全文获取类型
收费全文 | 8476篇 |
免费 | 728篇 |
国内免费 | 440篇 |
专业分类
电工技术 | 274篇 |
综合类 | 506篇 |
化学工业 | 3030篇 |
金属工艺 | 1294篇 |
机械仪表 | 258篇 |
建筑科学 | 92篇 |
矿业工程 | 417篇 |
能源动力 | 196篇 |
轻工业 | 232篇 |
水利工程 | 18篇 |
石油天然气 | 426篇 |
武器工业 | 62篇 |
无线电 | 437篇 |
一般工业技术 | 1358篇 |
冶金工业 | 925篇 |
原子能技术 | 59篇 |
自动化技术 | 60篇 |
出版年
2024年 | 15篇 |
2023年 | 97篇 |
2022年 | 145篇 |
2021年 | 179篇 |
2020年 | 201篇 |
2019年 | 168篇 |
2018年 | 190篇 |
2017年 | 249篇 |
2016年 | 242篇 |
2015年 | 254篇 |
2014年 | 292篇 |
2013年 | 434篇 |
2012年 | 473篇 |
2011年 | 492篇 |
2010年 | 400篇 |
2009年 | 430篇 |
2008年 | 417篇 |
2007年 | 637篇 |
2006年 | 689篇 |
2005年 | 672篇 |
2004年 | 530篇 |
2003年 | 454篇 |
2002年 | 388篇 |
2001年 | 329篇 |
2000年 | 249篇 |
1999年 | 226篇 |
1998年 | 148篇 |
1997年 | 120篇 |
1996年 | 104篇 |
1995年 | 86篇 |
1994年 | 66篇 |
1993年 | 55篇 |
1992年 | 45篇 |
1991年 | 37篇 |
1990年 | 28篇 |
1989年 | 23篇 |
1988年 | 9篇 |
1987年 | 6篇 |
1986年 | 10篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 8篇 |
1982年 | 5篇 |
1981年 | 6篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 3篇 |
1975年 | 4篇 |
1951年 | 1篇 |
排序方式: 共有9644条查询结果,搜索用时 31 毫秒
31.
《International Journal of Hydrogen Energy》2022,47(90):38124-38133
The construction of a bifunctional electrocatalyst with excellent performance and low cost plays a key role in the application prospect of renewable energy. Herein, nickel sulfide/CoFe layered double hydroxide heterostructures on nickel foam (NiS/LDH/NF) have been constructed by using hydrothermal and electro-deposition methods. The amorphous nickel sulfide is deposited on the surface of crystalline LDH mesh-like nanosheets to form a hierarchical flower-like structure. The deposition of amorphous NiS can control the morphology and modulate the electronic structure of NiS/LDH/NF. The obtained NiS/LDH/NF is employed as a bifunctional catalyst for overall water splitting, which can achieve a current density of 10 mA cm?2 at a low voltage of 1.51 V in 1 M KOH. The results show that the high electrocatalytic activity is ascribed to the formation of amorphous NiS/crystalline LDH heterostructure with abundant surface defects and active sites. The synthetic strategy holds a great promise for accelerating the development of hydrogen energy by highly efficient electrocatalytic production of hydrogen. 相似文献
32.
镀镍层对手汗渍非常敏感,容易形成汗渍性指纹腐蚀。经过试验研制了镀镍层专用的水性LP-1068C和溶剂型SP-2068C防汗渍性指纹的电接触润滑保护剂。其作用是防止钢铁和铝基体腐蚀,保护镀层不失光泽,并能充当镀镍后脱水材料,同时保持和保护镀镍层固有的电气性能。试验表明:只有使用具有协同效应的保护材料,才能起到防汗渍性指纹的保护作用。 相似文献
33.
34.
35.
Microwave irradiated and thermally heated olive stone activated carbon for nickel adsorption from synthetic wastewater: A comparative study 下载免费PDF全文
Tamer M. Alslaibi Ismail Abustan Mohd Azmier Ahmad Ahmad Abu Foul 《American Institute of Chemical Engineers》2014,60(1):237-250
In attempt to compare the removal efficiency and yield of the activated carbon prepared using the conventional and microwave‐assisted heating is the focus of this work. Toward this olive stone (a biomass precursor) is activated using the popular activating agent potassium hydroxide. The process optimization exercise is carried out by using the standard full factorial statistical design of experiments (response surface methodology). The activated carbons prepared under the optimized conditions are compared based on the adsorption capacity and yield. The adsorption capacity was found higher using microwave heating as compared with conventional heating. The microwave heating requires significantly lesser holding time as compared to conventional heating method to produce activated carbon of comparable quality, with higher yield. The BET surface area of carbon using microwave heating is significantly higher than the conventional heating. Although the mesopore surface area of carbon is not vary significantly, the activation time, power, and nitrogen gas consumption are significantly lower than the conventional heating rendering that the activation process via microwave is more economical than that via conventional heating. The adsorption isotherm data fitted the Langmuir isotherm well and the monolayer adsorption capacity was found to be 12.0 and 8.42 mg/g for microwave and thermally heated activated carbon, respectively. Regeneration studies showed that microwave‐irradiated and thermally heated olive stone could be used several times by desorption with an HCl reagent. Both carbons can be used for the efficient removal of Ni2+ (>99%) from contaminated wastewater. © 2013 American Institute of Chemical Engineers AIChE J, 60: 237–250, 2014 相似文献
36.
37.
以氯氧化锆、硝酸铈、硝酸铝为原料,按n(Ce)∶n(Zr)=0.7∶0.3的比例,采用化学共沉淀法与有机物共沸蒸馏法,将CeO2、ZrO2分散到γ-Al2O3表面上使其形成Ce0.7Zr0.3O2/γ-Al23固溶体。用XRD考察纳米固溶体在不同温度下焙烧后的相结构。结果表明:Ce0.7Zr0.3O2/γ-Al2O3纳米固溶体为立方晶型,且随着焙烧温度的升高,样品的衍射峰依次变强,峰宽变窄。 相似文献
38.
39.
运用微波消解样品预处理技术,对训练集光谱测试数据进行小波压缩,然后用最小二乘支持向量机建立数学模型,并用检验集光谱数据考察模型的优劣,表明小波压缩—支持向量机建立的数学模型泛化能力好。试验表明,用建立的方法,测定重油中的铁、镍和钒,使测试时间由2 d缩短为5 h,与原子吸收的测试结果一致。 相似文献
40.