全文获取类型
收费全文 | 103380篇 |
免费 | 1499篇 |
国内免费 | 1227篇 |
专业分类
电工技术 | 1952篇 |
综合类 | 141篇 |
化学工业 | 10597篇 |
金属工艺 | 5471篇 |
机械仪表 | 3206篇 |
建筑科学 | 2040篇 |
矿业工程 | 159篇 |
能源动力 | 2983篇 |
轻工业 | 6122篇 |
水利工程 | 705篇 |
石油天然气 | 667篇 |
武器工业 | 15篇 |
无线电 | 15997篇 |
一般工业技术 | 21864篇 |
冶金工业 | 25362篇 |
原子能技术 | 1417篇 |
自动化技术 | 7408篇 |
出版年
2022年 | 418篇 |
2021年 | 708篇 |
2020年 | 533篇 |
2019年 | 682篇 |
2018年 | 1139篇 |
2017年 | 1100篇 |
2016年 | 1192篇 |
2015年 | 935篇 |
2014年 | 1509篇 |
2013年 | 4703篇 |
2012年 | 2610篇 |
2011年 | 3872篇 |
2010年 | 3122篇 |
2009年 | 3754篇 |
2008年 | 3919篇 |
2007年 | 4100篇 |
2006年 | 3705篇 |
2005年 | 3342篇 |
2004年 | 3196篇 |
2003年 | 3047篇 |
2002年 | 2694篇 |
2001年 | 2986篇 |
2000年 | 2734篇 |
1999年 | 3093篇 |
1998年 | 9499篇 |
1997年 | 6177篇 |
1996年 | 4787篇 |
1995年 | 3178篇 |
1994年 | 2802篇 |
1993年 | 2736篇 |
1992年 | 1638篇 |
1991年 | 1601篇 |
1990年 | 1520篇 |
1989年 | 1327篇 |
1988年 | 1177篇 |
1987年 | 867篇 |
1986年 | 890篇 |
1985年 | 920篇 |
1984年 | 810篇 |
1983年 | 700篇 |
1982年 | 702篇 |
1981年 | 685篇 |
1980年 | 569篇 |
1979年 | 483篇 |
1978年 | 418篇 |
1977年 | 535篇 |
1976年 | 964篇 |
1975年 | 300篇 |
1974年 | 277篇 |
1973年 | 259篇 |
排序方式: 共有10000条查询结果,搜索用时 46 毫秒
11.
12.
13.
14.
Bochkareva N. I. Ivanov A. M. Klochkov A. V. Kogotkov V. S. Rebane Yu. T. Virko M. V. Shreter Y. G. 《Semiconductors》2015,49(6):827-835
Semiconductors - It is shown that the emission efficiency and the 1/f noise level in light-emitting diodes with InGaN/GaN quantum wells correlate with how the differential resistance of a diode... 相似文献
15.
Naoki Yokokawa Yutaro Masuda Eri Amasawa Hirokazu Sugiyama Masahiko Hirao 《Packaging Technology and Science》2020,33(11):445-459
This study presents systematic packaging design tools integrating functional and environmental consequences on product life cycle. To design packaging for sustainability, the trade-offs between functional and environmental aspects of packaging throughout the product life cycle should be considered. However, it is difficult for packaging designers to understand the overall trade-offs because the extent of the design consequences on the entire life cycle of packaging and its contents is unclear. We developed two tools for packaging design: the Life Cycle Association Matrix (LCAM) and the Function Network Diagram (FND). The following three steps, based on literature reviews and interviews with industrial experts, were applied. Firstly, we listed the product functions and design variables related to the functions as the attributes allocated to the product life cycle. Secondly, the attributes were connected appropriately based on causal relationships. Lastly, we identified the factors to support decision making in the packaging design procedure. As a result, the LCAM depicts the design consequences on the life cycle, and the FND determines the stakeholders affected by the design consequences. Two case studies were demonstrated to analyze the trade-offs by using our tools. In the case studies, a liquid laundry detergent bottle and a milk carton were redesigned. The tools identified the design consequences and stakeholders affected by the redesign of the usability and protective function for the detergent and milk cases, respectively. The results showed the significance of understanding the design consequences on the product life cycle by integrating the functional and environmental aspects. 相似文献
16.
17.
18.
Ming-Puu Chen Asta Y. Z. Lord Yu-Yao Cheng Ku-Chou Tai Wen-Harn Pan 《Journal of Computer Assisted Learning》2020,36(3):383-396
Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies. 相似文献
19.
Machine Learning - We consider the problem of learning a binary classifier from only positive and unlabeled observations (called PU learning). Recent studies in PU learning have shown superior... 相似文献
20.
Dr. Jiayao Y. Wang Dr. Jiaqi Q. Li Prof. Dr. Yumei M. Xiao Prof. Dr. Bin Fu Prof. Dr. Zhaohai H. Qin 《ChemMedChem》2020,15(5):404-410
Mitochondrial oxidative damage and dysfunction contribute to a wide range of human diseases. Considering the limitation of conventional antioxidants and that mitochondria are the main source of reactive oxygen species (ROS) which induce oxidative damage, mitochondria-targeted antioxidants which can selectively block mitochondrial oxidative damage and prevent various types of cell death have been widely developed. As a lipophilic cation, triphenylphosphonium (TPP) has been commonly used in designing mitochondria-targeted antioxidants. Conjugated with the TPP moiety, antioxidants can achieve more than 1000-fold higher mitochondrial concentration depending on cell membrane potentials and mitochondrial membrane potentials. Herein we discuss the deficiencies of conventional antioxidants and the advantages of mitochondrial targeting, and review various types of TPP-based mitochondria-targeted antioxidants. These provide theoretical and background support for the design of new anti-oxidant. 相似文献