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The bioleaching of arsenical gold-bearing sulphide ores and concentrates solubilises iron, arsenic and sulphur. Previous work has shown that high concentrations of iron and arsenic in solution inhibit bacterial growth, with As(III) reported to inhibit bacteria to a greater degree than As(V).Batch bioleaching experiments were carried out over periods of one month. Varying quantities of either 0.020–0.040 M As(III) or 0.107–0.220 M As(V), were added to a slurry, consisting of a pyrite-arsenopyrite concentrate (20% solids (m.v−1)) in a nutrient solution. The slurry was inoculated with a culture, consisting primarily of Leptospirillum ferrooxidans and Thiobacillus thiooxidans. The culture was obtained from a continuous bioleaching mini-plant treating the same concentrate. The results obtained were compared with those of a culture to which no arsenic was added. The effect of the added arsenic was determined by monitoring three parameters: the oxygen utilisation rate, rO2, of the culture, the rate at which the arsenic in the concentrate was solubilised and the speciation of the dissolved arsenic.The results suggest that the nature of the As(III) and As(V) toxicity is different. The addition of the culture to a slurry containing As(III) resulted in a reduced rate of bacterial oxidation. However, the addition of the culture to a slurry containing As(V) resulted in both a lag phase and a reduced rate of bacterial oxidation. At sufficiently high dosages of As(III) and As(V) the maximum oxygen utilisation rate, rO2max, of the culture was also affected. The results indicate that As(V) toxicity, and the relative toxicity of As(III) and As(V) to a mixed culture, appear to be affected by the availability of an energy source. Hence the toxicity of As(III) is not necessarily in the region of three times that of As(V). Furthermore, the results suggest that the mechanism of arsenic resistance may be attributed to the Pst+ Pit− mutations and an energy dependent efflux pump. 相似文献
995.
《中国有色金属学会会刊》2019,29(10):2170-2182
This paper elaborated on the sustainability of the copper extraction process. In fact, an alternative copper extraction route from mixed sulphide ores, chalcopyrite and chalcocite using mesophilic biomass consortium at 33.3 °C and ferric leaching process were attempted. Bioleaching experiments were settled with a fraction size of −75+53 µm. Bacteria were used as the catalyst. A copper yield of 65.50% was obtained. On the other hand, in ferric leaching process, with a fraction size of −53+38 µm, when the temperature was increased to 70 °C, the copper leaching rate increased to 78.52%. Thus, comparatively, the mesophilic bioleaching process showed a more obvious advantage in copper extraction than leaching process with a high temperature. However, it has been resolved from the characterization performed using SEM−EDS, FTIR and XRD observations coupled with different thermodynamic approaches that, the indirect mechanism is the main leaching mechanism, with three transitory mechanisms (polysulphide, thiosulphate and elemental sulphur mechanisms) for the mixed chalcopyrite−chalcocite ore. Meanwhile, the speciation turns into Cu2S−CuS−Cu5FeS4−Cu2S before turning into CuSO4. While ferrous oxidation and the formation of ferric sulphate occur, and there is a formation of strong acid as bacteria digest sulphide minerals into copper sulphate at low temperature, which is why this copper production scenario requires a redox potential more than 550 mV at room temperature for high copper leaching rate. 相似文献
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997.
相山铀矿田邹家山矿床矿石矿物组成研究 总被引:1,自引:0,他引:1
相山铀矿田邹家山矿床深部铀矿石中钛含量升高,影响常规水冶的铀浸出率和产品质量。为从矿物学角度了解其原因,同时采用微生物浸出工艺提高铀浸出效率,通过电子探针和化学分析方法对该区铀矿石进行矿物组成研究。研究结果初步表明,该矿床矿石中铀矿物种类比较单一,主要以沥青铀矿和钛铀矿为主,其次为铀石等;铀矿物主要呈细脉状、浸染状、不规则团状、颗粒状、斑点状分布,多以独立矿物形式存在,部分铀矿物生长于黄铁矿;铀含量与P2O5、TiO2和CaO等含量呈正相关;该铀矿石中黄铁矿含量较高,部分铀矿物赋存于石英颗粒裂隙及裂缝中,有利于微生物浸出。磷灰石含量高是酸耗量高的原因,黏土矿物含量较高,可影响矿堆渗透能力。上述研究结果可为改进微生物浸铀工艺、提高微生物浸铀效率提供矿物学依据。 相似文献
998.
采用乳状液膜技术对含铀溶液中的铀进行回收处理,研究了制乳原料的最佳体积比,制乳时的搅拌速度、温度等因素,及回收处理铀时的温度、pH值、铀初始质量浓度、提取时间等因素对乳状液膜技术提取回收含铀废液的影响;探讨了乳状液膜提取回收铀过程中铀的迁移机理;通过热力学对乳状液膜技术提取回收铀的液膜传输过程进行了分析。结果表明,当制乳原料中P204和液体石蜡的体积分数为0.1和0.05,Span80、磺化煤油与P204的体积比分别为0.06、0.79,搅拌速度为2000 r/min,内水相盐酸的浓度为4 mol/L时,可制得稳定的油包水型乳状液膜。在常温常压、pH值2.5、铀初始质量浓度小于100 mg/L、含铀废液与乳状液膜的体积比为5时,用乳状液膜对铀废液提取0.5 h,铀的回收率可达到99%以上,Gibbs自由能ΔG<0,说明外水相的铀可自发地向内水相富集。 相似文献
999.
总结了近年来离子液体用于铀的水法及干法后处理相关的基础研究成果,主要内容包括铀在离子液体中的存在物种及电化学行为研究,归纳和分析了其中关键的科学问题。同时,基于当前的研究现状展望了离子液体在铀的净化分离方面的应用研究前景。 相似文献
1000.
通过稀释分离方法从江西德兴铜矿矿山废水中富集而来的混合菌中分离得到菌株 Leptospirillum ferriphilum YXW,再利用超声波、紫外线和微波对其进行诱变,筛选出更高效的细菌用于金矿的浸出。生理生化特性实验显示,菌株YXW为极端化能自养型细菌,最佳的生长条件为温度40°C,pH=1.5。诱变后,细菌浓度分别可达到9×109(超声波)、8.4×109(紫外线)和4.3×108 mL?1(微波),与原始菌相比,分别提高了291%、265%和87%。微波和紫外诱变后,细菌总蛋白活性升高,而超声诱变后,细菌总蛋白活性降低。诱变对细菌浸出金矿的影响由大到小的排列顺序是微波、紫外线、超声波。在金矿浸出过程中,微波诱变后的细菌具有最好的浸出效果。浸出10 d后,As和Fe的浸出率分别高出原始菌19.6%和17.7%。结果表明,诱变对细菌浸出金矿效果的提高,可能不在于细菌浓度的增大,而是取决于细菌总蛋白活性的提高。 相似文献