全文获取类型
收费全文 | 7084篇 |
免费 | 1117篇 |
国内免费 | 1098篇 |
专业分类
电工技术 | 119篇 |
综合类 | 1125篇 |
化学工业 | 160篇 |
金属工艺 | 48篇 |
机械仪表 | 280篇 |
建筑科学 | 1055篇 |
矿业工程 | 91篇 |
能源动力 | 69篇 |
轻工业 | 131篇 |
水利工程 | 112篇 |
石油天然气 | 62篇 |
武器工业 | 28篇 |
无线电 | 489篇 |
一般工业技术 | 443篇 |
冶金工业 | 523篇 |
原子能技术 | 28篇 |
自动化技术 | 4536篇 |
出版年
2024年 | 69篇 |
2023年 | 155篇 |
2022年 | 304篇 |
2021年 | 306篇 |
2020年 | 278篇 |
2019年 | 208篇 |
2018年 | 175篇 |
2017年 | 184篇 |
2016年 | 236篇 |
2015年 | 274篇 |
2014年 | 469篇 |
2013年 | 405篇 |
2012年 | 566篇 |
2011年 | 590篇 |
2010年 | 605篇 |
2009年 | 646篇 |
2008年 | 631篇 |
2007年 | 645篇 |
2006年 | 517篇 |
2005年 | 441篇 |
2004年 | 336篇 |
2003年 | 221篇 |
2002年 | 183篇 |
2001年 | 157篇 |
2000年 | 117篇 |
1999年 | 90篇 |
1998年 | 50篇 |
1997年 | 68篇 |
1996年 | 40篇 |
1995年 | 33篇 |
1994年 | 34篇 |
1993年 | 34篇 |
1992年 | 20篇 |
1991年 | 22篇 |
1990年 | 13篇 |
1989年 | 18篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 20篇 |
1985年 | 16篇 |
1975年 | 4篇 |
1966年 | 4篇 |
1965年 | 7篇 |
1964年 | 14篇 |
1963年 | 5篇 |
1962年 | 5篇 |
1961年 | 10篇 |
1960年 | 9篇 |
1956年 | 5篇 |
1955年 | 7篇 |
排序方式: 共有9299条查询结果,搜索用时 15 毫秒
1.
以“创新、协调、绿色、开放、共享”为内核的新发展理念,是对马克思主义发展理念的继承和发扬,极具时代精神,富含问题意识,为高校思想政治教育发展、教育教学改革实践提供了强大的理论支撑。本文以“通信原理”为例,阐述了新发展理念在课程改革中的思路和方法,实现了思想政治教育与专业基础课程有机融合,为深化高校教学改革、创新人才培养模式提供了思路。 相似文献
2.
Susan Sabra Khalid Mahmood Malik Muhammad Afzal Vian Sabeeh Ahmad Charaf Eddine 《Expert Systems》2020,37(1):e12388
Clinical narratives such as progress summaries, lab reports, surgical reports, and other narrative texts contain key biomarkers about a patient's health. Evidence-based preventive medicine needs accurate semantic and sentiment analysis to extract and classify medical features as the input to appropriate machine learning classifiers. However, the traditional approach of using single classifiers is limited by the need for dimensionality reduction techniques, statistical feature correlation, a faster learning rate, and the lack of consideration of the semantic relations among features. Hence, extracting semantic and sentiment-based features from clinical text and combining multiple classifiers to create an ensemble intelligent system overcomes many limitations and provides a more robust prediction outcome. The selection of an appropriate approach and its interparameter dependency becomes key for the success of the ensemble method. This paper proposes a hybrid knowledge and ensemble learning framework for prediction of venous thromboembolism (VTE) diagnosis consisting of the following components: a VTE ontology, semantic extraction and sentiment assessment of risk factor framework, and an ensemble classifier. Therefore, a component-based analysis approach was adopted for evaluation using a data set of 250 clinical narratives where knowledge and ensemble achieved the following results with and without semantic extraction and sentiment assessment of risk factor, respectively: a precision of 81.8% and 62.9%, a recall of 81.8% and 57.6%, an F measure of 81.8% and 53.8%, and a receiving operating characteristic of 80.1% and 58.5% in identifying cases of VTE. 相似文献
3.
Massive Open Online Courses (MOOCs) are becoming an essential source of information for both students and teachers. Noticeably, MOOCs have to adapt to the fast development of new technologies; they also have to satisfy the current generation of online students. The current MOOCs’ Management Systems, such as Coursera, Udacity, edX, etc., use content management platforms where content are organized in a hierarchical structure. We envision a new generation of MOOCs that support interpretability with formal semantics by using the SemanticWeb and the online social networks. Semantic technologies support more flexible information management than that offered by the current MOOCs’ platforms. Annotated information about courses, video lectures, assignments, students, teachers, etc., can be composed from heterogeneous sources, including contributions from the communities in the forum space. These annotations, combined with legacy data, build foundations for more efficient information discovery in MOOCs’ platforms. In this article we review various Collaborative Semantic Filtering technologies for building Semantic MOOCs’ management system, then, we present a prototype of a semantic middle-sized platform implemented at Western Kentucky University that answers these aforementioned requirements. 相似文献
4.
现阶段的语义解析方法大部分都基于组合语义,这类方法的核心就是词典。词典是词汇的集合,词汇定义了自然语言句子中词语到知识库本体中谓词的映射。语义解析一直面临着词典中词汇覆盖度不够的问题。针对此问题,该文在现有工作的基础上,提出了基于桥连接的词典学习方法,该方法能够在训练中自动引入新的词汇并加以学习,为了进一步提高新学习到的词汇的准确度,该文设计了新的词语—二元谓词的特征模板,并使用基于投票机制的核心词典获取方法。该文在两个公开数据集(WebQuestions和Free917)上进行了对比实验,实验结果表明,该文方法能够学习到新的词汇,提高词汇的覆盖度,进而提升语义解析系统的性能,特别是召回率。 相似文献
5.
Semantic search is gradually establishing itself as the next generation search paradigm, which meets better a wider range of information needs, as compared to traditional full-text search. At the same time, however, expanding search towards document structure and external, formal knowledge sources (e.g. LOD resources) remains challenging, especially with respect to efficiency, usability, and scalability.This paper introduces Mímir—an open-source framework for integrated semantic search over text, document structure, linguistic annotations, and formal semantic knowledge. Mímir supports complex structural queries, as well as basic keyword search.Exploratory search and sense-making are supported through information visualisation interfaces, such as co-occurrence matrices and term clouds. There is also an interactive retrieval interface, where users can save, refine, and analyse the results of a semantic search over time. The more well-studied precision-oriented information seeking searches are also well supported.The generic and extensible nature of the Mímir platform is demonstrated through three different, real-world applications, one of which required indexing and search over tens of millions of documents and fifty to hundred times as many semantic annotations. Scaling up to over 150 million documents was also accomplished, via index federation and cloud-based deployment. 相似文献
6.
Similarities and differences between male and female novice designers on color‐concept associations for warnings,action required,and signs and equipment status messages
下载免费PDF全文
![点击此处可从《Color research and application》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This research examined the male and female novice designers toward color associations for the concepts used for ‘warnings’, ‘action required’, and ‘signs and equipment status’ through a questionnaire‐based study. A total of 178 Hong Kong Chinese final year undergraduate design students (89 males and 89 females) participated in the study. The test used required the participants to indicate their choice of one of nine colors to associations with each of 38 concepts in a color‐concept table, so that any one color could be associated with any one of the concepts. For both male and female groups of novice designers, chi‐square tests revealed a strong color association for each concept tested in this study (P < .05). The results showed males and females agreed on some color‐concept association stereotypes which were therefore gender neutral. The male and female novice designers had the same color associations and similar levels of stereotype strengths for 21 concepts. The nine strongest and therefore most useful color‐concept association stereotypes for both male and female novice designers were: red‐danger, red‐fire, red‐hot, red‐stop, red‐emergency, red‐error, blue‐cold, blue‐male, and green‐exit. However, the male and female novice designers had different color association stereotypes for the standby (green vs. yellow), emergency exit (green vs. red), and toxic (purple vs. black) concepts, and the strengths of the 14 remaining associations for both groups were not at equivalent levels. Overall, it is anticipated that the findings of this study will act as a useful reference for novice designers and other design practitioners to optimize color coding in the design of ‘warnings’, ‘action required’, and ‘signs and equipment status’ messages. 相似文献
7.
8.
Hovius Marjolijn; Kellenbach Marion L.; Graham Kim S.; Hodges John R.; Patterson Karalyn 《Canadian Metallurgical Quarterly》2003,17(1):100
The authors investigated the impact of semantic knowledge on visual object analysis by assessing the performance of patients with semantic dementia on a different-views object matching test and on 2 object decision tests differing, for example, in whether the nonreal items were nonsense objects or chimeras of 2 real objects. On average, the patients scored normally on both the object matching and the object decision test including nonsense objects but were impaired on the object decision test including chimeras; this latter was also the only visual object test that correlated significantly with degree of semantic impairment. These findings demonstrate that object decision is not a single task or ability and that it is not necessarily independent of conceptual knowledge. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
9.
Retrieving the answer to a general knowledge question has been shown to involve two metacognitive processes--a feeling-of-knowing that initiates the search of long-term memory and a willingness to continue searching until an answer can be confidently stated. To extend this model, college students were asked to retrieve as many members of 2 natural categories as they could in 1 min. Examination of the points at which they switched categories revealed that they searched longer in categories of higher potency, and they switched earlier when the other category was of higher potency. They also searched the first category longer when they were allowed to switch only once during a trial rather than as often as they wished. It was concluded that feeling-of-knowing maintained search of a category and also contributed to the willingness to continue searching, and the constraint on switching impacted the willingness to continue. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
10.
G. LABEAS T. H. KERMANIDIS 《Fatigue & Fracture of Engineering Materials & Structures》2003,26(5):449-457
ABSTRACT Research results concerning the simulation of the crushing behaviour of composite systems with energy absorption characteristics are presented in the present work. The study is focused on the ‘tensor skin’ concept, an energy absorbing composite system that was originally developed to improve the crashworthiness of helicopters under water impact and which is promising for utilization in the construction of the lower part of composite fuselage aircraft. The ‘tensor skin’ concept comprises a folded or corrugated composite construction, which upon loading unfolds by forming ‘plastic hinges’, leading to an increase in the load bearing capability of the structure. The numerical modelling issues and the critical aspects of the simulation are discussed. Verification of the numerical simulation procedure is performed by experimental work. The experimental results utilized to assess and validate the numerical procedure were derived within the European Research Project ‘Design for Crash Survivability – CRASURV’ (BRITE – Aeronautics Area). The results of the simulations are generally in good agreement with experimental data. 相似文献