全文获取类型
收费全文 | 174篇 |
免费 | 22篇 |
国内免费 | 1篇 |
学科分类
工业技术 | 197篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 16篇 |
2020年 | 6篇 |
2019年 | 15篇 |
2018年 | 15篇 |
2017年 | 18篇 |
2016年 | 8篇 |
2015年 | 5篇 |
2014年 | 14篇 |
2013年 | 24篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 7篇 |
2009年 | 6篇 |
2008年 | 8篇 |
2007年 | 3篇 |
2006年 | 1篇 |
2005年 | 2篇 |
1999年 | 2篇 |
1998年 | 4篇 |
1997年 | 2篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1971年 | 1篇 |
1969年 | 1篇 |
排序方式: 共有197条查询结果,搜索用时 15 毫秒
101.
102.
Seyed Abbas Taher Ali Karimian Mohammad Hasani 《Simulation Modelling Practice and Theory》2011,19(2):662-672
This paper presents an optimization algorithm for simultaneous improvement of power quality (PQ), optimal placement and sizing of fixed capacitor banks in radial distribution networks in the presence of voltage and current harmonics. The algorithm is based on particle swarm optimization (PSO). The objective function includes the cost of power losses, energy losses and those of the capacitor banks. Constraints include voltage limits, number/size of installed capacitors at each bus, and PQ limits of standard IEEE-519. Using a newly proposed fitness function, a suitable combination of the objective function and relevant constraints is defined as a criterion to select a set of the most suitable buses for capacitor placement. This method is also capable of improving particles in several steps for both converging more readily to the near global solution as well as improving satisfaction of the power quality constraints. Simulation results for the 18-bus and 33-bus IEEE distorted networks using the proposed method are presented and compared with those of previous works. In the 18-bus IEEE distorted network, this indicated an improvement of 3.29% saving compared with other methods. Using the proposed optimization method and simulation performed on the 33-bus IEEE distorted network an annual cost reduction of 31.16% was obtained. 相似文献
103.
C. J. Luo Shirin Loh Eleanor Stride Mohan Edirisinghe 《Food and Bioprocess Technology》2012,5(6):2285-2300
Novel applications of efficient and economical techniques such as electrospraying and electrospinning in chocolate processing could be a strategy to help manufacturers improve declining sales growth rate in a saturated confectionery market. In this study, electrosprayed near-monodisperse particles have been produced using chocolate suspensions. Electrospun fibres have also been created from a commercial chocolate sauce. The effects of process parameters such as sugar concentration, addition of electrolytes (NaCl), flow rate, applied voltage and collection distance on the production and morphology of as-sprayed chocolate particles were studied. A positive linear trend in the electrosprayed chocolate particle diameter and diameter distribution range with increasing sugar concentration in the chocolate suspension was demonstrated. Sugar concentrations of 30–35%w/w resulted in very fine, near-monodisperse chocolate particles. Trace amounts of electrolyte at 1%w/w were found to decrease the average particle diameter and improve the monodispersity of the particles produced. The addition of NaCl at low concentrations increased the electrical conductivity and, to a lesser extent, the surface tension of the chocolate samples. Further increases in NaCl concentration to 3%w/w did not bring any additional decrease in the average diameter of the chocolate particles. In addition, the observed modes of electrospraying and the characteristics of chocolate particles obtained under these were investigated. Bead-on-string morphology was commonly observed among electrospun chocolate fibres. Moreover, satellite particles and very fine fibres were obtained during the transition between electrospraying and electrospinning. The continuous alternating shape of elongated spheres and thin fibres may have the potential for varying the microtexture of the chocolate products. 相似文献
104.
Shirin Safaei Iraj Mohammadpoor‐Baltork Ahmad R. Khosropour Majid Moghadam Shahram Tangestaninejad Valiollah Mirkhani 《Advanced Synthesis \u0026amp; Catalysis》2012,354(16):3095-3104
An efficient protocol for the excellent diastereoselective synthesis of pyrazolines via a three‐component reaction of aldehydes, hydrazines and dimethyl acetylenedicarboxylate (DMAD) in the presence of a bifunctional Brønsted acidic ionic liquid as a reusable catalyst under solvent‐free conditions is reported. Easy work‐up, short reaction times, high yields of the products and an environmentally benign procedure avoiding toxic organic solvents are other significant features of this method. 相似文献
105.
Depth-profiling of environmental pharmaceuticals in biological tissue by solid-phase microextraction
Zhang X Oakes KD Hoque ME Luong D Taheri-Nia S Lee C Smith BM Metcalfe CD de Solla S Servos MR 《Analytical chemistry》2012,84(16):6956-6962
The parallel in vivo measurement of chemicals at various locations in living tissues is an important approach furthering our understanding of biological uptake, transportation, and transformation dynamics. However, from a technical perspective, such measurements are difficult to perform with traditional in vivo sampling techniques, especially in freely moving organisms such as fish. These technical challenges can be well addressed by the proposed depth-profiling solid-phase microextraction (DP-SPME) technique, which utilizes a single soft, flexible fiber with high spatial resolution. The analytical accuracy and depth-profiling capability of DP-SPME was established in vitro within a multilayer gel system and an onion artificially contaminated with pharmaceuticals. In vivo efficacy was demonstrated by monitoring pharmaceutical distribution and accumulation in fish muscle tissue. The DP-SPME method was validated against pre-equilibrium SPME (using multiple small fibers), equilibrium SPME, and liquid extraction methods; results indicated DP-SPME significantly improved precision and data quality due to decreased intersample variation. No significant adverse effects or increases in mortality were observed in comparisons of fish sampled by DP-SPME relative to comparable fish not sampled by this method. Consequently, the simplicity, effectiveness, and improved precision of the technique suggest the potential for widespread application of DP-SPME in the sampling of heterogeneous biotic and abiotic systems. 相似文献
106.
An aqueous synthesis method to obtain highly luminescent cadmium telluride nanocrystals is described. We have shown water-soluble semi-conductor quantum dots with high photoluminescence quantum yield have great potential for biological applications. The spectral properties of these nanocrystals can be easily tuned according to their particle size to yield multicolours simultaneously by a single excitation light source. A stable precursor material sodium tellurite is utilised instead of the traditional oxygen sensitive NaHTe or H2Te as Te source. We have introduced mercaptosuccinic acid and propylisobutyl polyhedral oligomeric silsesquioxane nanoparticles as novel capping agents to stabilize the nanocrystals, synthesized in borate-citrate buffering system. Inclusion of propylisobutyl polyhedral oligomeric silsesquioxane nanoparticles in the capping procedure showed enhanced stability and biocompatibility. The presence of mercaptosuccinic acid/propylisobutyl polyhedral oligomeric silsesquioxane coatings was confirmed by Fourier Transform Infrared spectroscopy and average sizes of 2-5 nm by transmission electron microscopy measurements. The functionalized and targeted quantum dots detected cancer cell death on exposure to some anticancer drugs. Studies have indicated that apoptotic cells can activate signaling pathways in dendritic cells via ligation of surface receptors. Cells treated with specific class of pro-apototic drug such as anthracyclines mount an anti-tumour immune response when introduced into mice. Apoptotic cells may be immunogenic or non-immunogenic depending on the presence of calreticulin on the plasma membrane of dying tumour cells. Here the confocal microscopy showed localization of conjugated mercaptosuccinic acid/propylisobutyl polyhedral oligomeric silsesquioxane cadmium telluride quantum dots on MCF-7 cells when exposed to cadmium ions at 50 microM, compared to coated quantum dots. We have used cadmium ions as a model drug as certain anticancer drugs (anthracyclines) induce translocation of calreticulin to the cell membrane, an indicator of apoptosis. Antibodies generated against a peptide to human calreticulin and conjugated to quantum dots detected the protein on cell membrane of stimulated cells were visualized by confocal microscopy. Stimulating natural immune response, against tumours has enormous potential to improve current regimens of cancer detection and therapy. 相似文献
107.
Mohammad Mahdi Hasani-Sadrabadi Erfan Dashtimoghadam Seyed Reza Ghaffarian Mohammad Hossein Hasani Sadrabadi Mahdi Heidari Homayoun Moaddel 《Renewable Energy》2010,35(1):226-231
In the present research, proton exchange membranes based on partially sulfonated poly (ether sulfone) (S-PES) with various degrees of sulfonation were synthesized. It was found that the increasing of sulfonation degree up to 40% results in the enhancement of water uptake, ion exchange capacity and proton conductivity properties of the prepared membranes to 28.1%, 1.59 meq g−1, and 0.145 S cm−1, respectively. Afterwards, nanocomposite membranes based on S-PES (at the predetermined optimum sulfonation degree) containing various loading weights of organically treated montmorillonite (OMMT) were prepared via the solution intercalation technique. X-ray diffraction patterns revealed the exfoliated structure of OMMT in the macromolecular matrices. The S-PES nanocomposite membrane with 3.0 wt% of OMMT content showed the maximum selectivity parameter of about 520,000 S s cm−3 which is related to the high conductivity of 0.051 S cm−1 and low methanol permeability of 9.8 × 10−8 cm2 s−1. Furthermore, single cell DMFC fuel cell performance test with 4 molar methanol concentration showed a high power density (131 mW cm−2) of the nanocomposite membrane at the optimum composition (40% of sulfonation and 3.0 wt% of OMMT loading) compared to the Nafion®117 membrane (114 mW cm−2). Manufactured nanocomposite membranes thanks to their high selectivity, ease of preparation and low cost could be suggested as the ideal candidate for the direct methanol fuel cell applications. 相似文献
108.
Development of methods for encapsulation of viruses into polymeric nano‐ and microparticles for aquaculture vaccines 下载免费PDF全文
Atoosa Maleki Shirin Fanaian Kaizheng Zhu Antje Hoenen Cheng Xu Øystein Evensen Gareth Griffiths Bo Nyström 《应用聚合物科学杂志》2014,131(17)
To meet an urgent need for improved vaccines against viral diseases in aquaculture, encapsulating the viruses into biodegradable and biocompatible polymers was suggested to protect viral antigens from premature degradation and gradually expose them to the immune system. We used water‐in‐oil‐in‐water emulsion to first encapsulate model red fluorescent polystyrene (PS) particles and then infectious salmon anemia virus (ISAV) into poly‐lactic‐co‐glycolic acid (PLGA) together with coumarin 6. A milder layer‐by‐layer method was applied to incorporate both PS and ISAV into chitosan (Cs)‐fluorescein isothiocyanate and alginate (Alg) followed by ionic crosslinking. All particles were characterized by dynamic light scattering, zeta‐sizer, fluorescence, transmission‐ and scanning electron microscopy. Successful encapsulation of PS beads and ISAV into PLGA, Cs, and Alg was accomplished. The prepared particles were of different size, surface charge density, and morphology. This yields opportunities for further developments of these structures as vaccine candidates to be delivered by injection or oral administration. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40714. 相似文献
109.
Nanocomposite of poly (methacrylate) and spirobenzopyran-based fluorescent dye was synthesized via miniemulsion polymerization. In this study, hexadecane was used as a co-stabilizer. Considering the effect of dye concentration of nanocomposites, the kinetic behavior of synthesis of fluorescent nanocomposites and the rate of reactions (R p) were investigated. The resulting nanocomposite was characterized by FTIR, TGA, DLS, TEM, SEM, and fluorescent spectroscopic techniques. Different properties of nanocomposites are discussed in comparison to the neat latex and pure dye. The results show nano-hybrid structure that provides a protective microenvironment for improving the thermo-stability of fluorescent dyes. 相似文献
110.
Mohammad Peydayesh Shirin Asarehpour Toraj Mohammadi Omid Bakhtiari 《Chemical Engineering Research and Design》2013
Different SAPO-34 zeolite loaded Matrimid® 5218 mixed matrix membranes (MMMs) were prepared by solution casting method and characterized using XRD and SEM analysis. Findings showed that semi crystalline neat polymer becomes more crystalline after thermal treatment at higher temperatures close to Matrimid® 5218 glass transition temperature. Furthermore, incorporation of crystalline filler particles of SAPO-34 zeolite resulted in more and more crystallinity of the MMMs. SEM images also exhibited acceptable contacts between the filler particles and the polymer chains. Permeation measurement showed that CO2 permeabilities and CO2/CH4 selectivities of the MMM with 20 wt% loading of SAPO-34 zeolite particles up to 6.9 (Barrer) and 67, respectively. This can be attributed to size discrimination of SAPO-34 pores that falls between CO2 and CH4 kinetic diameters. 相似文献