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   604篇
  免费   20篇
  国内免费   1篇
电工技术   7篇
综合类   1篇
化学工业   241篇
金属工艺   26篇
机械仪表   18篇
建筑科学   9篇
矿业工程   3篇
能源动力   33篇
轻工业   40篇
水利工程   4篇
石油天然气   2篇
无线电   28篇
一般工业技术   87篇
冶金工业   24篇
原子能技术   7篇
自动化技术   95篇
  2023年   8篇
  2022年   64篇
  2021年   63篇
  2020年   28篇
  2019年   30篇
  2018年   33篇
  2017年   26篇
  2016年   28篇
  2015年   26篇
  2014年   24篇
  2013年   30篇
  2012年   36篇
  2011年   28篇
  2010年   32篇
  2009年   26篇
  2008年   17篇
  2007年   17篇
  2006年   22篇
  2005年   16篇
  2004年   7篇
  2003年   10篇
  2002年   10篇
  2001年   4篇
  2000年   1篇
  1999年   4篇
  1998年   3篇
  1997年   2篇
  1996年   5篇
  1994年   1篇
  1993年   1篇
  1992年   1篇
  1990年   4篇
  1989年   4篇
  1988年   1篇
  1986年   2篇
  1985年   1篇
  1984年   3篇
  1980年   1篇
  1979年   2篇
  1977年   2篇
  1976年   1篇
  1973年   1篇
排序方式: 共有625条查询结果,搜索用时 0 毫秒
91.
Decomposition of methyl tert-butyl ether (MTBE) in the gas phase was studied using carbon catalysts with chemically modified surface. Carbon samples with different surface chemical properties were obtained from commercial activated carbon D43/1 (CarboTech, Essen, Germany) by oxidation in liquid phase with various oxidants as well as in air. The catalytic tests were performed in a flow reactor at a temperature range of 353–473 K. Isobutene and methanol are the only products of the MTBE decomposition. The generation of surface acidic oxides considerably enhances the catalytic activity of the carbons. However, the activity is controlled not only by the number and strength of acidic groups, but also by their accessibility. The most active carbon is that oxidized with air at 673 K, which contains pores wider than the pores of other oxidized carbons.  相似文献   
92.
Summary Apex graph grammars are a particular type of directed node-label controlled (DNLC) graph grammars: the embedding edges are established between terminal nodes only. Apex graph grammars, slightly generalized, can generate the sets of dependency graphs of attribute grammars. The other way around, every apex graph language can be obtained from such a dependency graph language by a graph replacement (which is an operation analogous to a string homomorphism).  相似文献   
93.
The Co/CeO2 catalysts obtained by co-precipitation method were used in the steam reforming of ethanol (SRE). The influence of cobalt active phase content (15–29 wt%), the reaction temperature (420–600 °C) and H2O/EtOH molar ratio (12/1 and 6/1) were examined. The physicochemical characterization revealed that the cobalt content of the catalyst influences the metal-support interaction which results in catalyst performance in SRE process. The differences between catalytic properties of the Co/CeO2 catalysts with different metal loading in SRE process decayed at 500 °C for H2O/EtOH = 12/1. The best performance among the tested catalysts showed the 29Co/CeO2 catalyst with the highest cobalt content, exhibiting the highest ethanol conversion, selectivity to two most desirable products and the lowest selectivity to by-products in comparison with catalysts containing smaller amount of metal. Its catalytic properties results probably from its unique physicochemical properties, i.e this catalyst contains large amount of cobalt but the metal crystallites are relatively small. Regardless cobalt content, an increase in the water-to-ethanol molar ratio in the feed increased the concentration of hydrogen an carbon dioxide and decreased formation of carbon monoxide, acetone, aldehyde and ethylene.  相似文献   
94.
Guidelines and instructions for Environmental Impact Assessment and Strategic Environmental Assessment (together referred to as EA here) are developed to improve the quality of legal requirements’ implementation and to support EA procedure accomplishment. However, to date, it has not been checked whether they are useful for practitioners. Therefore, the aim of the study underlying this paper was to verify, based on the experience of Polish EA experts, whether guidelines and instructions are useful in their everyday work. A qualitative study comprising of a questionnaire survey and interviews tested whether (1) EA practitioners know and use the Polish and EU guidelines, (2) how EA practitioners evaluate the validity and usefulness of such instructions, and (3) in which areas there is a lack of instructions and guidelines. The results show a low level of knowledge of national and EU handbooks. Those guidelines focusing on legal procedures, road investments and designing animal passageways are considered to be the most useful. Moreover, practitioners indicate that EU guidelines should be translated into Polish. Most important for practitioners is the linking of guidelines with the EA procedure, so that they can become a platform for dialogue of all stakeholders.  相似文献   
95.
ABSTRACT

We present the methodology and results of participatory design of a robot for presenting an epileptic seizure and a scenario of the educational workshop using this robot. Children with epilepsy encounter stigma and stereotypes and may receive inadequate aid when having an epileptic seizure. The goal of the larger project was to use the prototype device in a series of workshops for improving teachers' actions during an epileptic seizure and their attitudes towards epileptic students. In this paper, we show how various design goals for an educational robot were accomplished to fit the needs of all identified stakeholders, particularly people with epilepsy.

We used a co-design (participatory design) approach through a series of meetings participated by members of the association Polish Association for People Suffering from Epilepsy, students and faculty members of the biomedical engineering and robotics departments, teachers, psychologists and medical specialists (epileptologist, neurologist).

These meetings created an opportunity for a better understanding of the (functional and nonfunctional) requirements and resulting tradeoffs and led the participants to find appropriate solutions. Participation of people with epilepsy in the design process allowed them to deal with the potentially stereotyped representation of themselves. The prototype robot, therefore, combined goals of various stakeholders, such as an accurate presentation of an epileptic seizure, lightweight, ease of use and control, while preserving the dignity of people with epilepsy.

As a result of the co-designing process, an inexpensive robot was created and used in a series of 10 pilot workshops with 217 participants, mainly teachers of primary and middle schools. Teachers improved their understanding of epilepsy and suggested further improvements to the system.  相似文献   
96.
97.
Scientometrics - We demonstrate that by using a triple of simple numerical summaries: an author’s productivity, their overall impact, and a single other bibliometric index that aims to...  相似文献   
98.
The Mizar system is one of the pioneering systems aimed at supporting mathematical proof development on a computer that have laid the groundwork for and eventually have evolved into modern interactive proof assistants. We claim that an important milestone in the development of these systems was the creation of organized libraries accumulating all previously available formalized knowledge in such a way that new works could effectively re-use all previously collected notions. In the case of Mizar, the turning point of its development was the decision to start building the Mizar Mathematical Library as a centrally-managed knowledge base maintained together with the formalization language and the verification system. In this paper we show the process of forming this library, the evolution of its design principles, and also present some data showing its current use with the modern version of the Mizar proof checker, but also as a rich corpus of semantically linked mathematical data in various areas including web-based and natural language proof presentation, maths education, and machine learning based automated theorem proving.  相似文献   
99.
100.
The purpose of this paper is to describe experiments carried out on laser stake welded T-joints of web-core steel sandwich structures. A special test setup was developed to measure the shear-induced rotation at the T-joint. The ratio of the shear force to rotation angle gave the joint stiffness. This stiffness was measured for specimens with two different face-plate thicknesses. The influence of weld thickness, root gap and occurrence of contact were further investigated with finite element simulations. Finally, the shear stiffness of the sandwich structure transverse to the web plate direction was determined using the experimentally obtained average joint stiffness value. The validation of the shear stiffness was carried out by considering a beam in four-point bending. The agreement between calculated deflection and stress and experimental results was found to be good.  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