全文获取类型
收费全文 | 198234篇 |
免费 | 18189篇 |
国内免费 | 10420篇 |
专业分类
电工技术 | 14310篇 |
技术理论 | 13篇 |
综合类 | 19313篇 |
化学工业 | 27248篇 |
金属工艺 | 8541篇 |
机械仪表 | 16298篇 |
建筑科学 | 21126篇 |
矿业工程 | 7246篇 |
能源动力 | 8530篇 |
轻工业 | 16451篇 |
水利工程 | 7758篇 |
石油天然气 | 9416篇 |
武器工业 | 2143篇 |
无线电 | 11420篇 |
一般工业技术 | 19723篇 |
冶金工业 | 7885篇 |
原子能技术 | 2784篇 |
自动化技术 | 26638篇 |
出版年
2024年 | 834篇 |
2023年 | 2486篇 |
2022年 | 4932篇 |
2021年 | 5835篇 |
2020年 | 6163篇 |
2019年 | 5182篇 |
2018年 | 5050篇 |
2017年 | 6119篇 |
2016年 | 7311篇 |
2015年 | 7701篇 |
2014年 | 12591篇 |
2013年 | 12582篇 |
2012年 | 14674篇 |
2011年 | 15977篇 |
2010年 | 11483篇 |
2009年 | 11709篇 |
2008年 | 10822篇 |
2007年 | 13195篇 |
2006年 | 11474篇 |
2005年 | 9747篇 |
2004年 | 8263篇 |
2003年 | 7086篇 |
2002年 | 5783篇 |
2001年 | 4770篇 |
2000年 | 4136篇 |
1999年 | 3381篇 |
1998年 | 2922篇 |
1997年 | 2477篇 |
1996年 | 2067篇 |
1995年 | 1700篇 |
1994年 | 1505篇 |
1993年 | 1126篇 |
1992年 | 1041篇 |
1991年 | 758篇 |
1990年 | 639篇 |
1989年 | 533篇 |
1988年 | 436篇 |
1987年 | 313篇 |
1986年 | 278篇 |
1985年 | 257篇 |
1984年 | 288篇 |
1983年 | 264篇 |
1982年 | 239篇 |
1981年 | 109篇 |
1980年 | 109篇 |
1979年 | 69篇 |
1978年 | 58篇 |
1977年 | 53篇 |
1976年 | 50篇 |
1959年 | 30篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
11.
Takeshi Nakajo 《Quality and Reliability Engineering International》1993,9(2):111-119
Work system improvements are implemented in various manufacturing processes to prevent problems caused by human errors. However, they are almost always applied to problems which have already occurred. This paper examines a method of identifying latent human errors existing within the work systems beforehand. A procedure for applying failure mode and effect analysis to this identification problem was defined based on over 1000 empirical errors: a work system decomposition criterion and fundamental error modes for listing latent human errors, and then applied to three practical manufacturing processes in order to evaluate its effectiveness. 相似文献
12.
超细Fe3O4粒子表面包覆酞菁钴性质研究 总被引:3,自引:1,他引:2
本文研究了合成载氧体的金属有机化学液相淀积法制造工艺,所得产物经TEM、XPS、Moss-bauer谱和B-H仪等手段,研究了它的结构和磁性能。实验表明,酞青钴以薄层形式包覆在Fe_3O_4的表面,封闭了Fe_3O_4的表面孔洞,稳定了Fe_3O_4的物相,增强了磁性能。 相似文献
13.
In this paper, symbolic code matrix ,constant matrix and count matrix are defined .The first twomatrices are used to describe the elemental expression of augmented matrix and the nede admittance equa-tion is thus obtained. The third matrix is used to obtain the incoming degree matrix, and according to thematrix all the 1- factors of the Coates graph are given. By using the data code, the determinant is expandedand the same items in the expansion are merged. Thus the symbolic network function in which no term can-cellation occurs is generated. 相似文献
14.
This paper considers the principles of algorithmic and software implementation of the software system NADRA 3D designed to
analyze processes in three-dimensional multicomponent soil media. The principles of operation of NADRA 3D are described.
__________
Translated from Kibernetika i Sistemnyi Analiz, No. 6, pp. 157–174, November–December 2006. 相似文献
15.
The failure of the conductor of the 460 kV overhead transmission line located along the crossing of the Paraná River was investigated. As a result of this failure, a blackout took place in the southern states of Brazil in January of 2002, reaching approximately 67 million inhabitants. Investigation of the external aluminium layer of the ACSR conductor near the fracture showed typical static deformation marks and dynamic fretting wear tangential marks, both associated with the presence of Al2O3 debris. Additionally, encrusted silicon particles were observed on the external surface of the strands. The internal Al layer showed elliptical deformation marks also associated with Al2O3 debris. Both Al2O3 and Si particles are efficient abrasive material, which associated with slight relative motion of metallic surfaces (clamp/strand and strand/strand) can promote fretting wear. Two types of fracture surface of the Al strands were identified: 45° and quasi-normal surfaces, the former being the predominant type. Delamination and particle detachment were the mechanisms of superficial degradation observed on the Al strands, indicating that the rupture of the strands occurred under a gross slip fretting regime induced by sub-conductor oscillation. Inspection of the internal surface of as-cast Al–10%Si spacer clamps revealed different stages of intense circumferential wear caused by the preferential cracking and particle detachment of the eutectic constituent of the as-cast microstructure. This intense wear reduces the clamping contact pressure, which allows higher displacement amplitude and leads to the critical fretting regime. Finally, a few suggestions are discussed to minimise the occurrence of future failures. 相似文献
16.
标准物质在分析测试中的重要地位及发展前景 总被引:2,自引:0,他引:2
标准物质在分析测试领域中无论在定值,方法的研究,误差确定等方面都有着重要地位。标准物质的质量保证及正确使用也应引起我们重视。随着科学技术迅速发展标准物质有着广阔发展前景。 相似文献
17.
18.
19.
20.
Heat resistant coatings are required primarily for stacks, exhaust pipes, reactors, space crafts and similar equipments that are permanently or occasionally exposed to elevated temperatures. High-temperature coatings are generally based on silicone resin with ceramic and metallic pigments. In this study, iron oxide, cobalt oxide (thermo chromic compound) and aluminum oxide are used for the preparation of four new types of coloured pigments. The thermal resistant characteristics of these ceramic pigments were studied by differential thermal analysis, thermo gravimetric analysis and differential scanning calorimetric analysis. These ceramic pigments are found to be thermally stable up to 400 °C. 相似文献