全文获取类型
收费全文 | 528篇 |
免费 | 33篇 |
专业分类
电工技术 | 3篇 |
综合类 | 1篇 |
化学工业 | 129篇 |
金属工艺 | 12篇 |
机械仪表 | 18篇 |
建筑科学 | 26篇 |
能源动力 | 51篇 |
轻工业 | 70篇 |
水利工程 | 2篇 |
石油天然气 | 4篇 |
无线电 | 36篇 |
一般工业技术 | 105篇 |
冶金工业 | 40篇 |
原子能技术 | 5篇 |
自动化技术 | 59篇 |
出版年
2024年 | 2篇 |
2023年 | 8篇 |
2022年 | 19篇 |
2021年 | 8篇 |
2020年 | 25篇 |
2019年 | 19篇 |
2018年 | 23篇 |
2017年 | 25篇 |
2016年 | 32篇 |
2015年 | 14篇 |
2014年 | 26篇 |
2013年 | 57篇 |
2012年 | 27篇 |
2011年 | 26篇 |
2010年 | 18篇 |
2009年 | 39篇 |
2008年 | 33篇 |
2007年 | 20篇 |
2006年 | 19篇 |
2005年 | 16篇 |
2004年 | 15篇 |
2003年 | 12篇 |
2002年 | 11篇 |
2001年 | 9篇 |
2000年 | 5篇 |
1999年 | 4篇 |
1998年 | 15篇 |
1997年 | 7篇 |
1996年 | 8篇 |
1995年 | 6篇 |
1994年 | 4篇 |
1993年 | 2篇 |
1992年 | 2篇 |
1991年 | 1篇 |
1989年 | 1篇 |
1987年 | 1篇 |
1985年 | 1篇 |
1977年 | 1篇 |
排序方式: 共有561条查询结果,搜索用时 15 毫秒
41.
Ufuk Yildiz Ignác Capek Dušan Berek Yanko Sarov Ivo W Rangelow 《Polymer International》2007,56(3):364-370
The inverse microemulsion copolymerization of acrylamide and butyl acrylate initiated by ammonium peroxodisulphate, a water‐soluble initiator, and stabilized by anionic emulsifiers sodium bis‐2‐ethylhexylsulfosuccinate and sodium dodecylsulphate (SDS) has been studied. An increase of SDS concentration was observed to increase both the rate of polymerization and the particle size. The average number of radicals per particle (n?) is much below 0.5, which indicates desorption of monomeric radicals from polymer particles. The exit (desorption) rate constants k′des (cm2 s?1) and kdes (s?1) were evaluated as a function of SDS concentration (or the particle size) according to the Ugelstad/O'Toole (I), Nomura (II) and Gilbert (III) models. The value of kdes (s?1) decreases with increasing particle size (or SDS concentration) for all three (I, II and III) models. A complex trend appears for k′des (cm2 s?1): the Ugelstad/O'Toole model estimates a decrease, the Nomura model finds no variation and the Gilbert model estimates even a slight increase in k′des with increasing SDS concentration. Copyright © 2006 Society of Chemical Industry 相似文献
42.
Esra Maltas Mustafa Ozmen Hasibe Cingilli Vural Salih Yildiz Mustafa Ersoz 《Materials Letters》2011,65(23-24):3499-3501
The magnetite (Fe3O4) nanoparticles were prepared by the co-precipitation of ferrous and ferric salts with NH4OH, and then modified with 3-aminopropyltriethoxysilane (APTES) by silanization reaction and subsequent reaction with glutaraldehyde (GA) to obtain functional groups on their surface. The influence of different terminated groups on protein binding was studied with bare and modified magnetite nanoparticles. Amine terminated magnetite nanoparticles were shown the highest binding ability for immobilization process compared to Fe3O4 NPs and GA bonded NPs. This binding ability was shown by using sodium dodecyl polyacrylamide gel electrophoresis technique (SDS-PAGE). Albumin attached magnetite nanoparticles were also examined by Scanning Electron Microscopy (SEM). 相似文献
43.
Eylem Dizman Tomak Mark Hughes Umit C. Yildiz Hannu Viitanen 《Journal of Materials Science》2011,46(3):598-607
The aim of the study was to screen any possible synergistic effect available with combination of plant oils and boron compounds
to decrease boron leaching and improve thermal degradation of wood by means of dual treatment. In order to reduce the leachability
of boron compounds, sapwood of beech and Scots pine samples were treated with oils to create a hydrophobic layer on the wood
cells that may prevent water uptake. Increase (%) of boron retained in double-treated samples after leaching was approximately
20% compared to boron-treated samples without oil. The most promising results on boron leaching obtained in the case of using
waste and sunflower oil. Thermogravimetric residues were increased by the higher loading of boron compounds in double-treated
samples. Spectra of FTIR-Photoacoustic spectrometer showed some deformation of lignin and cellulose followed by degradation
of hemicelluloses of treated wood samples due to heat effect at 160 °C. 相似文献
44.
A. Yildiz D. Crisan N. Dragan N. Iftimie D. Florea D. Mardare 《Journal of Materials Science: Materials in Electronics》2011,22(9):1420-1425
0.5 wt% Pd-doped titanium oxide thin films were obtained by dip-coating on silicon substrates. The films were compacted by
annealing in air at 300 and 500 °C. Temperature dependent electrical conductivity measurements were performed in the temperature
range 373–623 K, in different environments (air, methane, acetone, ethanol, formaldehyde and liquefied petroleum gas), to
test the films sensing gas properties. Formaldehyde was found to be the test gas that produces the most significant changes
in the electrical conductivity of the studied films. This was the reason why it was chosen to investigate its effect on their
electrical conductivity. A model was proposed, the model of the potential fluctuations at grain boundaries. A comparison between
some parameters obtained in the proposed model was performed as a function of annealing temperature, and as a function of
gas atmosphere. The values of the mean barrier height and the standard deviation were estimated to range between 0.336–0.588 eV
and 0.175–0.199 eV, respectively. It was found that formaldehyde leads to a rather sharp decrease in the values of the barrier
height and the standard deviation, and to an increase in the conductivity. We have observed the best sensing gas performance
for the films annealed at 300 °C, comparing to their counterparts annealed at 500 °C, explained by the lowest values of the
barrier energy height and the standard deviation. 相似文献
45.
A Ozünlü A Dündar A Yildirim FR Yildiz 《Canadian Metallurgical Quarterly》1995,74(12):831-3, 837, 839
Rosai-Dorfman disease, or sinus histiocytosis with massive lymphadenopathy (SHML), is a benign, self-limited pseudolymphomatous entity with characteristic histologic features. The disease may be atypically present in the absence of detectable nodal involvement. This is a case of nasal septum involvement of Rosai-Dorfman disease without clinically apparent lymphadenopathy. 相似文献
46.
A UV-curable acrylated urethane prepolymer was synthesized from tolylene-2,4-diisocyanate (TDI), a polyether polyol (Arcol 1131) and endcapped with 2-hydroxyethyl methacrylate (HEMA) by addition reaction in the presence of dibutyltin dilaurate as catalyst. UV curing was performed with either diethylene glycol diacrylate or thiodiethylene glycol diacrylate as reactive diluent. The effects of reactive diluent types, their concentrations and the humidity of environment on mechanical properties of cured films were investigated. Changes in the tensile strength, elongation and Young's modulus values of the cured films upon addition of reactive diluents with different concentrations were related to the effect of the diluent on the crosslinking density of cured films. The increase of relative humidity from 50 to 95% caused a decrease of tensile strength and Young's modulus values of cured films. It is proposed that the decrease of these physical properties in high relative humidity is due to the formation of hydrogen bonding in polymer chains caused by water molecules. 相似文献
47.
Ilkay Orhan Murat Kartal Qamar Naz Asma Ejaz Gülderen Yilmaz Yüksel Kan Belma Konuklugil Bilge Şener M. Iqbal Choudhary 《Food chemistry》2007,103(4):1247-1254
Since Salvia species (Lamiaceae) have been recorded to be used against memory loss in European folk medicine, we herein examined in vitro anticholinesterase and antioxidant activities of 56 extracts prepared with petroleum ether, chloroform, ethyl acetate and methanol obtained from 14 Salvia species (Salvia albimaculata Hedge and Hub, Salvia aucheri Bentham var. canescens Boiss and Heldr, Salvia candidissima Vahl. ssp. occidentalis, Salvia ceratophylla L., Salvia cryptantha Montbret and Bentham, Salvia cyanescens Boiss and Bal., Salvia frigida Boiss, Salvia forskahlei L., Salvia halophilaHedge, Salvia migrostegia Boiss and Bal., Salvia multicaulis Vahl., Salvia sclarea L., Salvia syriaca L., Salvia verticillata L. ssp. amasiaca) growing in Turkey. The antioxidant activities were assessed by both chemical and enzymatic methods against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and xanthine/xanthine oxidase (XO) system generated superoxide anion radical inhibition. Anticholinesterase effect of the extracts was tested against both acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) at concentrations of 0.2 and 1 mg/ml using a microplate-reader assay based on the Ellman method. Most of the extracts did not show any activity against AChE at 0.2 mg/ml, while the chloroform extracts had noticeable inhibition against BChE between 47.7% and 74.7%. The most active extracts at 1 mg/ml for AChE inhibition were observed to be petroleum ether extract of Salvia albimaculata (89.4%) and chloroform extract of Salvia cyanescens (80.2%), whereas ethyl acetate extracts of Salvia frigida and Salvia migrostegia, chloroform extracts of Salvia candidissima ssp. occidentalis and Salvia ceratophylla, as well as petroleum ether extract of Salvia cyanescens were found to inhibit potently BChE (92.2%, 89.6%, 91.1%, 91.3%, and 91.8%, respectively). Particularly, the ethyl acetate and methanol extracts were observed to be highly active against both DPPH and XO. Our data indicates that nonpolar extracts of Salvia species for anticholinesterase activity and the polar extracts for antioxidant activity are worth further phytochemical evaluation for identifying their active components. 相似文献
48.
Coupled transport of thiocyanate ions through a liquid membrane containing quaternary ammonium chloride salts in chloroform was examined. The influences of the carrier type in the membrane phase on the coupled transport of thiocyanate ions were investigated. The kinetics of the coupled transport were analyzed in the formalism of two consecutive irreversible first-order reactions and the kinetic parameters (k1d, k2m, k2a, Rmmax, tmax, Jdmax, Jamax) were also calculated. For the coupled transport of thiocyanate ions, quaternary ammonium chloride salts having different carbon atom numbers (Cn) used as carriers were found to increase thiocyanate ions transport efficiency with increasing carbon atom numbers. Tetradecyl trimethylammonium chloride (TDTMACl), hexadecyl trimethylammonium chloride (HDTMACl), and tetraoctyl ammonium chloride (TOACl) were found to be the most effective carrier types for transport of thiocyanate ions when Cn is greater than 16. The activation energies for maximum membrane entrance and exit fluxes were calculated as 32.45 kJ/mol and 34.75 kJ/mol, respectively. The values of the activation energy indicate that the process is controlled by species diffusion. 相似文献
49.
This paper investigates the dynamic shear amplification in reinforced concrete shear walls designed according to the seismic provisions of the current Turkish Building Earthquake Code (TBEC-2018). Shear walls with a high ductility level and different aspect ratios are examined to evaluate the design shear force calculated by using the dynamic amplification factor (βv) and overstrength factor (D) defined in TBEC-2018. For this purpose, response spectrum analyses (RSAs) are first carried out on two-dimensional cantilever shear walls with heights of 30, 45, and 60 m and with lengths of 1.5, 3, and 4.5 m in the plan. Then, a total of 198 nonlinear time history analyses (NLTHAs) are performed with real and simulated ground motions matched to the elastic design spectrum defined in TBEC-2018. The comparison of the design shear forces obtained from RSA and the shear demands obtained from NLTHA along the heights of the walls reveals that the design shear forces calculated according to TBEC-2018 may underestimate the actual shear demands from studied ground motions. Moreover, the applicability of the updates proposed to TBEC-2018 for the design shear force and shear force diagram along the wall height in reinforced concrete shear wall-frame systems to cantilever shear walls is also examined. 相似文献
50.
Various applications of slurry transportation through pipelines exist. A transportation problem is formulated to determine the pipe diameters and amounts of transported slurry from the production to the consumption points. The minimisation of the cost consisting of the pipe and energy cost terms is considered as the objective function. Pipe cost is given as the function of pipe diameters and the energy cost is defined as the function of pipe diameters and slurry amounts. Energy cost is obtained by using the relation that is previously determined after the experimental studies have been made for the magnetite ore. Genetic algorithm is used as the optimisation method and to apply this method a commercially available software written in the C language is used and modified. The proposed methodology to solve this non-linear programming problem is applied to a transportation system and it is found that the proposed methodology has made the complex, labour-intensive solution process very convenient for the users. 相似文献