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81.
Dissolved organic nitrogen (DON) represents a significant portion of nitrogen in the final effluent of wastewater treatment plants (WWTPs). Biodegradable portion of DON (BDON) can support algal growth and/or consume dissolved oxygen in the receiving waters. The fate of DON and BDON has not been studied for trickling filter WWTPs. DON and BDON data were collected along the treatment train of a WWTP with a two-stage trickling filter process. DON concentrations in the influent and effluent were 27% and 14% of total dissolved nitrogen (TDN). The plant removed about 62% and 72% of the influent DON and BDON mainly by the trickling filters. The final effluent BDON values averaged 1.8 mg/L. BDON was found to be between 51% and 69% of the DON in raw wastewater and after various treatment units. The fate of DON and BDON through the two-stage trickling filter treatment plant was modeled. The BioWin v3.1 model was successfully applied to simulate ammonia, nitrite, nitrate, TDN, DON and BDON concentrations along the treatment train. The maximum growth rates for ammonia oxidizing bacteria (AOB) and nitrite oxidizing bacteria, and AOB half saturation constant influenced ammonia and nitrate output results. Hydrolysis and ammonification rates influenced all of the nitrogen species in the model output, including BDON. 相似文献
82.
I. Uslu Saime Sebnem Cetin A. Aytimur S. Yuceyurt M. O. Erdal 《Journal of Inorganic and Organometallic Polymers and Materials》2012,22(4):766-771
Sodium cobalt oxide (NaCo2O4) nanofibers with diameters ranging between 20 and 200?nm were prepared by electrospinning a precursor mixture of PVA/(Na–Co) acetate. This was the first time any such attempt was made. Afterwards, the electrospun nanofibers were subjected to calcination treatment. The characteristics of the fibers were investigated using a Fourier transform infrared spectroscopy, a X-ray diffractometer, and a scanning electron microscopy. The boron doped and undoped NaCo2O4 nanofibers calcined at 850?°C were polycrystalline of the γ NaxCo2O4 phase having diameters ranging between 20 and 60?nm with grain sizes of 5–10?nm, and the nanofibers calcined at 800?°C were single crystals having linked particles or crystallites with particle sizes ranging between 60 and 200?nm. The results indicated a significant effect of calcination temperature on the crystalline phase and morphology of the nanofibers. It could be seen in the SEM micrograph of the fibers that when boron was added, this resulted in the formation of cross-linked bright-surfaced fibers. The average fiber diameter for boron doped and undoped fiber mats were 204 and 123?nm, respectively. The grain diameters of boron doped and undoped nanocrystalline sintered powders were measured as 140 and 118?nm, respectively. 相似文献
83.
84.
Arsenic adsorption properties of mono- (Fe or Al) and binary (Fe-Al) metal oxides supported on natural zeolite were investigated at three levels of temperature (298, 318 and 338 K). All data obtained from equilibrium experiments were analyzed by Freundlich, Langmuir, Dubinin-Radushkevich, Sips, Toth and Redlich-Peterson isotherms, and error functions were used to predict the best fitting model. The error analysis demonstrated that the As(V) adsorption processes were best described by the Dubinin-Raduskevich model with the lowest sum of normalized error values. According to results, the presence of iron and aluminum oxides in the zeolite network improved the As(V) adsorption capacity of the raw zeolite (ZNa). The X-ray photoelectron spectroscopy (XPS) analyses of ZNa-Fe and ZNa-AlFe samples suggested that the redox reactions are the postulated mechanisms for the adsorption onto them while the adsorption process is followed by surface complexation reactions for ZNa-Al. 相似文献
85.
A better understanding of the mixing and stoking process is crucial for an optimization of the combustion process on grate firing systems. Thus experimental studies were carried out to analyse the response of a particle assembly on varying grate operational parameters. To reduce the number of variables which affect the system a generic grate design was chosen and a material of monodisperse spheres was selected. The grate system applied uses vertically moving parallel bars to induce mixing. Different patterns of bar motion were created by linking the bars in groups of uniform movement. A transparent polycarbonate side wall gives optical access to front layer of spheres. The mixing process was measured and quantified by image analysis of this visible layer. When applying a constant number of bar strokes it is found that the mixing performance is independent of the bar velocity. However, mixing performance increases nearly linearly with the stroke length. It turned out that specific “movement patterns” could be identified which show improved mixing behaviour. The results provided here may also be used for comparison with simulations of the particle mixing with the Discrete Element Method (DEM). 相似文献
86.
HfO2 thin films were prepared by reactive DC magnetron sputtering technique on (100) p-Si substrate. The effects of O2/Ar ratio, substrate temperature, sputtering power on the structural properties of HfO2 grown films were studied by Spectroscopic Ellipsometer (SE), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, and X-ray photoelectron spectroscopy (XPS) depth profiling techniques. The results show that the formation of a SiOx suboxide layer at the HfO2/Si interface is unavoidable. The HfO2 thickness and suboxide formation are highly affected by the growth parameters such as sputtering power, O2/Ar gas ratio during sputtering, and substrate temperature. XRD spectra show that the deposited films have (111) monoclinic phase of HfO2, which is also supported by FTIR spectra. XPS depth profiling spectra shows that highly reactive sputtered Hf atoms consume some of the oxygen atoms from the underlying SiO2 to form HfO2, leaving Si-Si bonds behind. 相似文献
87.
A polymer electrolyte membrane (PEM) fuel cell stack requires gaskets in each cell to keep the reactant gases within their respective regions. Both sealing and electrochemical performance of the fuel cell depend on the long‐term stability of the gasket materials. In this paper, the change in properties and structure of a silicone rubber gasket brought about by use in a fuel cell was studied and compared to the changes in the same silicone rubber gasket material brought about by accelerated aging. The accelerated aging conditions were chosen to relate to the PEM fuel cell environment, but with more extreme conditions of elevated temperature (140°C) and greater acidity. The dilute sulfuric acid accelerated aging solutions used had pH values of 1, 2, and 4. In an additional test, Nafion® membrane suspended in water was used for accelerated aging, to more closely correspond to a PEM fuel cell environment. The analysis showed that acid hydrolysis was the most likely mechanism of degradation and that similar degradation occurred under both real fuel cell and accelerated aging conditions. It was concluded that the accelerated aging test is a good one for rapidly screening materials for resistance to the acidic environment of the fuel cell. ©2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献
88.
Simsek Dogan Ozyurek Dursun Salman Serdar 《Powder Metallurgy and Metal Ceramics》2022,60(11-12):706-716
Powder Metallurgy and Metal Ceramics - With the developing technology, aluminum matrix composites (AMCs) are widely used in many system parts in the automotive industry. One of the most important... 相似文献
89.
Arzu Cagri-Mehmetoglu Guliz Yaldirak Tulay Bodur Merve Simsek Hamza Bozkir N. Mine Eren 《Food Control》2011,22(5):762-766
This study was designed to determine the presences of two environmental pathogens in two dairy factories in Sakarya, Turkey. A total of 264 environmental samples, raw milk and cheese samples were taken at four different seasons. According to the results, Listeria monocytogenes or Escherichia coli O157:H7 was isolated from 26 or 2.7% of the samples collected from both factories, respectively. None of the cheese or curd samples were found to be positive for Listeria or E. coli O157:H7. However, 50% of raw milk samples contained Listeria innocua. Listeria was mostly isolated from the swap samples taken from the drains or the floors in processing or packaging areas. However, E. coli was also isolated from the swap samples taken from the workers’ hands and gloves as well as the drains and the floor. Only one raw milk sample contained E. coli O157:H7. A higher prevalence of both pathogens was observed in the summer months than in the other months. 相似文献
90.
Assist. Prof. Dr. Bedia Simsek 《Journal für Verbraucherschutz und Lebensmittelsicherheit》2011,13(2):175-181
Yayik butter produced by churning of yoghurt is one of the popular traditional dairy products of Turkey. In this study, yayik butter was divided into four lots. Two lots were stored with a daylight lamp at 4 and 20°C (L4; L20) and the other two lots were stored at 4 and 20°C in dark (D4: control; D20) for 60 days. Then, the oxidative stability of yayik butter was evaluated. The end of self life was determined from sensory data. Generally acceptability was negatively correlated with peroxide value (PV), free fatty acid (FFA), thiobarbituric acid (TBA) and titratable acidity (TA). While general acceptability of control samples (D4) was between 8.26 ± 0.20 and 7.80 ± 0.10, those of L20 sample was lower than 3.00 (dislike moderately) on 60th day. As a result of decrease detected for sensory quality, the storage process was ended. L20 sample was evaluated as unacceptable on the 60th day and the evaluation result of this sample was accepted as the limiting value. The limiting values of TA, FFA and PV, TBA were determined as 0.14 ± 0.01%, 1.93 ± 0.11 mg KOH/g oil, 0.80 ± 0.007 meq O2/g oil and 0.37 ± 0.02 mg malonaldehyde/kg butter in this yayik butter. 相似文献