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   442篇
  免费   21篇
电工技术   4篇
综合类   2篇
化学工业   127篇
金属工艺   9篇
机械仪表   5篇
建筑科学   16篇
矿业工程   5篇
能源动力   10篇
轻工业   43篇
水利工程   1篇
石油天然气   5篇
无线电   51篇
一般工业技术   61篇
冶金工业   80篇
原子能技术   2篇
自动化技术   42篇
  2024年   8篇
  2023年   9篇
  2022年   25篇
  2021年   34篇
  2020年   19篇
  2019年   11篇
  2018年   27篇
  2017年   13篇
  2016年   19篇
  2015年   14篇
  2014年   11篇
  2013年   21篇
  2012年   15篇
  2011年   21篇
  2010年   16篇
  2009年   16篇
  2008年   16篇
  2007年   10篇
  2006年   19篇
  2005年   7篇
  2004年   9篇
  2003年   14篇
  2002年   7篇
  2001年   4篇
  1999年   5篇
  1998年   11篇
  1997年   9篇
  1996年   10篇
  1995年   2篇
  1994年   4篇
  1993年   3篇
  1992年   4篇
  1991年   4篇
  1990年   8篇
  1989年   4篇
  1988年   2篇
  1985年   2篇
  1981年   4篇
  1979年   2篇
  1978年   3篇
  1976年   7篇
  1973年   1篇
  1972年   1篇
  1970年   1篇
  1969年   1篇
  1968年   1篇
  1967年   2篇
  1966年   1篇
  1962年   1篇
  1943年   1篇
排序方式: 共有463条查询结果,搜索用时 0 毫秒
11.
Mine Water and the Environment - Dysart Woods is the largest (≈ 23 ha) old-growth forest in southeastern Ohio. It was donated to Ohio University for research purpose and public...  相似文献   
12.
13.
Evidence for adverse effects of screen media exposure has led to recommendations to limit children's screen time. This paper describes a randomized controlled trial of SMART (Student Media Awareness to Reduce Television), an 18-lesson, theory-based classroom curriculum to reduce screen time among third and fourth grade children in two matched public elementary schools ( n = 181). Intervention school children significantly reduced their weekday television viewing and weekday and Saturday video game playing compared to controls. Greater effects were found among boys and more adult-supervised children. Mothers, fathers, and siblings and other children in intervention school households also reduced their television viewing. The findings demonstrate the efficacy of a classroom intervention to reduce screen time among elementary school children and their family/household members.  相似文献   
14.
15.
A significant source of confusion in the marital observation area is the proliferation of systems for collapsing microbehavioral codes into categories. This study used an archival data set of 995 couples' videotaped conflict negotiations coded with the Marital Interaction Coding System-IV (MICS). A factor analysis was conducted to provide some empirically based guidance for the formation of coding categories. Four factors emerged for both men and women: Hostility, Constructive Problem Discussion, Humor, and Responsibility Discussion. Suggestions are made for category formation with MICS codes and for the development of a new coding system based on these results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   
16.
[1-14C]Heptane was aromatized under 5 atm pressure over a “nonacidic” 3% platinum on alumina catalyst maintained at 500 °C. The reactant was pumped in at a HLSV of 0.88, and the hydrogen-to-heptane mole ratio was 5.1. The samples of product were collected (one during the first 90 min and another during the next 90 min), the toluene was separated from the respective samples, and the radioactivity in each position of the toluene was determined by a degradation sequence. The distribution of radioactivity in sample 1 was as follows: in position 1–2.6%, 2–38.6%; 3–14.5%; 4–4.2%, and in the methyl group—40.1%. Approximately similar distribution of radioactivity was found in sample 2. 1,6-Ring closure is the most important pathway leading to the formation of toluene from [1-14C]heptane; lesser amounts of repetitive, 1,5-ring closure and hydrogenolysis, and bond shift reactions followed by 1,6-ring closure and dehydration can explain the distribution of radioactivity. The participation of 1,7-ring closure in the reaction is also indicated.  相似文献   
17.
18.
In the paper the microstructural phenomena in terms of average grain size occurring in friction stir welding (FSW) processes are focused. A neural network was linked to a finite element model (FEM) of the process to predict the average grain size values. The utilized net was trained starting from experimental data and numerical results of butt joints and then tested on further butt, lap and T-joints. The obtained results show the capability of the AI technique in conjunction with the FE tool to predict the final microstructure in the FSW joints.  相似文献   
19.
Following calls to advance the integration of risk and business process modeling paradigms, this paper formalizes the process of incorporating risk into business process models through the principles of Value-Focused Process Engineering (VFPE). In doing so, the paper aims to extend the existing VFPE modeling notation to reflect a set of necessary constructs required to adequately represent risk in goal-oriented business-process models. The extended set of constructs is proposed to support a formal systems view of process-based risk. Process-based risk is formalized on the one hand, as a product of complex interactions between activity-based elements, and on the other hand, as a natural component of the value creation mechanism of an elementary function or a complex process. The proposed risk-aware VFPE formalism also formulates rules for decomposing risk in process models according to the organizational values, thereby enabling better risk visibility, reducing process complexity, and ensuring continuity of business processes.  相似文献   
20.
SCADA (supervisory control and data acquisition) systems are used for controlling and monitoring industrial processes. We propose a methodology to systematically identify potential process-related threats in SCADA. Process-related threats take place when an attacker gains user access rights and performs actions, which look legitimate, but which are intended to disrupt the SCADA process. To detect such threats, we propose a semi-automated approach of log processing. We conduct experiments on a real-life water treatment facility. A preliminary case study suggests that our approach is effective in detecting anomalous events that might alter the regular process workflow.  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