全文获取类型
收费全文 | 225篇 |
免费 | 15篇 |
专业分类
电工技术 | 10篇 |
化学工业 | 41篇 |
金属工艺 | 3篇 |
机械仪表 | 18篇 |
建筑科学 | 2篇 |
能源动力 | 12篇 |
轻工业 | 17篇 |
水利工程 | 1篇 |
无线电 | 37篇 |
一般工业技术 | 52篇 |
冶金工业 | 8篇 |
原子能技术 | 3篇 |
自动化技术 | 36篇 |
出版年
2024年 | 1篇 |
2023年 | 5篇 |
2022年 | 13篇 |
2021年 | 10篇 |
2020年 | 18篇 |
2019年 | 18篇 |
2018年 | 14篇 |
2017年 | 12篇 |
2016年 | 14篇 |
2015年 | 12篇 |
2014年 | 15篇 |
2013年 | 20篇 |
2012年 | 7篇 |
2011年 | 16篇 |
2010年 | 7篇 |
2009年 | 4篇 |
2008年 | 11篇 |
2007年 | 6篇 |
2006年 | 5篇 |
2005年 | 2篇 |
2003年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 4篇 |
1994年 | 2篇 |
1993年 | 2篇 |
1992年 | 4篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1985年 | 3篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有240条查询结果,搜索用时 31 毫秒
81.
Mehvish Saleem Saba Zahid Sarah Ghafoor Hina Khalid Haffsah Iqbal Rabia Zeeshan Sarfraz Ahmad Anila Asif Abdul Samad Khan 《应用聚合物科学杂志》2021,138(18):50336
This study aimed to synthesize experimental composites reinforced with various concentrations (0, 40, 50, and 60 wt%) of nano-hydroxyapatite grafted glass fibers. The release of monomers, residual monomers, and in-vitro bioactivity of composite groups were evaluated after 1, 7, and 28 days. Compressive strength/ modulus, cell viability (by direct and indirect method), and bacterial adhesion were evaluated. The results showed that bis-GMA was released from all samples. TEGDMA released from 50 and 60 wt% samples on day 1 and UDMA showed negligible release. Compressive strength values of 40 wt% sample were higher than other experimental groups. New apatite layer was formed, whereby both direct and indirect methods demonstrated cell viability. The numbers of active colonies grown were least for 60 wt% sample while their number increased over time. The nano-hydroxyapatite/glass fibers have potential to be used as filler in dental composites and experimental composites were found to be biocompatible and comparable with commercial material. 相似文献
82.
A Valizadeh H Mikaeili N Zarghami SM Farkhani M Kouhi M Samiei S Davaran A Akbarzadeh 《Nanoscale research letters》2012,7(1):480
ABSTRACT: This review introduces quantum dots (QDs) and explores their properties, synthesis, applications, delivery systems in biology, and their toxicity. QDs are one of the first nanotechnologies to be integrated with the biological sciences and are widely anticipated to eventually find application in a number of commercial consumer and clinical products. They exhibit unique luminescence characteristics and electronic properties such as wide and continuous absorption spectra, narrow emission spectra, and high light stability. The application of QDs, as a new technology for biosystems, has been typically studied on mammalian cells. Due to the small structures of QDs, some physical properties such as optical and electron transport characteristics are quite different from those of the bulk materials. 相似文献
83.
We employ high-order weights to extend the class of optimization problems that can be solved with neural networks. Hopfield and Tank networks are used; the associated energy function is a polynomial with order equal to the highest order weights in the network. As an example, we consider the problem of partitioning a graph into triangles. Simulation results indicate that multiple runs on a problem can be considered independent trials; high performance can thereby be achiebed feasibly. 相似文献
84.
SK.Abdus Samad 《International Journal of Engineering Science》1981,19(9):1221-1232
The steady flow of viscous, incompressible, electrically conducting fluids through circular pipes in the presence of an applied uniform transverse magnetic field is considered. In this analysis, the finite conductivity and wall thickness of the pipe have been taken into account. An exact solution and its numerical calculation have been presented. Some interesting results have been obtained. 相似文献
85.
Torque and efficiency maximization for a wave energy harvesting turbine: an approach to modify multiple design variables 下载免费PDF全文
Multiple design variables modifications are carried out for a bidirectional flow turbine used in an oscillating water column wave energy converter to enhance its performance by maximizing the peak torque‐coefficient (TC) and the corresponding efficiency (EFF), which are the objective functions of this problem. The Latin hypercube sampling technique selects samples from a designed space created by the design parameters defined for the blade sweep and aerofoil profile thickness modifications. The objective function values are obtained by solving Reynolds‐averaged Navier–Stokes equations and are approximated by surrogate models. The models help in generating populations of the genetic algorithm, which finally produces a set of optimal designs in a Pareto optimal front. Only two extreme designs among the five clustered points are further evaluated by solving Reynolds‐averaged Navier–Stokes equations to cross‐check the validity of the optimization steps. It is found that the TC is increased by 33% and the EFF is decreased by 5% at one extreme cluster point, while the other extreme point gives that both the TC and the EFF are higher by 1.8% and 2.9%, respectively, as compared with the reference geometry. The optimal geometry has a wider operating range, which is an important parameter to get continuous power from a wave energy converter. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
86.
Mohammadreza Hazhirpasand Barkadehi Mehrbaksh Nilashi Othman Ibrahim Ali Zakeri Fardi Sarminah Samad 《Telematics and Informatics》2018,35(5):1491-1511
One of the most important parts of any system is authentication. Appreciated as the first and the last line of defense in the great majority of cases, authentication systems can usually prevent the kleptomaniac from unauthorized accessing to users’ data. However, the traditional text-based password is still used in many websites and applications which are vulnerable to different kinds of attacks. Accordingly, there exist some other alternative ways to boost this traditional method. In this study, we classified and identified different types of authentication systems in a variety of platforms. Their usage, similarity, usability, performance and drawbacks were discussed. The goal of this study is to provide useful, classified information with the aim of understanding of how different authentication systems work and of what their usability and drawbacks are to the readers. 相似文献
87.
88.
89.
Shahrzad Jalali Mazlouman Samad Sheikhaei Shahriar Mirabbasi 《Analog Integrated Circuits and Signal Processing》2011,68(3):329-340
Two frequency-translating hybrid analog-to-digital converters (FTH-ADCs) are implemented using building blocks that are designed
and fabricated in a 90-nm CMOS technology. These blocks include a mixer, a filter, and an ADC that are cascaded to build each
analog processing path of the FTH-ADC. The mixer-filter path is designed with sufficient linearity and signal-to-noise-and-distortion
ratio (SNDR) to accommodate for the desired resolution of the path ADC. A 4-bit flash ADC structure is used in each path.
This path has a signal bandwidth of 0.5 GHz and frequency-translates the input signal into baseband and digitizes it with
the sample rate of 2 GHz. Multiple such mixer-filter-ADC paths are then combined together with proper mixing frequencies in
order to implement two- and three-channel ADC systems. The two- and three-channel systems have overall input bandwidths of
2 and 3 GHz and effective conversion rates of 4 and 6 GS/s, respectively, while maintaining their single-path resolution across
their entire input bandwidths. The implemented architecture provides an extendible solution to improve the speed of ADCs by
incorporating them in an FTH-ADC architecture. 相似文献