全文获取类型
收费全文 | 23108篇 |
免费 | 942篇 |
国内免费 | 725篇 |
专业分类
电工技术 | 292篇 |
综合类 | 910篇 |
化学工业 | 4359篇 |
金属工艺 | 2293篇 |
机械仪表 | 3230篇 |
建筑科学 | 729篇 |
矿业工程 | 481篇 |
能源动力 | 967篇 |
轻工业 | 1454篇 |
水利工程 | 246篇 |
石油天然气 | 1469篇 |
武器工业 | 96篇 |
无线电 | 1676篇 |
一般工业技术 | 3586篇 |
冶金工业 | 819篇 |
原子能技术 | 358篇 |
自动化技术 | 1810篇 |
出版年
2024年 | 50篇 |
2023年 | 229篇 |
2022年 | 490篇 |
2021年 | 542篇 |
2020年 | 507篇 |
2019年 | 491篇 |
2018年 | 413篇 |
2017年 | 556篇 |
2016年 | 689篇 |
2015年 | 711篇 |
2014年 | 1018篇 |
2013年 | 1626篇 |
2012年 | 1177篇 |
2011年 | 1754篇 |
2010年 | 1208篇 |
2009年 | 1386篇 |
2008年 | 1335篇 |
2007年 | 1468篇 |
2006年 | 1337篇 |
2005年 | 1121篇 |
2004年 | 1077篇 |
2003年 | 967篇 |
2002年 | 822篇 |
2001年 | 592篇 |
2000年 | 523篇 |
1999年 | 460篇 |
1998年 | 406篇 |
1997年 | 353篇 |
1996年 | 285篇 |
1995年 | 256篇 |
1994年 | 187篇 |
1993年 | 177篇 |
1992年 | 105篇 |
1991年 | 92篇 |
1990年 | 83篇 |
1989年 | 62篇 |
1988年 | 54篇 |
1987年 | 35篇 |
1986年 | 28篇 |
1985年 | 29篇 |
1984年 | 15篇 |
1983年 | 11篇 |
1982年 | 8篇 |
1981年 | 3篇 |
1980年 | 7篇 |
1979年 | 2篇 |
1978年 | 6篇 |
1976年 | 6篇 |
1965年 | 2篇 |
1962年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
101.
Yuning Lou Yajuan Dong Xiaoyong Wang Feirong Gong Min Zhao Zongming Rong 《Journal of surfactants and detergents》2021,24(1):3-13
Two generations of novel linear-dendritic carboxylate surfactants C18-G1-(COONa)2 and C18-G2-(COONa)4 have been synthesized by the divergent method and their structures are characterized by 1H Nuclear Magnetic Resonance and Infrared analysis. The electrical conductivity measurement is used to measure the Krafft temperatures of C18-G1-(COONa)2 and C18-G2-(COONa)4, which are much smaller than those of the corresponding conventional surfactant sodium stearate. The markedly enhanced solubility of two linear-dendritic surfactants is ascribed to the high hydrophilicity of surfactant headgroups induced by the carboxylate and ester groups. The critical micelle concentration (CMC) values obtained from both the electrical conductivity and surface tension measurements indicate that the micellizations of linear-dendritic surfactants become favorable with the increase in the number of the surfactant headgroup. However, the surface activity parameters including the surface tension at the CMC, maximum surface excess, and minimum surface area reveal that C18-G1-(COONa)2 exhibits greater efficiency in absorbing at the air/water interface compared to C18-G2-(COONa)4, owing to their different steric repulsions of the surfactant headgroups. In addition, C18-G1-(COONa)2 and C18-G2-(COONa)4 have higher emulsifying ability than the conventional surfactants sodium stearate and sodium octadecyl sulfate. 相似文献
102.
铝质材料的摩擦学表面改性 总被引:1,自引:0,他引:1
铝质材料阳极氧化膜系均匀、规则的微观多孔质结构,利用物理、化学或电化学的方法在其中沉积或原位合成润滑性物质,在保持阳极氧化膜质硬、耐磨特性的基础上,使其具有一定的白润滑性,是近十多年来铝质材料表面改性研究的热点领域之一,本文对该研究的基本原理和国内外发展概况进行了概述,并重点介绍了我们在这一方面研究中的一些最新进展和结果,分别介绍了三种新型体系的自润滑改性阳极氧化铝材料. 相似文献
103.
A unique electrochemical technique, namely continuous noise resistance calculation (CNRC), was used to obtain electrochemical kinetic information from the formation process of chromate conversion coatings (CCC) on aluminium electrodes. It was found that the noise resistance (Rn) of aluminium electrodes remained almost unchanged during electrodes' immersion in a chromate containing acidic solution where the CCC films were supposed to form rapidly. This result indicates that the formation of CCC was associated with continuous corrosion of the aluminium electrodes and that the CCC films formed on aluminium surface were not intact barrier films, but most likely porous layers. The CCCs became protective only after they were aged in the environment. Based on these findings, the formation and inhibition mechanisms of CCC have been discussed. 相似文献
104.
1,12-bis(1,2,4-triazolyl)dodecane (dTC12) is an excellent corrosion inhibitor for carbon steel in deaerated 1 M HCl solution. In this work electrochemical and analytical techniques were used to study the inhibition of corrosion on carbon steel in acidic medium. The carbon steel corrosion inhibition of dTC12 was attributed to the synergistic effect between chloride anion and quaternary ammonium ion. The protective efficiency of the film was higher than 90%, indicating that corrosion of carbon steel in 1 M HCl is reduced by dTC12.The effect of dissolved oxygen on the inhibition efficiency was also investigated. The results show that the inhibition efficiency increases in early stage and decreases for a long immersion time. 相似文献
105.
本文介绍了液压数控冲剪式C型钢成型机的PLC控制系统的设计、实现及应用,该系统工作可靠,使用方便,极大地提高了C型钢成型机的自动化程度及生产效率。 相似文献
106.
The effect of tempering on the magnetic Barkhausen noise (MBN) signal profile was studied in case-carburised EN36 steel using a range of magnetic excitation frequencies and a number of frequency ranges for analysis of the MBN signal. The MBN level generally increases with tempering due to coarsening of the microstructure. With higher values of excitation frequency, fEX, the MBN profile exhibits a single peak, but with low values of fEX, double peaks are observed. The MBN peak obtained with higher fEX was found to correlate well with hardness changes in a region, down to 100 μm below the surface. The analysis of the MBN signal produced with low fEX, in narrow frequency ranges selected by software frequency filtering, showed variations in the extent of changes in the relative height of the two MBN peaks in the profile. After taking into account the skin depth-frequency relation for the MBN signal, variations in the values of the two MBN peaks in different analysing frequency ranges were found to correlate well with hardness variations at different depths down to 425 μm below the surface. An empirical relationship has been established between the hardness-depth profile and the MBN measurements. 相似文献
107.
X.F. Liu 《Corrosion Science》2007,49(9):3494-3513
In the study, on the basis of material analysis of 6016 aluminum alloy widely used in Europe automotive industry, the influences of surface pretreatment on filiform corrosion and adhesion of epoxy coating/aluminum alloy interface were investigated, and the effect of rolling direction and coating property on filiform corrosion was also examined. The alloy surfaces were pretreated with etching solution, and then, respectively, with Aminopropyl silane solution, Aminopropyl phosphonate solution, and hexamethyldisiloxane plasma.The results showed that the susceptibility of pretreated surface to filiform corrosion was basically consistent with the distribution of intermetallic particles, and that water permeation and the tensility of coating were necessary for filament to grow. HMDSO plasma pretreatment could not only efficiently cover the matrix of 6016 aluminum alloy and cathodic intermetallic particles containing Al, Si, Mn, and Fe, but also apparently promote the adhesion of epoxy coating/aluminum alloy, as a result, the specimens with plasma pretreatment exhibited the superior performance in the filiform corrosion and peeling tests, so it was suitable to apply for the pretreatment of aluminum alloy in automotive industry. 相似文献
108.
针对应用Pro/E软件进行注射模分型面设计中出现的靠破孔问题,以阿尔卡特的OT535手机为例,归纳总结了设计分型面时填补破孔的基本思路和主要方法,解决了分型面设计中的关键问题。 相似文献
109.
在我军装备延寿中开发应用各种表面工程新技术、新工艺、新材料,不仅可以修复大量的装备零部件,而且能有效提高装备的防腐性、耐磨性、可靠性,延长装备使用寿命,降低修理费用,减少修理时间.从而提高装备完好率和战斗力。 相似文献
110.
Dai Ruixiang 《中国表面工程》1997,(2)
本文根据96年各表面工程推广站技术工作总结中反映的情况,整理出各站在主要表面技术:电刷镀、热喷涂和粘接粘涂方面的应用实例.反映建站以来各站在装备维修中推广应用表面工程技术的实际状况和取得的主要成绩。 相似文献