全文获取类型
收费全文 | 75309篇 |
免费 | 18326篇 |
国内免费 | 2401篇 |
专业分类
电工技术 | 3377篇 |
综合类 | 2724篇 |
化学工业 | 22767篇 |
金属工艺 | 2716篇 |
机械仪表 | 3236篇 |
建筑科学 | 4647篇 |
矿业工程 | 1117篇 |
能源动力 | 1938篇 |
轻工业 | 10078篇 |
水利工程 | 1039篇 |
石油天然气 | 2153篇 |
武器工业 | 413篇 |
无线电 | 11801篇 |
一般工业技术 | 15479篇 |
冶金工业 | 2151篇 |
原子能技术 | 441篇 |
自动化技术 | 9959篇 |
出版年
2024年 | 187篇 |
2023年 | 714篇 |
2022年 | 1359篇 |
2021年 | 2041篇 |
2020年 | 2713篇 |
2019年 | 4157篇 |
2018年 | 4179篇 |
2017年 | 4631篇 |
2016年 | 4978篇 |
2015年 | 5581篇 |
2014年 | 5934篇 |
2013年 | 7263篇 |
2012年 | 5462篇 |
2011年 | 5301篇 |
2010年 | 5322篇 |
2009年 | 5025篇 |
2008年 | 4488篇 |
2007年 | 4256篇 |
2006年 | 3883篇 |
2005年 | 3261篇 |
2004年 | 2611篇 |
2003年 | 2307篇 |
2002年 | 2167篇 |
2001年 | 1889篇 |
2000年 | 1842篇 |
1999年 | 1250篇 |
1998年 | 620篇 |
1997年 | 550篇 |
1996年 | 447篇 |
1995年 | 334篇 |
1994年 | 308篇 |
1993年 | 205篇 |
1992年 | 173篇 |
1991年 | 116篇 |
1990年 | 110篇 |
1989年 | 78篇 |
1988年 | 52篇 |
1987年 | 27篇 |
1986年 | 40篇 |
1985年 | 15篇 |
1984年 | 23篇 |
1983年 | 13篇 |
1982年 | 21篇 |
1981年 | 18篇 |
1980年 | 17篇 |
1979年 | 9篇 |
1977年 | 7篇 |
1976年 | 7篇 |
1974年 | 9篇 |
1959年 | 8篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
2.
Bijan Nasri‐Nasrabadi Akif Kaynak Shayan Seyedin Zahra Komeily‐Nia Abbas Z Kouzani 《Polymer International》2019,68(5):922-928
Recent advances in three‐dimensional (3D) printing have enabled the fabrication of interesting structures which are not achievable using traditional fabrication approaches. The 3D printing of carbon microtube composite inks allows fabrication of conductive structures for practical applications in soft robotics and tissue engineering. However, it is challenging to achieve 3D printed structures from solution‐based composite inks, which requires an additional process to solidify the ink. Here, we introduce a wet 3D printing technique which uses a coagulation bath to fabricate carbon microtube composite structures. We show that through a facile nanogrooving approach which introduces cavitation and channels on carbon microtubes, enhanced interfacial interactions with a chitosan polymer matrix are achieved. Consequently, the mechanical properties of the 3D printed composites improve when nanogrooved carbon microtubes are used, compared to untreated microtubes. We show that by carefully controlling the coagulation bath, extrusion pressure, printing distance and printed line distance, we can 3D print composite lattices which are composed of well‐defined and separated printed lines. The conductive composite 3D structures with highly customised design presented in this work provide a suitable platform for applications ranging from soft robotics to smart tissue engineering scaffolds. © 2019 Society of Chemical Industry 相似文献
3.
Changbai Long Ning Ji Li Yang Wenjie Zhou Kun Zheng Wei Ren Laijun Liu 《Journal of the European Ceramic Society》2021,41(6):3369-3378
With co-substitution of (Li0.5Sm0.5) at A site and W at B site, the electrical properties of modified Ca0.92(Li0.5Sm0.5)0.08Bi2Nb2-xWxO9 [(CLS)BN-xW, x = 0, 0.015 and 0.03] piezoceramics with ultrahigh Curie temperature (TC) of > 930 °C were enhanced dramatically. The increased resistivity induced by the co-substitution ensure them to be polarized under an enough high field. Combined with the increase of spontaneous ferroelectric polarization (PS), the significant enhancements in the piezoelectric, dielectric and ferroelectric properties can be obtained in the composition x = 0.015. Furthermore, the piezoelectric activity (d33) and bulk resistivity (ρb) of (CLS)BN-0.015 W can be further enhanced at an appropriate sintering temperature. This optimum composition sintered at 1170 °C shows ultrahigh TC of ~948 °C, d33 of ~17.3 pC/N and ρb of ~6.9 MΩ cm at 600 °C, which are comparable to those of the reported high-temperature Aurivillius piezoceramics with TC > 850 °C. 相似文献
4.
A novel CdS/CaFe2O4 (CS/CFO) heterogeneous p-n junction was created by thermal deposition of CaFe2O4 nanoparticles on CdS rods. The CS/CFO hetero-structured photocatalysts exhibited increasingly efficient visible light harvesting compared to the bare CdS. The CS/CFO composites also presented higher photocurrent and slower decay of photoluminescence, suggesting a better separation of the photo-generated electrons and holes. The photocatalytic H2 evolution quantity on the optimized CS/CFO composite from water in the presence of ethanol was up to 2200 μmol after 3-h visible light illumination, which is more than twice that of the pristine CdS. The chemical interaction between CdS and CaFe2O4 was confirmed by the shifts in the XPS peaks, which made it possible for the charge carriers to transfer across the p-n junction interface. This research highlights the importance of forming an interfacial p-n heterojunction between two semiconductors for efficient charge separation and improved photocatalytic performance. 相似文献
5.
Karolina Storesund Francine Amon Anne Steen‐Hansen Shayesteh Haghighatpanah Ida Larsson 《火与材料》2021,45(1):181-190
The aim of this exploratory study has been to investigate the fire properties and environmental aspects of different upholstery material combinations, mainly for domestic applications. An analysis of the sustainability and circularity of selected textiles, along with lifecycle assessment, is used to qualitatively evaluate materials from an environmental perspective. The cone calorimeter was the primary tool used to screen 20 different material combinations from a fire performance perspective. It was found that textile covers of conventional fibres such as wool, cotton and polyester, can be improved by blending them with fire resistant speciality fibres. A new three‐dimensional web structure has been examined as an alternative padding material, showing preliminary promising fire properties with regard to ignition time, heat release rates and smoke production. 相似文献
6.
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)
7.
ABSTRACT In this study, effect of calcium and gypsum on scheelite and fluorite was investigated using sodium oleate as collector. Micro-flotation and contact angle results showed that the adsorption of calcium could inhibit the hydrophobicity of scheelite and fluorite. Moreover, sulfate could enhance the inhibition. FT-IR results showed that calcium could be priori precipitated into calcium oleate and adsorb on mineral surface. The adsorption of calcium could increase the scheelite potential to IEP, while it showed limited effect on fluorite potential. However, the interaction of calcium on scheelite and fluorite in gypsum solution was more complex than that in calcium solution. 相似文献
8.
9.
SPEEK/cSMM membrane for simultaneous electricity generation and wastewater treatment in microbial fuel cell
下载免费PDF全文
![点击此处可从《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》网站下载免费的PDF全文](/ch/ext_images/free.gif)
10.
Efficacy of Crude and Purified Chitinases (SsChi50) Extracted from Offal Red Scorpion Fish in Biological Control of Chickpea Weevil (Callosobruchus maculatus L.)
下载免费PDF全文
![点击此处可从《Journal of Food Processing and Preservation》网站下载免费的PDF全文](/ch/ext_images/free.gif)