全文获取类型
收费全文 | 81193篇 |
免费 | 9201篇 |
国内免费 | 4876篇 |
专业分类
电工技术 | 6812篇 |
技术理论 | 8篇 |
综合类 | 6872篇 |
化学工业 | 11646篇 |
金属工艺 | 5169篇 |
机械仪表 | 5240篇 |
建筑科学 | 6486篇 |
矿业工程 | 2984篇 |
能源动力 | 2374篇 |
轻工业 | 5781篇 |
水利工程 | 2069篇 |
石油天然气 | 3974篇 |
武器工业 | 1022篇 |
无线电 | 9477篇 |
一般工业技术 | 8704篇 |
冶金工业 | 3425篇 |
原子能技术 | 1114篇 |
自动化技术 | 12113篇 |
出版年
2024年 | 463篇 |
2023年 | 1519篇 |
2022年 | 3336篇 |
2021年 | 4290篇 |
2020年 | 3251篇 |
2019年 | 2389篇 |
2018年 | 2749篇 |
2017年 | 3035篇 |
2016年 | 2724篇 |
2015年 | 3909篇 |
2014年 | 4783篇 |
2013年 | 5686篇 |
2012年 | 6412篇 |
2011年 | 6704篇 |
2010年 | 5843篇 |
2009年 | 5525篇 |
2008年 | 5367篇 |
2007年 | 5027篇 |
2006年 | 4658篇 |
2005年 | 3807篇 |
2004年 | 2686篇 |
2003年 | 1904篇 |
2002年 | 1755篇 |
2001年 | 1444篇 |
2000年 | 1277篇 |
1999年 | 1008篇 |
1998年 | 710篇 |
1997年 | 579篇 |
1996年 | 585篇 |
1995年 | 413篇 |
1994年 | 343篇 |
1993年 | 250篇 |
1992年 | 213篇 |
1991年 | 124篇 |
1990年 | 110篇 |
1989年 | 82篇 |
1988年 | 79篇 |
1987年 | 45篇 |
1986年 | 36篇 |
1985年 | 31篇 |
1984年 | 17篇 |
1983年 | 13篇 |
1982年 | 14篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 7篇 |
1976年 | 9篇 |
1975年 | 3篇 |
1959年 | 13篇 |
1951年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
21.
22.
Chuncheng Wei Zhen Liu Yun Wu Yeqing Liu Heng Zhang Peng Wang Qiyan Sun Lijuan Zhou 《Ceramics International》2021,47(13):18693-18698
Laminated Si3N4/SiCw ceramics were successfully prepared by tape casting and hot-pressing. Its mechanical properties were measured and the impact resistance was discussed. The toughness of the laminated Si3N4/SiCw ceramics was 13.5 MPa m1/2, which was almost 1.6 times that of Si3N4/SiCw composite ceramics, namely 8.5 MPa m1/2. Moreover, the indentation strength of laminated Si3N4/SiCw ceramics was not sensitive to increasing indentation loads and exhibited a rising R-curve behaviour, indicating that the laminated Si3N4/SiCw ceramics had excellent impact resistance. The improved toughness and impact resistance of laminated Si3N4/SiCw ceramics was attributed to the residual stress caused by a thermal expansion coefficient mismatch between the different layers, resulting in crack deflection and bridging of SiC whiskers in the interface layer, thus consuming a large amount of fracture work. 相似文献
23.
Nan Wu Xiaodong Li Mu Zhang Yi Ren Qi Zhu Haijun Peng Hongqiang Ru Xudong Sun 《Journal of the European Ceramic Society》2021,41(4):2898-2907
Refining ceramic microstructures to the nanometric range to minimize light scattering provides an interesting methodology for developing novel optical ceramic materials. In this work, we reported the fabrication and properties of a new nanocomposite optical ceramic of Gd2O3-MgO. The citric acid sol-gel combustion method was adopted to fabricate Gd2O3-MgO nanocomposites with fine-grain sizes, dense microstructures and homogeneous phase domains. Nanopowders with low agglomeration and improved sinterability can be obtained by elaborating Φ values. Further refining of the microstructure of the nanocomposites was achieved by elaborating the hot-pressing conditions. The sample sintered at 65 MPa and 1300 °C showed a quite high hardness value of 14.3 ± 0.2 GPa, a high transmittance of 80.3 %–84.7 % over the 3?6 μm wavelength range, due mainly to its extremely fine-grain size of Gd2O3 and MgO (93 and 78 nm, respectively) and high density. 相似文献
24.
25.
Fluorescence‐Activated Cell Sorters: Standing Surface Acoustic Wave (SSAW)‐Based Fluorescence‐Activated Cell Sorter (Small 40/2018)
下载免费PDF全文
![点击此处可从《Small (Weinheim an der Bergstrasse, Germany)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
26.
针对传统铁矿石磁化焙烧技术与装备存在焙烧产品质量差、产能低、能耗高和环境污染严重等问题,创造性提出了一种“预热-蓄热还原-再氧化”悬浮磁化焙烧新工艺。该工艺具有原料适应性广、焙烧产品质量均匀、回收率高、生产能耗低、无污染等特点,适合处理赤铁矿、褐铁矿、菱铁矿及其混合型难选铁矿石。通过多年的潜心基础研究与技术攻关,形成了非均质矿石颗粒悬浮态流动控制、蓄热式高效低温还原、铁物相精准调控与余热同步回收等一系列关键技术,建成了500kg/h复杂难选铁矿石悬浮磁化焙烧-高效分选半工业试验平台。 相似文献
27.
28.
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
30.