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161.
Molds made of gray cast iron for casting pig iron ingots are subjected to severe temperature fluctuations. The main life-
limiting factor for mold damage is the formation of surface cracks arising from thermal fa-tigue. Various flame and plasma
sprayed coatings were investigated to extend the life of these molds. Coating materials studied include plasma sprayed ceramic
coatings with bond coats as well as flame sprayed oxidation- resistant alloy powders. The results of cyclic furnace tests
from room temperature to 1100 °C in air, simulating the thermal cycle in casting, indicated that failure occurred along the
interface between the bond coat and the gray iron substrate because of iron oxidation, and not at the interface between the
ceramic top coat-ing and the bond coating for a superalloy substrate. The field test results indicated that plasma sprayed
alumina coatings with 200 μm top coating thickness are the most promising materials for pig iron casting. 相似文献
162.
太原工业大学煤化工研究所
《工业催化》1994,2(1):44-51
《工业催化》1994,2(1):44-51
回顾了氧化铁脱硫技术的发展历程。指出活性氧化铁在常低温下能将H2S精脱除至0.1~1 ppm以下,可同(200~350) ℃下中温氧化铁脱硫相媲美。讨论了氧化铁常低温精脱硫的理论依据。介绍了太原工业大学近年开发的TG型氧化铁系列脱硫剂的性能及应用。 相似文献
163.
D-HPG废水的预处理 总被引:1,自引:0,他引:1
D-对羟基苯甘氨酸制药废水 COD高 ,成分复杂。采用 Fe粉及 Fenton试剂预处理 ,COD总去除率高达98%以上。小试确定了 Fe粉加入量为 14 0 g/ L、曝气时间为 7h、Fenton法预处理 D- HPG废水的最佳反应条件 :H2 O2 质量浓度为 2 1.5 g/ L,Fe SO4 质量浓度为 3.8g/ L,氧化时间为 4 h,p H为 5 相似文献
164.
Koji Fushimi 《Electrochimica acta》2006,51(7):1255-1263
Micro-indentation test of passive iron electrode in deaerated pH 8.4 borate buffer solution was carried out to investigate the rupture and repair of passive film. During driving a conical diamond micro-indenter with a load of 0.1 N order downward to the electrode and driving upward from the electrode, a couple of anodic current peaks were observed. The first current peak spiked during loading was responsible for partial exposure of iron substrate to the solution due to rupture of the passive film when the indenter tip contacted. The second peak emerged during unloading when elastic deformation recovered, which was ascribed to repair at the ruptured sites. The second peak current was larger than the first one. Both peaks were sensitively influenced by electrode potential or concentration of sulfate ions containing in solution. The model for a series of rupture and repair processes of the passive film by micro-indentation was proposed to discuss the current transients. 相似文献
165.
Saleh Al-Sayari Albert F. Carley Stuart H. Taylor Graham J. Hutchings 《Topics in Catalysis》2007,44(1-2):123-128
The preparation of Au/ZnO and Au/Fe2O3 catalysts using two coprecipitation methods is investigated to determine the important factors that control the synthesis
of high activity catalysts for the oxidation of carbon monoxide at ambient temperature. In particular, the factors involved
in the preparation of catalysts that are active without the need for a calcination step are evaluated. The two preparation
methods differ in the manner in which the pH is controlled during the precipitation, either constant pH throughout or variable
pH in which the pH is raised from an initial low value to a defined end point. Non-calcined Au/ZnO catalysts prepared using
both methods are very sensitive to pH and ageing time, and catalysts prepared at a maximum pH = 5 with a short ageing time
(ca. 0–3 h) exhibit high activity. Catalysts prepared at higher pH give lower activity. However, all catalysts require a short
operation period during which the oxidation activity increases. In contrast, the calcined catalysts are not particularly sensitive
to the preparation conditions. Non-calcined Au/Fe2O3 catalysts exhibit high activity when prepared at pH ≥ 5. Calcined Au/Fe2O3 prepared using the controlled pH method retain high activity, whereas calcined catalysts prepared using the variable pH method
are inactive. The study shows the immense sensitivity of the catalyst performance to the preparation methods. It is therefore
not surprising that marked differences in the performance of supported Au catalysts for CO oxidation that are apparent in
the extensive literature on this subject, particularly the effect of calcination, can be expected if the preparation parameters
are not carefully controlled and reported. 相似文献
166.
167.
In order to analyse iron phosphate complexes and gel-like phases encountered in the single superphosphate process, experiments were performed with a free-Al, Fe apatite crystal of Durango from Mexico phosphate rock and sulfuric acid. Reaction products were studied by X-ray diffraction and surface analysis methods namely X-ray photoelectron spectroscopy and scanning electron microscopy. Results show that in a free Al, Fe-system, part of the Ca(H2PO4 )2.H2O (MCPM) forms before precipitation of any CaSO4(CS) and gel-like phase such H2SO4.yH3PO4.xH2O is formed. When iron is added, the precipitation rate of (CS) and (MCPM) increases and Fe3(H3O)H8(PO4)6.6H2O is formed. When Fe and Al are added, a gel-like phase is quickly formed with a molar ratio that changes with time and develops into crystalline compounds. The composition of this gel may be represented as a mixture of two phases: H2SO4.yH3PO4.xH2O and a gel containing Al-Fe-Si. 相似文献
168.
氧化铁生产废液的治理和利用 总被引:1,自引:0,他引:1
氧化铁生产产生的含铁硫酸铵废液和洗涤废水中含有铁、硫酸根、铵等离子。采用化学沉淀、过滤、蒸发等方法处理该废水可回收废水中的硫酸铵、氧化铁、处理后的废水可回用于生产。 相似文献
169.
以硫酸法钛白粉生产工艺中间体浓钛液(硫酸氧钛)和偏钛酸为原料,分析了浓钛液中二氧化钛和铁的含量。总Ti的测试采用Al片还原法和高铁盐氧化还原滴定法,浓钛液中Ti3 直接用高铁盐氧化还原滴定法测定,铁含量用KMnO4氧化还原滴定法进行分析。采用无机陶瓷膜洗涤分离方法考查了水解后偏钛酸中的除铁效率,利用分光光度法和火焰原子吸收法分别测定洗涤液和二氧化钛粉体中的铁含量。试验表明,无机陶瓷膜洗涤分离方法可以将二氧化钛粉体中铁含量降到30×10-3‰以下,煅烧后产品白度大于94。陶瓷膜洗涤工艺可以实现连续操作,是一种值得推广的新工艺。 相似文献
170.
纳米氧化铁粉体分散技术研究进展 总被引:1,自引:0,他引:1
阐述了纳米氧化铁粉体的团聚及分散原理 分散技术,指出了目前在制备纳米氧化铁粉体和分散技术中存在的问题,提出了建议和发展方向。 相似文献