全文获取类型
收费全文 | 132篇 |
免费 | 4篇 |
专业分类
化学工业 | 34篇 |
金属工艺 | 5篇 |
机械仪表 | 14篇 |
建筑科学 | 1篇 |
能源动力 | 6篇 |
轻工业 | 19篇 |
水利工程 | 1篇 |
无线电 | 14篇 |
一般工业技术 | 24篇 |
冶金工业 | 4篇 |
原子能技术 | 3篇 |
自动化技术 | 11篇 |
出版年
2023年 | 1篇 |
2021年 | 14篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 5篇 |
2017年 | 6篇 |
2016年 | 1篇 |
2015年 | 5篇 |
2014年 | 4篇 |
2013年 | 11篇 |
2012年 | 11篇 |
2011年 | 14篇 |
2010年 | 8篇 |
2009年 | 6篇 |
2008年 | 3篇 |
2007年 | 5篇 |
2006年 | 2篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 3篇 |
2002年 | 1篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 3篇 |
1995年 | 3篇 |
1994年 | 1篇 |
1992年 | 1篇 |
1987年 | 1篇 |
1986年 | 1篇 |
1979年 | 1篇 |
排序方式: 共有136条查询结果,搜索用时 18 毫秒
1.
Sara Asadi Mohsen Jahan Alireza Farid Hosseini 《International journal of remote sensing》2019,40(18):7153-7168
Rapid and accurate estimation of Ground Cover (GC) at regional and global scales for agricultural management application is only possible by using remote sensing (RS). In this study, two Vegetation Indices (VIs) including the Perpendicular Vegetation Index (PVI) and Normalized Difference Vegetation Index (NDVI) were used for estimating GC. Since the parameters of the bare soil line have an important role in calculating GC based on PVI, this line was extracted based on the red-NIRmin (minimum near infrared) method with different intervals (0.0001, 0.0005, and 0.0010). In addition to traditional statistics such as Root Mean Square Error (RMSE), the sensitivity analysis (S) was also used to sharpen the accuracy of the models' estimations. The results indicated that the PVI-based method, in contrast to the NDVI-based approach, had a better performance in estimating GC of wheat. The highest correlation between the observed GC and the estimated GC based on PVI method was achieved in interval length of 0.0005 (R2 = 0.91) with RMSE equal to 8.82. This regression line (GCEST = -3.47 + 0.96 GCOBS) was not significantly different from the 1:1 line. As expected, the best estimation was achieved when the sensitivity of estimated GC based on PVI (length of the interval: 0.0005) was almost constant and low compared to the other models. 相似文献
2.
Electrically charged cellular ferroelectrets can show excellent thermally stable piezoelectric activity and are therefore progressively used in electrochemical transducers. Given that an optimized cellular structure is a key for improving charge density and the associated piezoelectric properties in this material, we investigated the influence of CO2 inflation treatment using various gas diffusion expansion or inflation procedures on the piezoelectric d33 coefficient and thermal stability of cellular poly(vinylidene) ferroelectrets and compare with the results (partially) obtained by N2 inflation as reported in our previous study (Jahan, Mighri, Rodrigue, Ajji, J. Appl. Polym. Sci. 2019, 136, 47540). Samples were prepared using the conventional extrusion–stretching–inflation–corona charging method. Maximum d33 coefficient for CO2-inflated samples is found to be around 30% higher than that of N2-inflated samples (327 pC/N compared to 251 pC/N) by stepwise pressure application method. The key parameters addressed in the inflation procedures are the changes in sample thickness, morphology, and the void-height distribution in both gas treatments. The ferroelectrets show excellent thermal stability for up to 4 days at 90, 110, and 120 °C in both treatments with a slightly improved performance in CO2 gas. The higher activation energy of CO2-inflated samples (0.52 eV) than the N2-inflated ones (0.43 eV) further confirms the stability data. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47929. 相似文献
3.
Chemical vapor deposition of poly(3‐alkylthiophene) nanoparticles on fabric: Chemical and electrochemical characterization 下载免费PDF全文
Chemical vapor deposition of poly(3‐methylthiophene) and poly (3‐hexylthiophene) as conductive polymers on the surface of polyester fabrics was successfully obtained. Fourier transform infrared spectroscopy confirmed the formation of polymers on surface of fabrics (the fingerprint of polythiophenes, υ 600–1500 cm?1). The uniformity of deposition and nanoparticles (average size of 60 nm) were proved with scanning electron microscopy. Electrochemical impedance spectroscopy showed that P3HT‐coated samples offer higher conductivity in compared to P3MT‐coated samples. The impedance modulus of P3HT‐coated samples was lowered nine times to that of row materials and reached to c8000 Ω. The samples have also shown electrochromic properties under electrical current, changing its color from yellowish green at 0 V to dark green at +12 V for poly (3‐hexylthiophene) samples and from brown at 0 V to red at +12 V for poly(3‐methylthiophene)‐coated fabrics (V = 0 V, λ = 450 nm; V = 12 V, λ = 650 nm). © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40673. 相似文献
4.
Hossein Vojoudi Jahan B. Ghasemi Ahmadreza Hajihosseinloo Bahareh Bastan Alireza Badiei 《Advanced Powder Technology》2021,32(4):1060-1069
A hybrid nanocomposite of alumina and hematite was synthesized by ultrasonic spray pyrolysis technique. The study of microscopic images, mapping analysis, and XRD patterns revealed that the Al2O3 – Fe2O3 nanocomposite was composed of separated spherical particles with a thin layer ball-shaped structure that metal oxides are uniformly distributed in the wall of hollow sphere particles, led to a coherent and monotonous construction. A series of coefficients of equilibrium sorption of polycyclic aromatic hydrocarbons (PAHs) as hazardous materials were measured on the prepared composite material in a batch technique. The free or pure Al2O3 or Fe2O3 showed negligible removal efficiency for the mentioned analytes. The various significant variables, such as initial analyte concentration, solution pH, adsorbent dose, and contact time to remove analyte, were studied in the aqueous solutions. Adsorption data were modeled to Langmuir, Freundlich, and Temkin isotherms, and a good correlation found in the case of Langmuir isotherm and adsorption capacity for anthracene, phenanthrene, and naphthalene were 370, 333, and 322 mg g?1, respectively. Investigation of the kinetic models proved a pseudo-second-order, and the prepared adsorbent can be reused more than 7 times without a significant decrease of adsorption performance. 相似文献
5.
Jahan Miremami Natasha Kyprianou 《International journal of molecular sciences》2014,15(12):23897-23908
Bladder cancer is the fourth most common malignancy in the US and is associated with the highest cost per patient. A high likelihood of recurrence, mandating stringent surveillance protocols, has made the development of urinary markers a focus of intense pursuit with the hope of decreasing the burden this disease places on patients and the healthcare system. To date, routine use of markers is not recommended for screening or diagnosis. Interests include the development of a single urinary marker that can be used in place of or as an adjunct to current screening and surveillance techniques, as well identifying a molecular signature for an individual’s disease that can help predict progression, prognosis, and potential therapeutic response. Markers have shown potential value in improving diagnostic accuracy when used as an adjunct to current modalities, risk-stratification of patients that could aid the clinician in determining aggressiveness of surveillance, and allowing for a decrease in invasive surveillance procedures. This review discusses the current understanding of emerging biomarkers, including miRNAs, gene signatures and detection of circulating tumor cells in the blood, and their potential clinical value in bladder cancer diagnosis, as prognostic indicators, and surveillance tools, as well as limitations to their incorporation into medical practice. 相似文献
6.
Nazish Jahan Saba Aslam Khalil ur Rahman Tuba Fazal Fareeha Anwar Rubab Saher 《Journal of Experimental Nanoscience》2016,11(1):72-80
Nanotechnology is a promising technique to increase the bioavailability of herbal medicines. This paper presents the nanosuspension approach for increasing the aqueous solubility and thereby bioactivity of important herbal extracts. Nanosuspensions of the seeds of three plants extract (Silybum marianum, Elettaria cardamomum and Coriandrum sativum) were prepared by using polyvinyl alcohol (1.5% w/v) as a stabiliser. Prepared nanoparticles were characterised by scanning electron microscope. Activity of nanosuspension formulation was assessed by using four in vitro antioxidant assays. S. marianum, E. cardamomum and C. sativum particle size was observed to fall in range of 446.1 ± 112.6, 456.63 ± 339.2 and 432.1 ± 172.8 nm, respectively, most of the particles were having spherical shape and smooth topology. These synthesised nanoparticles were found to be more effective against quenching free radical than their crude extracts and standards [butylated hydroxyl toluene and ascorbic acid]. C. sativum nanosuspension showed most free radical scavenging potential against 2,2-diphenyl-1-picrylhdrazyl (DPPH) and superoxide free radical scavenging assays (IC50 0.59 ± 0.01 and 0.81 ± 0.11 mg/ml). S. marianum nanosuspension was found to be most effective against DPPH radicals scavenging (IC50 0.34 ± 0.02 mg/ml). It was concluded that nanosuspension of herbal medicines potentiates the antioxidant potential. 相似文献
7.
In this paper, we investigated the activation energies of the aggregation–disaggregation self-oscillation induced by the Belousov-Zhabotinsky (BZ) reaction by utilizing the nonthermoresponsive polymer chain in a wide temperature range. This is because the conventional type self-oscillating polymer chain, with thermoresponsive poly(Nisopropylacrylamide) (poly(NIPAAm) main-chain covalently bonded to the ruthenium catalyst (Ru(bpy)3) of the BZ reaction, cannot evaluate the activation energy over the lower critical solution temperature (LCST). The nonthermoresponsive self-oscillating polymer chain is composed of a poly-vinylpyrrolidone (PVP) main-chain with the ruthenium catalyst (Ru(bpy)3). As a result, we clarified that the activation energy of the aggregation–disaggregation self-oscillation of the polymer chain is hardly affected by the concentrations of the BZ substrates. In addition, the activation energy of the nonthermoresponsive self-oscillating polymer chain was found to be almost the same value as normal BZ reaction, i.e., not including the self-oscillating polymer system with Ru moiety. 相似文献
8.
Jahan Taghizadeh Mehdi Ahmadi Najafabadi 《Russian Journal of Nondestructive Testing》2011,47(7):491-500
The objective of this study is to utilize a mathematical procedure for the evaluation of damage mechanism in ultra high molecular
weight polypropylene/epoxy composite (UHMWPP/epoxy) specimen with different configuration based on the analysis of the AE
signals of presented. Principal component analysis (PCA) is powerful tool, which utilized for the classification of the monitored
AE transients. We worked on epoxy L160 resin, UHMWPP fiber bundle and UHMWPP/epoxy unidirectional specimens, subjected to
tensile loading. Using model specimens exhibiting a predominant damage mechanism, correlations were established between the
observed damage growth mechanisms and the AE parameter variances result in PCA. Outputs from this study revealed that the
PCA is an effective tool for identifying damage modes such as matrix cracking, fibre/matrix debonding, fibre breakage and
fibre pull-out in the UHMWPP/epoxy composites. The presence of damage modes in UHMWPP/epoxy composites was proven with scanning
electron microscopy (SEM) images. 相似文献
9.
10.
A facile and one-step method for fabrication of Pd/Pt bimetallic microstructure using galvanic replacement reaction is presented. This electroless deposition was performed without any additive reagent via simple immersion of the copper sheet in cation aqueous solution of Pd and Pt. The as-prepared electrode was characterized by using the techniques of scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and cyclic voltammetry and tested for the hydrogen evolution reaction (HER) in the acidic media. Comparison of the HER on the Pd/Pt bimetallic catalysts with different Pd:Pt percentage compositions indicated that the Pd60Pt40 catalyst had the highest HER activity among all the Pd/Pt catalysts and a better performance than the pure Pt. The effects of galvanic replacement time and concentration of H2SO4 on the catalytic activity of as-prepared electrode for HER were comparatively investigated. 相似文献