全文获取类型
收费全文 | 62394篇 |
免费 | 5908篇 |
国内免费 | 3282篇 |
专业分类
电工技术 | 4207篇 |
技术理论 | 5篇 |
综合类 | 4542篇 |
化学工业 | 10177篇 |
金属工艺 | 3614篇 |
机械仪表 | 4171篇 |
建筑科学 | 4802篇 |
矿业工程 | 1395篇 |
能源动力 | 1802篇 |
轻工业 | 4603篇 |
水利工程 | 1274篇 |
石油天然气 | 2814篇 |
武器工业 | 515篇 |
无线电 | 7920篇 |
一般工业技术 | 8108篇 |
冶金工业 | 2437篇 |
原子能技术 | 788篇 |
自动化技术 | 8410篇 |
出版年
2024年 | 209篇 |
2023年 | 924篇 |
2022年 | 1705篇 |
2021年 | 2586篇 |
2020年 | 1852篇 |
2019年 | 1608篇 |
2018年 | 1685篇 |
2017年 | 1893篇 |
2016年 | 1910篇 |
2015年 | 2610篇 |
2014年 | 3151篇 |
2013年 | 3813篇 |
2012年 | 4081篇 |
2011年 | 4543篇 |
2010年 | 4084篇 |
2009年 | 3721篇 |
2008年 | 3760篇 |
2007年 | 3462篇 |
2006年 | 3458篇 |
2005年 | 2974篇 |
2004年 | 2185篇 |
2003年 | 2076篇 |
2002年 | 2322篇 |
2001年 | 1948篇 |
2000年 | 1589篇 |
1999年 | 1381篇 |
1998年 | 1092篇 |
1997年 | 914篇 |
1996年 | 838篇 |
1995年 | 726篇 |
1994年 | 615篇 |
1993年 | 459篇 |
1992年 | 334篇 |
1991年 | 265篇 |
1990年 | 197篇 |
1989年 | 156篇 |
1988年 | 131篇 |
1987年 | 76篇 |
1986年 | 59篇 |
1985年 | 43篇 |
1984年 | 31篇 |
1983年 | 17篇 |
1982年 | 23篇 |
1981年 | 21篇 |
1980年 | 18篇 |
1979年 | 11篇 |
1976年 | 8篇 |
1975年 | 7篇 |
1959年 | 6篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
采用直流磁控溅射和后退火氧化工艺在p型GaAs单晶衬底上成功制备了n-VO_2/pGaAs异质结,研究了不同退火温度和退火时间对VO_2/GaAs异质结性能的影响,并分析其结晶取向、化学组分、膜层质量以及光电特性。结果表明,在退火时间2 h和退火温度693 K下能得到相变性能最佳的VO_2薄膜,相变前后电阻变化约2个数量级。VO_2/GaAs异质结在308 K、318 K和328 K温度下具有较好的整流特性,对应温度下的阈值跳变电压分别为6.9 V、6.6 V和6.2 V,该结果为基于VO_2相变特性的异质结光电器件的设计与应用提供了可行性。 相似文献
2.
3.
Hong Sae Jin Park Nam Il Hwang Dae Keun Yi Tae Gyu Eum Hyang Lan 《Food science and biotechnology》2022,31(6):669-679
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex... 相似文献
4.
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
5.
Jia Dai Xiang Cheng Xiaofeng Li Zhisheng Wang Yufeng Wang Jing Zheng Jun Liu Jiawei Chen Changjin Wu Jinyao Tang 《Advanced functional materials》2021,31(48):2106204
Synthetic active matters are perfect model systems for non-equilibrium thermodynamics and of great potential for novel biomedical and environmental applications. However, most applications are limited by the complicated and low-yield preparation, while a scalable synthesis for highly functional microswimmers is highly desired. In this paper, an all-solution synthesis method is developed where the gold-loaded titania-silica nanotree can be produced as a multi-functional self-propulsion microswimmer. By applying light, heat, and electric field, the Janus nanotree demonstrated multi-mode self-propulsion, including photochemical self-electrophoresis by UV and visible light radiation, thermophoresis by near-infrared light radiation, and induced-charge electrophoresis under AC electric field. Due to the scalable synthesis, the Janus nanotree is further demonstrated as a high-efficiency, low-cost, active adsorbent for water decontamination, where the toxic mercury ions can be reclaimed with enhanced efficiency. 相似文献
6.
Xiao-juan Li Yi-xiang Xu Xiang Li Zhi-jiang Jin Jin-yuan Qian 《International Journal of Hydrogen Energy》2021,46(7):5537-5547
Ambient condition, especially the wind condition, is an important factor to determine the behavior of hydrogen diffusion during hydrogen release. However, only few studies aim at the quantitative study of the hydrogen diffusion in a wind-exist condition. And very little researches aiming at the variable wind condition have been done. In this paper, the hydrogen diffusion in different wind condition which including the constant wind velocity and the variable wind velocity is investigated numerically. When considering the variable wind velocity, the UDF (user defined function) is compiled. Characteristics of the FGC (flammable gas cloud) and the HMF (hydrogen mass fraction) are analyzed in different wind condition and comparisons are made with the no-wind condition. Results indicate that the constant wind velocity and the variable wind velocity have totally different effect for the determination of hydrogen diffusion. Comparisons between the constant wind velocity and the variable wind velocity indicate that the variable wind velocity may cause a more dangerous situation since there has a larger FGC volume. More importantly, the wind condition has a non-negligible effect when considering the HMF along the radial direction. As the wind velocity increases, the distribution of the HMF along the radial direction is not Gaussian anymore when the distance between the release hole and the observation line exceeds to a critical value. This work can be a supplement of the research on the hydrogen release and diffusion and a valuable reference for the researchers. 相似文献
7.
随着经济的发展,消防救援队伍承担的任务越来越繁重.重大灾害事故的发生,对消防战勤保障方面提出了更高的要求.文章主要从消防战勤保障的主要任务职能、消防战勤的任务分类以及消防战勤保障体系建设存在的问题与建议等几个方面进行了详细的阐述,以期消防战勤保障得到更好的发展. 相似文献
8.
5G-oriented Virtual Augmented Reality Scene Construction and Business Information Flow Demonstration
Mobile Networks and Applications - Aiming at the problems of large data volume, long calculation time, and information feedback speed in traditional virtual augmented reality-based scenes, this... 相似文献
9.
10.
Bokyung Kim Young Ho Ko Massimiliano Runfola Simona Rapposelli Gabriella Ortore Grazia Chiellini Jin Hae Kim 《International journal of molecular sciences》2021,22(7)
Thyromimetics, whose physicochemical characteristics are analog to thyroid hormones (THs) and their derivatives, are promising candidates as novel therapeutics for neurodegenerative and metabolic pathologies. In particular, sobetirome (GC-1), one of the initial halogen-free thyromimetics, and newly synthesized IS25 and TG68, with optimized ADME-Tox profile, have recently attracted attention owing to their superior therapeutic benefits, selectivity, and enhanced permeability. Here, we further explored the functional capabilities of these thyromimetics to inhibit transthyretin (TTR) amyloidosis. TTR is a homotetrameric transporter protein for THs, yet it is also responsible for severe amyloid fibril formation, which is facilitated by tetramer dissociation into non-native monomers. By combining nuclear magnetic resonance (NMR) spectroscopy, computational simulation, and biochemical assays, we found that GC-1 and newly designed diphenyl-methane-based thyromimetics, namely IS25 and TG68, are TTR stabilizers and efficient suppressors of TTR aggregation. Based on these observations, we propose the novel potential of thyromimetics as a multi-functional therapeutic molecule for TTR-related pathologies, including neurodegenerative diseases. 相似文献