全文获取类型
收费全文 | 377篇 |
免费 | 24篇 |
国内免费 | 7篇 |
专业分类
电工技术 | 8篇 |
综合类 | 3篇 |
化学工业 | 105篇 |
金属工艺 | 15篇 |
机械仪表 | 10篇 |
建筑科学 | 11篇 |
矿业工程 | 1篇 |
能源动力 | 27篇 |
轻工业 | 16篇 |
水利工程 | 5篇 |
石油天然气 | 1篇 |
无线电 | 38篇 |
一般工业技术 | 70篇 |
冶金工业 | 21篇 |
原子能技术 | 2篇 |
自动化技术 | 75篇 |
出版年
2023年 | 4篇 |
2022年 | 7篇 |
2021年 | 25篇 |
2020年 | 24篇 |
2019年 | 29篇 |
2018年 | 36篇 |
2017年 | 22篇 |
2016年 | 26篇 |
2015年 | 19篇 |
2014年 | 27篇 |
2013年 | 29篇 |
2012年 | 27篇 |
2011年 | 42篇 |
2010年 | 20篇 |
2009年 | 13篇 |
2008年 | 14篇 |
2007年 | 11篇 |
2006年 | 5篇 |
2005年 | 7篇 |
2004年 | 4篇 |
2003年 | 5篇 |
2002年 | 2篇 |
2000年 | 1篇 |
1997年 | 2篇 |
1995年 | 2篇 |
1993年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 1篇 |
排序方式: 共有408条查询结果,搜索用时 46 毫秒
41.
M. Behzad 《Engineering Fracture Mechanics》2008,75(16):4695-4705
In this paper, a new linear theory for bending stress-strain analysis of a cracked beam has been developed. A displacement field has been suggested for the beam strain and stress calculations. The bending differential equation for the beam has been written using equilibrium equations. The required constant for this model is also obtained from fracture mechanics. The bending equation has been solved for a simply supported beam with rectangular cross-section and the results are compared with finite element and empirical results. There is an excellent agreement between theoretical results and those obtained by numerical and empirical methods. The model developed in this research is a simple and precise approximation of the behavior of the cracked beams in bending. 相似文献
42.
A robust and stable film comprising n-octylpyridinum hexafluorophosphate ([C8Py][PF6]) and 1:12 phosphomolybdic acid (PMo12) was prepared on glassy carbon electrodes modified with multiwall carbon nanotubes (GCE/MWCNTs) by dip-coating. The cyclic voltammograms of the GCE/MWCNTs/[C8Py][PF6]-PMo12 showed three well-defined pairs of redox peaks due to the PMo12 system. The surface coverage for the immobilized PMo12 and the average values of the electron transfer rate constant for three pairs of redox peaks were evaluated. The GCE/MWCNTs/[C8Py][PF6]-PMo12 showed great electrocatalytic activity towards the reduction of H2O2 and iodate. The kinetic parameters of the catalytic reduction of hydrogen peroxide and iodate at the electrode surface and analytical features of the sensor for amperometric determination of hydrogen peroxide and iodate were evaluated. 相似文献
43.
Zahir Nikraftar Esmaeel Parizi Seiyed Mossa Hosseini Behzad Ataie-Ashtiani 《Journal of Great Lakes research》2021,47(4):955-969
Lake Urmia is the second-largest hypersaline lake in the world. There has been a drastic water level drop of 7.2 m from 1995 to 2016. Beginning in October 2013, the Lake Urmia Restoration Plan (LURP) launched a 10-year program. An increase in water level and a relative improvement in Lake Urmia condition has been observed since 2017. It is an undecided and controversial issue whether the recent positive trend of Lake Urmia has been due to the LURP activities or it is a natural contribution of climate factors variations. To shed some light on this issue, we examine three other lakes, adjacent to the Lake Urmia basin, with similar rainfall variability to investigate their status during the same period. Van (Turkey), Mosul, and Tharthar (both in Iraq), are evaluated as well as Lake Urmia. Three decades of remotely sensed data including precipitation (), water level (), and lake extent () were considered for the mentioned lakes. A significant correlation was observed between standardized , and over the long-term period, especially for the recent three years (2 = 0.63–0.87). We show that the cumulative precipitation in the antecedent months played a major role in the improvement of these lakes' situation but with different time lags (up to 6 months for Van and Mosul lakes and up to 36 months for Lake Urmia and Tharthar lake). These findings could inform the planners of LURP to adopt strategies for achieving a sustainable state of Lake Urmia based on a more realistic outlook. 相似文献
44.
Mojtaba Kooshki Hamid Abdollahi Somayyeh Bozorgzadeh Behzad Haghighi 《Electrochimica acta》2011,(24):8618
Three-way data obtained from different pulse heights of differential pulse voltammetry (DPV) was analyzed using multivariate curve resolution by alternating least squares (MCR-ALS) algorithm. Differential pulse voltammograms of tryptophan were recorded at a gold nanoparticles decorated multiwalled carbon nanotube modified glassy carbon electrode (GCE/MWCNTs-nanoAu). The determination of tryptophan was performed even in the presence of unexpected electroactive interference(s). Both the simulated and experimental data were non-bilinear. Therefore a potential shift algorithm was used to correct the observed shift in the data. After correction, the data was augmented and MCR-ALS was applied to the augmented data. A relative error of prediction of less than 8% for the determination of the simulated analyte of interest and tryptophan in synthetic samples indicated that the methodology employing voltammetry and second-order calibration could be applied to complex analytical systems. 相似文献
45.
Behzad Kord 《应用聚合物科学杂志》2011,120(1):607-610
This research was carried out to investigate on the effect of organomodified montmorillonite (OMMT) on the flame retarding characteristics and clay dispersion of composites based on high‐density polyethylene and rice husk flour. To meet this objective, the blend nanocomposites were prepared through the melt mixing of high‐density polyethylene and rice husk flour at 50% weight ratios, with various amounts of OMMT (0, 2, 4, and 6 per hundred compounds) in Hakee internal mixer; then, the samples were made by injection molding. Results indicated that the burning rate, total smoke production, and heat release rate of samples decreased with increasing the OMMT content. Also, the char residue and time to ignition increased with increasing the nanoclay loading. X‐ray diffraction patterns revealed that the nanocomposites formed were intercalated. Also, morphological findings showed that samples containing 2 per hundred compounds of OMMT had higher order of intercalation and better dispersion. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
46.
47.
Next-generation wireless networks will support a wide range of data rates over several frequency bands and require adaptive and programmable system resources. Radio transceivers used in these wireless networks will incorporate self-calibration and full programmability to support their high performance and adaptivity. Low power designs at the circuit architectural, and overall system levels will enable longer battery life for portable devices. Many additional challenges exist in implementing high data rate programmable orthogonal frequency division multiplexing (OFDM) multiple-input/multiple-output (MIMO) radio transceivers that cover different frequency bands, maintain low current consumption, and are low cost. This article is an examination of the challenges in implementing high data rate programmable orthogonal frequency division multiplexing multiple-input/multiple-output radio transceivers that cover different frequency bands, maintain low current consumption, and are low cost. 相似文献
48.
Seyed Ahmad Hosseini Pour Behzad PourabbasMahdi Salami Hosseini 《Materials Chemistry and Physics》2014
Conductive immiscible multiphase blends of PMMA/LDPE filled with carbon black (CB) were studied in this work. Thermo-electrical behavior of the blends was compared with the composites made up of individual polymers in the blend, PMMA and LDPE filled with CB. The conductivity of the immiscible binary blend at different CB content was followed and modeled using a model circuit in which resistors resembling different phases and the interface between them present in the blend. Electrical percolation threshold was measured for the blend and compared with the single component polymers in order to judge the preferred phase for CB distribution in it. Rheological network formation by CB particles in the blend was also studied using dynamic rheology. The effect of CB loading on the morphology of the multiphase blend was also studied using FESEM images. Theoretical models were also used to predict the percolation thresholds for electrical and rheological network formation and compared with the experimental values. 相似文献
49.
Behzad Babaei Steven D. Abramowitch Elliot L. Elson Stavros Thomopoulos Guy M. Genin 《Journal of the Royal Society Interface》2015,12(113)
The viscoelastic behaviour of a biological material is central to its functioning and is an indicator of its health. The Fung quasi-linear viscoelastic (QLV) model, a standard tool for characterizing biological materials, provides excellent fits to most stress–relaxation data by imposing a simple form upon a material''s temporal relaxation spectrum. However, model identification is challenging because the Fung QLV model''s ‘box’-shaped relaxation spectrum, predominant in biomechanics applications, can provide an excellent fit even when it is not a reasonable representation of a material''s relaxation spectrum. Here, we present a robust and simple discrete approach for identifying a material''s temporal relaxation spectrum from stress–relaxation data in an unbiased way. Our ‘discrete QLV’ (DQLV) approach identifies ranges of time constants over which the Fung QLV model''s typical box spectrum provides an accurate representation of a particular material''s temporal relaxation spectrum, and is effective at providing a fit to this model. The DQLV spectrum also reveals when other forms or discrete time constants are more suitable than a box spectrum. After validating the approach against idealized and noisy data, we applied the methods to analyse medial collateral ligament stress–relaxation data and identify the strengths and weaknesses of an optimal Fung QLV fit. 相似文献
50.
It is well-known that transit-time ultrasonic flowmeters (TTUF) are unsuitable for bubble-contained flows. This paper presents a new online monitoring method based on optical observation, which monitors the functionality of the TTUF in the presence of bubbles in the fluid. The method avoids the unnecessary Emergency Shutdowns (ESD) due to bubble presence in the fluid by bubble detection. The proposed method accomplishes bubble identification through a combination of image processing and wavelet analysis. In addition, a new method is proposed which estimates single bubble size in horizontal pipes using a data fusion approach. 相似文献