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101.
Veronica Gil-Costa Mauricio Marin Carolina Bonacic Roberto Solar 《The Journal of supercomputing》2018,74(5):2006-2034
Large-scale similarity search engines are complex systems devised to process unstructured data like images and videos. These systems are deployed on clusters of distributed processors communicated through high-speed networks. To process a new query, a distance function is evaluated between the query and the objects stored in the database. This process relays on a metric space index distributed among the processors. In this paper, we propose a cache-based strategy devised to reduce the number of computations required to retrieve the top-k object results for user queries by using pre-computed information. Our proposal executes an approximate similarity search algorithm, which takes advantage of the links between objects stored in the cache memory. Those links form a graph of similarity among pre-computed queries. Compared to the previous methods in the literature, the proposed approach reduces the number of distance evaluations up to 60%. 相似文献
102.
Cremona M Mauricio MH Scavarda Do Carmo LC Prioli R Nunes VB Zanette SI Caride AO Albuquerque MP 《Journal of microscopy》2000,197(3):260-267
The influence of the deposition temperature on the grain size of polycrystalline lithium fluoride (LiF) thin films is studied using a mathematical morphology method. On atomic force microscopy images of the LiF surface, the grain sizes and shapes are determined by applying the watershed technique, together with a shape factor algorithm. Also, the domain size of the film structure, determined by an X-ray diffraction data analysis, is compared and correlated with the mean grain size as a function of the deposition temperature. In both cases a linear increase with temperature and a very good agreement among the two structural parameters (grain and domain size) was found. 相似文献
103.
Gabriel Salierno Mauricio Maestri Stella Piovano Miryan Cassanello María Angélica Cardona Daniel Hojman Héctor Somacal 《中国化学工程学报》2018,26(6):1370-1382
Features of the motion of gel particles in a three-phase bubble column with non-foaming and foaming gas–liquid systems,determined by using experiments of radioactive particle tracking(RPT),have been compared.The tracer used is a gel particle which resembles typical immobilized biocatalyst.The tracer trajectory is analyzed to extract relevant information for design purposes.The solid velocity field,turbulence parameters,dispersion coefficients,mixing times and flow transitions are determined and compared.The presence of foam significantly affects many quantified parameters,especially within the heterogeneous flow regime.The hydrodynamic stresses are reduced in the presence of foam,especially close to the disengagement.The dispersion coefficients also decrease,and the solid mixing time is only slightly affected by the presence of foam.Gas holdup,inferred both from RPT experiments and from gamma ray scanning,is higher for foaming systems and leads to a shift in the transition gas velocity towards higher values. 相似文献
104.
Karina Donadel Marcos D.V. Felisberto Valfredo T. Fávere Mauricio Rigoni Nelson Jhoe Batistela Mauro C.M. Laranjeira 《Materials science & engineering. C, Materials for biological applications》2008,28(4):509-514
Magnetic particles are extremely interesting for several biomedical applications; amongst these are therapeutic applications, such as: hyperthermia and release of drugs. The use of magnetic particles to induce hyperthermia in biological tissues is an important factor in cancer therapy. The aim of this study was to prepare and characterize iron oxide magnetic particles coated with biopolymer chitosan, and also to produce ferrofluids from the magnetic particles. The iron oxide magnetic particles (IOMP) were coated with chitosan (CS) by spray-drying method using two IOMP/coating ratios (IOMP/CS = 1.6 and IOMP/CS = 4.5). The magnetic particles were characterized by way of scanning electronic microscopy and energy-dispersive X-ray. The analysis by energy-dispersive X-ray was carried out to determine the chemical composition of particles in samples. The size distribution the iron oxide magnetic particles uncoated and coated were evaluated by the laser diffraction analysis and image analysis, respectively. Amongst the prepared ferrofluids, the sample IOMP/CS = 1.6 proved to be the one that has brought about the best results in therapeutics applications, such as in hyperthermia treatment. This sample was placed within an alternating magnetic field during 40 min, it was observed that 1 °C heated in 3 min and underwent a temperature variation of 7 °C, since it varied from 25 °C to 32 °C. Considering that the experiment would be carried out at body temperature 37 °C, probably, the temperature variation would be very close to the one reported at 25 °C. In such a way, the cancerous cells would reach 44–45 °C and at such temperatures the cancer cells generally perish. 相似文献
105.
Alvizo-Paez ER Romo-Herrera JM Terrones H Terrones M Ruiz-Garcia J Hernandez-Lopez JL 《Nanotechnology》2008,19(15):155701
A soft method for purifying multi-wall carbon nanotubes (N-doped and undoped) is presented. The technique includes a hydrothermal/ultrasonic treatment of the material in conjunction with other subsequent treatments, including the extraction of polyaromatic compounds, dissolution of metal particles, bundle exfoliation, and uniform dispersion. This method avoids harsh oxidation protocols that burn (via thermal treatments) or functionalize (by introducing chemical groups) the nanotubes. We show a careful analysis of each purification step and demonstrate that the technique is extremely efficient when characterizing the materials using scanning electron microscopy (SEM), energy dispersive x-ray analysis (EDAX), scanning tuneling electron microscopy (STEM), x-ray powder diffraction (XRD), diffuse reflectance Fourier transform infrared (DRFTIR) spectroscopy and thermogravimetric analysis (TGA). 相似文献
106.
Andrés R. Botello-Méndez Florentino López-Urías Mauricio Terrones Humberto Terrones 《Nano Research》2008,1(5):420-426
Inspired by recent experimental results, the electronic and magnetic properties of sulfur-passivated ZnO clusters and zigzag
nanoribbons have been studied using first principles calculations in the framework of the local spin density approximation.
In the case of the ZnO nanoribbons, the sulfur atoms or thiol groups were attached in different ways to the zinc or oxygen
atoms located at the edges, whereas in clusters, the sulfur atoms were set on the surface, mainly interacting with atoms with
low-coordinate number. After an exhaustive atomic relaxation, we found that a magnetic moment emerges in zigzag nanoribbons
both with and without sulfur-passivation on the edges. However, the magnitude of the magnetic moment is very sensitive to
sulfur passivation. In particular, we found that when sulfur is attached to the zinc atoms in an alternating fashion along
the ribbon edges, the magnetic moment is a maximum (1.4 μB/unit cell). In the case of clusters, we found that the Zn15O15 cluster exhibits a high spin moment of 5.5 μB when capped with sulfur atoms. Our calculations indicate that sulfur-passivating of ZnO nanosystems could be responsible
for recently observed ferromagnetic responses.
This article is published with open access at Springerlink.com 相似文献
107.
Disposal of domestic sludge and sludge ash on volcanic soils 总被引:1,自引:0,他引:1
Escudey M Förster JE Becerra JP Quinteros M Torres J Arancibia N Galindo G Chang AC 《Journal of hazardous materials》2007,139(3):550-555
Column leaching experiments were conducted to test the ability of Chilean volcanic soils in retaining the mineral constituents and metals in sewage sludge and sludge ash that were incorporated into the soils. Small or negligible amounts of the total content of Pb, Fe, Cr, Mn, Cd, and Zn (0 to <2%), and more significant amounts of mineral constituents such as Na (7-9%), Ca (7-13%), PO4 (4-10%), and SO4 (39-46%) in the sludge and sludge ash were readily soluble. When they were incorporated on the surface layer of the soils and leached with 12 pore volumes of water over a 3 month period of time, less than 0.1% of the total amount of heavy metals and PO4 in the sludge and sludge ash were collected in the drainage water. Cation exchange selectivity, specific anion adsorption and solubility are the processes that cause the reduction of leaching. The volcanic soils were capable of retaining the mineral constituents, P, and metals in applied sewage sludge and sludge ash and gradually released them as nutrients for plant growth. 相似文献
108.
109.
110.
Maycon Athayde Mauricio Cota Fonseca Bagatini Maurício Covcevich 《Mineral Processing and Extractive Metallurgy Review》2018,39(4):266-275
Drying is a critical process step to achieve excellent pellet quality in pelletizing process. The complexity and energy consumption toward moisture removing, especially for highly hydrated iron ore, increased the need for breakthrough enhancements to this process. The present study has evaluated kinetics parameters of the moisture release from iron ore green pellet using energy transmitted through microwave (frequency of 2.45 GHz). The influence of pellet size and output power on the moisture effective diffusivity (Deff) and the drying activation energy (Ea) were evaluated. The results make possible to compare the cutting-edge approach with traditional convective drying. Pellet physical quality was investigated through the green crushing strength (GCS), which shows smooth reduction in earlier stages, however not affecting the final dry GCS results. Bonded hematite reduction and calcination of goethite was identified at the microstructure through reflected light microscopy, SEM showed micro cracks formation in several grains. 相似文献