stored for a period of at least 8 months. The RuNPs can subsequently be used for the catalytic, quantitative hydrolysis of ammonia‐borane (AB) yielding hydrogen gas with 21.8 turnovers per min at 25 °C. The high surface area available for hydrolysis of AB on the metastable RuNPs translated to an Ea of 27.5 kJ mol‐1, which is notably lower than previously reported values for RuNP based catalysts.  相似文献   
40.
Electrochemical oxidation of stabilized landfill leachate on DSA electrodes   总被引:1,自引:0,他引:1  
The electrochemical oxidation of stabilized landfill leachate with 2960 mg L(-1) chemical oxygen demand (COD) over a Ti/IrO(2)-RuO(2) anode was investigated in the presence of HClO(4) as the supporting electrolyte. Emphasis was given on the effect of electrolysis time (up to 240 min) and temperature (30, 60 and 80°C), current density (8, 16 and 32 mA cm(-2)), initial effluent's pH (0.25, 3, 5 and 6), HClO(4) concentration (0.25 and 1M) and the addition of NaCl (20 and 100mM) or Na(2)SO(4) (20mM) as source of extra electrogenerated oxidants on performance; the latter was evaluated regarding COD, total carbon (TC), total phenols (TPh) and color removal. Moreover, the anode was studied by scanning electron microscopy and cyclic voltammetry. The main parameters affecting the process were the effluent's pH and the addition of salts. Treatment for 240 min at 32 mA cm(-2) current density, 80°C and the pH adjusted from its inherent value of 0.25 (i.e. after the addition of HClO(4)) to 3 yielded 90% COD, 65% TC and complete color and TPh removal at an electricity consumption of 35 kWh kg(-1) COD removed. Comparable performance (i.e. 75% COD reduction) could be achieved without pH adjustment but with the addition of 100mM NaCl consuming 20 kWh kg(-1) COD removed.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号