全文获取类型
收费全文 | 501448篇 |
免费 | 8477篇 |
国内免费 | 2978篇 |
专业分类
电工技术 | 9316篇 |
技术理论 | 4篇 |
综合类 | 1712篇 |
化学工业 | 74219篇 |
金属工艺 | 18670篇 |
机械仪表 | 15451篇 |
建筑科学 | 13323篇 |
矿业工程 | 2569篇 |
能源动力 | 13406篇 |
轻工业 | 46564篇 |
水利工程 | 5005篇 |
石油天然气 | 7708篇 |
武器工业 | 175篇 |
无线电 | 62331篇 |
一般工业技术 | 96195篇 |
冶金工业 | 90654篇 |
原子能技术 | 10222篇 |
自动化技术 | 45379篇 |
出版年
2021年 | 4310篇 |
2020年 | 3301篇 |
2019年 | 3899篇 |
2018年 | 6209篇 |
2017年 | 6341篇 |
2016年 | 6747篇 |
2015年 | 4938篇 |
2014年 | 8132篇 |
2013年 | 23084篇 |
2012年 | 13513篇 |
2011年 | 18691篇 |
2010年 | 14545篇 |
2009年 | 16447篇 |
2008年 | 17231篇 |
2007年 | 17223篇 |
2006年 | 15486篇 |
2005年 | 14188篇 |
2004年 | 13509篇 |
2003年 | 13183篇 |
2002年 | 12491篇 |
2001年 | 12757篇 |
2000年 | 11943篇 |
1999年 | 12673篇 |
1998年 | 29936篇 |
1997年 | 21198篇 |
1996年 | 16316篇 |
1995年 | 12426篇 |
1994年 | 10922篇 |
1993年 | 10795篇 |
1992年 | 7814篇 |
1991年 | 7396篇 |
1990年 | 7167篇 |
1989年 | 6921篇 |
1988年 | 6557篇 |
1987年 | 5633篇 |
1986年 | 5541篇 |
1985年 | 6441篇 |
1984年 | 5869篇 |
1983年 | 5391篇 |
1982年 | 5059篇 |
1981年 | 5085篇 |
1980年 | 4900篇 |
1979年 | 4590篇 |
1978年 | 4490篇 |
1977年 | 5052篇 |
1976年 | 6474篇 |
1975年 | 3808篇 |
1974年 | 3675篇 |
1973年 | 3753篇 |
1972年 | 3050篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
1.
Journal of Materials Science - 相似文献
2.
Wireless Personal Communications - Chronic kidney disease (CKD) is a gradual loss of kidney function over the period of time and it is irrevocable once functionality reaches the critical state.... 相似文献
3.
Xiao Zhu Chen Yanxun Jiang Hongbo Hu Zhenzhen Lui John C. S. Min Geyong Dustdar Schahram 《Wireless Networks》2022,28(7):3305-3322
Wireless Networks - Unmanned aerial vehicles (UAV) have been widely used in various fields because of their high mobility and portability. At the same time, due to the rapid development of... 相似文献
4.
5.
Muniyandi Kasipandi Jagadeesan Gayathri George Blassan P. Manoharan Ashwini Lydia Nataraj Gayathri Abrahamse Heidi Thangaraj Parimelazhagan 《Food science and biotechnology》2022,31(13):1717-1728
Food Science and Biotechnology - A rich source of nutrients, figs have a number of clinically validated benefits. This study aimed to evaluate the in vitro simulated gastrointestinal digestion, and... 相似文献
6.
Multimedia Tools and Applications - In this work, a new fuzzy logic-based algorithm is proposed for the enhancement of low light color images. A generalization of a fuzzy set known as an... 相似文献
7.
Karimi Bayan Chang Yu-Cheng Pekola Jukka P. 《Journal of Low Temperature Physics》2022,207(3-4):220-225
We discuss the temperature dependence of a common low temperature local thermometer, a tunnel junction between a superconductor and a normal metal (NIS junction). Towards the lowest temperatures its characteristics tend to saturate, which is usually attributed to selfheating effects. In this technical note, we reanalyze this saturation and show that the temperature independent subgap current of the junction alone explains in some cases the low temperature behavior quantitatively.
相似文献8.
Qian Wu Xiangmei Liu Bo Li Lei Tan Yong Han Zhaoyang Li Yanqin Liang Zhenduo Cui Shengli Zhu Shuilin Wu Yufeng Zheng 《材料科学技术学报》2021,67(8):70-79
Pathogens pose a serious challenge to environmental sanitation and a threat to public health.The frequent use of chemicals for sterilization in recent years has not only caused secondary damage to the environment but also increased pathogen resistance to drugs,which further threatens public health.To address this issue,the use of non-chemical antibacterial means has become a new trend for environmental disinfection.In this study,we developed red phosphorus nanoparticles(RPNPs),a safe and degradable photosensitive material with good photocatalytic and photothermal properties.The red phosphorus nanoparticles were prepared using a template method and ultrasonication.Under the irradiation of simulated sunlight for 20 min,the RPNPs exhibited an efficiency of 99.98%in killing Staphylococcus aureus due to their excellent photocatalytic and photothermal abilities.Transmission electron microscopy and ultraviolet–visible spectroscopy revealed that the RPNPs exhibited degradability within eight weeks.Both the RPNPs and their degradation products were nontoxic to fibroblast cells.Therefore,such RPNPs are expected to be used as a new type of low-cost,efficient,degradable,biocompatible,and eco-friendly photosensitive material for environmental disinfection. 相似文献
9.
To investigate the evolution of the structural and enhanced magnetic properties of GdMnO3 systems induced by the substitution of Mn with Cr, polycrystalline GdMn1-xCrxO3 samples were synthesized via solid-state reactions. XRD characterization shows that all GdMn1-xCrxO3 compounds with single-phase structures crystallize well and that Cr3+ ions entering the lattice sites of GdMnO3 induce structural distortion. SEM results indicate that the grain size of the synthesized samples (a few microns) decreases as the Cr substitution concentration increases. Positron annihilation lifetime spectroscopy reveals that vacancy-type defects occur in GdMn1-xCrxO3 ceramics and that the vacancy size and concentration clearly change with the Cr content. The temperature and field dependence of the magnetization curves show that Cr substitution significantly influences the magnetic ordering of the gadolinium sublattice, improving the weak ferromagnetic transition temperature and magnetization of GdMn1-xCrxO3. The enhanced magnetization of GdMn1-xCrxO3 is closely related to the vacancy defect concentration. 相似文献
10.
Seredin P. V. Radam Ali Obaid Goloshchapov D. L. Len’shin A. S. Buylov N. S. Barkov K. A. Nesterov D. N. Mizerov A. M. Timoshnev S. N. Nikitina E. V. Arsentyev I. N. Sharafidinov Sh. Kukushkin S. A. Kasatkin I. A. 《Semiconductors》2022,56(4):253-258
Semiconductors - Abstract—In our work, we carry out a structural-spectroscopic study of AlGaN/GaN epitaxial layers grown by molecular-beam epitaxy with nitrogen-plasma activation on a hybrid... 相似文献