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排序方式: 共有117条查询结果,搜索用时 15 毫秒
31.
Bojana Vukadinović Ivanka Popović Aleksandar Subotin 《Energy Sources, Part A: Recovery, Utilization, and Environmental Effects》2018,40(3):259-265
The approach proposed in this paper emphasizes the methodology of examining the possibility of increasing energy efficiency in the case of industry, such as a petrochemical complex, which is at the same time marked as the major pollutant of the environment. The improved cleaner production methodology was used based on the conditions and needs of the major Serbian petrochemical company. This paper presents results obtained by steam system optimization and modifications. The implemented measures lead to a decrease in total energy consumption by 6% and a decrease in greenhouse gas emissions by 9 t CO2e. 相似文献
32.
33.
Sanja Milošević Igor Milanović Bojana Paskaš Mamula Anđelka Đukić Dragan Rajnović Luca Pasquini Jasmina Grbović Novaković 《International Journal of Hydrogen Energy》2013
To improve hydrogen desorption properties of MgH2, mechanical milling of MgH2 with low concentration (2 and 5%) of NaNH2 has been performed. Pre-milling of MgH2 for 10 h has been done and then six samples have been synthesised with different milling times from 15 to 60 min. Microstructural characterisation has been performed using X-ray diffraction (XRD), scanning electron microscopy (SEM) and laser scattering measurements (PSD), and correlated to desorption properties examined using Differential Scanning Calorimetry (DSC) and Hydrogen Sorption Analyser (HSA). Thermal analysis shows that desorption temperatures are shifted towards lower values. It also highlights the significance of milling time and additive concentration on desorption behaviour. 相似文献
34.
Bojana Paskaš Mamula Jasmina Grbović Novaković Ivana Radisavljević Nenad Ivanović Nikola Novaković 《International Journal of Hydrogen Energy》2014
Ab initio electronic structure calculations of the Mg15TMH32 (TM – transition metals – 6.25 at.%) systems for the entire 3d TM series have been performed using full-potential (linearized) augmented plane waves with addition of local orbitals (FP-LAPW + LO and APW + lo) as implemented in WIEN2k code and projected augmented waves (PAW) method using Abinit code. Details of bonding and mechanism of the TM impurities influence on destabilization of MgH2 were established by investigation of changes of electronic structure after the TM impurities insertion into MgH2 and by using the “atoms in molecules” (AIM) Bader's charge density topology analysis. The obtained trends of all calculated observables show that along the 3d series TMs accomplish different kinds of bonding with nearest and next-nearest neighbor hydrogen atoms that in general weaken related Mg–H bonds and destabilize the surrounding MgH2 matrix. 相似文献
35.
Bojana Balanč Ana Kalušević Ivana Drvenica Maria Teresa Coelho Verica Djordjević Vitor D Alves Isabel Sousa Margarida Moldão‐Martins Vesna Rakić Viktor Nedović Branko Bugarski 《Journal of food science》2016,81(1):E65-E75
Carqueja (Pterospartum tridentatum) is an endemic species and various bioactive compounds have been identified in its aqueous extract. The aim of this study was to protect the natural antioxidants from the aqueous extract of carqueja by encapsulation in Ca–alginate microbeads and Ca–alginate microbeads containing 10% and 20% (w/v) of inulin. The microbeads produced by electrostatic extrusion technique had an average diameter from 625 μm to 830 μm depending on the portion of inulin. The sphericity factor of the hydrogel microbeads had values between 0.014 and 0.026, while freeze dried microbeads had irregular shape, especially those with no excipient. The reduction in microbeads size after freeze drying process (expressed as shrinkage factor) ranged from 0.338 (alginate microbeads with 20% (w/v) of inulin) to 0.523 (plain alginate microbeads). The expressed radical scavenging activity against ABTS and DPPH radicals was found to be between 30% and 40% for encapsulated extract, while the fresh extract showed around 47% and 57% of radical scavenging activity for ABTS and DPPH radicals, respectively. The correlation between antioxidant activity and the total phenolic content were found to be positive (in both assay methods, DPPH and ABTS), which indicate that the addition of inulin didn't have influence on antioxidant activity. The presence of inulin reduced stiffness of the hydrogel, and protected bead structure from collapse upon freeze‐drying. Alginate–inulin beads are envisaged to be used for delivery of aqueous P. tridentatum extract in functional food products. 相似文献
36.
Oskar Bera Jelena Pavličević Bojana Ikonić Jelena Lubura Dragan Govedarica Predrag Kojić 《Polymer Engineering and Science》2021,61(3):879-890
Although extensive research has been carried out on the understanding of the complex vulcanization process, the influence of reversion through exposure time and temperature on the vulcanization degree remains unclear. Therefore, the main aim of this study was a novel optimization approach that can help the industrial practitioners to select the optimal operating parameters, exposure time, and molding temperature, to achieve desired vulcanization degree of selected product. Spheres of four different diameters (2.5, 5, 10, and 20 cm) were selected as test geometry for simulation and optimization of rubber molding. Obtained vulcanization rheometer data for commercially available rubber blend (NR/SBR) were fitted by a new modeling approach, dividing vulcanization curve into two fitting sets: curing and reversion. The heat transfer equations for chosen geometry were coupled with proposed kinetic model. A new temperature-dependent kinetic parameter x, as the maximal reversion degree, was introduced, enabling determination of the lowest operating molding temperature (Tmin = 132.36 °C), preventing high reversion and overheating of the rubber product. The final optimization goal was assessment of the optimal temperature and vulcanization time dependence on the rubber products dimensions. Proposed models have precise prediction with R2 values greater than 0.8328 and MAPE less than 2.3099%. 相似文献
37.
Lidija Škodič Julija Volmajer Valh Tina Željko Bojana Vončina Aleksandra Lobnik 《臭氧:科学与工程》2017,39(1):14-23
The decolorization and mineralization of two reactive dyes C.I. Reactive Blue 4 (RB 4) and C.I. Reactive Blue 268 (RB 268) were studied using various advanced oxidation processes (AOPs) such as H2O2/UV, H2O2/UV/Fe2+, and the H2O2/UV/Fe°. All processes were performed within a laboratory-scale photo-reactor setup. The experimental results were assessed in terms of absorbance (A) and total organic carbon (TOC) reduction. The main degradation products were identified by high resolution gas chromatography/high resolution mass spectrometry analyses. The results of our study demonstrated that the additions of moderate concentrations of H2O2 and Fe catalyst during the AOPs evidently increased the decolorization efficiencies within the first few minutes of the processing time (5–10 min) for both tested dyes, and prolonged irradiation does not necessarily significantly improve decolorization. On contrary, TOC removal rate increased with the processing time and with the addition of the catalyst from 40–50% up to 70–80% at defined experimental conditions. All the tested AOPs were very successful methods for RB 268 decolorization, having very complex structure and much higher molecular weight compared to the dye RB 4. This is important from both economic and ecological points of view. 相似文献
38.
Slobodan Cvetkovic Branko Bugarski Bojana Obradovic 《Korean Journal of Chemical Engineering》2018,35(2):324-327
Emulsification followed by freezing and thawing cycles was applied to produce poly(vinyl alcohol) (PVA) microparticles and to simultaneously immobilize activated sludge. Activity of the obtained microparticles (~400 μm in diameter) was evaluated in glucose syrup solutions and heat-pretreated wastewater from a starch factory by measurements of permanganate index (COD Mn ) reduction. The reaction followed first-order kinetics, revealing slight mass transfer limitations in PVA microparticles as determined from the kinetic rate constant that was ~35% lower than that in the freely suspended activated sludge culture. Yet, efficiency of the microparticles increased almost five-fold in a laboratory airlift bioreactor operating either in batch or continuous regimes. Over 19 days of operation under high organic loadings in the industrial wastewater (~100 kgCOD m?3 d?1), PVA microparticles (12.4% volume fraction) remained active and induced a decrease of over 90% of biodegradable COD Mn at the hydraulic retention time of 8 h. 相似文献
39.
Bojana M Marković Ivan S Stefanović Radmila V Hercigonja Marija V Pergal Jelena P Marković Antonije E Onjia Aleksandra B Nastasović 《Polymer International》2017,66(5):679-689
Macroporous copolymers of poly[(glycidyl methacrylate)‐co ‐(ethylene glycol dimethacrylate)] (PGME ) with various crosslinker (ethylene glycol dimethacrylate) concentrations and porosity parameters and additionally functionalized with hexamethylene diamine (PGME‐HD ) were tested as potential Cr(VI ) oxyanion sorbents from aqueous solutions. Kinetics of Cr(VI ) sorption was investigated in the temperature range 298–343 K and the results were fitted to chemical reaction and particle diffusion models. The Cr(VI ) sorption obeys the pseudo‐second‐order model with definite influence of pore diffusion. A temperature rise promotes chromium removal, with a maximum experimental uptake capacity of 4.21 mmol g?1 at 343 K for the sample with the highest amino group concentration. Equilibrium data were analysed with Langmuir, Freundlich and Temkin adsorption isotherm models. Thermodynamic parameters, i.e. Gibbs free energy (ΔG 0), enthalpy (ΔH 0) and entropy change (ΔS 0) and activation energy of sorption (E a), were calculated. The Cr(VI) adsorption onto PGME‐HD was found to be spontaneous and endothermic, with increased randomness in the system. Desorption experiments show that chromium anion sorption was reversible and the PGME‐HD sample GMA 60 HD was easily regenerated with 0.1 mol L?1 NaOH up to 90% recovery in the fourth sorption/desorption cycle. In the fifth cycle, a substantial sorption loss of 37% was observed. © 2016 Society of Chemical Industry 相似文献
40.
Milena Todorovic Balint Jelena Jelicic Biljana Mihaljevic Jelena Kostic Bojana Stanic Bela Balint Nadja Pejanovic Bojana Lucic Natasa Tosic Irena Marjanovic Maja Stojiljkovic Teodora Karan-Djurasevic Ognjen Perisic Goran Rakocevic Milos Popovic Sava Raicevic Jelena Bila Darko Antic Bosko Andjelic Sonja Pavlovic 《International journal of molecular sciences》2016,17(5)
The existence of a potential primary central nervous system lymphoma-specific genomic signature that differs from the systemic form of diffuse large B cell lymphoma (DLBCL) has been suggested, but is still controversial. We investigated 19 patients with primary DLBCL of central nervous system (DLBCL CNS) using the TruSeq Amplicon Cancer Panel (TSACP) for 48 cancer-related genes. Next generation sequencing (NGS) analyses have revealed that over 80% of potentially protein-changing mutations were located in eight genes (CTNNB1, PIK3CA, PTEN, ATM, KRAS, PTPN11, TP53 and JAK3), pointing to the potential role of these genes in lymphomagenesis. TP53 was the only gene harboring mutations in all 19 patients. In addition, the presence of mutated TP53 and ATM genes correlated with a higher total number of mutations in other analyzed genes. Furthermore, the presence of mutated ATM correlated with poorer event-free survival (EFS) (p = 0.036). The presence of the mutated SMO gene correlated with earlier disease relapse (p = 0.023), inferior event-free survival (p = 0.011) and overall survival (OS) (p = 0.017), while mutations in the PTEN gene were associated with inferior OS (p = 0.048). Our findings suggest that the TP53 and ATM genes could be involved in the molecular pathophysiology of primary DLBCL CNS, whereas mutations in the PTEN and SMO genes could affect survival regardless of the initial treatment approach. 相似文献