全文获取类型
收费全文 | 507篇 |
免费 | 5篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 1篇 |
综合类 | 4篇 |
化学工业 | 70篇 |
金属工艺 | 5篇 |
能源动力 | 164篇 |
无线电 | 186篇 |
一般工业技术 | 97篇 |
冶金工业 | 3篇 |
自动化技术 | 2篇 |
出版年
2023年 | 20篇 |
2022年 | 33篇 |
2021年 | 45篇 |
2020年 | 33篇 |
2019年 | 21篇 |
2018年 | 16篇 |
2017年 | 21篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 13篇 |
2013年 | 21篇 |
2012年 | 23篇 |
2011年 | 26篇 |
2010年 | 10篇 |
2009年 | 24篇 |
2008年 | 21篇 |
2007年 | 10篇 |
2006年 | 21篇 |
2005年 | 11篇 |
2004年 | 9篇 |
2003年 | 7篇 |
2002年 | 5篇 |
2001年 | 11篇 |
2000年 | 12篇 |
1999年 | 12篇 |
1998年 | 14篇 |
1997年 | 16篇 |
1996年 | 10篇 |
1995年 | 14篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 5篇 |
1988年 | 3篇 |
1986年 | 1篇 |
1980年 | 1篇 |
1977年 | 2篇 |
排序方式: 共有532条查询结果,搜索用时 15 毫秒
91.
《International Journal of Hydrogen Energy》2020,45(7):4113-4121
The direct Z-scheme ZnIn2S4/LaNiO3 nanohybrid based on ZnIn2S4 nanosheets and LaNiO3 cubes was synthesized by a facile hydrothermal method. The ZnIn2S4/LaNiO3 nanohybrid showed improved photocatalytic H2 evolution and stability. The photocatalytic H2 evolution activity of ZnIn2S4/LaNiO3 nanohybrid is 3-fold enhanced than that of bare ZnIn2S4. The enhanced performance of ZnIn2S4/LaNiO3 nanohybrid is mainly ascribed to the formation of heterojunction between LaNiO3 and ZnIn2S4. The heterojunction can facilitate charge transport on the interface between LaNiO3 and ZnIn2S4 and suppress the recombination of photo-generated charge carriers over ZnIn2S4/LaNiO3 nanohybrid, which were well demonstrated by photoelectrochemical tests. Moreover, the direct Z-scheme photocatalytic reaction mechanism was proposed to elucidate the improved performance of ZnIn2S4/LaNiO3 nanohybrid photocatalyst. This study may provide some guidance on the construction of direct Z-scheme photocatalytic system for photocatalytic H2 evolution. 相似文献
92.
Xiaofang Feng Zongxue Yu Yuxi Sun Runxuan Long Mengyuan Shan Xiuhui Li Yuchuan Liu Jianghai Liu 《Ceramics International》2021,47(6):7321-7343
Two-dimensional titanium carbide (MXene) with an adjustable bandgap (0.92–1.75eV), excellent structural stability, high conductivity and hydrophilicity has always been a hotspot in the field of environmental photocatalysis. However, the rapid recombination of light-excited carriers of a single photocatalytic material decreases quantum efficiency and photocatalytic performance. The modification of MXene could overcome these problems to improve photocatalytic properties. Among various improvement strategies, the composition of MXene heterostructure and Schottky junction is an effective and straightforward strategy for adjusting electronic structure and accelerating photocatalytic performance. This review aims to design typical, cost-effective heterojunctions and Schottky junctions and their progress, mechanisms, and trends in environmental organic pollutants' degradation. This review detailed the heterogeneous catalytic mechanism of MXene-based photocatalysts for the degradation of organic pollutants. It is discussed the way to improve the photocatalytic performance of MXene by constructing heterojunction and Schottky junction. The surface properties, catalyst performance and pollution management of various MXene-based catalysts were compared, and then some dilemmas and application strategies of MXene development were analyzed in depth. This review can open up ideas for new approaches and provide valuable clues for designing MXene as a cocatalyst to develop more effective photocatalysts for practical application in environmental pollution management. 相似文献
93.
《International Journal of Hydrogen Energy》2019,44(57):29964-29974
Honeycomb-like graphitic carbon nitride (H–C3N4) with unique morphology has been studied as a promising polymer photocatalyst. Herein, a novel binary metal sulfide constructed with H–C3N4 (Cd0·5Zn0·5S/H–C3N4) was prepared though the facile in situ precipitation method. The characterization data suggest that Cd0·5Zn0·5S quantum dots (QDs) are well dispersed on the macroporous structure of H–C3N4 (156 m2 g−1), which can provide higher surface area, more catalytic active sites and larger interface contact area with accelerating the migration and separation of charge carriers. By taking advantage of 0D/3D heterojunction structure, the Cd0·5Zn0·5S/H–C3N4 dramatically boosts the photocatalytic H2 evolution rate with the visible-light illumination. The Cd0·5Zn0·5S/H–C3N4-3 yields the highest photocatalytic activity of 5145 μmol h−1 g−1, which is 4.3 times as high as that of pure Cd0·5Zn0.5S. Furthermore, Cd0·5Zn0·5S/H–C3N4 composite presents high stability after four recycles. The enhanced visible-light-driven photocatalytic H2 production is attributed to the construction of n-n type heterojunction as well as the large surface area, which can inhibit the agglomeration of Cd0·5Zn0·5S nanoparticles, and efficiently transfer the photoexcited electron-hole pairs in Cd0·5Zn0.5S. Therefore, this work provides a potential way for designing advanced 0D/3D heterojunction. 相似文献
94.
95.
测量了Si/SiGe HBT在23~260℃温度范围内的Gummel图、理想因子n、不同基极电流下的发射结电压VBE、电流增益β、共发射极输出特性,以及Early电压VA的变化情况。结果表明,随电流和温度的增加,β减少,VBE随温度的变化率dVBE/dT小于同质结Si BJT。在高集电极-发射极电压和大电流下,在输出特性曲线上观察到了负微分电阻(NDR)特性。结果还显示,电流增益-Early电压积与温度的倒数(1/T)呈线性关系,这对模拟电路应用是很重要和有用的。 相似文献
96.
讨论应变层异质结价带偏移的剪裁、设计方法,研究Si/Ge应变层异质结价带偏移设计参数与应变条件的关系,基于异质结中平均键能“对齐”,得到适用于Si/Ge异质结价带偏移剪裁与设计的计算公式和图表。 相似文献
97.
研究一种新型的非晶硅PIN异质结荧光探测器的结构和制备工艺,详细讨论了探测器单元的结构优化设计和暗电流和灵敏度等特性,实验表明,采用α-SiC/α-Si异质结构,提高沉积非晶硅基薄膜的本底真空度,优化制备工艺,可制备高信噪比的非晶硅荧光探测器。 相似文献
98.
PNP和NPN高频异质结双极晶体管的设计有明显不同,这主要归因于砷化镓中电子与空穴的迁移率存在显著差别。这种差别在基区和子集电区外延层的设计中体现得尤为明显。文中详细讨论了PNP和NPN两种类型的异质结双极晶体管各自外延层的设计考虑。 相似文献
99.
H.-Y. He 《Particulate Science and Technology》2017,35(4):410-417
Interface-induced effects and large specific area of heteronanostructures are attracting much attention due to applications in photocatalysis. In this work, ultrafine bismuth sulfide (Bi2S3) nanocrystalline-modified Fe-doped TiO2 nanotubes (NTs) were fabricated with facile methods. The effect of the ratio of Bi2S3 to the Fe-doped TiO2 NTs on the microstructural, optical, and photocatalytic properties of the NTs and hybrids was studied. The NTs showed an actual Fe content of ~ 2.93 at.%. The optical bandgap of the NTs and hybrids was ~2.90 eV and ~2.46–2.88 eV, respectively, and decreased with increasing Bi2S3/NTs ratio. The specific surface area of the NTs was ~333 m2 · g?1; whereas the hybrids showed obviously larger specific surface area of ~ 527–689 m2 · g?1 than the NTs because of well-controlled formation process of Bi2S3 nanoparticles. The sunlight-excited degradation experiments of dyes in the water indicated that the photocatalytic activity of the hybrids was higher than that of the NTs and increased with increasing Bi2S3/NTs ratio. Moreover, the degradation rates of two dyes at different initial pH values were very different. The high photocatalytic activity of the hybrids was mainly ascribed to the narrow bandgap, large specific surface area, and effective heterojunction. 相似文献
100.