全文获取类型
收费全文 | 952篇 |
免费 | 71篇 |
国内免费 | 12篇 |
专业分类
电工技术 | 16篇 |
综合类 | 5篇 |
化学工业 | 242篇 |
金属工艺 | 47篇 |
机械仪表 | 36篇 |
建筑科学 | 44篇 |
矿业工程 | 1篇 |
能源动力 | 49篇 |
轻工业 | 57篇 |
水利工程 | 21篇 |
石油天然气 | 13篇 |
武器工业 | 2篇 |
无线电 | 98篇 |
一般工业技术 | 184篇 |
冶金工业 | 48篇 |
原子能技术 | 1篇 |
自动化技术 | 171篇 |
出版年
2024年 | 1篇 |
2023年 | 17篇 |
2022年 | 29篇 |
2021年 | 60篇 |
2020年 | 63篇 |
2019年 | 61篇 |
2018年 | 89篇 |
2017年 | 75篇 |
2016年 | 75篇 |
2015年 | 46篇 |
2014年 | 74篇 |
2013年 | 92篇 |
2012年 | 74篇 |
2011年 | 81篇 |
2010年 | 59篇 |
2009年 | 34篇 |
2008年 | 33篇 |
2007年 | 21篇 |
2006年 | 13篇 |
2005年 | 7篇 |
2004年 | 5篇 |
2003年 | 6篇 |
2002年 | 1篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 4篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1985年 | 4篇 |
1982年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有1035条查询结果,搜索用时 39 毫秒
31.
Seyyed Ali Shojaee Mohammad Maleki Shahraki Mohammad Ali Faghihi Sani Ali Nemati Abbas Yousefi 《Journal of Materials Science: Materials in Electronics》2010,21(6):571-577
This paper describes a solution-based technique for fabrication of varistor grade composite nanopowders. The method consists
of coating major varistor dopants on the surface of the ZnO nanoparticles. As a result, a homogenous mixture of dopants and
ZnO nanoparticles will be achieved. TEM results indicated that a composite layer of dopants with the average particle size
of 9 nm on the surface of ZnO nanoparticles has been successfully prepared. Sintering of the coated powders was performed
in temperatures as low as 850 °C and final specimens with average particle size of 900 nm and density of 98.5% were achieved.
In comparison to conventional mixing, varistors prepared from coated nanopowders exhibited superior electrical properties
and microstructure homogeneity. The improvement of electrical properties can be attributed to small grain size, homogenous
distribution of dopants and elimination of large Bi-Pockets. In addition, the processing route of schottky barrier formation
is quite different from what is generally considered as the method of barrier formation in ZnO grain boundaries. 相似文献
32.
Arash Ajoudani Andrea Maria Zanchettin Serena Ivaldi Alin Albu-Schäffer Kazuhiro Kosuge Oussama Khatib 《Autonomous Robots》2018,42(5):957-975
Recent technological advances in hardware design of the robotic platforms enabled the implementation of various control modalities for improved interactions with humans and unstructured environments. An important application area for the integration of robots with such advanced interaction capabilities is human–robot collaboration. This aspect represents high socio-economic impacts and maintains the sense of purpose of the involved people, as the robots do not completely replace the humans from the work process. The research community’s recent surge of interest in this area has been devoted to the implementation of various methodologies to achieve intuitive and seamless human–robot-environment interactions by incorporating the collaborative partners’ superior capabilities, e.g. human’s cognitive and robot’s physical power generation capacity. In fact, the main purpose of this paper is to review the state-of-the-art on intermediate human–robot interfaces (bi-directional), robot control modalities, system stability, benchmarking and relevant use cases, and to extend views on the required future developments in the realm of human–robot collaboration. 相似文献
33.
We have investigated a TPTQ state as an input state of a non-ideal ferromagnetic detectors. Minimal spin polarization required to demonstrate spin entanglement according to entanglement witness and CHSH inequality with respect to (w.r.t.) their two free parameters have been found, and we have numerically shown that the entanglement witness is less stringent than the direct tests of Bell’s inequality in the form of CHSH in the entangled limits of its free parameters. In addition, the lower limits of spin detection efficiency fulfilling secure cryptographic key against eavesdropping have been derived. Finally, we have considered TPTQ state as an output of spin decoherence channel and the region of ballistic transmission time w.r.t. spin relaxation time and spin dephasing time has been found. 相似文献
34.
Hydrogenation of p‐Nitrophenol to p‐Aminophenol as a Test Reaction for the Catalytic Activity of Supported Pt Catalysts
下载免费PDF全文
![点击此处可从《化学工程与技术》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Michael Goepel Majd Al‐Naji Patrick With Gerald Wagner Oliver Oeckler Dirk Enke Roger Gläser 《化学工程与技术》2014,37(3):551-554
Hydrogenation of p‐nitrophenol (PNP) to p‐aminophenol (PAP) using NaBH4 as a reducing agent was studied as a test reaction for determining the catalytic activity of supported Pt catalysts. The initial reaction rate, which is accessible within less than 10 min via online UV‐vis spectroscopy at room temperature, ambient pressure, and in water as solvent, was applied as measure for catalytic activity. For three Pt catalysts supported on porous SiO2, porous glass, and Al2O3, respectively, significant differences in the catalytic activity by almost one order of magnitude were observed. However, especially in the case of very active catalysts, limitations of the reaction by internal or external mass transfer have to be considered. 相似文献
35.
36.
Seyyed Ahmadreza Amirsadat Babak Moradi Ali Zeinolabedini Hezave Siamak Najimi Mehdi Hojjat Farsangi 《Korean Journal of Chemical Engineering》2017,34(12):3119-3124
Due to the vast production of crude oil and consequent pressure drops through the reservoirs, secondary and tertiary oil recovery processes are highly necessary to recover the trapped oil. Among the different tertiary oil recovery processes, foam injection is one of the most newly proposed methods. In this regard, in the current investigation, foam solution is prepared using formation brine, C19TAB surfactant and air concomitant with nano-silica (SiO2) as foam stabilizer and mobility controller. The measurements revealed that using the surfactant-nano SiO2 foam solution not only leads to formation of stable foam, but also can reduce the interfacial tension mostly considered as an effective parameter for higher oil recovery. Finally, the results demonstrate that there is a good chance of reducing the mobility ratio from 1.12 for formation brine and reservoir oil to 0.845 for foam solution prepared by nanoparticles. 相似文献
37.
In this paper new dependencies are added to the hierarchy of the distribution-sensitive properties for data structures. Most remarkably, we prove that the working-set property is equivalent to the unified-bound property; a fact that had gone unnoticed since the introduction of such bounds in the Eighties by Sleator and Tarjan. 相似文献
38.
39.
Khalid Almutairi Seyyed Shahabaddin Hosseini Dehshiri Seyyed Jalaladdin Hosseini Dehshiri Ali Mostafaeipour Alibek Issakhov Kuaanan Techato 《International Journal of Hydrogen Energy》2021,46(36):18795-18815
Increasing energy demand has led to a substantial growth in the use of wind energy across the world, which can be attributed to the low initial and running costs and rapid and easy deployment of this technology. The development of hydrogen from wind energy is an excellent way to store the excess wind power produced, as the produced hydrogen can be used not only as clean fuel but also as input for various industries. Considering the good wind potentials of Yazd province, the variety of industries that are active in this area, and the central location of this province in Iran, which gives it ample access to major transport routes and other industrial hubs, hydrogen production from wind power in this province could benefit not only this region but the entire country. Given these considerations, we conducted a technical, economic, and environmental assessment of the potential for wind power generation and hydrogen production in Yazd province. Overall, the assessments showed that the best locations for harvesting wind energy in this province are Bahabad and Halvan stations. For these two stations, it is recommended to use EWT DW 52-900 turbine to take advantage of its higher nominal capacity to achieve higher electricity and hydrogen output and emission reduction. For Abarkoh and Kerit stations, which have a low wind energy potential, it is recommended to use small turbines such as Eovent EVA120 H-Darrieus. Also, economic and technical assessments showed that it is not economically justified to harvest wind energy in Ardakan station. The results of ranking the stations with the Step-wise Weight Assessment Ratio Analysis (SWARA) and Evaluation based on Distance from Average Solution (EDAS) techniques showed that Bahabad station was introduced as the best place to produce hydrogen from wind energy. 相似文献
40.