全文获取类型
收费全文 | 57504篇 |
免费 | 5120篇 |
国内免费 | 3394篇 |
专业分类
电工技术 | 3878篇 |
技术理论 | 3篇 |
综合类 | 4421篇 |
化学工业 | 9199篇 |
金属工艺 | 3423篇 |
机械仪表 | 3378篇 |
建筑科学 | 6293篇 |
矿业工程 | 2610篇 |
能源动力 | 1970篇 |
轻工业 | 3287篇 |
水利工程 | 1487篇 |
石油天然气 | 1833篇 |
武器工业 | 853篇 |
无线电 | 4090篇 |
一般工业技术 | 7822篇 |
冶金工业 | 3532篇 |
原子能技术 | 497篇 |
自动化技术 | 7442篇 |
出版年
2024年 | 253篇 |
2023年 | 686篇 |
2022年 | 1530篇 |
2021年 | 1763篇 |
2020年 | 1804篇 |
2019年 | 1427篇 |
2018年 | 1382篇 |
2017年 | 1806篇 |
2016年 | 1848篇 |
2015年 | 1923篇 |
2014年 | 3287篇 |
2013年 | 3150篇 |
2012年 | 3930篇 |
2011年 | 4291篇 |
2010年 | 3380篇 |
2009年 | 3592篇 |
2008年 | 3171篇 |
2007年 | 4256篇 |
2006年 | 3703篇 |
2005年 | 3298篇 |
2004年 | 2692篇 |
2003年 | 2458篇 |
2002年 | 2067篇 |
2001年 | 1655篇 |
2000年 | 1403篇 |
1999年 | 1099篇 |
1998年 | 809篇 |
1997年 | 665篇 |
1996年 | 604篇 |
1995年 | 467篇 |
1994年 | 420篇 |
1993年 | 298篇 |
1992年 | 178篇 |
1991年 | 133篇 |
1990年 | 100篇 |
1989年 | 100篇 |
1988年 | 73篇 |
1987年 | 33篇 |
1986年 | 23篇 |
1985年 | 36篇 |
1984年 | 18篇 |
1983年 | 21篇 |
1982年 | 17篇 |
1981年 | 14篇 |
1980年 | 14篇 |
1979年 | 9篇 |
1965年 | 13篇 |
1963年 | 12篇 |
1959年 | 9篇 |
1955年 | 15篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
201.
202.
高水固结尾砂充填采矿充填体合理配比的研究 总被引:7,自引:4,他引:3
高水固结尾砂充填采矿是一种新型充填采矿法。试验测定了高水固结尾矿充填体的强度和变形特征;研究分析了影响充填体强度的主要因素、高水充填工艺的特殊要求,以及上向,下向进路开采对充填体强度和稳定性的要求,提出了满足支护强度,工艺及经济需求的充填材料的合理配比范围。 相似文献
203.
作者研制成一种带光纤的电力变压器局放超声PZT传感器.文中分析了它的灵敏度与宽频带特性,介绍了原理、结构设计、实验数据及现场成功实例.理论与实验研究表明:具有这种高灵敏传感器的超声定位系统是确定电力变压器绝缘故障部位的一种方法. 相似文献
204.
本文简要介绍了国外在开发超酸性气体过程中遇到的材料选择、腐蚀监测、水化物堵塞、超酸性气的处理和加工等问题所采取的措施和办法。 相似文献
205.
Diedrichsen J?rn; Ivry Richard B.; Hazeltine Eliot; Kennerley Steven; Cohen Asher 《Canadian Metallurgical Quarterly》2003,29(1):64
Four experiments were conducted to identify the locus of interference observed during the preparation of bimanual reaching movements. Target locations were specified by color, and the right-hand and left-hand targets could be either the same or a different color. Movements of different amplitudes (Experiment 1) or different directions (Experiment 2) to targets of the same color were initiated more quickly than symmetric movements to targets of different colors. These results indicate that costs observed during bimanual movements arise during target selection rather than during motor programming. Experiments 3 and 4 further examined the interference associated with target selection. Reaction time costs were found with unimanual movements when the target was presented among distractors associated with responses for the other hand. Interference observed during bimanual reaching appears to reflect difficulty in segregating the response rules assigned to each hand. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
206.
采用SBS、APP复合改性渣油,可以得到性能优良的改性沥青材料。其最佳配料和共混工艺条件为:SBS/(SBS+APP)之比0.4、外掺量20%、转速1930rPm、共混时间1.0 hr,共混温度20℃。 相似文献
207.
Wrinkling is a well known phenomenon experimented by tension membranes in Civil Engineering applications. This paper will
present an efficient numerical technique for the computational simulation of such wrinkles in a prestressed membrane. In particular,
the relaxed energy approach (Pipkin in IMA J Appl Math 36:85–99, 1986) is particularized for prestressed membranes (Gil in
Textile composites and inflatable structures, CIMNE, 2003) undergoing moderate strains. Wrinkling conditions in terms of the
Euler-Lagrange finite deformation tensor along principal directions will be obtained. This will provide a framework to describe
properly the initial instant when wrinkles start to be encountered in a prestressed Saint Venant–Kirchhoff hyperelastic membrane.
Subsequently, a modified Helmholtz’s free energy functional will be introduced with the purpose of describing the modified
constitutive behaviour of the continuum after the onset of wrinkling. Consistent derivations of the stress tensor as well
as the constitutive tensor will de depicted. The results will be particularized for membranes and cables in a Finite Element
discretization basis. Some numerical examples will prove the accuracy and robustness of the described algorithm. 相似文献
208.
209.
210.
Although methods of product design and materials selection have been developed, the recent rise of multimaterials (composites, hybrids, etc.) has shown a lack of tools for engineering in this domain. The present contribution aims at the development of a multimaterials design method based on the adaptation of existing methods and on the conclusions of a case study. In comparison with materials selection, the originality of multimaterials design relates to searching materials coupling mechanisms to satisfy a set of requirements. More, it appears that manufacturing process and validation tests are very important points that must be integrated early in the design process. 相似文献