全文获取类型
收费全文 | 4425篇 |
免费 | 471篇 |
国内免费 | 565篇 |
专业分类
电工技术 | 158篇 |
综合类 | 244篇 |
化学工业 | 938篇 |
金属工艺 | 1395篇 |
机械仪表 | 147篇 |
建筑科学 | 18篇 |
矿业工程 | 46篇 |
能源动力 | 153篇 |
轻工业 | 55篇 |
水利工程 | 2篇 |
石油天然气 | 57篇 |
武器工业 | 46篇 |
无线电 | 543篇 |
一般工业技术 | 1281篇 |
冶金工业 | 250篇 |
原子能技术 | 33篇 |
自动化技术 | 95篇 |
出版年
2024年 | 12篇 |
2023年 | 93篇 |
2022年 | 104篇 |
2021年 | 147篇 |
2020年 | 144篇 |
2019年 | 153篇 |
2018年 | 153篇 |
2017年 | 182篇 |
2016年 | 142篇 |
2015年 | 169篇 |
2014年 | 217篇 |
2013年 | 219篇 |
2012年 | 272篇 |
2011年 | 319篇 |
2010年 | 233篇 |
2009年 | 263篇 |
2008年 | 237篇 |
2007年 | 295篇 |
2006年 | 302篇 |
2005年 | 226篇 |
2004年 | 229篇 |
2003年 | 219篇 |
2002年 | 170篇 |
2001年 | 118篇 |
2000年 | 111篇 |
1999年 | 102篇 |
1998年 | 73篇 |
1997年 | 90篇 |
1996年 | 76篇 |
1995年 | 58篇 |
1994年 | 62篇 |
1993年 | 45篇 |
1992年 | 47篇 |
1991年 | 37篇 |
1990年 | 28篇 |
1989年 | 35篇 |
1988年 | 11篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 10篇 |
1984年 | 16篇 |
1983年 | 3篇 |
1982年 | 7篇 |
1981年 | 5篇 |
1980年 | 3篇 |
1979年 | 9篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
排序方式: 共有5461条查询结果,搜索用时 78 毫秒
101.
102.
103.
Leonardo Resende Naira M. Balzaretti Altair S. Pereira Marcos A. Z. Vasconcellos Silvio Buchner 《Journal of the American Ceramic Society》2021,104(6):2552-2559
In this work, high-density lithium disilicate (LS2) vitreous systems were produced by melting and quenching under high pressure (7.7 GPa) following two distinct experimental routes. In the first case, LS2 glass was remelted at 7.7 GPa and 1600°C and, then, quenched. In the second case, a stoichiometric mixture of precursor oxides (Li2O and SiO2) was melted at 1600°C and 7.7 GPa before quenching. A reference LS2 glass sample was produced at atmospheric pressure using conventional melting and quenching procedure. The samples were characterized by X-ray diffraction, differential thermal analysis, and instrumented ultramicro hardness measurements. X-ray diffraction confirmed that all samples were amorphous and thermal analysis suggests that different glassy structures were produced depending on the route of synthesis. Hardness and elastic modulus of the glasses produced under high pressure were higher than those of the reference glass, reflecting the irreversible densification effect induced by the high-pressure processing. 相似文献
104.
This study reports a green and powerful strategy for preparing cellulose nanocrystal (CNC)/graphene oxide (GO)/natural rubber (NR) nanocomposites hosting a 3D hierarchical conductive network. Due to good dispersibility and amphiphilic nature of CNC, well dispersed CNC/GO nanohybrids were prepared. Hydrogen bonding interactions between CNC and GO greatly enhanced the stability of the CNC/GO nanohybrids. CNC/GO nanohybrids were introduced into NR latex under sonication and the mixture was cast. Self-assembled CNC/GO nanohybrids preferentially dispersed in the interstice between latex microspheres allowing the construction of a 3D hierarchical conductive network. By combining strong hydrogen bonds and 3D conductive network, both electrical conductivity and mechanical properties (tensile strength and modulus) have been significantly improved. The electrical conductivity of the nanocomposite with 4 wt% GO and 5 wt% CNC exhibited an increase of nine orders of magnitude compared to the nanocomposite with only 4 wt% GO; meanwhile, the electrical percolation threshold was 3-fold lower than for NR/GO composites. 相似文献
105.
Engineering oxygen vacancy-rich Co3O4 nanowire as high-efficiency and durable bifunctional electrocatalyst for overall alkaline water splitting
下载免费PDF全文
![点击此处可从《化工学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
A novel kind of vacancy-rich nanowire arrays were prepared by reducing rough Co3O4 nanowires with NaBH4 solution on 3D nickel foam at room temperature for overall water splitting. Co3O4/NF treated by NaBH4 for 10 min was highly active for oxygen evolution reaction (OER) and simultaneously efficient for hydrogen evolution reaction (HER) with the need of the overpotentials of 240 and 132 mV to drive 10 mA·cm-2 in alkaline media, respectively. Furthermore, the electrocatalysts as both cathode and anode in a two-electrode system presented excellent durability for over 60 h at 10 mA·cm-2, maintaining the cell voltage of merely 1.63 V. This work provides new methods and ideas for the preparation of transition metal oxide bifunctional electrocatalysts rich in oxygen vacancies. 相似文献
106.
Preparation and lithium storage properties of Mo2N quantum dots@nitrogen-doped graphene composite
下载免费PDF全文
![点击此处可从《化工学报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
WANG Lixia ZHANG Zhenhua LI Lei ZHANG Linsen FANG Hua SONG Yanhua LI Xiaofeng 《化工学报》2021,71(12):5854-5862
To improve the electrochemical lithium storage performance of molybdenum nitrides, Mo2N quantum dots@nitrogen-doped graphene oxide sponge (Mo2N-QDs@Ngs) was prepared by hydrothermal reaction, freeze-drying and calcination in H2/N2 mixture with ammonium molybdate ((NH4)Mo7O24·4H2O), hexamethylenetetramine (C6H12N4) and graphene oxide (GO) as raw materials. The effect of GO content on the electrochemical lithium storage performance was investigated. The transmission electron microscope (TEM) results show that the size of the prepared Mo2N quantum dots is about 2—5 nm, and the Mo2N quantum dots are uniformly distributed on the surface of nitrogen-doped graphene. The electrochemical test results show that when the GO content is 30%, the prepared Mo2N-QDs@Ngs-30 has the best electrochemical lithium storage performance, which has 699 mA·h·g-1 specific capacity at the current density of 0.1 A·g-1, and has 286 mA·h·g-1 specific capacity even at the current density of 2 A·g-1. 相似文献
107.
Electrocatalytic properties of Ni-S-Co coating electrode for hydrogen evolution in alkaline medium 总被引:2,自引:0,他引:2
Amorphous Ni-S-Co alloy was prepared by means of chemical electro-deposition method on the foam nickel matrix. The surface morphology and microstructure of Ni-S-Co coatings were studied usmg SEM and XRD, and the electrochemical properties were tested by electrochemical methods. The results show that the coating has amorphous structure and the particles of the surface are fine with large specific surface area. The Ni-S-Co alloy is more active with lower potential for hydrogen evolution, higher exchange current density and lower activation energy compared with Ni and Ni-S electrode. Its hydrogen evolution reaction(HER) is enhanced, the size of particles of surface decreases and the surface area increases after being activated by KOH alkaline solution. 相似文献
108.
根据分子动力学理论建立了非晶Ni64Pd16Al20的结构模型,利用Recursion方法计算了Ni64X17Al20系非晶及相应晶态的电子结构。结果表明,Ni64X16Al20合金的非晶形成能力与过渡元素局域电子态密度的双峰位置、电子得失形成的离子键及非晶与晶态合金的总结构能差有关。局域电子态密度的结果表明,A1与过渡元素间存在电子耦合一共价相互作用,合金元素使Ni64X16Al2合金非晶形成能力从强到弱的顺序是:Ir,Pt,Rh,Pd,Au,Ag,Cu;Ni64X16Al20合金中离子键的存在使其非晶形成能力增强。非晶与晶态合金的总结构能差越小的过渡元素使其形成非晶的驱动力越强,对非晶形成越有利,由此得出的规律与上述共价键的作用规律一致。 相似文献
109.
Wang Lingling Zhao Lihua Hu Wangyu Wu Lijun * Zhang Bangwei Department of Applied Physics Hunan University Changsha * Materials Research Test Center Hunan University Changsha 《中国有色金属学会会刊》1997,(2)
EFFECTOFCOMPOSITIONONPHYSICALPROPERTIESOFAMORPHOUSFeSiBALLOYS①WangLingling,ZhaoLihua,HuWangyu,WuLijun,ZhangBangweiDepartme... 相似文献
110.
1 INTRODUCTIONMetallicglassisregardedasastatethatisofdis orderunlikecrystalalloyswith periodicatomstruc ture.Soitshowsexcellentcapabilitiesofsoftmag netism ,mechanics ,corrosionresistance ,etc .How ever ,mostofamorphousalloyswereproducedbyus ingrapidsolidificationmethodssuchassplatquench ing ,meltspinning ,andsoon ,withcharacteristiccoolingratesof 10 4 10 6 K/s .Becauseamorphousal loysarepreparedwithsilk ,powderandribbon ,itisgreatlylimitedinengineeringapplication .Recently ,severalbulk… 相似文献