全文获取类型
收费全文 | 1353篇 |
免费 | 117篇 |
国内免费 | 5篇 |
专业分类
电工技术 | 9篇 |
化学工业 | 461篇 |
金属工艺 | 33篇 |
机械仪表 | 54篇 |
建筑科学 | 39篇 |
能源动力 | 85篇 |
轻工业 | 200篇 |
水利工程 | 27篇 |
石油天然气 | 20篇 |
无线电 | 98篇 |
一般工业技术 | 219篇 |
冶金工业 | 31篇 |
原子能技术 | 7篇 |
自动化技术 | 192篇 |
出版年
2024年 | 5篇 |
2023年 | 26篇 |
2022年 | 60篇 |
2021年 | 126篇 |
2020年 | 113篇 |
2019年 | 101篇 |
2018年 | 127篇 |
2017年 | 123篇 |
2016年 | 103篇 |
2015年 | 52篇 |
2014年 | 107篇 |
2013年 | 146篇 |
2012年 | 103篇 |
2011年 | 85篇 |
2010年 | 59篇 |
2009年 | 41篇 |
2008年 | 27篇 |
2007年 | 22篇 |
2006年 | 9篇 |
2005年 | 8篇 |
2004年 | 6篇 |
2003年 | 1篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 1篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1990年 | 2篇 |
1988年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 1篇 |
1976年 | 1篇 |
1975年 | 2篇 |
排序方式: 共有1475条查询结果,搜索用时 15 毫秒
51.
Computational Visual Media - Photometric stereo is a fundamental technique in computer vision known to produce 3D shape with high accuracy. It uses several input images of a static scene taken from... 相似文献
52.
53.
Vahid Ghasemzadeh-mohammadi Bahman Zamani Maryam Afsharpour Abdorreza Mohammadi 《Food science and biotechnology》2017,26(5):1281-1290
In this research, optimal conditions for extraction of caffeine and polyphenols were established from Iranian green tea leaves. In the first step, caffeine was extracted with efficacy about 86% versed to 4.5% of EGC + EGCG. The EGCG + EGC was extracted from partially decaffeinated green tea leaves through microwave-assisted extraction (MAE) and ultrasound-assisted extraction (USE) with efficiency levels of 95 and 85%, respectively. The best results for the MAE process were obtained with 7.8 min and three number of extraction cycles and for the USE process were as followed: time 57 min, temperature 65 °C, and the number of extraction cycles 3. The total phenol content values at the best conditions of MAE and the USE processes were 125 ± 5 and 96 ± 6 mg gallic acid/g DW. The 50% inhibition (IC50) on 1,1-diphenyl-2-picrylhydrazyl (DPPH) were 56 and 66 mg/g of phenol for the MAE and USE processes. 相似文献
54.
Maryam Fattahi Hassan Abedini Mohammad Amin Anbaz 《Petroleum Science and Technology》2017,35(11):1117-1123
Favorable properties of aqueous solutions are improved with the addition of different materials for separation of hydrogen sulfide (H2S). Also, equilibrium data and available equations for solubility estimation of this gas are only valid for specific solutions and limited ranges of temperature and pressure. In this regard, a machine learning model based on Support vector machine (SVM) algorithm is proposed and developed with mixtures containing different amines and ionic liquids to predict H2S solubility over wide ranges of temperature (298–434.5 K), pressure (13–9319 kPa), overall mass concentration (3.82–100%) and mixture's apparent molecular weight (18.39–556.17 g/mol). The accuracy of the performance of this network was evaluated by regression analysis on calculated and experimental data, which had not been used in network training. 相似文献
55.
S. Siavash Saei‐Dehkordi Aziz A. Fallah Mahbubeh Heidari‐Nasirabadi Mehran Moradi 《International Journal of Food Science & Technology》2012,47(8):1579-1585
This study aimed to determine the chemical composition, antimicrobial and antioxidative activity of Satureja khuzestanica Jamzad essential oil. The oil was analysed by GC and GC/MS. Twenty‐eight constituents were identified. The oxygenated monoterpenes (78.22%) were the principal compound group. Among them, carvacrol (53.86%) and thymol (19.84%) were the most abundant constituents. The oil exhibited an acceptable antimicrobial activity against most of the tested microorganisms. The checkerboard method was applied to determine fractional inhibitory concentration indices (FICIs) to interpret the synergetic, additive, indifference or antagonistic interactions between essential oil and each of antimicrobials (lysozyme, ciprofloxacin, fluconazole and amphotericin B) against food‐related microorganisms. The synergetic phenomenon (FICI ≤ 0.5) was observed in majority of combinations with the exception of the essential oil and lysozyme. The oil exhibited good 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity (IC50 = 28.71 μg mL?1). Also, the oil had strong antioxidative activity in β‐carotene‐linoleic acid assay relative antioxidant activity (RAA% = 95.45). This study demonstrated that the essential oil has beneficial biological properties and its simultaneous application with standard antimicrobials against food‐related microorganisms result in reduction in inhibitory doses of the antimicrobials in vitro. 相似文献
56.
Maryam Masjedi-Arani Masoud Salavati-Niasari 《International Journal of Hydrogen Energy》2017,42(2):858-866
Zn2SnO4 nanostructures were obtained via facile and rapid co-precipitation approach in presence of amines with different long chain as a novel basic and capping agents. The effect of different amines such as NH3, ethylenediamine, triethylenetetramine, tetraethylenepentamine on the size of Zn2SnO4 nanostructures were investigated. The results demonstrated that applying the appropriate amount of organic amine could be effective in particle size control. The obtained nanostructure products were specified by powder X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX) and ultraviolet–visible (UV–vis) spectroscopy. Dye sensitized solar cells (DSSC) were created by the constructed electrodes as working electrode and then were studied by current density–voltage (J–V) curve. It was found that incorporating of TiO2 nanoparticles to optimized Zn2SnO4 nanostructures has significant role on the constructed DSSCs photovoltaic properties. 相似文献
57.
Iman Rad Hamid Mobasheri Farhood Najafi Maryam Rezaei 《Journal of materials science. Materials in medicine》2014,25(6):1539-1551
Membrane sealing effects of polymersomes made of tri-block copolymer, PEG-co-FA/SC-co-PEG, (PFSP) were studied on isolated spinal cord strips, PC12 cell lines and artificial bilayer following mechanical impact implemented by aneurism clip, sonication and electric shock, respectively. The homogeneity and size of PFSP, membrane permeability and cell viability were assessed by dynamic light scattering, LDH release and MTT assays. According to the results, the biocompatible, physico-chemical, size, surface charge and amphipathic nature of PFSP polymersome makes it an ideal macromolecule to rapidly reseal damaged membranes of cells in injured spinal cord as well as in culture medium. Compound action potentials recorded from intentionally damaged spinal cord strips incubated with PFSP showed restoration of neural excitability by 82.24 % and conduction velocity by 96.72 % after 5 min that monitored in real time. Thus, they triggered efficient instant and sustained sealing of membrane and reactivation of temporarily inactivated axons. Treatment of ultrasonically damaged PC12 cells by PFSP caused efficient cell membrane repair and led to their increased viability. The optimum effects of PFSP on stabilization and impermeabilizing of the lipid bilayer occurred at the same concentrations applied to the damaged cells and spinal cord fibers and was approved by restoration of membrane conductance and calcein release manifested by NanoDrop technique. The unique physico-chemical characteristics of novel polymersomes introduced here, make them capable to reorganize membrane lipid molecules, reseal the breaches and restore the hydrophobic insulation in spinal cord damaged cells. Thus, they might be considered in the clinical treatment of SCI at early stages. 相似文献
58.
Maryam M. Akho‐Zahieh Nasser Abdellatif 《Wireless Communications and Mobile Computing》2015,15(2):203-214
The wavelet packets based multicarrier (MC) multicode (MCD) code‐division multiple‐access (CDMA) transceiver consists of the MCD part, which ensures the transmission for high speed and flexible data rate; the MC part contributing to robustness to frequency‐selective fading and flexibility for handling multiple data rates; and wavelet packets (WPs) modulation technique, which contributes to the mitigation of the interference problems. As WPs have lower sidelobes compared with sinusoidal carriers, this system is very effective in reducing the problem of inter‐carrier interference. Of course, like any CDMA system, the system can suppress a given amount of interference. This paper considers an interference suppression scheme which will enhance the performance of the system. The receiver employs suppression filters to mitigate the effect of narrow‐band jammer interference. The framework for the system and the performance evaluation are presented in terms of the bit error rate and the outage probability over a Nakagami fading channel. Also, we investigate how the performance is influenced by various parameters, such as the number of taps of the suppression filter and the ratio of narrow‐band interference bandwidth to the spread‐spectrum bandwidth. Finally, the performance of the system is compared with the performance of sinusoidal based MC/MCD‐CDMA system denoted Sin‐MC/MCD‐CDMA. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
59.
A simple and fast method based on solid phase extraction (SPE) applying zinc oxide (ZnO) nanoparticles and atomic absorption spectrometry (AAS) was developed for the trace amount determination of silver (Ag) in aqueous samples. The method linearity was in the range of 14 to 700 ng mL?1. The extraction efficiency of Ag was greater than 98% and limit of detection (LOD) was 4.2 ng mL?1. The preconcentration factor was 200 and the relative standard deviation (RSD%) of the method was 3.7% (n = 6). 相似文献
60.
Polyester composite water uptake and organic contaminant release affected by carbon nanofiber reinforcements
下载免费PDF全文
![点击此处可从《应用聚合物科学杂志》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Maryam Salehi Ajay Krishnamurthy Aaron M. Forster Kuang–Ting Hsiao Andrew J. Whelton 《应用聚合物科学杂志》2016,133(30)
The incorporation of carbon nanofiber (CNF) into glass fiber (GF) composites is a potential route to extend polymer composite service‐life and enhance mechanical properties. Under nonstatic conditions, only limited information concerning water uptake and contaminant release properties of nanocomposite materials is currently available. Polyester composites containing GF and oxidized CNF were immersed in water for 30 days under nominal pressure at 23 °C, below the polymer's glass‐transition temperature. Water was analyzed and changed every three days to simulate water chemistry regeneration similar to exposures in flowing systems. Composites with oxidized CNF had greater water sorption capacity and leaching rates than CNF‐free composites. The total mass of organic contaminant released correlated with the amount of water sorbed by each composite (r2 = 0.91), although CNF dispersion was found to vary greatly within composites. The greatest and least contaminant release rates were found for the polyester‐CNF and the polyester‐GF composites, respectively. While volatile aromatic resin solvents and stabilizer compounds were detected, their concentrations declined over the 30 day exposure period. We hypothesize that the hydrophilic nature of the oxidized CNF increased the water sorption capacity of the polyester composites. Additional studies are warranted that examine the impact of this phenomenon on composite mechanical and long‐term durability properties. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43724. 相似文献