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The volumetric mass transfer coefficients, kLa, measured in a pilot plant (0.1 m3) and an industrial (67.5 m3) fermentor during an actual fermentation process are presented. Problems related to the estimation of the phsyical properties as well as to the correlation of experimental data and to scale up procedures are discussed. Although the scale up factor was rather high, both sets of data could be represented by single correlation. Comparison of the experimental data with several available correlations demonstrated the need for pilot plant experiments and scale up procedures, since it is almost impossible to take into account all relevant system properties. 相似文献
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Water Sorption and Diffusion in (Reduced) Graphene Oxide‐Alginate Biopolymer Nanocomposites 下载免费PDF全文
Karolis Vilcinskas Jure Zlopasa Kaspar M. B. Jansen Fokko M. Mulder Stephen J. Picken Ger J. M. Koper 《大分子材料与工程》2016,301(9):1049-1063
The water sorption and diffusion in (reduced) graphene oxide‐alginate composites of various compositions is analyzed. Water sorption of sodium alginate can be significantly reduced by the inclusion of graphene oxide sheets due to the formation of an extensive hydrogen bonding network between oxygenated groups. Crosslinking alginate with divalent metal ions and the presence of reduced graphene oxide can further improve the swelling resistance due to the strong interactions between metal ions, alginate, and filler sheets. Depending on conditions and composition, the overall water barrier properties of alginate composites improve upon (reduced) graphene oxide filling, making them attractive for moisture barrier coating applications. Water sorption kinetics in all alginate composites indicate a non‐Fickian diffusion process that can be accurately described by the Variable Surface Concentration model. In addition, the water barrier properties of sodium alginate‐graphene oxide composites can be adequately predicted using a simple model that takes the orientational order of filler sheets and their effective aspect ratio into account.
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This work presents the main features of the new power plant that comprises the modified reversible hydroelectric (HE) power plant operating together with the photovoltaic (PV) power plant. Such Solar Hydroelectric Power Plant (SHE) uses solar energy as the only input for production of solar and hydro energy. Thereat, water reservoir serves for daily and seasonal energy storage, thus basically solving the problem of energy storage, which is the biggest problem of wider use of solar energy. The most expensive part of SHE is the PV generator, whose optimal sizing is essential for providing energetic independence of a settlement or isolated consumer. A systematic approach that includes all relevant elements of this system has been implemented for optimal sizing of the PV power plant. The developed model was used in analysis of certain parameters of the SHE system. The results of the analysis show the system characteristics and that the proposed model describes the operation of the power plant very well. The feasibility and characteristics of the power plant were tested on electric energy supply of the island of Vis in Croatia. It has been established that the system is real, feasible and can be very successfully applied on different locations, for different consumers and can vary in size. The prerequisite for realization of such system is the construction of a modified reversible HE power plant. The presented SHE represents a permanently sustainable energy source that can continuously provide power supply to a consumer, using exclusively natural and renewable energy sources, without causing harmful effects on the environment. 相似文献
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A mechanical thermostat is a device that switches heating or cooling appliances on or off based on temperature. For this kind of use, electronic or mechanical switching concepts are applied. During the production of electrical contacts, several irregularities can occur leading to improper switching events of the thermostat electrical contacts. This paper presents a non-obstructive method based on the fact that when the switching event occurs it can be heard and felt by human senses. We performed several laboratory tests with two different methods. The first method includes thermostat switch sound signal analysis during the switching event. The second method is based on sampling of the accelerometer signal during the switching event. The results show that the sound analysis approach has great potential. The approach enables an accurate determination of the switching event even if the sampled signal carries also the switching event of the neighbour thermostat. 相似文献
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ABSTRACT: Throughout the 1980s conditions worsened for children and youth in urban areas throughout the US. Lacking a national youth policy, formulation and implementation of youth policy has been left to the states and localities. One of the most innovative youth policy responses was enacted in Florida where the state authorized the creation of children's services councils at the county level. This paper traces the efforts of Florida's urban counties to develop programs, strategies, and the use of special tax districts that target unmet needs and children's issues. The Florida legislation and the experience of local governments offer one approach for other states and localities, as well as a model for national youth policy. 相似文献
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Lidija Androš Dubraja Damir Pajić Martina Vrankić Jure Dragović Matjaz Valant Metka Benčina Marijana Jurić 《Journal of the American Ceramic Society》2019,102(11):6697-6704
Chromium niobate and tantalate (CrNbO4 and CrTaO4) were synthesized by pyrolysis of the oxalate-based heterometallic complexes [Cr2(bpy)4(μ-O)4Nb2(C2O4)4]·3H2O (Cr-Nb) and [Cr(bpy)2(H2O)(μ-O)Ta(C2O4)3]2·3.5H2O (Cr-Ta) (bpy = 2,2'-bipyridine). Compared to conventional solid-state synthesis, herein studied oxides are prepared at lower temperatures, in one step without repeating grinding procedures. The structure, morphology, and optical properties of the as-synthesized oxides were characterized using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (SEM), the thermogravimetric and differential thermal analysis (TG/DTA) and UV-vis diffuse reflectance spectroscopy (UV-vis DRS). The determined band gap energies of CrNbO4 and CrTaO4 are 2.39 and 2.82 eV, respectively, which prompted us to investigate photocatalytic activity of these oxides in degradation of dyes. Microscopy studies show that the particles of both oxides began to aggregate into bigger particles, leading to an increase in grain size. Additionally, magnetization measurements on both oxides revealed spin-glass behavior at low temperatures. 相似文献
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