全文获取类型
收费全文 | 332157篇 |
免费 | 25162篇 |
国内免费 | 12532篇 |
专业分类
电工技术 | 17930篇 |
技术理论 | 56篇 |
综合类 | 19726篇 |
化学工业 | 56594篇 |
金属工艺 | 18550篇 |
机械仪表 | 21200篇 |
建筑科学 | 25732篇 |
矿业工程 | 10968篇 |
能源动力 | 9772篇 |
轻工业 | 18656篇 |
水利工程 | 5257篇 |
石油天然气 | 22990篇 |
武器工业 | 2602篇 |
无线电 | 36655篇 |
一般工业技术 | 39802篇 |
冶金工业 | 18397篇 |
原子能技术 | 3215篇 |
自动化技术 | 41749篇 |
出版年
2024年 | 1288篇 |
2023年 | 5208篇 |
2022年 | 8872篇 |
2021年 | 12467篇 |
2020年 | 9817篇 |
2019年 | 8004篇 |
2018年 | 9202篇 |
2017年 | 10378篇 |
2016年 | 9281篇 |
2015年 | 12230篇 |
2014年 | 15880篇 |
2013年 | 19209篇 |
2012年 | 20189篇 |
2011年 | 22474篇 |
2010年 | 19234篇 |
2009年 | 18364篇 |
2008年 | 18024篇 |
2007年 | 17427篇 |
2006年 | 18304篇 |
2005年 | 16158篇 |
2004年 | 10366篇 |
2003年 | 9136篇 |
2002年 | 8139篇 |
2001年 | 7477篇 |
2000年 | 8012篇 |
1999年 | 9657篇 |
1998年 | 8155篇 |
1997年 | 6769篇 |
1996年 | 6362篇 |
1995年 | 5339篇 |
1994年 | 4378篇 |
1993年 | 3089篇 |
1992年 | 2492篇 |
1991年 | 1961篇 |
1990年 | 1504篇 |
1989年 | 1232篇 |
1988年 | 1019篇 |
1987年 | 681篇 |
1986年 | 535篇 |
1985年 | 342篇 |
1984年 | 243篇 |
1983年 | 204篇 |
1982年 | 196篇 |
1981年 | 129篇 |
1980年 | 130篇 |
1979年 | 67篇 |
1978年 | 33篇 |
1977年 | 38篇 |
1976年 | 55篇 |
1975年 | 20篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Qingna Gong Songtao Cao Yu Zhou Ruixin Wang Weizhou Jiao 《International Journal of Hydrogen Energy》2021,46(41):21442-21453
Ni2P nanoparticles and CdS nanorods were grew together on a mesoporous g-C3N4 through a facile in-situ solvothermal approach. Under visible light (λ > 400 nm), the as-prepared ternary PCN–CdS-5% Ni2P composite displays a high H2 evolution rate with 2905.86 μmol g?1 h?1, which is about 14, 18 and 279 times that of PCN–CdS, PCN–Ni2P and PCN, respectively. The enhanced photocatalytic activity is mainly attributed to the improved separation efficiency of the photocarriers by the type II PCN–CdS heterojunction and the effective extraction of photogenerated electrons by Ni2P. Meanwhile, Ni2P acts as co-catalyst to provide the photocatalytic active site for hydrogen reduction. In addition, PCN–CdS-5% Ni2P composite exerts good stability in 12-h cycles. 相似文献
92.
Chenxu Liu Shuguang Zhang Ruonan Ji Peng Wang Jin Zhang Yu Tian Yonggang Meng Yedong He 《Ceramics International》2019,45(4):4747-4755
Semiconductor particles doped Al2O3 coatings were prepared by cathode plasma electrolytic deposition in Al(NO3)3 electrolyte dispersed with SiC micro- and nano-particles (average particle sizes of 0.5–1.7?µm and 40?nm respectively). The effects of the concentrations and particle sizes of the SiC on the microstructures and tribological performances of the composite coatings were studied. In comparison with the case of dispersing with SiC microparticles, the dispersion of SiC nanoparticles in the coatings was more uniform. When the concentration of SiC nanoparticles was 5?g/L, the surface roughness of the composite coating was reduced by 63%, compared with that of the unmodified coating. Friction results demonstrated that the addition of 5?g/L SiC nanoparticles reduced the friction coefficient from 0.60 to 0.38 and decreased the wear volume under dry friction. The current density and bath voltage were measured to analyze the effects of SiC particles on the deposition process. The results showed that the SiC particles could alter the electrical behavior of the coatings during the deposition process, weaken the bombardment of the plasma, and improve the structures of the coatings. 相似文献
93.
Magnetic Resonance Materials in Physics, Biology and Medicine - To investigate the value of using diffusion-weighted imaging (DWI) and intravoxel incoherent motion DWI (IVIM-DWI) to assess the... 相似文献
94.
As a solid state joining process, ultrasonic spot welding has been proven to be a promising technique for joining copper alloys. However, challenges still remain in employing ultrasonic spot welding to join copper alloys. This article comprehensively reviews the current state of ultrasonic spot welding of copper alloys with a number of critical issues including materials flow, plastic deformation, temperature distribution, vibration, relative motion, vertical displacement, interface friction coefficient, online monitoring technique, coupled with the macrostructure and microstructure, the mechanical properties and electrical conductivity. In addition, the future trends in this field are provided. 相似文献
95.
Wang Yunfei Zheng Wang Zhang Xiaofei Shen Jinqing 《Multidimensional Systems and Signal Processing》2020,31(3):907-926
Multidimensional Systems and Signal Processing - Generalized coprime structure decomposes the interleaved subarrays in the conventional coprime array by introducing a displacement and the resulting... 相似文献
97.
结合结构支撑理论,探究节点网络结构支持力的一些性质,提出了社交网络结构中的全网支持力和被支持力的总量一致性,并进一步提出计算节点支持力的方法。谣言作为特殊信息,在支持力不同节点之间的传播特性有所不同,借鉴随机游走模型中的PageRank计算方法,对不同节点支持力的谣言传播以及传播后的辟谣状况进行了仿真模拟,结果表明支持力不同的节点对于谣言传播和辟谣影响明显。 相似文献
98.
99.
100.