全文获取类型
收费全文 | 60997篇 |
免费 | 6530篇 |
国内免费 | 3443篇 |
专业分类
电工技术 | 4590篇 |
综合类 | 4831篇 |
化学工业 | 14067篇 |
金属工艺 | 7738篇 |
机械仪表 | 3134篇 |
建筑科学 | 2890篇 |
矿业工程 | 2736篇 |
能源动力 | 892篇 |
轻工业 | 5940篇 |
水利工程 | 469篇 |
石油天然气 | 3175篇 |
武器工业 | 775篇 |
无线电 | 3255篇 |
一般工业技术 | 9442篇 |
冶金工业 | 4083篇 |
原子能技术 | 582篇 |
自动化技术 | 2371篇 |
出版年
2024年 | 138篇 |
2023年 | 912篇 |
2022年 | 1689篇 |
2021年 | 2060篇 |
2020年 | 1916篇 |
2019年 | 1728篇 |
2018年 | 1809篇 |
2017年 | 2360篇 |
2016年 | 2483篇 |
2015年 | 2646篇 |
2014年 | 3241篇 |
2013年 | 3409篇 |
2012年 | 4158篇 |
2011年 | 4604篇 |
2010年 | 3361篇 |
2009年 | 3568篇 |
2008年 | 2965篇 |
2007年 | 4133篇 |
2006年 | 3782篇 |
2005年 | 3328篇 |
2004年 | 2741篇 |
2003年 | 2476篇 |
2002年 | 2032篇 |
2001年 | 1647篇 |
2000年 | 1413篇 |
1999年 | 1224篇 |
1998年 | 1020篇 |
1997年 | 826篇 |
1996年 | 743篇 |
1995年 | 580篇 |
1994年 | 523篇 |
1993年 | 355篇 |
1992年 | 309篇 |
1991年 | 196篇 |
1990年 | 118篇 |
1989年 | 123篇 |
1988年 | 72篇 |
1987年 | 52篇 |
1986年 | 35篇 |
1985年 | 32篇 |
1984年 | 40篇 |
1983年 | 29篇 |
1982年 | 39篇 |
1981年 | 13篇 |
1980年 | 11篇 |
1979年 | 8篇 |
1975年 | 3篇 |
1974年 | 3篇 |
1959年 | 7篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
31.
《Ceramics International》2021,47(22):31713-31723
Continuous carbon-fibre-reinforced Cs-geopolymer composite (Cf/CsGP) were prepared, and its in-situ conversion was investigated during high-temperature treatments. The effect of treatment temperature on the thermal evolution process and mechanical properties of the resulting products were systematically evaluated. The results indicated that the crystallization temperature of Cf/CsGP composite was considerably delayed because the amorphous structure of carbon fibres was not conducive as a nucleation substrate for pollucite derived from the CsGP matrix. Moreover, the integrity of the corresponding resulting products derived from the Cf/CsGP composite were damaged due to thermal shrinkage that occurred during the high-temperature treatment process. When treatment temperature was ≤1200oC, the mechanical properties of the corresponding products exhibited an upward trend, which was ascribed to the improvement of the densification degree of the resulting composite and well interface-bonding state between carbon fibres and pollucite. However, the mechanical properties of the resulting composites decreased with the treatment temperature continued increased from 1200 to 1400oC. This phenomenon was attributed to the impairment of fibre properties caused by interfacial reactions. 相似文献
32.
针对某酸轧机组检查站穿带困难、检查效率低、产生废品多、故障率高的问题,开发了一种离线式带钢双面检查站。该检查站新增了带钢翻转装置,将在入口分切剪处完成定尺剪切的带钢试样由两侧压板夹紧,中间可升降皮带机落下,翻转装置将带钢试样张紧,并翻转90°或者180°,实现带钢的双面检查。皮带机两侧布置有可升降、可横移的活动操作平台,检测人员站在平台上对带钢进行打磨检查,可同时对带钢上下表面进行检测。由于缩短了带钢的传输距离,有效减少了其他擦划伤的影响,提高了带钢表面质量检测准确性。 相似文献
33.
34.
35.
36.
Xiaojin Li Quanxin Yang Hongliang Liu Yingying Ren Xuping Wang Pengfei Wu 《Ceramics International》2021,47(9):11989-11992
We observe enhancements of both conductive and dielectric properties under UV illumination by using a ferroelectric absorber, potassium tantalate niobate (KTa1-xNbxO3, KTN). The UV-generated electron-hole pairs weaken the intrinsic ferroelectric polarization while enhance the conductive property. The UV-induced heat effect causes the enhancement of the dielectric property. The results are further confirmed by the maximal rectification ratio which shows an opposite trend between the direct heating process and the UV illumination. Our results are useful for better understanding of ferroelectric properties under UV illumination and the development of new optoelectronic devices. 相似文献
37.
This study aimed to prepare an efficient, cost-effective, and separable magnetic zeolite/chitosan composite (MZFA/CS) adsorbent from solid waste to deal with the water pollution of Cr(VI). The MZFA/CS was characterized by X-ray fluorescence (XRF), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), and vibrating sample magnetometer (VSM) techniques. Then, the effect of pH, temperature, initial concentration of Cr(VI) ions, and contact time was considered in the study. For a sorbent dose of 0.1 g in 50 mL of a Cr(VI) solution, at a contact time of 30 min, temperature of 30°C, and a pH of 3, an adsorption capacity (qe) of 16.96 mg g−1 was achieved. Adsorption kinetics and isotherm data obtained for all adsorption systems were well-fitted by pseudo-second-order and Langmuir models, respectively. The thermodynamic study suggested that the adsorption process is spontaneous and endothermic in nature. In summary, the adsorbent with better separability (Ms = 16.83 emu g−1) and adsorbability was successfully fabricated. 相似文献
38.
综述了近几年国内外改性聚乳酸(PLA)发泡技术的研究进展,针对PLA在发泡方面熔体强度和结晶性能的不足,介绍了通过加入扩链剂、交联剂、成核剂、纤维和其他聚合物等物质来改善PLA发泡性能的方法、效果和机理;最后,对改性聚乳酸发泡技术的未来发展进行了展望。 相似文献
39.
40.
To improve the hydrophobicity of bagasse hemicellulose-based films, glutaraldehyde was applied when preparing films of original and cationic bagasse hemicellulose with the addition of polyvinyl alcohol and sorbitol. The results showed that the cationic modification could increase the hydrophobicity of the hemicellulose-based film, and the hydrophobicity of hemicellulose-based films crosslinked with glutaraldehyde also increased. However, cationic modification of hemicellulose decreased the stress of the hemicellulose-based film. While crosslinking with glutaraldehyde increased the stress of both the original and cationic hemicellulose-based films. Macrophotography indicated that the film formability of the original hemicellulose was better than that of cationic hemicellulose. Through SEM observation, the degree of bonding of different components of the films was found to be increased due to crosslinking with glutaraldehyde. The crosslinking reaction between glutaraldehyde and hemicellulose was further confirmed by FT-IR spectroscopy. 相似文献