全文获取类型
收费全文 | 2045篇 |
免费 | 206篇 |
国内免费 | 59篇 |
专业分类
电工技术 | 127篇 |
综合类 | 116篇 |
化学工业 | 498篇 |
金属工艺 | 386篇 |
机械仪表 | 72篇 |
建筑科学 | 21篇 |
矿业工程 | 66篇 |
能源动力 | 28篇 |
轻工业 | 36篇 |
水利工程 | 3篇 |
石油天然气 | 46篇 |
武器工业 | 4篇 |
无线电 | 234篇 |
一般工业技术 | 135篇 |
冶金工业 | 489篇 |
原子能技术 | 20篇 |
自动化技术 | 29篇 |
出版年
2024年 | 19篇 |
2023年 | 50篇 |
2022年 | 61篇 |
2021年 | 68篇 |
2020年 | 65篇 |
2019年 | 46篇 |
2018年 | 32篇 |
2017年 | 68篇 |
2016年 | 48篇 |
2015年 | 71篇 |
2014年 | 96篇 |
2013年 | 122篇 |
2012年 | 113篇 |
2011年 | 132篇 |
2010年 | 118篇 |
2009年 | 90篇 |
2008年 | 88篇 |
2007年 | 118篇 |
2006年 | 108篇 |
2005年 | 121篇 |
2004年 | 72篇 |
2003年 | 91篇 |
2002年 | 89篇 |
2001年 | 67篇 |
2000年 | 65篇 |
1999年 | 69篇 |
1998年 | 39篇 |
1997年 | 33篇 |
1996年 | 36篇 |
1995年 | 28篇 |
1994年 | 27篇 |
1993年 | 10篇 |
1992年 | 11篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 2篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1975年 | 1篇 |
排序方式: 共有2310条查询结果,搜索用时 15 毫秒
51.
本文提出了铝箔-磷酸·硼酸混合液组成的除氯、除氟体系,有效地消除氟、氯等元素对硫的电导法测定的干扰;系统地研究了铝箔的用量、燃烧温度、燃烧时间、氧气流速对除氯、除氟和二氧化硫的析出及测定的影响。提出了采用燃烧-电导法测定电解镍粉中硫含量的最佳条件。本法测定含硫量为0.0020%的镍粉试样时,相对标准偏差为0.0002%,硫的回收率为98.38%,检测下限为0.0002%,该法操作简便,测量下限低,结果准确可靠,经济实用。 相似文献
52.
The effect of hard anodic oxide and plasma electrolytic oxide coatings on the fatigue strength of 7475-T6 aluminium alloy has been investigated. The coated aluminium alloy was tested using constant load uniaxial tensile fatigue machine. Hard anodising led to an appreciable reduction in the fatigue strength of 7475-T6 alloy of about 75% for a 60 μm thick coating. Further, plasma electrolytic oxidation resulted in reduction of the fatigue strength of about 58% for a 65 μm thick oxide coating. The decrease in fatigue strength of the hard anodic oxide coatings was associated with the stress concentration at the microcracks in the coating. The better fatigue performance of the PEO coatings was attributed to the development of the compressive residual internal stress within the coatings. The reduction in the fatigue strength of the PEO coatings as compared to the uncoated material was associated with the development of the tensile residual internal stress within the substrate. This may cause an early crack initiation in the substrate adjacent to the coating. 相似文献
53.
Vasyl Pokhmurskii Hrygorij Nykyforchyn Mykhajlo Student Mykhajlo Klapkiv Hanna Pokhmurska Bernhard Wielage Thomas Grund Andreas Wank 《Journal of Thermal Spray Technology》2007,16(5-6):998-1004
Different posttreatment methods, such as heat treatment, mechanical processing, sealing, etc., are known to be capable to
improve microstructure and exploitation properties of thermal spray coatings. In this work, a plasma electrolytic oxidation
of aluminum coatings obtained by arc spraying on aluminum and carbon steel substrates is carried out. Microstructure and properties
of oxidized layers formed on sprayed coating as well as on bulk material are investigated. Oxidation is performed in electrolyte
containing KOH and liquid glass under different process parameters. It is shown that thick uniform oxidized layers can be
formed on arc-sprayed aluminum coatings as well as on solid material. Distribution of alloying elements and phase composition
of obtained layers are investigated. A significant improvement of wear resistance of treated layers in two types of abrasive
wear conditions is observed.
This article is an invited paper selected from presentations at the 2007 International Thermal Spray Conference and has been
expanded from the original presentation. It is simultaneously published in Global Coating Solutions, Proceedings of the 2007 International Thermal Spray Conference, Beijing, China, May 14-16, 2007, Basil R. Marple, Margaret M. Hyland, Yuk-Chiu Lau, Chang-Jiu Li, Rogerio S. Lima, and Ghislain
Montavon, Ed., ASM International, Materials Park, OH, 2007. 相似文献
54.
Initial stages of plasma electrolytic oxidation of titanium 总被引:1,自引:0,他引:1
T. H. Teh A. Berkani S. Mato P. Skeldon G. E. Thompson H. Habazaki K. Shimizu 《Corrosion Science》2003,45(12):2757-2768
The initial stages of oxide growth on titanium are examined in a recently developed commercial alkaline pyrophosphate/aluminate electrolyte of interest for plasma electrolytic oxidation of light metal alloys. Constant current anodizing was employed, with resultant films examined by scanning and transmission electron microscopies and Rutherford backscattering spectroscopy. The initial film is relatively uniform and composed of TiO2, with low concentrations of aluminium and phosphorus species incorporated from the electrolyte. With increase in voltage the film breaks down locally, and regions of original and modified film develop simultaneously, with the latter occupying more of the surface as the voltage rises. Porous regions due to dielectric breakdown also become increasingly evident. At 240 V, sparking commences, and the surface reveals extensive, relatively uniform porosity, with the coating now containing much enhanced concentrations of aluminium and phosphorus species compared with the coating at lower voltages. The films develop at low efficiency due to generation of oxygen. The oxygen is produced within the original film material and at sites of dielectric breakdown. The former type of film develops a two-layered morphology, with an outer layer of amorphous TiO2 and an inner layer with numerous fine and course cavities. The cavities are due to the generation of oxygen that may be associated with the formation of anatase in the inner layer. 相似文献
55.
Natalya N. Barabanova Victor V. Belyaev Dmitriy L. Bogdanov Vladimir G. Chigrinov Artem K. Dadivanyan Artem P. Nazarov Olga V. Noah 《Journal of the Society for Information Display》2015,23(10):486-490
A method of controlling anchoring energy of surface interaction of liquid crystal photoaligning substances is considered to enhance the liquid crystal display performances. An important parameter of the dye's molecular structure that determines the ratio of polar and azimuthal anchoring energy is the ability to form dimers. The values of dimerization thermodynamic potentials have been found. The probability of the formation of dye molecules dimers is evaluated. The bonds conjugation transfer via intermolecular hydrogen bond is revealed, and anisotropy of polarizability of the hydrogen bond is evaluated. The effect of dimerization on polar and azimuthal anchoring energy of liquid crystal — azo dye system — is shown. 相似文献
56.
针对铝电解过程中,槽电压的参数调节主要采用“试探法”、过于依赖技术员、耗时长等问题,提出了一种基于状态转移算法(State Transition Algorithm, STA)的槽电压优化方法。首先,采用灰色关联度分析方法确定槽电压模型的输入变量;然后,基于改进的最小二乘支持向量机(Least Square Support Vector Machine, LSSVM)建立槽电压软测量模型;最后,采用状态转移算法对槽电压优化控制模型进行实验,获得槽电压优化值和一组优化操作参数。结果表明,建立的槽电压软测量模型具有较高的预测精度,STA算法可寻到3.819 7 V的优化槽电压值,相较于优化前降低了115.8 mV,每吨铝直流电耗降低了363 kW·h,实现了槽电压的优化控制,达到了较好的节能降耗目的。 相似文献
57.
采用吹砂处理、砂带抛光、毡轮抛光3种表面处理使铸态单晶(SX)Ni基高温合金叶片表面形成塑性变形层,对叶片表面变形层进行电解腐蚀实验,然后进行标准热处理,研究了单晶高温合金叶片表面处理的变形层及其电解腐蚀后显微组织。结果表明:3种表面处理的铸态单晶高温合金叶片表面变形层深度分别约为6,3.5μm和2μm,并在吹砂处理和砂带抛光的表面变形层周围存在显微裂纹;表面变形层电解腐蚀过渡区内存在大量γ′变形组织,且3种表面处理的塑性变形残存量依次递减,而变形层完全电解腐蚀区内无塑性变形痕迹;标准热处理后,变形层未电解腐蚀区存在凹陷特征和再结晶晶粒,但无塑性变形痕迹;变形层完全电解腐蚀区无明显凹坑和再结晶晶粒。 相似文献
58.
Ke Wang Baodan Liu Jing Li Xiaoyuan Liu Yang Zhou Xinglai Zhang Xiaoguo Bi Xin Jiang 《材料科学技术学报》2019,35(4):615-622
TiO_2 nanostructures with strong interfacial adhesion and diverse morphologies have been in-situ grown on Ti foil substrate through a multiple-step method based on conventional plasma electrolytic oxidation(PEO) technology, hydrothermal reaction and ion exchange process. The PEO process is critical to the formation of TiO_2 seeding layer for the nucleation of Na_2Ti_3O_7 and H_2Ti_3O_7 mediates that are strongly attached to the Ti foil. An ion exchange reaction can finally lead to the formation of H_2Ti_3O_7 nanostructures with diverse morphologies and the calcination process can turn the H_2Ti_3O_7 nanostructures into TiO_2 nanostructures with enhanced crystallinity. The morphology of the TiO_2 nanostructures including nanoparticles(NP), nanowhiskers(NWK), nanowires(NW) and nanosheets(NS) can be easily tailored by controlling the NaOH concentration and reaction time during hydrothermal process. The morphology, composition and optical properties of TiO_2 photocatalysts were analyzed using scanning electron microscope(SEM), X-ray diffraction(XRD), photoluminescence(PL) spectroscopy and UV–vis absorption spectrum. Photocatalytic tests indicate that the TiO_2 nanosheets calcined at 500?C show good crystallization and the best capability of decomposing organic pollutants. The decoration of Ag cocatalyst can further improve the photocatalytic performance of the TiO_2 nanosheets as a result of the enhanced charger separation efficiency. Cyclic photocatalytic test using TiO_2 nanostructures grown on Ti foil substrate demonstrates the superior stability in the photodegradation of organic pollutant, suggesting the promising potential of in-situ growth technology for industrial application. 相似文献
59.
Qunfeng Zeng Zhao Wang Wanjun He Zeming Pang Zekun Ning Ruiquan Chen Chenjie Zheng Chao Yan Leilei Guo 《Advanced Engineering Materials》2023,25(17):2300228
Ti6Al4V alloy has good corrosion resistance due to the formation of the passive oxide films on the surface of Ti6Al4V alloy. However, Ti6Al4V alloy has poor tribocorrosion resistance in the seawater environment. Herein the present work, plasma electrolytic oxidation (PEO) with the electrolyte of glycerol and sodium borate is used to generate PEO coatings on the surface of Ti6Al4V alloy to improve its tribocorrosion properties. The microstructure and tribocorrosion properties of PEO coatings are investigated by using scanning electron microscopy, X-ray diffraction, and tribometer, respectively. The growth kinetics and the tribocorrosion mechanisms of PEO coatings are discussed in detail. It is shown in the results that PEO coatings deposited on the surface of Ti6Al4V alloy are composed of rutile and anatase phases. The surface hardness and thickness of PEO coatings are enhanced with the increase of the voltage and time. The wear rate of Ti6Al4V alloy with PEO coatings is significantly reduced in artificial seawater. 相似文献
60.