全文获取类型
收费全文 | 8098篇 |
免费 | 412篇 |
国内免费 | 259篇 |
专业分类
电工技术 | 757篇 |
综合类 | 1112篇 |
化学工业 | 318篇 |
金属工艺 | 128篇 |
机械仪表 | 368篇 |
建筑科学 | 2016篇 |
矿业工程 | 339篇 |
能源动力 | 131篇 |
轻工业 | 160篇 |
水利工程 | 435篇 |
石油天然气 | 243篇 |
武器工业 | 62篇 |
无线电 | 396篇 |
一般工业技术 | 291篇 |
冶金工业 | 862篇 |
原子能技术 | 42篇 |
自动化技术 | 1109篇 |
出版年
2024年 | 12篇 |
2023年 | 36篇 |
2022年 | 118篇 |
2021年 | 161篇 |
2020年 | 162篇 |
2019年 | 88篇 |
2018年 | 109篇 |
2017年 | 139篇 |
2016年 | 167篇 |
2015年 | 179篇 |
2014年 | 449篇 |
2013年 | 379篇 |
2012年 | 477篇 |
2011年 | 641篇 |
2010年 | 553篇 |
2009年 | 527篇 |
2008年 | 497篇 |
2007年 | 669篇 |
2006年 | 616篇 |
2005年 | 467篇 |
2004年 | 439篇 |
2003年 | 375篇 |
2002年 | 358篇 |
2001年 | 252篇 |
2000年 | 196篇 |
1999年 | 171篇 |
1998年 | 62篇 |
1997年 | 81篇 |
1996年 | 82篇 |
1995年 | 57篇 |
1994年 | 49篇 |
1993年 | 26篇 |
1992年 | 27篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1989年 | 9篇 |
1988年 | 11篇 |
1987年 | 13篇 |
1986年 | 7篇 |
1985年 | 8篇 |
1984年 | 4篇 |
1981年 | 2篇 |
1977年 | 2篇 |
1968年 | 11篇 |
1965年 | 5篇 |
1964年 | 3篇 |
1959年 | 2篇 |
1957年 | 3篇 |
1956年 | 7篇 |
1955年 | 6篇 |
排序方式: 共有8769条查询结果,搜索用时 15 毫秒
1.
开展智慧化阅读推广,紧跟时代步伐,有效提升读者多重阅读体验和满意度,增强智慧化阅读推广的价值,促进智慧化阅读推广服务的有效化、规范化、科学化、常态化、长期化发展,已成为当前阅读推广研究中一个重要的切入点。文章基于智慧化阅读研究,结合"新媒体"高新技术环境,提出智慧化阅读推广的内容分析、具体实施、环境构建、推广评估与效果、推广改进等几个方面组成的以读者为中心的核心服务体系。本文分析了智慧化阅读基本方面,以我校图书馆实际运用推广效果,智慧化阅读存在的优、劣势及相应的对策。 相似文献
2.
《International Journal of Hydrogen Energy》2022,47(51):21613-21633
When planning large-scale 100% renewable energy systems (RES) for the year 2050, the system capacity is usually oversized for better supply-demand matching of electrical energy since solar and wind resources are highly intermittent. This causes excessive excess energy that is typically dissipated, curtailed, or sold directly. The public literature shows a lack of studies on the feasibility of using this excess for country-scale co-generation. This study presents the first investigation of utilizing this excess to generate green hydrogen gas. The concept is demonstrated for Jordan using three solar photovoltaic (PV), wind, and hybrid PV-wind RESs, all equipped with Lithium-Ion battery energy storage systems (ESSs), for hydrogen production using a polymer electrolyte membrane (PEM) system. The results show that the PV-based system has the highest demand-supply fraction (>99%). However, the wind-based system is more favorable economically, with installed RES, ESS, and PEM capacities of only 23.88 GW, 2542 GWh, and 20.66 GW. It also shows the highest hydrogen annual production rate (172.1 × 103 tons) and the lowest hydrogen cost (1.082 USD/kg). The three systems were a better option than selling excess energy directly, where they ensure annual incomes up to 2.68 billion USD while having payback periods of as low as 1.78 years. Furthermore, the hydrogen cost does not exceed 2.03 USD/kg, which is significantly lower than the expected cost of hydrogen (3 USD/kg) produced using energy from fossil fuel-based systems in 2050. 相似文献
3.
Stefanie Vanbecelaere Katrien Van den Berghe Frederik Cornillie Delphine Sasanguie Bert Reynvoet Fien Depaepe 《Journal of Computer Assisted Learning》2020,36(4):502-513
For the training of academic skills, digital educational games with integrated adaptivity are promising. Adaptive games are considered superior to non-adaptive games, because they constantly assess children's performance, and accordingly adapt the difficulty of the tasks corresponding to the children's individual level. However, empirical evidence with regard to the effectivity of adaptive compared to non-adaptive games is limited. A study was conducted with 191 children from the third year of Kinder garten who were enrolled in one of three conditions, that is, playing an adaptive version of the reading game (RG), a non-adaptive version of the RG or training with pen-and-paper exercises. In all three conditions, children trained emergent reading (phonological awareness and letter knowledge) once a week for 30 min over a period of 5 weeks. Children's performance on cognitive (phonological awareness, letter knowledge, reading fluency) and non-cognitive (motivation, self-concept) factors was assessed. Results revealed a significant improvement in phonological awareness and letter knowledge in all conditions. However, no differences between the conditions were observed with respect to children's improvement on phonological awareness and letter knowledge or on their post-test scores for reading fluency. With regard to motivation and self-concept, again, no differences in these non-cognitive factors were observed across conditions. 相似文献
4.
Reading requires the orchestration of visual, attentional, language-related, and oculomotor processing constraints. This study replicates previous effects of frequency, predictability, and length of fixated words on fixation durations in natural reading and demonstrates new effects of these variables related to 144 sentences. Such evidence for distributed processing of words across fixation durations challenges psycholinguistic immediacy-of-processing and eye-mind assumptions. Most of the time the mind processes several words in parallel at different perceptual and cognitive levels. Eye movements can help to unravel these processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
5.
6.
Reading Motivation: Multidimensional and Indeterminate. 总被引:1,自引:0,他引:1
The Motivations for Reading Questionnaire (MRQ) contains 54 items that are posited to tap 11 dimensions of reading motivation. The structural validity of the MRQ was investigated with 2 samples: (a) 328 students in Grades 3-5 from 2 suburban mid-Atlantic elementary schools and (b) 735 students in Grades 3-5 in 2 suburban southwestern elementary schools. With confirmatory factor analyses (CFAs), the theoretical 11-factor structure did not adequately fit the data in either sample. Subsequently, exploratory factor analyses found 8 factors for each sample with 6 factors defined by only 3 or 4 common items. However, a double CFA cross-validation found an inadequate fit for both samples. Given these results, the authors suggest that the MRQ be revised. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
7.
织金电视台通过对有线电视网络进行双向改造,为Internet宽带接入、数字电视、VOD等多媒体应用提供了运行平台,介绍织金县城区HFC双向网络设计方案。 相似文献
8.
9.
10.
中国未来电力需求与核能 总被引:5,自引:0,他引:5
本文介绍了我国未来电力需求和能源结构,阐述了核能是我国满足经济发达地区电力需求的合理选择,并提出了我国“九五”核电计划和中期目标,以及发展核电中面临的问题和基本对策。 相似文献