全文获取类型
收费全文 | 31514篇 |
免费 | 4850篇 |
国内免费 | 1891篇 |
专业分类
电工技术 | 3206篇 |
技术理论 | 2篇 |
综合类 | 3070篇 |
化学工业 | 2844篇 |
金属工艺 | 1526篇 |
机械仪表 | 2588篇 |
建筑科学 | 3814篇 |
矿业工程 | 2163篇 |
能源动力 | 1964篇 |
轻工业 | 3437篇 |
水利工程 | 1854篇 |
石油天然气 | 2489篇 |
武器工业 | 442篇 |
无线电 | 2218篇 |
一般工业技术 | 2401篇 |
冶金工业 | 1770篇 |
原子能技术 | 352篇 |
自动化技术 | 2115篇 |
出版年
2024年 | 180篇 |
2023年 | 726篇 |
2022年 | 1425篇 |
2021年 | 1634篇 |
2020年 | 1697篇 |
2019年 | 1297篇 |
2018年 | 1094篇 |
2017年 | 1332篇 |
2016年 | 1400篇 |
2015年 | 1459篇 |
2014年 | 2126篇 |
2013年 | 1925篇 |
2012年 | 2429篇 |
2011年 | 2503篇 |
2010年 | 1897篇 |
2009年 | 1847篇 |
2008年 | 1491篇 |
2007年 | 1761篇 |
2006年 | 1597篇 |
2005年 | 1406篇 |
2004年 | 1166篇 |
2003年 | 981篇 |
2002年 | 816篇 |
2001年 | 667篇 |
2000年 | 619篇 |
1999年 | 527篇 |
1998年 | 391篇 |
1997年 | 295篇 |
1996年 | 270篇 |
1995年 | 258篇 |
1994年 | 211篇 |
1993年 | 162篇 |
1992年 | 107篇 |
1991年 | 103篇 |
1990年 | 91篇 |
1989年 | 66篇 |
1988年 | 48篇 |
1987年 | 38篇 |
1986年 | 25篇 |
1985年 | 18篇 |
1984年 | 18篇 |
1983年 | 10篇 |
1982年 | 16篇 |
1981年 | 7篇 |
1980年 | 16篇 |
1966年 | 7篇 |
1964年 | 14篇 |
1962年 | 6篇 |
1959年 | 10篇 |
1957年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 156 毫秒
101.
102.
103.
NiTi形状记忆合金激光气体氮化层表面特征 总被引:2,自引:0,他引:2
为改善NiTi合金的表面性能,利用2kW连续波Nd:YAG对NiTi合金进行激光气体氮化处理。采用SEM、TEM、XRD、XPS和纳米压痕研究了氮化层的显微组织及表面特征.结果表明:激光气体氮化可以在NiTi合金表面制备连续、无裂纹、厚度为2μm的TiN表面层,该表面层中基本不合有Ni元素且具有很高的硬度,其纳米压痕硬度为29.28GPa. 相似文献
104.
After the break-up of Czechoslovakia in 1993 the primary metrological standards authority almost fully remained in Slovakia. So we had to build our primary vacuum metrology anew. But we could do it using uptodate techniques that are more effective and they enable us to fulfil our task more effectively and in a shorter time.The steady demand to widen the lower pressure range and a steady demand for maximal accuracy collide with the financial possibilities open to a small country. So it is impossible to follow the classical pattern for the vacuum standards: liquid columns, static expansion system and dynamic expansion system. But it is possible to utilize contemporary progress in construction of piston manometers. This enables us to discard liquid column and static expansion techniques in favour of piston technique [Tesar J, Prazak D. Vacuum 2002; 67: 311, Tesar J, Prazak D, Krajicek Z. In:Proceedings of international symposium on Pressure and Vacuum, 2003. p. 169, Tesar J, Repa P, Prazak D, Krajicek Z, Peksa L. Vacuum 2004; 76: 491.]. Such system fulfils all the needs of a little industrial country and is economically acceptable. 相似文献
105.
This article reports research intended to assess and extend a recent theory of peer responses to low-performing team members (J. A. LePine & L. Van Dyne, 2001a). An instrument that assesses 4 types of peer responses to low performers (compensating for, training, motivating, and rejecting) was developed and then cross-validated in a subsequent study. Results of the study supported the validity of the peer responses measure and were generally consistent with the attributional theory of peer responses. Low-performer characteristics influenced the peer responses. These effects were mediated in part by peer attributions, affect, and cognitions, which explained variance in the peer responses over and above the variance explained by respondents' personality characteristics (i.e., The Big Five). (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
106.
Much research has examined gender and age effects on compensation, concluding that a wage gap exists favoring men and negative stereotypes against older workers persist. Although the effect of an employee's gender or age has been widely studied, little work has examined the impact of the demographic characteristics of a focal employee's immediate referent groups (e.g., subordinates, peers, or supervisors) on pay. The effect of the gender and age composition of a focal manager's subordinates, peers, and supervisor on the manager's compensation levels was investigated in a sample of 2,178 managers across a wide range of organizations and functional areas. After controlling for a number of human capital variables, results indicated that not only does a wage gap favoring men exist, but also managerial pay is lower when managers' referent groups are largely female, when subordinates are outside the prime age group, and when peers and supervisors are younger. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
107.
民族特色词语的英汉互译 总被引:1,自引:0,他引:1
彭术根 《湖南冶金职业技术学院学报》2004,(4)
语言在其发展演变过程中,逐步具有了鲜明的民族文化色彩。阐述了民族特色词语的可译性,并提出了具体的翻译方法。 相似文献
108.
109.
建立了斜拉桥动力分析的三维有限单元模型 ,研究了单元类型和参数变化对斜拉桥动力特性的影响。详细地讨论了斜拉桥非线性来源 ,并运用 6节点薄壁单元和 4节点索单元分别考虑了斜拉桥弯曲构件和索的非线性特性。通过对一斜拉桥的数值分析 ,得到了关于斜拉桥动力参数敏感性的一般结论。 相似文献
110.
Electrodeposition of conducting polyaniline (Pani) was made under potentiostatic condition at pH 1.0 in different electrolyte media (H2SO4 and HClO4) in the absence and presence of two organic dopants, disodium salts of naphthalene-1,5-disulphonic acid (NSA) and of catechol-3,5-disulphonic acid (CSA). The rate and yield of Pani deposition were dependent on the acid medium and the dopant employed. NSA in H2SO4 caused an increase in rate and yield but CSA decrease when compared to the rate and yield of H2SO4 alone. In HClO4 medium, both the dopants showed a decrease. With regard to DC electrical conductivity, both the dopants exhibited an enhancement in H2SO4 medium but NSA a decline in HClO4. Characterisation of the electrosynthesised polymer samples by various instrumental techniques (cyclic voltammetric: CV, FTIR, UV-Visible: UV-Vis, EPR, XRD, TGA and DTG methods) revealed that between the two acid media, H2SO4 was the better one. Further, it enlightened the role of two organic dopants in relation to the acid media. The advantageous role of NSA in H2SO4 had origin on its molecular characteristics such as non-polarity, larger π-electron cloud etc., while CSA could not perform such a role because of its easily oxidisable hydroxyl groups. In HClO4, however, both the dopants could play only an unfavourable role owing to its greater polarity and oxidizing power than H2SO4. 相似文献