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   4449篇
  免费   61篇
电工技术   28篇
综合类   2篇
化学工业   410篇
金属工艺   51篇
机械仪表   60篇
建筑科学   60篇
矿业工程   12篇
能源动力   41篇
轻工业   387篇
水利工程   21篇
石油天然气   7篇
无线电   195篇
一般工业技术   376篇
冶金工业   2548篇
原子能技术   36篇
自动化技术   276篇
  2022年   26篇
  2021年   37篇
  2020年   23篇
  2019年   31篇
  2017年   35篇
  2016年   51篇
  2015年   41篇
  2014年   53篇
  2013年   69篇
  2012年   57篇
  2011年   94篇
  2010年   83篇
  2009年   77篇
  2008年   93篇
  2007年   88篇
  2006年   57篇
  2005年   68篇
  2004年   54篇
  2003年   67篇
  2002年   57篇
  2001年   47篇
  2000年   50篇
  1999年   137篇
  1998年   781篇
  1997年   418篇
  1996年   311篇
  1995年   201篇
  1994年   172篇
  1993年   174篇
  1992年   43篇
  1991年   43篇
  1990年   56篇
  1989年   35篇
  1988年   43篇
  1987年   31篇
  1986年   43篇
  1985年   47篇
  1984年   28篇
  1983年   20篇
  1982年   26篇
  1981年   29篇
  1980年   27篇
  1978年   27篇
  1977年   81篇
  1976年   123篇
  1975年   26篇
  1972年   28篇
  1971年   20篇
  1970年   25篇
  1969年   18篇
排序方式: 共有4510条查询结果,搜索用时 0 毫秒
61.
62.
63.
A study of the effect of long-term alcohol consumption on the liver of well-nourished rats is described. Rats fed for 16 weeks on a semipurified diet supplemented with high levels of vitamins and lipotropic factors and alcohol corresponding to 35% of the total caloric intake developed marked fatty changes of the liver. Mild fatty changes were observed in pair-fed controls receiving as isoenergetic equivalent of sucrose instead of alcohol. Intracellular hyaline bodies, corresponding ultrastructurally to giant mitochondria were abundantly found in the hepatocytes of alcoholic rats, while in the controls they were not seen. Te findings in this investigation are postulated to provide further evidence that the long-term intake of alcohol exerts a direct causative role in the pathogenesis of liver damage.  相似文献   
64.
65.
The kinetics of the overall reactions of carbon gasification at temperatures up to 1600 K is studied. The kinetic characteristics of the reactions are taken into account in a distributed mathematical model of filtration combustion of carbon. By computational experiment at different values of process control parameters (the gas flow rate, the fraction of the oxidant in the gas, and the mass ratio of carbon to the inert material in the combustible mixture), it is found that, in the wave of filtration combustion of carbon under superadiabatic conditions, carbon gasification can predominately yield either CO2 or CO.  相似文献   
66.
Mobile applications and services relying on mobility prediction have recently spurred lots of interest. In this paper, we propose mobility prediction based on cellular traces as an infrastructural level service of telecom cloud. Mobility Prediction as a Service (MPaaS) embeds mobility mining and forecasting algorithms into a cloud-based user location tracking framework. By empowering MPaaS, the hosted 3rd-party and value-added services can benefit from online mobility prediction. Particularly we took Mobility-aware Personalization and Predictive Resource Allocation as key features to elaborate how MPaaS drives new fashion of mobile cloud applications. Due to the randomness of human mobility patterns, mobility predicting remains a very challenging task in MPaaS research. Our preliminary study observed collective behavioral patterns (CBP) in mobility of crowds, and proposed a CBP-based mobility predictor. MPaaS system equips a hybrid predictor fusing both CBP-based scheme and Markov-based predictor to provide telecom cloud with large-scale mobility prediction capacity.  相似文献   
67.
Given the strong increase in regulatory requirements for business processes the management of business process compliance becomes a more and more regarded field in IS research. Several methods have been developed to support compliance checking of conceptual models. However, their focus on distinct modeling languages and mostly linear (i.e., predecessor-successor related) compliance rules may hinder widespread adoption and application in practice. Furthermore, hardly any of them has been evaluated in a real-world setting. We address this issue by applying a generic pattern matching approach for conceptual models to business process compliance checking in the financial sector. It consists of a model query language, a search algorithm and a corresponding modelling tool prototype. It is (1) applicable for all graph-based conceptual modeling languages and (2) for different kinds of compliance rules. Furthermore, based on an applicability check, we (3) evaluate the approach in a financial industry project setting against its relevance for decision support of audit and compliance management tasks.  相似文献   
68.
Four years after introduction of the first instrument for measurement of sparkle, the foundations have been reconsidered, and the pool of practical experience has been analyzed to provide a more detailed and complete picture of the subject matter. The following aspects are introduced and discussed: observation conditions and resulting requirements for imaging (sampling) and filtering, analysis of spatial periods and frequencies as a basis for filtering, spatial filtering concepts, sparkle in the frequency domain, sparkle evaluation based on analysis of single images and difference images, origins of unwanted sparkle components, scaling and offset in sparkle evaluation, and verification of the method.  相似文献   
69.
Difficulties in integrating technical, economic and institutional factors present a major gap in analytical capacity to guide water policy. This article presents an integrated framework to support water policy and guide water management choices, with application to Israel. That framework rests on the theory of economic policy originally developed by Tinbergen. It sees national water challenges as consisting of external factors, constraints, policy instruments and targets. The need for a modern implementation of the theory of economic policy is motivated by emerging environmental requirements, scarce water, growing demands for domestic use, and ongoing needs to implement existing and potential peace agreements.  相似文献   
70.
During software system evolution, software architects intuitively trade off the different architecture alternatives for their extra-functional properties, such as performance, maintainability, reliability, security, and usability. Researchers have proposed numerous model-driven prediction methods based on queuing networks or Petri nets, which claim to be more cost-effective and less error-prone than current practice. Practitioners are reluctant to apply these methods because of the unknown prediction accuracy and work effort. We have applied a novel model-driven prediction method called Q-ImPrESS on a large-scale process control system from ABB consisting of several million lines of code. This paper reports on the achieved performance prediction accuracy and reliability prediction sensitivity analyses as well as the effort in person hours for achieving these results.  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