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31.
Manganese dioxide electrode shows reversible charge storage capacity, if the charge-discharge process is limited to 0.3e− exchange. Addition of small amount of Bi2O3 to manganese dioxide induces reversibility with an exchange of 2e−/Mn. Nickel hydroxide is known to reversibly exchange 1e−. In spite of isostructural relationship between the cobalt hydroxide, nickel hydroxide and manganese dioxide, cobalt hydroxide does not show any electrochemical activity. Bi2O3 modified cobalt hydroxide electrodes exchanges 0.3-0.5e−/Co during the charge discharge process. The oxidation-reduction process in cobalt hydroxide and Bi2O3 modified cobalt hydroxide electrodes were monitored using the PXRD patterns. 相似文献
32.
Barium sulfate is the chief source for the manufacture of barium compounds, which have a wide range of applications in chemical industries. In the preparation of these compounds, the first step is the reaction between barium sulfate and carbon to produce barium sulfide. In the present work, the mechanism of reaction between barium sulfate and carbon is investigated experimentally, covering a wide range of temperatures, times of reaction, and stoichiometric ratios of reactants. The reaction is conducted in air, nitrogen, and vacuum. It is also studied using the reactants in pellet form to determine the effect of compaction pressure on rate of reaction. A model is developed to estimate the kinetic parameters and mechanism of the reaction. An attempt is also made to study the feasibility of conducting the reaction for continuous production of barium sulfide in a moving bed rector using the reactants in pellet form. 相似文献
33.
Tejas J. Bhatelia Harisinh B. Parmar Chi Phan Vishnu K. Pareek Moses O. Tadé Geoffrey M. Evans 《加拿大化工杂志》2013,91(1):122-126
Volume of fluid and continuum surface force methodologies were applied to two‐ and three‐dimensionally model the motion of a liquid jet injected vertically downward from a rectangular nozzle into another immiscible liquid. Grid independent solutions were obtained for a 10 mm2 nozzle with aspect ratios in the range 1–10. It was found that unlike the 3D simulation, the 2D CFD model was not able to predict the necking and breakup features observed in the experimental system. The 3D model showed that upon exiting the rectangular nozzle the liquid jet underwent a transition before becoming circular in cross‐section and eventually reaching an equilibrium diameter prior to breakup into droplets. For a given nozzle geometry it was found that equilibrium jet diameter increased with increasing liquid volumetric flowrate, with good agreement between CFD simulations and experimental observations. The 3D model was applied to rectangular nozzles with different aspect ratios and it was found that for a given liquid flowrate there was an optimum aspect ratio for generating minimum‐sized droplets, which was approximately 30% less than for a circular nozzle with the same cross‐sectional area. © 2011 Canadian Society for Chemical Engineering 相似文献
34.
Parthasarathi Bera Michael Rajamathi M. S. Hegde P. Vishnu Kamath 《Bulletin of Materials Science》2000,23(2):141-145
Mass spectrometric analysis of gases evolved during thermal decomposition of divalent metal hydroxides, hydroxysalts and hydrotalcites
show that all these compounds undergo dehydration in the temperature range 30 <T < 220°C followed by decomposition at temperatures above 250°C. The latter step involves simultaneous deanation and dehydroxylation
of the layers. Our observations conclusively prove that alternative mechanisms which envisage CO2 evolution due to deanation at lower temperatures proposed by Kanezaki to be wrong. 相似文献
35.
Kendell R. Jillson Vishnu Chapalamadugu B. Erik Ydstie 《Journal of Process Control》2009,19(9):1470-1485
We present control strategies for an Integrated Gasification Combined Cycle (IGCC) power plant with CO2 recycles. One recycle allows for composition control and is useful when the side objective is to produce synthesis gas for chemicals. The second recycle enables temperature control in the gas turbine by using CO2 as a diluent. The main advantages of the second recycle are that NOx is not produced and that CO2/H2O separation is significantly easier than CO2/N2 separation, which reduces cost if the CO2 is to be sequestered. Models and control systems are developed using process network theory. We introduce a novel method for controlling quality variables and functions of inventories. Dynamic simulations using MATLAB/Simulink models show the response to step changes in setpoints and disturbances. The inventory control method is derived from conservation laws and the second law and it is applicable to process system models of any degree of complexity. A steady-state sensitivity analysis is performed, examining the effect of changing the temperature and C:O ratio within the gasifier on the power production. 相似文献
36.
P. Rajesh U. Nagaraju G. Harinath Gowd T. Vishnu Vardhan 《The International Journal of Advanced Manufacturing Technology》2017,89(1-4):65-75
To ensure overall quality of a precision large-scale component, a tool condition monitoring (TCM) technique for multi-step form milling is presented. The form milling of fir tree slots for a steam turbine rotor is an appropriate example that requires a fine surface finish and high dimensional accuracy. Therefore, we propose a novel TCM system based on a multi-sensor fusion strategy which utilises the combination of spindle motor current and acoustic emission (AE) as well as adaptive thresholding for multiple manufacturing steps (roughing, semi-finishing and finishing). To investigate the tool deterioration process, tool longevity tests using a test piece are carried out for each step. With the aid of qualitative inspection, it is found that AE signals provide comprehensive tool state information regarding tool flank wear, crack propagation and severe adhesive wear. In addition, by intentionally adding a bundle of chips to the surface, bursts of AE of large amplitudes occur in finishing, which provides the possibility of discovering anomalous events related to surface quality. By careful consideration of such characteristics, provisional alert levels are determined using a two-dimensional diagram with respect to both sensors. The strategy is verified throughout the actual manufacturing processes of the rotors. The proposed TCM system shows not only an excellent ability to prevent catastrophic tool failure and surface irregularities in form milling but also acceptable expendability for various groove specifications. 相似文献
37.
Krishnamachari VV Potma EO 《Journal of the Optical Society of America. A, Optics, image science, and vision》2007,24(4):1138-1147
The coherent anti-Stokes Raman scattering (CARS) signal is calculated as a function of focal-field distributions with engineered phase jumps. We show that the focal fields in CARS microscopy can be shaped such that the signal from the bulk is suppressed in the forward detection mode. We present the field distributions that display enhanced sensitivity to vibrationally resonant object interfaces in the lateral dimension. The use of focus-engineered CARS provides a simple means to detect chemical edges against the strong background signals from the bulk. 相似文献
38.
Buhari Adamu Muhammad Ooi Chee-Pun Baskaran Vishnu Monn Phan Raphael CW Wong KokSheik Tan Wooi-Haw 《Multimedia Tools and Applications》2022,81(7):9151-9176
Multimedia Tools and Applications - The interest in real-time micro-expression recognition has increased with the current trend in human-computer interaction applications. Presently, there are... 相似文献
39.
Mohammad Bani Ismail Peramaiyan Rajendran Hamad Mohammed AbuZahra Vishnu Priya Veeraraghavan 《International journal of molecular sciences》2021,22(8)
Doxorubicin increases endothelial permeability, hence increasing cardiomyocytes’ exposure to doxorubicin (DOX) and exposing myocytes to more immediate damage. Reactive oxygen species are major effector molecules of doxorubicin’s activity. Mangiferin (MGN) is a xanthone derivative that consists of C-glucosylxanthone with additional antioxidant properties. This particular study assessed the effects of MGN on DOX-induced cytotoxicity in human umbilical vein endothelial cells’ (HUVECs’) signaling networks. Mechanistically, MGN dramatically elevated Nrf2 expression at both the messenger RNA and protein levels through the upregulation of the PI3K/AKT pathway, leading to an increase in Nrf2-downstream genes. Cell apoptosis was assessed with a caspase-3 activity assay, transferase-mediated dUTP-fluorescein nick end labeling (TUNEL) staining was performed to assess DNA fragmentation, and protein expression was determined by Western blot analysis. DOX markedly increased the generation of reactive oxygen species, PARP, caspase-3, and TUNEL-positive cell numbers, but reduced the expression of Bcl-2 and antioxidants’ intracellular concentrations. These were effectively antagonized with MGN (20 μM), which led to HUVECs being protected against DOX-induced apoptosis, partly through the PI3K/AKT-mediated NRF2/HO-1 signaling pathway, which could theoretically protect the vessels from severe DOX toxicity. 相似文献
40.
Vishnu Vijaykumar Gurudeo Nirala Dharmendra Yadav Upendra Kumar Shail Upadhyay 《国际能源研究杂志》2020,44(6):4652-4663
Nanocrystalline powders of co-doped ceria oxides Ce0.85La0.10Sr0.05O2-δ (CLSO) and Ce0.85Gda0.10Sr0.05O2-δ (CGSO) have been synthesized by auto combustion method at 100°C using sucrose as fuel. Thermal analysis (TGA/DSC) of as-prepared powders indicated calcination above 400°C to remove organic residue. The average grain size of the pellets sintered at 1200°C for 4 hours is 436 and 683 nm for CLSO and CGSO, respectively. The electrical conductivity of the sintered samples was determined by impedance measurements in the temperature range 300°C to 600°C and the frequency range 20 Hz to 2 MHz. At 600°C, the total electrical conductivity (σt) of CGSO is 6.78 × 10−3 S cm−1, 2.5 times higher than 2.72 × 10−3 S cm−1 of CLSO. Further, it is found that the value of grain boundaries blocking factor (αgb) of CGSO is 0.47 which is 30% lesser than 0.68 of CLSO at 600°C. The higher value of electrical conductivity of CGSO as compared to CLSO is attributed to the lesser blocking effect of grain boundaries, smaller lattice distortion and denser microstructure of CGSO as compared to CLSO. The electrical conductivity of synthesized samples has been compared with the electrical conductivity of similar compositions of co-doped CeO2 oxides. Our study indicated that the sintering temperature, and hence, the morphology of sintered samples has a significant role in determining the electrical conductivity. The presence of oxygen vacancies in the synthesized samples is experimentally supported by using UV-visible spectroscopy, Raman spectroscopy, and thermal analysis techniques. 相似文献