全文获取类型
| 收费全文 | 435篇 |
| 免费 | 9篇 |
| 国内免费 | 6篇 |
专业分类
| 电工技术 | 8篇 |
| 综合类 | 3篇 |
| 化学工业 | 106篇 |
| 金属工艺 | 12篇 |
| 机械仪表 | 9篇 |
| 建筑科学 | 13篇 |
| 矿业工程 | 1篇 |
| 能源动力 | 24篇 |
| 轻工业 | 15篇 |
| 水利工程 | 19篇 |
| 石油天然气 | 6篇 |
| 无线电 | 42篇 |
| 一般工业技术 | 76篇 |
| 冶金工业 | 11篇 |
| 原子能技术 | 2篇 |
| 自动化技术 | 103篇 |
出版年
| 2024年 | 17篇 |
| 2023年 | 20篇 |
| 2022年 | 32篇 |
| 2021年 | 44篇 |
| 2020年 | 38篇 |
| 2019年 | 40篇 |
| 2018年 | 34篇 |
| 2017年 | 30篇 |
| 2016年 | 36篇 |
| 2015年 | 14篇 |
| 2014年 | 22篇 |
| 2013年 | 27篇 |
| 2012年 | 29篇 |
| 2011年 | 26篇 |
| 2010年 | 10篇 |
| 2009年 | 6篇 |
| 2008年 | 5篇 |
| 2007年 | 5篇 |
| 2006年 | 4篇 |
| 2004年 | 3篇 |
| 2003年 | 1篇 |
| 2002年 | 1篇 |
| 2000年 | 1篇 |
| 1999年 | 1篇 |
| 1998年 | 1篇 |
| 1991年 | 1篇 |
| 1987年 | 1篇 |
| 1982年 | 1篇 |
排序方式： 共有450条查询结果，搜索用时 15 毫秒
411.
Farhad Fazlollahi;Sajjad Asadizadeh;Milad Ahmadi Khoshooei;Mohammad Reza Sardashti Birjandi;Majid Sarkari 《Oil & Gas Science and Technology》2020,76(1)
Hydrogen sulfide exists mostly as a detrimental byproduct in the gas processing units as well as refineries,and it must be eliminated from natural gas streams. In a Sulfur Recovery Unit (SRU),hydrogen sulfide is converted into the elemental sulfur during the modified Claus process. Efficiency of sulfur recovery units significantly depends on the reaction furnace temperature. In this work,the effect of oxygen and acid gas enrichment on the reaction furnace temperature and accordingly on sulfur recovery is studied,using both numerical modeling and process simulation. Then,simulation and numerical model are benchmarked against the experimental data of an SRU unit. The validated model provides spotlight on optimizing the upstream sulfur removal unit as well as the oxygen purification process. Two cases of acid gas streams with low and high H2S content,30% and 50%,are studied to investigate the effect of operating parameters on the overall recovery. Finally,average errors of the models are presented. According to the absolute difference with experimental values,the developed numerical model shows great potential for accurately estimating overall efficiency of the recovery unit. 相似文献
412.
A Dynamic Model for Vulnerability Assessment of Regional Water Resources in Arid Areas: A Case Study of Bayingolin, China 总被引：5，自引：0，他引：5
Guangyang Wu Lanhai Li Sajjad Ahmad Xi Chen Xiangliang Pan 《Water Resources Management》2013,27(8):3085-3101
Water scarcity is a common problem in many countries, especially those located in arid zones. The vulnerability of water resources due to climate change is an imperative research focus in the field of water resources management. In this study, a System Dynamics (SD) model was developed to simulate the water supply-and-demand process in Bayingolin, a prefecture in China, and to evaluate water resources vulnerability currently as well as in the future. The model was calibrated and validated using historical data. Three alternative scenarios were designed by changing parameters to test the vulnerability of water resources: i) increase the Wastewater Treatment Rate by 50 %; ii) decrease the Irrigation Water Demand per Hectare by 20 %; iii) increase Total Water Supply by 5 %. Results show that the baseline vulnerability of study region is high. The agricultural irrigation is the largest water use, and the water demand structure will change in future. Decreasing the irrigation water demand is the most suitable intervention to relatively reduce the vulnerability. Results also demonstrated that SD is a suitable method to explore management options for a complex water supply and demand system. 相似文献
413.
Dariush Semnani Elham Naghashzargar Mehdi Hadjianfar Fahimeh Dehghan Manshadi Sajjad Mohammadi Saeed Karbasi 《国际聚合物材料杂志》2017,66(3):149-157
In this investigation, a nanofibrous scaffold was fabricated through electrospinning of polycaprolactone (PCL) and chitosan (CS) using a novel collector to make better orientation and pore size for cell infiltration. PCL/CS nanofibers with 90-rpm collector speed and 40° angle between collector wires of the new collector have fewer diameters with better pore, size and nanofibers orientation. Mechanical properties, roughness parameters, topology, structure, hydrophilicity, and cell growing were considered for liver tissue engineering. The cell culture was done using epithelial liver mouse cells. The developed electrospun PCL/CS scaffold using novel collector would be an excellent matrix for biomedical applications especially liver tissue engineering. 相似文献
414.
Yuanbao Lin Begimai Adilbekova Yuliar Firdaus Emre Yengel Hendrik Faber Muhammad Sajjad Xiaopeng Zheng Emre Yarali Akmaral Seitkhan Osman M. Bakr Abdulrahman El‐Labban Udo Schwingenschlgl Vincent Tung Iain McCulloch Frdric Laquai Thomas D. Anthopoulos 《Advanced materials (Deerfield Beach, Fla.)》2019,31(46)
The application of liquid‐exfoliated 2D transition metal disulfides (TMDs) as the hole transport layers (HTLs) in nonfullerene‐based organic solar cells is reported. It is shown that solution processing of few‐layer WS2 or MoS2 suspensions directly onto transparent indium tin oxide (ITO) electrodes changes their work function without the need for any further treatment. HTLs comprising WS2 are found to exhibit higher uniformity on ITO than those of MoS2 and consistently yield solar cells with superior power conversion efficiency (PCE), improved fill factor (FF), enhanced short‐circuit current (JSC), and lower series resistance than devices based on poly(3,4‐ethylenedioxythiophene):poly(styrenesulfonate) and MoS2. Cells based on the ternary bulk‐heterojunction PBDB‐T‐2F:Y6:PC71BM with WS2 as the HTL exhibit the highest PCE of 17%, with an FF of 78%, open‐circuit voltage of 0.84 V, and a JSC of 26 mA cm?2. Analysis of the cells' optical and carrier recombination characteristics indicates that the enhanced performance is most likely attributed to a combination of favorable photonic structure and reduced bimolecular recombination losses in WS2‐based cells. The achieved PCE is the highest reported to date for organic solar cells comprised of 2D charge transport interlayers and highlights the potential of TMDs as inexpensive HTLs for high‐efficiency organic photovoltaics. 相似文献
415.
Sajjad S. Mofarah Esmaeil Adabifiroozjaei Raheleh Pardehkhorram M. Hussein N. Assadi Manuel Hinterstein Yin Yao Xinhong Liu Mohammad B. Ghasemian Kourosh Kalantar‐Zadeh Rashid Mehmood Claudio Cazorla Reza Shahmiri Ghazaleh Bahmanrokh Saroj Bhattacharyya Maria Chiara Spadaro Jordi Arbiol Sean Lim Yuwen Xu Hamidreza Arandiyan Jason Scott Pramod Koshy Charles C. Sorrell 《Advanced materials (Deerfield Beach, Fla.)》2019,31(52)
Holey 2D metal oxides have shown great promise as functional materials for energy storage and catalysts. Despite impressive performance, their processing is challenged by the requirement of templates plus capping agents or high temperatures; these materials also exhibit excessive thicknesses and low yields. The present work reports a metal‐based coordination polymer (MCP) strategy to synthesize polycrystalline, holey, metal oxide (MO) nanosheets with thicknesses as low as two‐unit cells. The process involves rapid exfoliation of bulk‐layered, MCPs (Ce‐, Ti‐, Zr‐based) into atomically thin MCPs at room temperature, followed by transformation into holey 2D MOs upon the removal of organic linkers in aqueous solution. Further, this work represents an extra step for decorating the holey nanosheets using precursors of transition metals to engineer their band alignments, establishing a route to optimize their photocatalysis. The work introduces a simple, high‐yield, room‐temperature, and template‐free approach to synthesize ultrathin holey nanosheets with high‐level functionalities. 相似文献
416.
Haris Mumtaz Mohammad Alshayeb Sajjad Mahmood Mahmood Niazi 《Journal of Software: Evolution and Process》2019,31(3)
Bad smells tend to have a negative impact on software by degrading its quality. It is beneficial to detect model smells to avoid their propagation to later stages of software development. The objective of this paper is to present the state‐of‐the‐art research on techniques for detecting UML model bad smells. The detection techniques are compared and evaluated using a proposed evaluation framework. The framework consists of two parts. The first part of the framework compares the techniques in terms of the implemented approach, the investigated model, and the explored model smells, while the experimental design is explored in the second part of the framework. We found that the detection of bad smells in class and sequence diagrams is accomplished via design patterns, software metrics, and predefined rules, while model smells in use cases are detected using metrics and predefined rules. We also found that the class diagram is the most investigated UML model in the context of model smell detection, whereas there is a lack of work on other UML models. In addition, there is a scarcity of independent studies on sequence diagrams. Furthermore, the studies investigating class diagrams are mostly validated, whereas use case diagrams and sequence diagrams are rarely validated. 相似文献
417.
Sajjad Shokouhyar Sudabeh Seifhashemi Hossein Siadat Mohammad Milad Ahmadi 《Expert Systems》2019,36(1)
In the business environment, information technology (IT) plays an important role for firms' performance. It provides information flow that makes the supply chain more robust and resilient without undermining its efficiency. Smart systems use artificial intelligence methods for solving problems and facilitating decision‐making through rule‐based deduction. Accordingly, these systems can present specialists' skills and simulate their thinking process. The primary goal of expert systems is to implement knowledge acquisition process by converting knowledge to wisdom. This process is vital for critical decision‐making regarding important issues such as determining necessities of a particular contract. Companies use professional liability insurance of the products and services to ensure the purchasers and prevent potential losses. Although this practice is highly prevalent, there is not any particular procedure for measuring necessities of contracts. The main purpose of this paper is to design a fuzzy expert system for measuring the necessities of professional contracts regarding insurance coverage and improve the supply chain management using IT. This system can measure and report these obligations, considering specifications of each project. Taking into perspective variety of professional services/products, we consider software as a type of professional contracts, extract its important indices and give it to the system as the input. After the necessary stages, the system produces a proper response and presents the generated response to the user. The software of this expert system is web based, and there are four operating layers in its architecture. We implemented this program in MS Visual Studio Framework with C#.NET programming language. Moreover, we implemented MS SQL‐Server Database Management. 相似文献
418.
Wasif Muhammad Muhammad Jehanzeb Irshad Sajjad Miran Muhammad Salman Haider 《国际能源研究杂志》2020,44(8):6511-6521
The direct conversion of thermal energy to mechanical energy is always been a challenging but demanding problem. In this article, we presented a nonconventional direct conversion mechanism of the readily available solar thermal and gravity energy to rotational mechanical energy. The developed rotating assembly affixed concentrically with a plurality of actuating arms harnesses the integrated solar-gravity energy. Each actuating arm shifts the center of gravity of the attached solid mass with concentrated solar heating. The alternate shift in the center of gravity of each actuating arm with exposure to solar radiation produces a continuous revolution of rotating assembly around its axis of rotation. With a particular set of the system parameters with Al/Si3N4 bimetallic strip the thermal efficiency of the proposed thermogravity bimetallic strip heat actuator/engine is 12.41% which is 100 times more efficient compared to a gravity-less thermal engine with same set up. The proposed thermogravity system can generate mechanical power ranges from less than 1 W to 40 kW with a particular set of system parameters. This solar-gravity rotary actuator is a novel work in this domain which has a huge impact and contribution in the available rotary actuator or energy harvester knowledge. 相似文献
419.
Sajjad Hussain Shi-Wei Qu Dinuo Bu Xiao-Hua Wang Abu Bakar Sharif 《国际射频与微波计算机辅助工程杂志》2022,32(1):e22950
A low-profile wide-scan phased array for 28 GHz 5G band operation, based on the current sheet array (CSA) concept, is presented in this work. The array is dual-polarized with horizontally and vertically polarized dipoles are placed in close proximity to leverage intentional capacitive coupling. A meta-surface based on fully split rings is printed on the top of the matching layer, contributing to wide-scan performance. A capacitive metallic plate is placed below the cross-section formed between orthogonal dipole elements to subdue the in-band coupled-loop modes. The design is demonstrated to operate at 26–30 GHz with voltage standing wave ratio (VSWR) <3 for ±60° scanning in principal planes, with a low-profile 0.26λh. The simulations are validated by measuring an 8 × 8 array prototype, which shows good agreement with the simulated predictions. 相似文献
420.
In the present study, the morphology of asymmetric poly(vinylidene fluoride) blend membranes which were prepared by the phase inversion method is rationalized by comparing two non‐dimensional number represent thermodynamic and kinetic properties of the prepared membrane. These two parameters change phase diagram and demixing rate between solvent and nonsolvent. TiO2 nanoparticles and polyvinylpyrrolidone were used as additives. Hansen solubility parameters of the components are calculated by Van Krevelen method. Furthermore, kinetic and thermodynamic properties of the prepared solutions are determined by drawing phase diagrams and controlling mass transfer rate during precipitation of casting solution. Besides, to further analyze different tests encompass; permeability, rejection, porosity, pore size determination, contact angle, and field emission scanning electron microscopy images were carried out. It is shown, additives as pore former induced higher permeability and porosity, however, at higher concentration of additives high viscosity obstacle mass transfer and sponge‐like morphology is obtained. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46225. 相似文献