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21.
O. S. Fatoki 《The International journal of environmental studies》2013,70(2):199-204
Surface soil and grass samples were collected in triplicates from seven locations perpendicular to three major roads in Eastern Cape. Total and available lead, cadmium and zinc were determined in the soil samples and total elements were determined in grass. Lead, cadmium and zinc concentrations declined with distance from road traffic. Significant correlation was also established between available elements in soil and in grass. Levels of total and available elements in the soils ranged from 1167-10834 v µg v g m 1 and from 200-" 5734 v µg v g m 1 , respectively. The levels of the element in grass varied between 200 v µg v g m 1 and 3900 v µg v g m 1 . Total and available cadmium levels in soil although lower than the levels are also significant with values ranging from 17-"2833 v µg v g m 1 and from 27 v µg v g m 1 and from 27-1867 v µg v g m 1 , respectively. The cadmium levels in grass varied between 7 v µg v g m 1 and 1100 v µg v g m 1 . The total and available zinc levels in soil ranged from 2833-8334 v µg v g m 1 and from 533-3600 v µg v g m 1 . The levels in grass varied between 0 and 2800 v µg v g m 1 . The degree of pollution measured would constitute a threat to livestock. Motor traffic appears to be the main source of the elements. 相似文献
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Pure and cadmium (Cd) doped hydroxyapatites (HA, Ca10(PO4)6(OH)2) were synthesized by a precipitation method from aqueous solutions of Ca(NO3)24·H2O for the former and Cd(NO3)24·H2O for the latter, by using (NH4)2HPO4 as the phosphate source, while pH was kept in the range of 11–12. The effect of incorporation of Cd2+ ions into the structure of HA was investigated after the air sintering at 1100 °C for 1 h. The results indicate that Cd2+ addition into HA yields nearly fully densified products with respect to pure stoichiometric HA. The XRD patterns showed that Cd doping increases the crystallinity of HA. The 2, 4.4, and 8.8 mol% Cd doped HAs had calcium oxide (CaO) impurity phase in their lattice. The CaO phase in the HA structure gradually disappeared with increasing Cd amount, and was replaced with cadmium oxide (CdO) in the CdHA doped with 11 mol% Cd. Cd2+ ion incorporation decreased the a- and c-axis lattice constants and unit cell volume of HA. 相似文献
24.
《Journal of Industrial and Engineering Chemistry》2014,20(1):308-314
The sorption profile of cadmium (II) ions from aqueous iodide media onto procaine hydrochloride (PQ+·Cl−) treated polyurethane foams (PUFs) solid sorbent was studied. PQ+·Cl− treated PUFs solid sorbent was found suitable and fast for Cd2+ uptake as [CdI4]aq2−. Thus, removal of Cd2+ at trace levels by the sorbent packed columns was achieved. The sorbed Cd2+ species onto packed column were recovered with HNO3 (10.0 mL, 1.0 mol L−1) prior determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). Plot of Cd2+ ions concentration was linear in the range 0.05–15 μg L−1. The limits of detection and quantification of Cd2+ were found 0.01 μg L−1 and 0.033 μg L−1, respectively. Such limits could be improved to lower values by retention of Cd2+ species from large sample volumes of the aqueous phase at the optimized conditions. The relative standard deviation of the packed column for the extraction and recovery of standard aqueous solutions (0.1 L) containing 1.0 and 5.0 μg L−1 (n = 3) of Cd2+ ions at flow rate of 5.0 mL min−1 were 1.98 and 2.9%, respectively. The method was validated by analysis of Cd in certified reference materials (CRMs) IAEA-Soil-7 and TMDW water and wastewater samples. 相似文献
25.
Chromium and cadmium are toxic heavy metals present in wastewaters from a variety of industries. A strong cationexchange resin, Amberlite IR 120, was used for the removal of chromium and cadmium. The resin was prepared in two different cationic forms, as Na+ and H+. The optimum conditions were concentration, pH, stirring time and resin amount. The concentration range was between 2–50 mg/L, pH range between 2–10, stirring time between 5–60 min, and the amount of resin was from 50–1000 mg. Exchange capacities, moisture content and optimum conditions of this resin were determined in a batch system. The stirring speed was 2000 rpm during all of the batch experiments. The initial and final chromium and cadmium amounts were determined by atomic absorption spectrophotometry. The optimum conditions were found to be a concentration of 20 mg/L, pH of 5.5, stirring time of 20 min and 100 mg of resin. The results obtained show that the Amberlite IR 120 strong cation-exchange resin performed well for the removal and recovery of chromium and cadmium. 相似文献
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Thin films of Fe and Cu-codoped CdO (CdO:Cu:Fe) with different Fe content and fixed Cu content were deposited in a high vacuum on glass and Si wafer substrates. These films were studied by X-ray fluorescence (XRF), X-ray diffraction (XED), optical spectroscopy, and dc-electrical measurements. The structural results show enhancement of film [1 1 1] orientation with Fe doping especially with 1.3%Fe film. Also, light doping with Fe improves the dc-conduction parameters of the CdO:Cu:Fe films so that the utmost enhancement of mobility (90.5 cm2/Vs) and conductivity (1470.6 S/cm) was found with 1.3 wt% Fe doping level. It was found that the variation in the bandgap is related to the variation in electron concentration that caused by Fe doping. For low Fe ion concentration (<1.3 wt% ), the bandgap varies according to the Moss–Burstein model. 相似文献
28.
We have investigated the photoelectrochemical properties of hybrid films of polythiophenes poly(4,4″dimethoxy-3′-methyl-2,2′:5′,2″ terthiophene) (PDM), poly(4,4″dipentoxy-3′-methyl-2,2′:5′,2″ terthiophene) (PDP), and cadmium sulfide/zinc sulfide (CdS(ZnS)) core-shell nanoparticles. Although CdS(ZnS) nanoparticles present enhanced exciton trapping, light harvesting by hybrid films was enhanced when compared to those of pure PDM and PDP films. This enhancement is explained in terms of electron and hole transfer mechanisms at different excitation wavelengths. The more efficient light harvesting of PDM/CdS(ZnS) when compared to that of PDP/CdS(ZnS) was attributed to its broader absorption spectrum and more efficient electron hopping. 相似文献
29.
The morphological manipulation, structural characterization, and photoluminescence properties of different CdSe nanocrystals are reported. Several different CdSe structures, including nanowires, nanorods, nanoparticles, and tetrapod crystals, have been grown on silicon substrates by means of simple, Si‐assisted chemical vapor deposition. By manipulating the growth driving force (i.e., the degree of supersaturation), the morphology of the CdSe nanocrystals can be varied sequentially from nanowires/nanorods to nanoparticles to tetrapod structures. The optical properties of the CdSe nanocrystals are investigated using photoluminescence spectroscopy. Some thermodynamic models are proposed to explain the results. 相似文献
30.
简述运用N2O-C2H2火焰原子吸收光谱法进行镉镍电池电解液中锂含量的测定,并介绍了锂最佳测定条件及呈良好线性范围的浓度。同时对样品的干扰因素、消化处理条件,在综合分析的基础上提出了有效的测定方案。该测定方法灵敏度好,准确度与精密度均能满足镉镍电池研制工作的要求。测定样品锂含量相对标准偏差均小于1.0%(测定次数n=10),标准加入回收率均在97.0%,100.0%(n=6)范围内,达到了实验室分析质量与质量控制的要求,适用于电解液中锂含量的控制分析和样品系统分析。 相似文献