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   439篇
  免费   15篇
电工技术   1篇
化学工业   77篇
金属工艺   17篇
机械仪表   28篇
建筑科学   5篇
能源动力   24篇
轻工业   31篇
水利工程   1篇
石油天然气   3篇
无线电   77篇
一般工业技术   97篇
冶金工业   65篇
原子能技术   3篇
自动化技术   25篇
  2024年   4篇
  2023年   12篇
  2022年   13篇
  2021年   15篇
  2020年   12篇
  2019年   8篇
  2018年   16篇
  2017年   15篇
  2016年   8篇
  2015年   4篇
  2014年   18篇
  2013年   26篇
  2012年   19篇
  2011年   16篇
  2010年   11篇
  2009年   10篇
  2008年   15篇
  2007年   16篇
  2006年   13篇
  2005年   10篇
  2004年   10篇
  2003年   13篇
  2002年   12篇
  2001年   11篇
  2000年   13篇
  1999年   6篇
  1998年   26篇
  1997年   10篇
  1996年   9篇
  1995年   10篇
  1994年   3篇
  1993年   9篇
  1992年   7篇
  1991年   9篇
  1990年   5篇
  1989年   2篇
  1988年   8篇
  1987年   3篇
  1986年   4篇
  1985年   3篇
  1984年   4篇
  1983年   5篇
  1982年   3篇
  1981年   2篇
  1979年   1篇
  1976年   2篇
  1973年   2篇
  1957年   1篇
排序方式: 共有454条查询结果,搜索用时 15 毫秒
21.
The application of electrogenerated iodonium ion, acting as catalytic electron carrier, has been taken into account in the intramolecular oxidative cyclization reaction of 2-nitroaniline on graphite anode in the preparation of benzofuroxan, which is of great synthetic utility.  相似文献   
22.
Seeds of two spices Coriandrum sativum and Foeniculum vulgare, were dressed separately with essential oil of Cedrus deodara as well as with five synthetic fungicides viz., phenylmercury acetate, 2-methoxyethyl mercury chloride, copper oxychloride, mancozeb and wettable sulphur. Treated seeds were stored in polythene bags for 12 months. On mycofloral analysis, the oil had checked the appearance of ten fungi, Absidia sp., Alternaria alternata, Aspergillus flavus, A. fumigatus, A. niger, A. ruber, A. versicolor, Cladosporium cladosporioides, Curvularia lunata, and Paecilomyces variotii on the seeds of C. sativum, and seven fungi, Absidia sp., A. flavus, A. fumigatus, A. niger, A. ruber, A. versicolor, and Rhizopus spp., on the seeds of F. vulgare. The oil proved to be more effective than the synthetic fungicides. Further, the oil did not show any adverse effect on seed germination and seedling growth of both spices.  相似文献   
23.
24.
25.
We carried out a comparative study on the electrical and magnetodielectric properties of polycrystalline BiFeO3, Bi0.9Ca0.1FeO2.95, Bi0.9Ba0.05Ca0.05FeO2.95, and Bi0.9Ba0.1FeO2.95 ceramics. The two dielectric anomalies, near 25 K and 281 K, are observed for BiFeO3. Interestingly, the anomaly near 25 K shifts towards a higher temperature above 60 K with Ca and/or Ba doping, attributed to the doping induced chemical pressure. In addition, the room temperature switchable magnetodielectric effect is witnessed for the doped BiFeO3 compounds, due to the quadratic magnetoelectric coupling. This indicates the improved magnetoelectric coupling in BiFeO3 with the Ca and Ba doping. This is essentially due to the enhanced magnetic ordering and reduced leakage current in BiFeO3 after the doping.  相似文献   
26.
The use of separate transport and economic models in urban planning provides a limited view of economic impacts, restricts the testing of network design options and lengthens the planning process. Furthermore, the standard methodology for economic appraisal assumes partial economic equilibrium and cannot determine the distribution of impacts from the transport sector to households. Computable general equilibrium (CGE) models can capture general equilibrium effects and measure welfare at the household level, but mostly lack integration with transport models and do not represent all trip generators. This paper develops an integrated traffic assignment and spatial CGE model in nonlinear complementarity form, casted as a framework for economic appraisal of urban transport projects. The CGE submodel generates commuting, shopping and leisure trips as inputs into the transport submodel, which then assigns trips to the network according to user equilibrium. The resulting travel times then feed back into household prices and freight margins. Households and firms fully account for travel times in decisions on where to shop, how much labour to supply and where to source production inputs. Calibration and applications of the model are demonstrated for 14 regions and 2 industries across Sydney using GAMS/PATH on the NEOS server. The welfare of various network improvements is measured using equivalent variations. The model can be calibrated to external strategic transport models, and be extended to simulate additional trip generators and land-use.  相似文献   
27.
Dixit  Shivam  Kala  Rahul 《Multimedia Tools and Applications》2021,80(21-23):32615-32637
Multimedia Tools and Applications - Heart disease patients are continuously increasing. The patients face the problem of a delayed diagnosis as the subjects do not undergo routine tests and consult...  相似文献   
28.
In the present work, a knowledge-based system is developed for the prediction of surface roughness in turning process. Neural networks and fuzzy set theory are used for this purpose. Knowledge acquired from the shop floor is used to train the neural network. The trained network provides a number of data sets, which are fed to a fuzzy-set-based rule generation module. A large number of IF–THEN rules are generated, which can be reduced to a smaller set of rules by using Boolean operations. The developed rule base may be used for predicting surface roughness for given process variables as well as for the prediction of process variables for a given surface roughness. The concise set of rules helps the user in understanding the behavior of the cutting process and to assess the effectiveness of the model. The performance of the developed knowledge-based system is studied with the experimental data of dry and wet turning of mild steel with HSS and carbide tools.  相似文献   
29.
Multimedia Tools and Applications - The world of electronics in particularly in the field of image processing, numerous distinguishable and noteworthy contributions have been made available....  相似文献   
30.
The design of a complex embedded control system involves integration of large number of components. These components need to interact in a timely fashion to achieve the system level end-to-end requirements. In practice, the component level timing specification consists of design attributes like component task mapping, task period and schedule definition but often lack details on their real-time (functional) requirements. As we observe, there is no systematic methodology in place for decomposing the feature level timing requirements into component level timing requirements. This paper proposes an early stage time-budgeting methodology to bridge the above gap. A salient proposal of this methodology is to consider parameterized component timing-requirements. A key step in the methodology involves computing a set of constraints by relating component requirements with feature requirements. This enables the separation of timing constraints from functionality decomposition, and facilitates early optimization of the component time-budget for a complex component based embedded system. This paper formalizes the proposed methodology by using Parametric Temporal Logic. A case study involving two advanced features from the automotive domain, namely Adaptive Cruise Control and Collision Mitigation is given to demonstrate the methodology.  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