全文获取类型
收费全文 | 4620篇 |
免费 | 319篇 |
国内免费 | 24篇 |
专业分类
电工技术 | 42篇 |
综合类 | 8篇 |
化学工业 | 1487篇 |
金属工艺 | 128篇 |
机械仪表 | 134篇 |
建筑科学 | 137篇 |
矿业工程 | 2篇 |
能源动力 | 340篇 |
轻工业 | 566篇 |
水利工程 | 44篇 |
石油天然气 | 39篇 |
武器工业 | 1篇 |
无线电 | 514篇 |
一般工业技术 | 809篇 |
冶金工业 | 146篇 |
原子能技术 | 35篇 |
自动化技术 | 531篇 |
出版年
2024年 | 15篇 |
2023年 | 76篇 |
2022年 | 164篇 |
2021年 | 284篇 |
2020年 | 196篇 |
2019年 | 229篇 |
2018年 | 242篇 |
2017年 | 238篇 |
2016年 | 248篇 |
2015年 | 184篇 |
2014年 | 274篇 |
2013年 | 463篇 |
2012年 | 295篇 |
2011年 | 332篇 |
2010年 | 221篇 |
2009年 | 213篇 |
2008年 | 151篇 |
2007年 | 120篇 |
2006年 | 115篇 |
2005年 | 54篇 |
2004年 | 72篇 |
2003年 | 58篇 |
2002年 | 59篇 |
2001年 | 58篇 |
2000年 | 58篇 |
1999年 | 47篇 |
1998年 | 56篇 |
1997年 | 50篇 |
1996年 | 39篇 |
1995年 | 30篇 |
1994年 | 23篇 |
1993年 | 18篇 |
1992年 | 24篇 |
1991年 | 19篇 |
1990年 | 15篇 |
1989年 | 12篇 |
1988年 | 19篇 |
1987年 | 13篇 |
1986年 | 17篇 |
1985年 | 20篇 |
1984年 | 14篇 |
1983年 | 15篇 |
1982年 | 12篇 |
1981年 | 12篇 |
1980年 | 14篇 |
1979年 | 9篇 |
1976年 | 14篇 |
1974年 | 7篇 |
1973年 | 8篇 |
1972年 | 9篇 |
排序方式: 共有4963条查询结果,搜索用时 15 毫秒
1.
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)
2.
3.
4.
5.
Mohamed A.El-Nemr Ibrahim M.A.Ismail Nabil M.Abdelmonem Ahmed El Nemr Safaa Ragab 《中国化学工程学报》2021,36(8):199-222
Watermelon peel residues were used to produce a new biochar by dehydration method. The new biochar has undergone two methods of chemical modification and the effect of this chemical modification on its ability to adsorb Cr(VI) ions from aqueous solution has been investigated. Three biochars, Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, were made from watermelon peel via dehydration with 50% sulfuric acid to give Melon-B followed by oxidation with ozone and amination using ammonium hydroxide to give Melon-BO-NH_2 or Triethylenetetramine(TETA) to give Melon-BO-TETA. The prepared biochars were characterized by BET, BJH,SEM, FT-IR, TGA, DSC and EDAX analyses. The highest removal percentage of Cr(VI) ions was 69% for Melon-B,98% for Melon-BO-NH_2 and 99% for Melon-BO-TETA biochars of 100 mg·L~(-1) Cr(VI) ions initial concentration and 1.0 g·L~(-1) adsorbents dose. The unmodified biochar(Melon-B) and modified biochars(Melon-BO-NH_2 and Melon-BO-TETA) had maximum adsorption capacities(Qm) of 72.46, 123.46, and 333.33 mg·g~(-1), respectively.The amination of biochar reduced the pore size of modified biochar, whereas the surface area was enhanced.The obtained data of isotherm models were tested using different error function equations. The Freundlich,Tempkin and Langmuir isotherm models were best fitted to the experimental data of Melon-B, Melon-BO-NH_2 and Melon-BO-TETA, respectively. The adsorption rate was primarily controlled by pseudo-second–order rate model. Conclusively, the functional groups interactions are important for adsorption mechanisms and expected to control the adsorption process. The adsorption for the Melon-B, Melon-BO-NH_2 and Melon-BO-TETA could be explained for acid–base interaction and hydrogen bonding interaction. 相似文献
6.
Nur Lina Rashidah Mohd Rashid Abdullah Abdul Samat Abdul Azim Jais Mahendra Rao Somalu Andanastuti Muchtar Nurul Akidah Baharuddin Wan Nor Roslam Wan Isahak 《Ceramics International》2019,45(6):6605-6615
The performance of low-to-intermediate temperature (400–800?°C) solid oxide fuel cells (SOFCs) depends on the properties of electrolyte used. SOFC performance can be enhanced by replacing electrolyte materials from conventional oxide ion (O2-) conductors with proton (H+) conductors because H+ conductors have higher ionic conductivity and theoretical electrical efficiency than O2- conductors within the target temperature range. Electrolytes based on cerate and/or zirconate have been proposed as potential H+ conductors. Cerate-based electrolytes have the highest H+ conductivity, but they are chemically and thermally unstable during redox cycles, whereas zirconate-based electrolytes exhibit the opposite properties. Thus, tailoring the properties of cerate and/or zirconate electrolytes by doping with rare-earth metals has become a main concern for many researchers to further improve the ionic conductivity and stability of electrolytes. This article provides an overview on the properties of four types of cerate and/or zirconate electrolytes including cerate-based, zirconate-based, single-doped cerate–zirconate and hybrid-doped cerate–zirconate. The properties of the proton electrolytes such as ionic conductivity, chemical stability and sinterability are also systematically discussed. This review further provides a summary of the performance of SOFCs operated with cerate and/or zirconate proton conductors and the actual potential of these materials as alternative electrolytes for proton-conducting SOFC application. 相似文献
7.
8.
Khalid Tauqeer Khan Abdul Nasir Ali Mazhar Adeel Adil ur Rehman Khan Atta Shuja Junaid 《Multimedia Tools and Applications》2019,78(17):24595-24615
Multimedia Tools and Applications - The world is facing many problems including that of traffic congestion. To highlight the issue of traffic congestion worldwide specially in urban areas and to... 相似文献
9.
10.
Abdul Rahman Mohtasebzadeh Longfei Ye Thomas M. Crawford 《International journal of molecular sciences》2015,16(8):19769-19779
We study magnetic-field directed self-assembly of magnetic nanoparticles onto templates recorded on perpendicular magnetic recording media, and quantify feature width and height as a function of assembly time. Feature widths are determined from Scanning Electron Microscope (SEM) images, while heights are obtained with Atomic Force Microscopy (AFM). For short assembly times, widths were ~150 nm, while heights were ~14 nm, a single nanoparticle on average with a 10:1 aspect ratio. For long assembly times, widths approach 550 nm, while the average height grows to 3 nanoparticles, ~35 nm; a 16:1 aspect ratio. We perform magnetometry on these self-assembled structures and observe the slope of the magnetic moment vs. field curve increases with time. This increase suggests magnetic nanoparticle interactions evolve from nanoparticle–nanoparticle interactions to cluster–cluster interactions as opposed to feature–feature interactions. We suggest the aspect ratio increase occurs because the magnetic field gradients are strongest near the transitions between recorded regions in perpendicular media. If these gradients can be optimized for assembly, strong potential exists for using perpendicular recording templates to assemble complex heterogeneous materials. 相似文献