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71.
Modeling of kinetics of pertechnetate removal by amino-functionalized glycidyl methacrylate copolymer 总被引:1,自引:1,他引:0
Danijela?D.?MaksinEmail author Radmila?V.?Hercigonja Magdalena??.?Lazarevi? Marija?J.??uni? Aleksandra?B.?Nastasovi? 《Polymer Bulletin》2012,68(2):507-528
Technetium-99 comprises a significant health risk, since edible plants can bioaccumulate and convert it to more lipophilic
species that cannot be excreted through urine. Batch kinetics of pertechnetate removal from aqueous solutions by two samples
of crosslinked poly(glycidyl methacrylate-co-ethylene glycol dimethacrylate) functionalized with diethylene triamine (PGME-deta) was investigated at the optimum pH value
of 3.0, and the initial solution activity of 325 MBq dm−3. PGME-deta was characterized by elemental analysis, mercury intrusion porosimetry, and scanning electron microscopy. Five
kinetic models (pseudo-first, pseudo-second order, Elovich, Bangham, and intraparticle diffusion) were used to determine the
best-fit equation for pertechnetate sorption. After 24 h, PGME-deta samples sorbed more than 98% of pertechnetate present,
with maximum sorption capacity of 25.5 MBq g−1, showing good potential for remediation of slightly contaminated groundwater. 相似文献
72.
Inferring the origin of rare fruit distillates from compositional data using multivariate statistical analyses and the identification of new flavour constituents 下载免费PDF全文
73.
Milena Rosi? Mihovil LogarAleksandar Deve?erski Marija PrekajskiAna Radosavljevi?-Mihajlovi? Vladan KusigerskiVojislav Spasojevi? Branko Matovi? 《Ceramics International》2011,37(4):1313-1319
Ca0.9Gd0.1MnO3 nanopowders with perovskite type crystal structure were synthesized by modified glycine nitrate procedure. Nanopowders were prepared by combining glycine with metal nitrates and/or metal acetates in their appropriate stoichiometric ratios. Modification of the procedure was performed by partial replacement of nitrates by acetates, in order to control the burn-up reaction. Obtained Ca0.9Gd0.1MnO3 powders were calcinated in the temperature interval from 850 °C to 950 °C for 10 min. Properties such as phase evolution, lattice parameters, chemical composition and magnetic properties were monitored by DTA, X-ray diffraction, SEM/EDS and magnetic measurements. Magnetic measurements performed at the sample with the smallest crystallite size showed that a 10% of Gd3+ substituted Ca2+ ions changes antiferromagnetic properties of CaMnO3 by the introduction of ferromagnetic interaction due to a double exchange between Mn3+ and Mn4+ ions. Presence of competing interactions and their randomness lead to a formation of a spin glass state below Neel temperature TN = 110 K. From the high temperature magnetic susceptibility measurements effective magnetic moment of manganese ions is determined which lies between the values for Mn3+ and Mn4+ ions. 相似文献
74.
Marija V. Pergal Vesna V. Antić Milutin N. Govedarica Dejan Goäevac Sanja Ostojić Jasna Djonlagić 《应用聚合物科学杂志》2011,122(4):2715-2730
Novel polyurethane copolymers derived from 4,4′‐methylenediphenyl diisocyanate (MDI), 1,4‐butanediol (BD) and α,ω‐dihydroxy‐[poly(caprolactone)‐poly (dimethylsiloxane)‐poly(caprolactone)] (α,ω‐dihydroxy‐(PCL‐PDMS‐PCL); = 6100 g mol?1) were synthesized by a two‐step polyaddition reaction in solution. In the synthesis of the polyurethanes, the PCL blocks served as a compatibilizer between the nonpolar PDMS blocks and the polar comonomers, MDI and BD. The synthesis of thermoplastic polyurethanes (TPU) with high soft segment contents was optimized in terms of the concentrations of the reactants, the molar ratio of the NCO/OH groups, and the time and temperature of the polyaddition reaction. The structure, composition, and hard MDI/BD segment length of the synthesized polyurethane copolymers were determined by 1H, 13C‐NMR, and two‐dimensional correlation (COSY, HSQC, and HMBC) spectroscopy, while the hydrogen bonding interactions in the copolymers were analyzed by FT‐IR spectroscopy. The influence of the reaction conditions on the structure, molecular weight, thermal, and some physical properties was studied at constant composition of the reaction mixture. A change in the molar ratio of the NCO/OH groups and the reaction conditions modified not only the molecular weight of the synthesized polyurethanes, but also the microstructure and therefore the thermal and physical properties of the copolymers. It was demonstrated that only PCL segments with high soft segment contents crystallize, thereby showing spherulitic morphology. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
75.
Ljerka Prester Jelena Macan Veda Marija Varnai Tatjana Orct Jelena Vukušić Dubravka Kipčić 《Food additives & contaminants. Part A, Chemistry, analysis, control, exposure & risk assessment》2013,30(3):355-362
Whole Atlantic mackerel (Scomber scombrus), sardine (Sardina pilchardus) and Mediterranean hake (Merluccius merluccius) from the Croatian Adriatic were stored at 22 °C and changes in histamine, putrescine, tyramine and cadaverine levels were monitored in relation to bacterial endotoxin. After 12 h, histamine levels in sardine were above the legal limit of 50 mg kg?1, set by the US Food and Drug Administration, and an increase in putrescine content preceded the increase in histamine. After 24 h, histamine contents in mackerel and sardine reached 1090 ± 101 and 577 ± 275 mg kg?1, respectively, which exceeded the toxic threshold of 500 mg kg?1. At the same time, the putrescine content was also high in both fish (353–420 mg kg?1). The time-course of endotoxin production was similar in all fish species stored at 22 °C. A high correlation was found between endotoxin and histamine, and between endotoxin and putrescine in mackerel and sardine. On the other hand, high endotoxin levels in hake, after 24 h, were associated with the low histamine and putrescine content (40–60 mg kg?1). 相似文献
76.
Mira Mandeljc Barbara Malič Marija Kosec Goran Dražič 《Integrated ferroelectrics》2013,141(1):329-338
The general problem of processing zirconium-rich lead-lanthanum-zirconate-titanate (PLZT) thin films at the commonly used temperatures between 600 and 650 C is lead-oxide loss, leading to the formation of a non-ferroelectric, surface pyrochlore-type phase. To avoid lead-oxide losses due to sublimation and/or the interaction of the film with the substrate, it is desirable that the annealing temperatures are as low as possible. Our goal was to study and prepare perovskite PLZT 9.5/65/35 (Pb 0.858 La 0.095 Zr 0.65 Ti 0.35 O 3 ) thin films below 500 C. At 400 C the growth of the perovskite phase follows the parabolic law typical of diffusion controlled processes. During prolonged annealing growth continues until the limiting stoichiometry of the perovskite phase with regard to the PbO is reached. We conclude that, even at this low temperature the amount of PbO in the film is the critical factor in the crystallization of the perovskite phase. 相似文献
77.
Dejan Ivezić Marija Živković Toma Tanasković Nenad Đajić 《Applied Thermal Engineering》2009,29(8-9):1440-1446
Economic evaluation of different energy supply systems (district or local heating by natural gas) in Serbia is considered in this paper. According to variety of Serbian settlements (in density, size and layout of buildings) model which has ability to represent their different characteristics is formed. Model is based on identification of smaller urban areas with identical or similar characteristics and their representations with one of predefined nominal urban areas. For various nominal urban areas preferred type of energy supply system was selected. Obtained results formed matrix of preferred type of energy supply system (district or local heating) for different urban structures. This models’ matrix could be simple and useful tool for initial decision about energy supply system. 相似文献
78.
Marija Prekajski Aleksandar Kremenovi? Milena Rosi? Ana Radosavljevi?-Mihajlovi? 《Materials Letters》2010,64(20):2247-614
Nanometric Bi2O3 powder was successfully synthesized by applying the method based on self-propagating room temperature reaction (SPRT) between bismuth nitrates and sodium hydroxide. X-ray powder diffraction (XRPD) and Rietveld's structure refinement method were applied to characterize prepared powder. It revealed that synthesized material is a single phase monoclinic α-Bi2O3 (space group P21/c with cell parameters a = 5.84605(4)Å, b = 8.16339(6) Å, c = 7.50788(6) Å and β = 112.9883(8)). Powder particles were of nanometric size (about 50 nm). Raman spectral studies conformed that the obtained powder is single phase α-Bi2O3. Specific surface area of obtained powder was measured by Brunauer-Emmet-Teller (BET) method. 相似文献
79.
Marija Djokić Jelena Djuriš Ljiljana Solomun Kyriakos Kachrimanis Zorica Djurić Svetlana Ibrić 《Chemical Engineering Research and Design》2014
The purpose of this study was to investigate the influence of spiral jet-milling process on the physicochemical characteristics of α polymorphic active pharmaceutical ingredient, using Carbamazepine form III as a model drug, and taking into consideration Quality by Design (QbD) approach to pharmaceutical development. A 2(4-1) factorial screening design was implemented to identify the spiral jet-milling process variables that significantly affect the particle size distribution of milled samples. Diameter of injector nozzles, diameter of ring nozzles and air pressure were selected for further analysis using a 2(3-1) factorial experimental design. Particle size distribution of additional samples was determined, while physicochemical properties were examined by differential scanning calorimetry (DSC), hot-stage polarized microscopy (HSPM), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), and compared to those of un-milled drug. The gathered results shown that applied experimental design approach is capable to predict material behavior and could help in better understanding of material behavior during jet-milling process. Created design space (DS) provides assurance of product quality, expressed as the powder particle sizes lower than 5 μm, as well as, in initial polymorph form existence after jet-milling through combination and interaction of input variables. 相似文献
80.
Petar Kljaji? Goran Andri? Marija Bodro?a-Solarov Ilija Peri? 《Journal of Stored Products Research》2010,46(1):1-6
The insecticidal effectiveness of two natural zeolite formulations (Minazel plus and Minazel), applied to wheat at selected rates of 0.25, 0.50 and 0.75 g/kg, and a diatomaceous earth formulation (DE) (Protect-It™), applied at the recommended rates of 0.15 g/kg for Sitophilus oryzae, 0.20 g/kg for Rhyzopertha dominica and 0.30 g/kg for Tribolium castaneum, were tested under laboratory conditions (24 ± 1 °C temperature and 45 ± 5% relative humidity). The highest adult mortality was observed after the longest exposure period of 21 days and 7 days of recovery, when all three zeolite dosage rates and the recommended DE dosage caused 97-100% mortality of S. oryzae and 94-100% of T. castaneum. On the other hand, 100% mortality was not achieved in any test variant involving R. dominica; the highest (about 92%) was detected for DE, while 52% and 79% mortality was achieved with the zeolites at the highest rate of 0.75 g/kg. Progeny reduction by >90% was achieved after 21 days of contact of all three beetle pests with DE-treated wheat, while the same level of reduction was achieved for S. oryzae and T. castaenum only after contact with the highest rate of the zeolite product, Minazel. Thus the two zeolite formulations are comparable to diatomaceous earth in controlling adult S. oryzae, R. dominica and T. castaneum, but only the Minazel formulation could effectively protect wheat from attack by S. oryzae or T. castaneum, and only with a higher rate of application than for the DE formulation. 相似文献