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   26386篇
  免费   2492篇
  国内免费   1423篇
电工技术   889篇
技术理论   8篇
综合类   3490篇
化学工业   1649篇
金属工艺   512篇
机械仪表   750篇
建筑科学   8131篇
矿业工程   1640篇
能源动力   746篇
轻工业   904篇
水利工程   3092篇
石油天然气   778篇
武器工业   236篇
无线电   1224篇
一般工业技术   1399篇
冶金工业   1086篇
原子能技术   168篇
自动化技术   3599篇
  2024年   92篇
  2023年   368篇
  2022年   765篇
  2021年   849篇
  2020年   791篇
  2019年   626篇
  2018年   541篇
  2017年   705篇
  2016年   781篇
  2015年   887篇
  2014年   1760篇
  2013年   1443篇
  2012年   1611篇
  2011年   2069篇
  2010年   1683篇
  2009年   1825篇
  2008年   1710篇
  2007年   2049篇
  2006年   1829篇
  2005年   1502篇
  2004年   1275篇
  2003年   1090篇
  2002年   938篇
  2001年   728篇
  2000年   565篇
  1999年   437篇
  1998年   297篇
  1997年   228篇
  1996年   182篇
  1995年   128篇
  1994年   109篇
  1993年   94篇
  1992年   73篇
  1991年   49篇
  1990年   46篇
  1989年   33篇
  1988年   29篇
  1987年   15篇
  1986年   12篇
  1985年   14篇
  1984年   13篇
  1983年   10篇
  1982年   5篇
  1981年   4篇
  1979年   5篇
  1978年   4篇
  1977年   3篇
  1966年   4篇
  1965年   3篇
  1959年   5篇
排序方式: 共有10000条查询结果,搜索用时 93 毫秒
61.
This paper presents a self-adapting approach to global level path planning in dynamic environments. The aim of this work is to minimize risk and delays in possible applications of mobile robots (e.g., in industrial processes). We introduce a hybrid system that uses case-based reasoning as well as grid-based maps for decision-making. Maps are used to suggest several alternative paths between specific start and goal point. The casebase stores these solutions and remembers their characteristics. Environment representation and casebase design are discussed. To solve the problem of exploration vs. exploitation, a decision-making strategy is proposed that is based on the irreversibility of decisions. Forgetting strategies are discussed and evaluated in the context of case-based maintenance. The adaptability of the system is evaluated in a domain based on real sensor data with simulated occupancy probabilities. Forgetting strategies and decision-making strategies are evaluated in simulated environments. Experiments show that a robot is able to adapt in dynamic environments and can learn to use paths that are less risky to follow.  相似文献   
62.
The 2004 Gold Medal Award for Life Achievement in the Application of Psychology was awarded to Edwin A. Fleishman, for his significant contributions to the science and applications of psychology, which he has sustained over his remarkable career. He is cited for his research, which has had a profound influence on our understanding of human capabilities, their measurement, their development, and their application in the world of work. Through his many influential leadership roles, as president of the International Association of Applied Psychology and three divisions of the American Psychological Association, and as editor of the Journal of Applied Psychology, he has helped shape our profession. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
63.
水环境标准与水资源的可持续发展   总被引:3,自引:0,他引:3  
从中国水资源严重短缺的现状出发,介绍我国水环境标准体系及现阶段的实施情况,论述水环境标准与可持续发展理论在实施过程中互为条件、互相促进的辩证关系:水环境标准是实施水资源可持续发展战略的前提和保障;可持续发展战略促进水环境标准日臻健全、完善。分析我国水环境标准与可持续发展论的差距,提出今后需进一步完善水环境标准的改进对策。  相似文献   
64.
陶瓷行业推行ISO14000探析   总被引:1,自引:0,他引:1  
黄弘  王毅成  陈斌 《陶瓷学报》2003,24(4):258-261
大力推行ISO14000系列标准已成为我国陶瓷企业适应加入WTO后新的竞争形式,参与国际绿色贸易的有力武器。本文根据我国陶瓷企业的现状,分析了在陶瓷行业推行ISO14000系列标准工作中所存在的问题,提出了在我国陶瓷行业广泛推行ISO14000系列标准的对策和建议。  相似文献   
65.
通过模型试验 ,对位于西安市东郊因采沙使河道破坏严重的灞河河段进行了复现试验和研究 ,并以此为依据 ,通过优化比较为设计部门提供了合理的橡胶坝坝址和坝座高程。在此基础上 ,又对建坝后橡胶坝对上下游冲淤变化的影响进行了试验研究和分析 ,解决了工程设计中的一些关键技术问题  相似文献   
66.
MITI has actively done R&D on industrial technology for waste and reclamation and so there are many research items from small scale to large scale. However, Ecofactory and researches on recycling of metallic materials are introduced here. Ecofactory was proposed by the Mechanical Engineering Laboratory and is now at the stage of the Leading Research, a new research scheme in AISt. Researches on recycling of metallic materials are being done with subsidy. Those researches should contribute to both the preservatin of the global environment and effective recycling of waste materials.Abbreviations AIST Agency of Industrial Science and Technology - MITI Ministry of International Trade and Industry - NEDO New Energy and Industrial Technology Development Organization  相似文献   
67.
68.
It is well known that the production of phosphoric fertilizers by traditional methods is connected with certain environmental problems, particularly related to use of acids during the decomposition of natural phosphates. A basic problem is also the fact that only 15 – 20% of the phosphorus contained in superphosphates is assimilated by plants.The development of methods to process natural phosphates without acid precipitation has potential advantages and in this respect biotechnological processing of natural phosphates in order to obtain organo-mineral fertilizers is very promising. The possibility of bioconverting the phosphorus of natural phosphates by usingAspergillus niger fungi through their deep incubation has been investigated. The investigations aim to achieve a high degree of P2O5 extraction from the phosphates with conversion from a non-utilizable to a utilizable form. The influence of the fungal strain, the kind of nutritive medium and the time of incubation of the process of biological mobilization of the phosphate rock is examined.It was established that the time of incubation, the kind of micro-organisms of theAspergillus niger group, as well as the kind of nutritive medium, influence significantly the process of bioconversion and the conversion of phosphorus from non-utilizable to water-soluble and utilizable for plants form. A maximum degree 90% of phosphorus extraction in the form of water-soluble and citrate-soluble has been reached for 10-day incubation. Physicochemical examinations have been carried out and they have proved that, as a result of the produced organic acids, a process of decomposition of the initial Tunisian phosphorite takes place.  相似文献   
69.
Density stratified flow with both the vertical temperature gradient and the verti-cal salinity gradient is simulated numerically, in which turbulent terms are calculated by a sim-plified turbulence stress/flux algebraic model. The feature of stratification and turbulence is de-scribed correctly by the model. The computational results agree well with the experimental data.However, the k-e turbulence model is not so successful.  相似文献   
70.
海洋是个特殊的环境,为许多光纤传感器提供了一个极好的应用领域。对于海洋这个特殊的“敌对”环境,光纤传感器将面临许多挑战。 本文着重介绍应用于海水温度、浊度、盐份浓度、浮游生物和溶解物光吸收量以及环境湿度等海洋环境参数监测的光纤传感器的原理、结构和特性,展望光纤传感器在海洋环境监测方面的美好前景。  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