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   11665篇
  免费   463篇
  国内免费   473篇
电工技术   319篇
综合类   1144篇
化学工业   306篇
金属工艺   117篇
机械仪表   782篇
建筑科学   1657篇
矿业工程   397篇
能源动力   325篇
轻工业   489篇
水利工程   289篇
石油天然气   382篇
武器工业   50篇
无线电   705篇
一般工业技术   839篇
冶金工业   546篇
原子能技术   174篇
自动化技术   4080篇
  2024年   3篇
  2023年   63篇
  2022年   118篇
  2021年   121篇
  2020年   179篇
  2019年   158篇
  2018年   153篇
  2017年   195篇
  2016年   250篇
  2015年   273篇
  2014年   644篇
  2013年   732篇
  2012年   780篇
  2011年   1104篇
  2010年   770篇
  2009年   658篇
  2008年   690篇
  2007年   800篇
  2006年   800篇
  2005年   689篇
  2004年   604篇
  2003年   585篇
  2002年   477篇
  2001年   367篇
  2000年   306篇
  1999年   269篇
  1998年   208篇
  1997年   130篇
  1996年   98篇
  1995年   80篇
  1994年   55篇
  1993年   39篇
  1992年   27篇
  1991年   21篇
  1990年   12篇
  1989年   21篇
  1988年   17篇
  1987年   15篇
  1986年   8篇
  1985年   22篇
  1984年   18篇
  1983年   13篇
  1982年   7篇
  1981年   10篇
  1980年   2篇
  1978年   2篇
  1973年   1篇
  1972年   1篇
  1971年   1篇
  1964年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
范永兴 《柳钢科技》2006,(F11):36-38
简要介绍焦化厂6m焦炉投产一年多以来的生产现状,整改措施和焦炉热工管理。  相似文献   
32.
赵崇广 《地矿测绘》2003,19(3):28-30
结合福州市行政区域界线勘查工作已结束的实际和社会信息化发展的趋势,提出建立该市市、县级行政区域界线信息管理系统的重要性,对该系统的基本框架、实施方案、建立步骤及与“数字福建”接轨等问题进行了初步讨论,提出了建议。  相似文献   
33.
Hybrid Approach for Addressing Uncertainty in Risk Assessments   总被引:3,自引:0,他引:3  
Parameter uncertainty is a major aspect of the model-based estimation of the risk of human exposure to pollutants. The Monte Carlo method, which applies probability theory to address model parameter uncertainty, relies on a statistical representation of available information. In recent years, other uncertainty theories have been proposed as alternative approaches to address model parameter uncertainty in situations where available information is insufficient to identify statistically representative probability distributions, due in particular to data scarcity. The simplest such theory is possibility theory, which uses so-called fuzzy numbers to represent model parameter uncertainty. In practice, it may occur that certain model parameters can be reasonably represented by probability distributions, because there are sufficient data available to substantiate such distributions by statistical analysis, while others are better represented by fuzzy numbers (due to data scarcity). The question then arises as to how these two modes of representation of model parameter uncertainty can be combined for the purpose of estimating the risk of exposure. This paper proposes an approach (termed a hybrid approach) which combines Monte Carlo random sampling of probability distribution functions with fuzzy calculus. The approach is applied to a real case of estimation of human exposure, via vegetable consumption, to cadmium present in the surficial soils of an industrial site located in the north of France. The application illustrates the potential of the proposed approach, which allows the uncertainty affecting model parameters to be represented in a way that is consistent with the information at hand. Also, because the hybrid approach takes advantage of the “rich” information provided by probability distributions, while retaining the conservative character of fuzzy calculus, it is believed to hold value in terms of a “reasonable” application of the precautionary principle.  相似文献   
34.
The development of autonomous mobile machines to perform useful tasks in real work environments is currently being impeded by concerns over effectiveness, commercial viability and, above all, safety. This paper introduces a case study of a robotic excavator to explore a series of issues around system development, navigation in unstructured environments, autonomous decision making and changing the behaviour of autonomous machines to suit the prevailing demands of users. The adoption of the Real-Time Control Systems (RCS) architecture (Albus, 1991) is proposed as a universal framework for the development of intelligent systems. In addition it is explained how the use of Partially Observable Markov Decision Processes (POMDP) (Kaelbling et al., 1998) can form the basis of decision making in the face of uncertainty and how the technique can be effectively incorporated into the RCS architecture. Particular emphasis is placed on ensuring that the resulting behaviour is both task effective and adequately safe, and it is recognised that these two objectives may be in opposition and that the desired relative balance between them may change. The concept of an autonomous system having “values” is introduced through the use of utility theory. Limited simulation results of experiments are reported which demonstrate that these techniques can create intelligent systems capable of modifying their behaviour to exhibit either ‘safety conscious’ or ‘task achieving’ personalities.  相似文献   
35.
The need for better protecting our vital infrastructure from being damaged or destroyed has received increased attention since the terrorist attacks on September 11, 2001. The tragedy of having thousands of innocent people die before the eyes of an entire nation awakened people to the reality of “managed” attacks of unthinkable magnitudes. However, tragedies of a smaller scale are a daily occurrence but accepted as “collateral damage” of work in an unsafe environment. This paper presents a cost-benefit analysis to address the question of how much money should be spent in protecting underground utilities from damage. During the study of an actual incident it was found that the total costs of such accidents are vastly underreported because only costs for emergency responses and repair are tallied up. This paper makes the case that a comprehensive approach for assessing the total economic impact of such incidents on the public, business, and government is the critical stepping stone to a mathematical optimization of expenditure for damage prevention. In addition, the reader will quickly realize that the use of the presented optimization model provides theoretical underpinning for the engineering profession in its effort to better protect our critical infrastructure from terrorist attacks.  相似文献   
36.
Uncertainty of Predictions of Embankment Dam Breach Parameters   总被引:3,自引:0,他引:3  
Risk assessment studies considering the failure of embankment dams often require the prediction of basic geometric and temporal parameters of a breach, or the estimation of peak breach outflows. Many of the relations most commonly used to make these predictions were developed from statistical analyses of data collected from historic dam failures. The prediction uncertainties of these methods are widely recognized to be very large, but have never been specifically quantified. This paper presents an analysis of the uncertainty of many of these breach parameter and peak flow prediction methods. Application of the methods and the uncertainty analysis are illustrated through a case study of a risk assessment recently performed by the Bureau of Reclamation for a large embankment dam in North Dakota.  相似文献   
37.
Business, not technology leaders should manage the change of Information Technology (IT) from a self-contained business support unit of the sixties to a distributed strategic business function of the nineties. Top management should recognize that a good business plan can only be developed and executed through the partnership between the business unit managers and the managers of the financial, the personnel, and the IT resource units. The technical problems associated with the management of IT may again be the easier part of the total management challenge.  相似文献   
38.
针对地市级电视台的业务特点和需求,设计了基于网络的非线性编辑系统,并对系统工作流程、方案设计、拓扑结构、网络性能、系统管理要求进行了分析,提出了具体实现方法.  相似文献   
39.
This study is concerned with the assessment of risk for major construction activities. Risk has been defined as a measure of the probability, the severity, and the exposure of all hazards of an activity. A risk assessor model (RAM) was developed and computerized to determine the risk associated with a particular activity and the justification factor for a proposed remedy. Knowing the value of risk would help contractors identify the high risk of major construction activities and would enable them to allocate safety precautions in a more efficient manner.  相似文献   
40.
This paper discusses the need for interface management within construction, with particular reference to building facade interfaces. It categorizes the three different types of interface management—physical, contractual, and organizational. The implication of interface management in construction contracting is discussed; it is explained how the U.K. procurement trends have changed, affecting the interface management within projects. U.K. cladding procurement is very fragmented, and the paper maps the development of a typical cladding system showing the complexities of interface management. Finally, the paper discusses CladdISS, a U.K. government funded research project to develop a standardized strategy for the design and management of window and cladding interfaces. It explains the principles of CladdISS with reference to process maps, action plans, management strategy, bibliography, advice on standards, materials, maintenance, joints, movement, and tolerances. This will enable strategies to be developed to avoid the endemic interface problems occurring on-site. It will also guide the management of the interfaces throughout the project.  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