全文获取类型
收费全文 | 20982篇 |
免费 | 1209篇 |
国内免费 | 717篇 |
专业分类
电工技术 | 1150篇 |
技术理论 | 4篇 |
综合类 | 6828篇 |
化学工业 | 1174篇 |
金属工艺 | 522篇 |
机械仪表 | 952篇 |
建筑科学 | 2169篇 |
矿业工程 | 223篇 |
能源动力 | 147篇 |
轻工业 | 451篇 |
水利工程 | 178篇 |
石油天然气 | 180篇 |
武器工业 | 45篇 |
无线电 | 1376篇 |
一般工业技术 | 867篇 |
冶金工业 | 1233篇 |
原子能技术 | 44篇 |
自动化技术 | 5365篇 |
出版年
2024年 | 126篇 |
2023年 | 279篇 |
2022年 | 446篇 |
2021年 | 677篇 |
2020年 | 569篇 |
2019年 | 432篇 |
2018年 | 349篇 |
2017年 | 401篇 |
2016年 | 518篇 |
2015年 | 714篇 |
2014年 | 1531篇 |
2013年 | 1195篇 |
2012年 | 1522篇 |
2011年 | 1728篇 |
2010年 | 1532篇 |
2009年 | 1526篇 |
2008年 | 1346篇 |
2007年 | 1257篇 |
2006年 | 1253篇 |
2005年 | 1065篇 |
2004年 | 935篇 |
2003年 | 927篇 |
2002年 | 767篇 |
2001年 | 443篇 |
2000年 | 410篇 |
1999年 | 245篇 |
1998年 | 115篇 |
1997年 | 65篇 |
1996年 | 46篇 |
1995年 | 45篇 |
1994年 | 37篇 |
1993年 | 22篇 |
1992年 | 25篇 |
1991年 | 21篇 |
1990年 | 21篇 |
1989年 | 18篇 |
1988年 | 33篇 |
1987年 | 25篇 |
1986年 | 15篇 |
1985年 | 19篇 |
1984年 | 17篇 |
1983年 | 12篇 |
1982年 | 17篇 |
1981年 | 9篇 |
1964年 | 9篇 |
1958年 | 9篇 |
1957年 | 19篇 |
1956年 | 8篇 |
1955年 | 19篇 |
1954年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
31.
为促进学校学位与研究生教育信息管理水平,在MVC设计模式基础上结合EF(ADO.NET Entity Framework)框架和Ajax技术,探讨学位与研究生教育信息管理系统的设计与实现。系统包括用户管理、学籍管理、课程管理、成绩管理、奖学金管理、导师管理、双盲评审管理和学位信息管理8个模块,具有较好的可用性、稳定性和可扩展性。 相似文献
32.
邓洪斌 《电脑编程技巧与维护》2012,(10):154-155
从学生学习计算机编程时能力的重要性出发,介绍了教师在进行编程教学时必须注重学生几种能力的培养,并阐述了教学过程中可以采用的几种教学方法。 相似文献
33.
王勇杰 《电脑编程技巧与维护》2012,(10):50-52
针对校园电子商务的产生和发展进行了阐述,对校园电子商务的功能模块进行设计和描述,提出了校园电子商务带来的影响,并探讨了校园电子商务在信用、物流、市场规划、管理模式、安全支付等方面存在的问题。 相似文献
34.
Bert Slof Anouschka van Leeuwen Jeroen Janssen Paul A. Kirschner 《Journal of Computer Assisted Learning》2021,37(1):39-50
In computer-supported collaborative learning research, studies examining the combined effects of individual level, group level and within-group differences level measures on individual achievement are scarce. The current study addressed this by examining whether individual, group and within-group differences regarding engagement and prior knowledge predict individual achievement. Engagement was operationalised as group members' exhibited activities in the task space (i.e., discussing domain-content) and social space (i.e., regulating ideas, actions and socioemotional processes). Prior knowledge and achievement were operationalised as group members' performance on a domain-related pre-test and post-test, respectively. Data was collected for 95 triads of secondary education students collaborating on a complex business-economics problem. Subsequently, three different multilevel models were tested to examine the combined effect. First a model with the individual level measures (model 1) was tested and in subsequent models the group level measures (model 2) and within-group levels measures (model 3) were added. Findings indicate model 2 showed the best fit; group members' individual engagement in the social space activities as well as the groups' average prior knowledge positively predicts individual achievement. No effects were found for either group members' or groups' engagement in the task space and for the within-group differences. 相似文献
35.
Valerie Shute Seyedahmad Rahimi Ginny Smith Fengfeng Ke Russell Almond Chih-Pu Dai Renata Kuba Zhichun Liu Xiaotong Yang Chen Sun 《Journal of Computer Assisted Learning》2021,37(1):127-141
In this study, we investigated the validity of a stealth assessment of physics understanding in an educational game, as well as the effectiveness of different game-level delivery methods and various in-game supports on learning. Using a game called Physics Playground, we randomly assigned 263 ninth- to eleventh-grade students into four groups: adaptive, linear, free choice and no-treatment control. Each condition had access to the same in-game learning supports during gameplay. Results showed that: (a) the stealth assessment estimates of physics understanding were valid—significantly correlating with the external physics test scores; (b) there was no significant effect of game-level delivery method on students' learning; and (c) physics animations were the most effective (among eight supports tested) in predicting both learning outcome and in-game performance (e.g. number of game levels solved). We included student enjoyment, gender and ethnicity in our analyses as moderators to further investigate the research questions. 相似文献
36.
Caihua Liu Didar Zowghi Matthew Kearney Muneera Bano 《Journal of Computer Assisted Learning》2021,37(1):1-23
Recent years have seen a growing call for inquiry-based learning in science education, and mobile technologies are perceived as increasingly valuable tools to support this approach. However, there is a lack of understanding of mobile technology-supported inquiry-based learning (mIBL) in secondary science education. More evidence-based, nuanced insights are needed into how using mobile technologies might facilitate students' engagement with various levels of inquiry and enhance their science learning. We, therefore, conducted a robust systematic literature review (SLR) of the research articles on mIBL in secondary school science education that have been published from 2000 to 2019. We reviewed and analysed 31 empirical studies (34 articles) to explore the types of mIBL, and the benefits and constraints of mIBL in secondary school science education. The findings of this SLR suggest new research areas for further exploration and provide implications for science teachers' selection, use and design of mIBL approaches in their teaching. 相似文献
37.
Roberto Truzoli Veronica Pirola Stella Conte 《Journal of Computer Assisted Learning》2021,37(4):940-952
The lockdown due to COVID-19 in Italy resulted in the sudden closure of schools, with a shift from traditional teaching to the online one. Through an online questionnaire, this survey explores teachers' experience of online teaching, the level of risk factors (e.g., stress) and protective factors (e.g., locus of control) and their impact on satisfaction levels during the social distancing. One hundred seven high school teachers from Lombardy, an Italian region very affected by the COVID-19 outbreak, participated. Results show that depression and stress are the main predictors of satisfaction levels for online teaching. In addition, coping, locus of control and self-efficacy emerge as important protective factors. Finally, although there is great satisfaction with the online teaching experience, critical elements emerged. This study is relevant because it describes the critical elements of the online teaching experience, and identifies some protective factors and the main risk factors in teachers operating in an area strongly marked by social restrictions imposed by the pandemic. High school teachers emerge as a sub-group of the general population with specific psychological reactions. Considering the results, it is possible to suggest providing high-quality educational support and crisis-psychological oriented services to teachers, and help to maintain the psychological well-being. 相似文献
38.
Nowadays, cities are the most relevant type of human settlement and their population has been endlessly growing for decades. At the same time, we are witnessing an explosion of digital data that capture many different aspects and details of city life. This allows detecting human mobility patterns in urban areas with more detail than ever before. In this context, based on the fusion of mobility data from different and heterogeneous sources, such as public transport, transport‐network connectivity and Online Social Networks, this study puts forward a novel approach to uncover the actual land use of a city. Unlike previous solutions, our work avoids a time‐invariant approach and it considers the temporal factor based on the assumption that urban areas are not used by citizens all the time in the same manner. We have tested our solution in two different cities showing high accuracy rates. 相似文献
39.
铁路信号电缆是保证列车安全运营的重要组成部分,其故障严重影响列车的安全运营;由于其经多个分线盒接线柱连接的敷设特点,存在中间接头过多,致使传统的电缆故障检测方法应用受到了极大的限制;为此,通过在电缆中间分线盒的备用芯线对接线柱中接入固定阻值的电阻,将备用芯线对形成闭合回路网络,然后在线监测其电阻阻值,利用回路阻值的变化来反映电缆状态,并以在线监测备用芯线对代替在用芯线对,进而在不影响正常列控信号传输的情况下实现了信号电缆的故障在线监测;经实际测试,有效地解决了铁路信号电缆断线故障的在线监测及定位。 相似文献
40.
李锦 《网络安全技术与应用》2012,(10):9-11
"超级网银"是我国第一个大规模跨CA的交叉认证平台,采用的是桥接交叉认证模式。不同的领域,应根据其自身特点,采用不同形式的交叉认证模型。最终的目的,是要在全国范围内建立一个交叉认证、相互融合又相互独立、相互协调的PKI整体体系,在这个过程中,国家和政府应发挥更加积极的作用。 相似文献