全文获取类型
收费全文 | 260961篇 |
免费 | 20530篇 |
国内免费 | 13240篇 |
专业分类
电工技术 | 16727篇 |
技术理论 | 51篇 |
综合类 | 36210篇 |
化学工业 | 28898篇 |
金属工艺 | 9677篇 |
机械仪表 | 14080篇 |
建筑科学 | 37369篇 |
矿业工程 | 14864篇 |
能源动力 | 7845篇 |
轻工业 | 14549篇 |
水利工程 | 13900篇 |
石油天然气 | 11111篇 |
武器工业 | 2492篇 |
无线电 | 16857篇 |
一般工业技术 | 18282篇 |
冶金工业 | 15368篇 |
原子能技术 | 2649篇 |
自动化技术 | 33802篇 |
出版年
2024年 | 800篇 |
2023年 | 2494篇 |
2022年 | 4944篇 |
2021年 | 5882篇 |
2020年 | 6090篇 |
2019年 | 5105篇 |
2018年 | 4814篇 |
2017年 | 5794篇 |
2016年 | 6972篇 |
2015年 | 7831篇 |
2014年 | 14478篇 |
2013年 | 13135篇 |
2012年 | 17177篇 |
2011年 | 18287篇 |
2010年 | 14557篇 |
2009年 | 15199篇 |
2008年 | 14224篇 |
2007年 | 18704篇 |
2006年 | 17747篇 |
2005年 | 15566篇 |
2004年 | 13256篇 |
2003年 | 11957篇 |
2002年 | 9864篇 |
2001年 | 8337篇 |
2000年 | 7039篇 |
1999年 | 5752篇 |
1998年 | 4347篇 |
1997年 | 3813篇 |
1996年 | 3540篇 |
1995年 | 2994篇 |
1994年 | 2674篇 |
1993年 | 2003篇 |
1992年 | 1779篇 |
1991年 | 1322篇 |
1990年 | 1155篇 |
1989年 | 1020篇 |
1988年 | 818篇 |
1987年 | 563篇 |
1986年 | 424篇 |
1985年 | 350篇 |
1984年 | 329篇 |
1983年 | 240篇 |
1982年 | 214篇 |
1981年 | 165篇 |
1980年 | 130篇 |
1979年 | 110篇 |
1978年 | 62篇 |
1977年 | 72篇 |
1976年 | 55篇 |
1975年 | 55篇 |
排序方式: 共有10000条查询结果,搜索用时 3 毫秒
991.
The optical and thermal properties of prepared poly(ethylene oxide)/MnCl2 films were studied as a function of MnCl2 concentration at room temperature. The observed optical energy gap (Eopt) and energy gap tail (ΔE) were determined from the measured absorption spectra. It was found that the optical energy gap decreases with MnCl2 concentration, and the absorption coefficient reduces sharply at concentration of 5 wt% MnCl2 compared with the neat PEO. Differential scanning calorimetry (DSC) measurement shows that the heat of fusion increases with the MnCl2 concentration, while the melting point decreases. Correlation between the observed optical energy gap and heat of fusion is presented. 相似文献
992.
本文通过对某液压挖掘机工作装置实验样本长度的研究,详细讨论了样本长度的确定方法,重点分析了趋势曲线拟合法,提出了样本长度精度区间分析的方法,并在处理大量实验数据的基础上,从载荷分布及寿命估算的角度做了实际的验证.编制了应用程序,使样本长度确定至寿命估算整个过程程序化. 相似文献
993.
李大为 《哈尔滨建筑大学学报》2002,35(3):92-95
9·11恐怖撞击事件,促使人们重新认识摩天大楼的安全性,由于这类建筑规模越大,其安全性受到的损害就越大,同时也带来其他方面的问题.因此,为减少灾害发生后的损失,必须控制其规模,确保摩天楼建设有序进行. 相似文献
994.
利用荷载平衡法的概念,将预应力度用等效荷载与外荷载的比值表达,设计可利用其比值确定预应力度,便其更简捷,明确,同时,提出了预应力度的真实值问题。 相似文献
995.
Chapman Derek S.; Uggerslev Krista L.; Webster Jane 《Canadian Metallurgical Quarterly》2003,88(5):944
This field study examined applicant reactions (N = 802) toward face-to-face as compared with technology-mediated interviews (through videoconferencing or by telephone) for 346 organizations. Face-to-face interviews were perceived as more fair and led to higher job acceptance intentions than were videoconferencing and telephone interviews. Perceived interview outcomes were higher with face-to-face and telephone interviews over videoconferencing. Self-monitoring moderated the relationship between interview medium and perceptions of fairness. Specifically, this relationship was (a) positive for face-to-face, (b) negative for telephone, and (c) nonsignificant for videoconferencing interviews. Moreover, the number of offers an applicant received moderated the relationship between interview medium over, and perceived fairness. The relationship between number of offers and perceived fairness was positive for face-to-face and negative for technology-mediated interviews. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
996.
Tillmann Barbara; Janata Petr; Birk Jeffrey; Bharucha Jamshed J. 《Canadian Metallurgical Quarterly》2003,29(2):470
Harmonic priming studies have shown that a musical context, with its established tonal center, influences target chord processing. This study investigated costs and benefits of priming tonal centers for target processing by adding a baseline condition (sequences without a specific tonal center). Results confirmed harmonic priming, with faster processing for related than for unrelated and less related targets (tonic chord, out-of-key chord, subdominant chord). Comparing targets in baseline contexts with targets in sequences with well-established tonal centers revealed a benefit of processing for related targets but a cost of processing for unrelated and less related targets. Findings are discussed in terms of tonal knowledge activation and suggest that an activated tonal center gives rise to strong expectations for the tonic. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
997.
超越离合器内星轮对数螺旋楔合面的设计 总被引:1,自引:0,他引:1
何为 《苏州大学学报(工科版)》2002,22(5):38-42
通过对采用平面楔合面内星轮的超越离合器的受力及磨损对其使用可靠性影响的分析,从而提出了用对数螺旋楔合而代替平面楔合面的设计方案,并对两种方案进行了比较。 相似文献
998.
红外加热节能技术的现状与发展前景 总被引:1,自引:0,他引:1
本文综述了国内外节能的现状与发展趋势,论述了远红外电加热领域的发展前景,强调了加强基础理论研究的重要性,介绍了我国红外加热应用的领域和国外新开发的红外产品。 相似文献
999.
The long-term effects of the Cognitive Adaptation Theory Index (CATI) on psychological and physical health outcomes among men (n=199) and women (n=99) treated for coronary artery disease with percutaneous transluminal coronary angioplasty were examined. The CATI reflects a positive view of the self, a positive view of one's future, and a sense of personal control over daily life. This index was created from questionnaires administered during hospitalization for the initial angioplasty. Four years later, the CATI predicted positive adjustment to disease, even when initial adjustment was taken into consideration. In addition, the CATI predicted a reduced likelihood of sustaining a subsequent cardiac event over 4 yrs. This association was more robust for men. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
1000.
门式脚手架在已建高层建筑外装修中的应用 总被引:1,自引:0,他引:1
介绍门式脚手架在已建高层建筑外排栅中的整体搭设和应用实例。 相似文献