全文获取类型
收费全文 | 78篇 |
免费 | 8篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 2篇 |
化学工业 | 23篇 |
金属工艺 | 6篇 |
机械仪表 | 3篇 |
建筑科学 | 1篇 |
能源动力 | 3篇 |
轻工业 | 3篇 |
水利工程 | 1篇 |
石油天然气 | 2篇 |
无线电 | 15篇 |
一般工业技术 | 11篇 |
冶金工业 | 2篇 |
自动化技术 | 16篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 2篇 |
2021年 | 3篇 |
2020年 | 5篇 |
2019年 | 5篇 |
2018年 | 4篇 |
2017年 | 9篇 |
2016年 | 6篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 8篇 |
2012年 | 9篇 |
2011年 | 12篇 |
2010年 | 2篇 |
2009年 | 1篇 |
2008年 | 1篇 |
2006年 | 1篇 |
2003年 | 1篇 |
1997年 | 1篇 |
1986年 | 1篇 |
排序方式: 共有88条查询结果,搜索用时 0 毫秒
1.
Effect of Different Cosolvents on Transesterification of Waste Cooking Oil in a Microreactor
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)
Biodiesel was prepared from waste cooking oil combined with methanol. The process was performed via transesterification in a microreactor using kettle limescale as a heterogeneous catalyst and various cosolvents under different conditions. n‐Hexane and tetrahydrofuran were selected as cosolvents to investigate fatty acid methyl esters (FAMEs). To optimize the reaction conditions, the main parameters affecting FAME% including reaction temperature, catalyst concentration, oil‐to‐methanol volumetric ratio, and cosolvent‐to‐methanol volumetric ratio were studied via response surface methodology. Under optimal reaction conditions and in the presence of the cosolvents n‐hexane and tetrahydrofuran, high FAME purities were achieved. Considering the experimental results, the limescale catalyst is a unique material, and the cosolvent method can reduce significantly the reaction time and biodiesel production cost. 相似文献
2.
Mohammed Tarique Kemal E. Tepe Sasan Adibi Shervin Erfani 《Journal of Network and Computer Applications》2009,32(6):1125-1143
This survey investigates multipath routing protocols for mobile ad hoc networks (MANETs). The main objectives of multipath routing protocols are to provide reliable communication and to ensure load balancing as well as to improve quality of service (QoS) of MANETs. These multipath protocols are broadly classified into five categories based on their major goals. The goals are to improve delay, provide reliability, reduce overhead, maximize network life and support hybrid routing. Multipath routing protocols address issues such as multiple paths discovery and maintaining these paths. Issues, objectives, performances, advantages and disadvantages of these protocols are investigated and summarized. A checklist is provided as a guideline so that a network designer can choose an appropriate multipath routing protocol to meet the network's application objectives. 相似文献
3.
Forrest G. Hall Kathleen Bergen Ralph Dubayah George Hurtt Michael Lefsky Sasan Saatchi Diane Wickland 《Remote sensing of environment》2011,115(11):2753-2775
Human and natural forces are rapidly modifying the global distribution and structure of terrestrial ecosystems on which all of life depends, altering the global carbon cycle, affecting our climate now and for the foreseeable future, causing steep reductions in species diversity, and endangering Earth's sustainability.To understand changes and trends in terrestrial ecosystems and their functioning as carbon sources and sinks, and to characterize the impact of their changes on climate, habitat and biodiversity, new space assets are urgently needed to produce high spatial resolution global maps of the three-dimensional (3D) structure of vegetation, its biomass above ground, the carbon stored within and the implications for atmospheric green house gas concentrations and climate. These needs were articulated in a 2007 National Research Council (NRC) report (NRC, 2007) recommending a new satellite mission, DESDynI, carrying an L-band Polarized Synthetic Aperture Radar (Pol-SAR) and a multi-beam lidar (Light RAnging And Detection) operating at 1064 nm. The objectives of this paper are to articulate the importance of these new, multi-year, 3D vegetation structure and biomass measurements, to briefly review the feasibility of radar and lidar remote sensing technology to meet these requirements, to define the data products and measurement requirements, and to consider implications of mission durations. The paper addresses these objectives by synthesizing research results and other input from a broad community of terrestrial ecology, carbon cycle, and remote sensing scientists and working groups. We conclude that:
- (1)
- Current global biomass and 3-D vegetation structure information is unsuitable for both science and management and policy. The only existing global datasets of biomass are approximations based on combining land cover type and representative carbon values, instead of measurements of actual biomass. Current measurement attempts based on radar and multispectral data have low explanatory power outside low biomass areas. There is no current capability for repeatable disturbance and regrowth estimates.
- (2)
- The science and policy needs for information on vegetation 3D structure can be successfully addressed by a mission capable of producing (i) a first global inventory of forest biomass with a spatial resolution 1 km or finer and unprecedented accuracy (ii) annual global disturbance maps at a spatial resolution of 1 ha with subsequent biomass accumulation rates at resolutions of 1 km or finer, and (iii) transects of vertical and horizontal forest structure with 30 m along-transect measurements globally at 25 m spatial resolution, essential for habitat characterization.
4.
Alberto Molinari Sasan Amirabdollahian Marco Zago Mats Larsson Ilaria Cristofolini 《粉末冶金学》2018,61(4):267-275
Sintering shrinkage of prior cold compacted iron rings with different geometry (height to wall thickness ratio) and green density in the 6.5–7.3?g/cm3 range was investigated. It displays a minimum at an intermediate green density. Axial, tangential and radial shrinkages are different, due to the gradients of green density along the axial and the radial directions. Therefore, the effect of height on shrinkage and its anisotropy is the result of their effect on the stress distribution in the green parts during cold compaction, and the resulting green density and deformation experienced by the powder. Anisotropy decreases on increasing shrinkage. 相似文献
5.
A conceptual design and statistical overview about passive direct methanol fuel cells that have been fabricated from 2002 to 2013, is performed [1–70]. The major components of passive DMFCs such as: active area, type of Nafion, catalyst loading on the anode and cathode side, characteristics and designs of current collectors (CC), and also the optimum methanol concentration which resulted in the best performance are categorized and studied statistically and individually. Finally, the best combination for the design and fabrication of a reliable passive DMFC is recommended. Obtained results indicated that a MEA with 4 cm2 active area, Nafion 117 and 4 mg/cm2 Pt/Ru at the anode and 2 mg/cm2 Pt black at the cathode (or 4 mg/cm2 Pt/Ru at the anode – 4 mg/cm2 Pt black at the cathode) as the catalyst loading, which is sandwiched between two stainless steel perforated current collectors that are coated by Pt (or Gold) could be a reliable design for a passive direct methanol single cell. 相似文献
6.
Applied Intelligence - In recent years, the number and severity of natural disasters have increased. These disasters always carry the risks of mortality and injury. But its mortality risks are much... 相似文献
7.
Bey Vrancken Sasan Dadbakhsh Raya Mertens Kim Vanmeensel Jef Vleugels Shoufeng Yang Jean-Pierre Kruth 《CIRP Annals》2019,68(1):221-224
Selective Laser Melting (SLM) was used to process a powder mixture of CP Ti, 6.5 wt% Mo and 3.5 wt% Mo2C. The process parameters were optimized to obtain full-density, crack free parts. After the in situ decomposition of Mo2C in favor of the formation of TiC, the material consisted of a homogeneous dispersion of submicrometer sized TiC platelets in a β-(Ti,Mo) matrix exhibiting a high hardness up to 550 HV and compressive yield stress of 1164 ± 37 MPa. The microstructure and mechanical properties could be tailored by variation of the process parameters within the high-density processing window, as well as through post-process heat treatments. 相似文献
8.
红外通信IrDA标准与应用 总被引:11,自引:1,他引:11
红外光是有许多优势的通信媒介,红外通信IrDA标准是目前IT和通讯业普遍支持的近距离无线数据传输规范。本文介绍了红外通信IrDA标准的内容以及它的物理层协议,脉冲调制的必要性,不同传输速率下不同的脉冲调制方式,连接建立协议层的帧结构。给出了符合IrDA标准的芯片TOIM32325和TFDS4500在高电压环境下调试实验设备的应用。 相似文献
9.
Serkan Şimşek Sasan Ahdi Rezaeieh 《AEUE-International Journal of Electronics and Communications》2013,67(11):981-983
An efficient design method for substrate integrated waveguide electromagnetic bandgap (SIW-EBG) filters is proposed which provides direct dimensional synthesis approach for desired filter objectives without using network representations. The method is applied to the design of an X band SIW-EBG filter and its response is compared with HFSS (high frequency structure simulator) simulations for validation purposes. Fairly good agreement between the results shows the applicability of the proposed method for SIW-EBG filter design. 相似文献
10.
Jeydmer Aristizabal Badr Omrane Clint Landrock Sasan Vosoogh-Grayli Yindar Chuo Jasbir N. Patel Bozena Kaminska Carlo Menon 《Journal of Electronic Testing》2011,27(3):403-410
An improved Tungsten light source system for photovoltaic cell testing made from low-cost, commercially available materials is presented as an alternative to standard expensive testing equipment. In this work, spectral correction of the Tungsten light source is achieved by increasing the color temperature to ??5200 K using inexpensive commercially available filters. Spectral measurements of the enhanced light source reveal that a better spectrum match towards the solar spectrum is achieved than what has been previously demonstrated. Specifically, the improved solar spectrum match is achieved by substantial filtering of the infrared range. The proposed setup is used to evaluate the performance of both silicon and organic based photovoltaic cells. 相似文献