全文获取类型
收费全文 | 408篇 |
免费 | 27篇 |
国内免费 | 3篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 74篇 |
金属工艺 | 3篇 |
机械仪表 | 12篇 |
建筑科学 | 9篇 |
矿业工程 | 1篇 |
能源动力 | 17篇 |
轻工业 | 34篇 |
水利工程 | 6篇 |
石油天然气 | 5篇 |
无线电 | 56篇 |
一般工业技术 | 103篇 |
冶金工业 | 7篇 |
原子能技术 | 7篇 |
自动化技术 | 93篇 |
出版年
2024年 | 1篇 |
2023年 | 20篇 |
2022年 | 45篇 |
2021年 | 50篇 |
2020年 | 32篇 |
2019年 | 40篇 |
2018年 | 29篇 |
2017年 | 40篇 |
2016年 | 20篇 |
2015年 | 13篇 |
2014年 | 24篇 |
2013年 | 28篇 |
2012年 | 19篇 |
2011年 | 19篇 |
2010年 | 11篇 |
2009年 | 7篇 |
2008年 | 4篇 |
2007年 | 6篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 1篇 |
2003年 | 4篇 |
2001年 | 2篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 2篇 |
1997年 | 5篇 |
1996年 | 3篇 |
1995年 | 1篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有438条查询结果,搜索用时 15 毫秒
101.
Bano Saleha Narejo Ghous Bakhsh Usman Ali Shah S. M. 《Wireless Personal Communications》2019,106(4):1875-1884
Wireless Personal Communications - This paper presents the designing of a low voltage low power single ended operational transconductance amplifier (OTA) for low frequency application. The designed... 相似文献
102.
Muhammad Usman Asad Umar Farooq Jason Gu Ghulam Abbas Rong Liu Valentina E. Balas 《IEEE/CAA Journal of Automatica Sinica》2019,6(5):1166-1178
State convergence is a novel control algorithm for bilateral teleoperation of robotic systems. First, it models the teleoperation system on state space and considers all the possible interactions between the master and slave systems. Second, it presents an elegant design procedure which requires a set of equations to be solved in order to compute the control gains of the bilateral loop. These design conditions are obtained by turning the master-slave error into an autonomous system and imposing the desired dynamic behavior of the teleoperation system. Resultantly, the convergence of master and slave states is achieved in a well-defined manner. The present study aims at achieving a similar convergence behavior offered by state convergence controller while reducing the number of variables sent across the communication channel. The proposal suggests transmitting composite master and slave variables instead of full master and slave states while keeping the operator’s force channel intact. We show that, with these composite and force variables; it is indeed possible to achieve the convergence of states in a desired way by strictly following the method of state convergence. The proposal leads to a reduced complexity state convergence algorithm which is termed as composite state convergence controller. In order to validate the proposed scheme in the absence and presence of communication time delays, MATLAB simulations and semi-real time experiments are performed on a single degree-of-freedom teleoperation system. 相似文献
103.
Jianmin Yuan Ammara Usman Scott A. Reid Kevin F. King Andrew J. Patterson Jonathan H. Gillard Martin J. Graves 《Magma (New York, N.Y.)》2018,31(1):183-190
Objective
The purpose of this work is to evaluate the repeatability of a compressed sensing (CS) accelerated multi-contrast carotid protocol at 3 T.Materials and methods
Twelve volunteers and eight patients with carotid disease were scanned on a 3 T MRI scanner using a CS accelerated 3-D black-blood multi-contrast protocol which comprises T 1w, T 2w and PDw without CS, and with a CS factor of 1.5 and 2.0. The volunteers were scanned twice, the lumen/wall area and wall thickness were measured for each scan. Eight patients were scanned once, the inter/intra-observer reproducibility of the measurements was calculated.Results
In the repeated volunteer scans, the interclass correlation coefficient (ICC) for the wall area measurement using a CS factor of 1.5 in PDw, T 1w and T 2w were 0.95, 0.81, and 0.97, respectively. The ICC for lumen area measurement using a CS factor of 1.5 in PDw, T 1w and T 2w were 0.96, 0.92, and 0.96, respectively. In patients, the ICC for inter/intra-observer measurements of lumen/wall area, and wall thickness were all above 0.81 in all sequences.Conclusion
The results show a CS accelerated 3-D black-blood multi-contrast protocol is a robust and reproducible method for carotid imaging. Future protocol design could use CS to reduce the scanning time.104.
Investigation of natural convection heat transfer in a unique scaled‐down dual‐channel facility
下载免费PDF全文
![点击此处可从《American Institute of Chemical Engineers》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Ibrahim A. Said Mahmoud M. Taha Shoaib Usman Brian G. Woods Muthanna H. Al‐Dahhan 《American Institute of Chemical Engineers》2017,63(1):387-396
Multiphase Reactors Engineering and Applications Laboratory (mReal) has designed and constructed a scaled‐down dual‐channel facility to investigate plenum‐to‐plenum natural circulation heat transfer through two channels for coolant flow that would be encountered during a loss of flow accident in the prismatic modular reactor (PMR). Heat transfer characterization of the current facility has been investigated under different upper plenum and cooled channel outer surface temperatures using sophisticated flush mounted heat transfer sensors. Results show a reduction in the values of local heat‐transfer coefficient and Nusselt number along the heated channel with increasing outer surface temperatures. One significant observation was the heat transfer reversal close to heated channel exit, where the heat flows from gas to the channel wall. This flow reversal is attributed to recirculation at the heated channel exit to the upper plenum. The average heat transfer results, when compared with previous literature, showed a similar qualitative trend. © 2016 American Institute of Chemical Engineers AIChE J, 63: 387–396, 2017 相似文献
105.
Sahrish?Rehmani Mahmood?AhmadEmail author Muhammad?Usman?Minhas Hina?Anwar Muhammad?Imad-ud-din?Zangi Muhammad?Sohail 《Polymer Bulletin》2017,74(3):737-761
This research paper describes the development, optimization and in vitro characterization of chemically cross-linked pectin–polyvinyl alcohol-co-poly(2-Acrylamido-2-methylpropane sulfonic acid) semi-interpenetrating polymer network hydrogel [pectin–PVA-co-poly(AMPS) semi-IPN hydrogel] for controlled delivery of model drug tramadol HCl. Response surface methodology based on 32 factorial design was used for optimization and investigating the effect of independent factors: polymer-blend ratio (pectin:PVA = X 1) and monomer (AMPS = X 2) concentration on the dependent variables, swelling ratio (q 18th), percent drug release (R 18th, %), time required for 80 % drug release (t 80 %, h), drug encapsulation efficiency (DEE, %) and drug loaded contents (DLC, mg/g) in pectin-PVA-co-poly(AMPS) gels prepared by free radical polymerization. The optimized semi-IPN gel (FPP-10) showed controlled in vitro drug release (R 18th) of 56.34 % in 18 h, t 80 % of 30 h, and DEE of 23.40 %. These semi-IPN hydrogels were also characterized through SEM, FTIR, sol–gel analysis, swelling studies and drug release characteristics. Therefore, this newly synthesized polymeric network could be a potential polymeric system for controlled drug delivery of tramadol HCl for prolonged drug release. 相似文献
106.
Solubilization of Ni Imidazole Complex in Micellar Media of Anionic Surfactants,Sodium Dodecyl Sulfate and Sodium Stearate
下载免费PDF全文
![点击此处可从《Journal of surfactants and detergents》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Nafisa Younas Muhammad Abid Rashid Muhammad Usman Sadia Nazir Sadia Noor Abdul Basit Muhammad Jamil 《Journal of surfactants and detergents》2017,20(6):1311-1320
The solubilization and physicochemical behavior of a coordination complex of nickel, namely [Ni(im)6]F2·5H2O [hexakis(imidazole)nickel(II) fluoride pentahydrate], in aqueous micellar media of anionic surfactants, i.e., sodium dodecyl sulfate (SDS) and sodium stearate (SS), were investigated by using UV–Vis spectroscopy and electrical conductivity measurements. Spectroscopic techniques were used for the computation of binding constant (Kb), partition coefficient (Kx), change in free energy of binding (ΔGb), and change in free energy of partition (ΔGp), whereas electrical conductivity data was helpful to calculate thermodynamic parameters of micellization of surfactants in the presence of the Ni complex, i.e., standard entropy of micellization (ΔSm), free energy (ΔGm), and enthalpy of micellization (ΔHm). It is evident from the results that solubilization of the Ni complex takes place because of electrostatic as well as hydrophobic interactions. The presence of the Ni complex in micellar media increases the critical micelle concentration of both surfactants owing to the structure‐breaking effect. 相似文献
107.
Integration operators for generating RDF/OWL-based user defined mediator views in a grid environment
Abdel-Rahman H. Tawil Adel Taweel Usman Naeem Matthew Montebello Rabih Bashroush Ameer Al-Nemrat 《Journal of Intelligent Information Systems》2014,43(1):1-32
Research and development activities relating to the grid have generally focused on applications where data is stored in files. However, many scientific and commercial applications are highly dependent on Information Servers (ISs) for storage and organization of their data. A data-information system that supports operations on multiple information servers in a grid environment is referred to as an interoperable grid system. Different perceptions by end-users of interoperable systems in a grid environment may lead to different reasons for integrating data. Even the same user might want to integrate the same distributed data in various ways to suit different needs, roles or tasks. Therefore multiple mediator views are needed to support this diversity. This paper describes our approach to supporting semantic interoperability in a heterogeneous multi-information server grid environment. It is based on using Integration Operators for generating multiple semantically rich RDF/OWL-based user defined mediator views above the grid participating ISs. These views support different perceptions of the distributed and heterogeneous data available. A set of grid services are developed for the implementation of the mediator views. 相似文献
108.
Muhammad Adnan Shahid Piero Boccardo Muhammad Usman Adriana Albanese Muhammad Uzair Qamar 《Water Resources Management》2017,31(3):793-810
Investigating the hydrological response of an area to adverse climate changes and extreme rainfall events is crucial for managing land and water resources and mitigating the natural hazards like floods. Limited availability of the in situ data, especially in case of Transboundary Rivers, further highlights the need to develop and evaluate decision support systems which may predict the flows in real time using open source rainfall data. This paper presents the study conducted in Chenab River catchment, Pakistan, to develop and evaluate a hydrologic model using HEC-HMS for predicting flows based on TRMM rainfall data. The catchment was analyzed for hydro-morphological properties using SRTM DEM in HEC-GeoHMS. To rely on open source data as much as possible, digital soil map of the world developed by FAO and global land cover map developed by European Space Agency were utilized to compute Curve Number grid data for the catchment. These preliminary data analyses were employed to set initial values of different parameters to be used for model calibration. The model was calibrated for five rainfall events occurred in the rainy seasons of 2006, 2010 and 2013. The calibrated model was then validated for four other rainfall events of similar type in the same years. Consistency in simulated and observed flows was found with percent difference in volume ranging from ?6.17 % to 5.47 % and percent difference in peak flows to be in the range of 6.96 % to 7.28 %. Values of Nash-Sutcliffe Efficiency were ranging from 0.299 to 0.909 with an average value of 0.586 for all flow events. The model was found well capable of capturing the hydrologic response of the catchment due to rainfall events and can be helpful in providing alerts of peak flows in real time based on real time/forecasted rainfall data. 相似文献
109.
Muhammad Zaman Usman Khalid Maria Abdul Ghafoor Raja Waqar Siddique Kishwar Sultana Muhammad Wahab Amjad 《Polymer-Plastics Technology and Engineering》2017,56(16):1713-1722
Transdermal patches loaded with ramipril and repaglinide were prepared with the ambition to develop matrix-type transdermal drug delivery system for enhanced permeability and hence improved bioavailability. Different formulations were designed by intermittent concentrations of hydroxypropyl methylcellulose K4M as hydrophilic polymer and ethyl cellulose as hydrophobic polymer. Solvent casting method was used for the fabrication of transdermal patches. Oleic acid and propylene glycol were used to enhance permeability along with polyethylene glycol 400 as plasticizer. Newly designed patches were then evaluated for various physicochemical and mechanical properties. Compatibility studies were performed by Fourier transformed infrared spectroscopy which did not reveal any interaction between drug and polymers. Crystalline nature of drugs was confirmed when they were subjected to X-ray diffraction study and surface morphological studies using scanning electron microscopy. Transdermal patches were of good mechanical strength with folding endurance of more than 300-fold and 100% flatness. Percent drug contents of ramipril and repaglinide ranged from 90 to 105%, i.e., analogous to official limits. In vitro and ex vivo permeation studies were executed using franz diffusion cell. The cumulative amount of drug permeated through skin was 55.22–112.72% for repaglinide and 73.14–91.46% for ramipril. The release behavior of the permeated drug was analyzed by the application of model-dependent approaches. The results showed that Korsmeyer–Peppas model was found to be dominating in most of the formulations and drugs followed diffusion mechanism. It could be concluded that hydroxypropyl methylcellulose K4M and ethyl cellulose has great potential for ramipril and repaglinide as a vector for transdermal drug delivery effectively because of the formation of smooth surfaces of patches, high folding endurance, and entrapment efficiency with the ability to release the drugs in sustained manner. 相似文献
110.
Ahmad Nisar Asif Hafiz Muhammad Shahzad Saleem Gulshan Younus Muhammad Usman Anwar Sadia Anjum Muhammad Rizwan 《Wireless Personal Communications》2021,121(2):1139-1168
Wireless Personal Communications - Identification of plant disease is usually done through visual inspection or during laboratory examination which causes delays resulting in yield loss by the time... 相似文献