全文获取类型
收费全文 | 16215篇 |
免费 | 2121篇 |
国内免费 | 1347篇 |
专业分类
电工技术 | 1379篇 |
综合类 | 1455篇 |
化学工业 | 1779篇 |
金属工艺 | 1760篇 |
机械仪表 | 928篇 |
建筑科学 | 966篇 |
矿业工程 | 873篇 |
能源动力 | 659篇 |
轻工业 | 706篇 |
水利工程 | 294篇 |
石油天然气 | 436篇 |
武器工业 | 301篇 |
无线电 | 1649篇 |
一般工业技术 | 1553篇 |
冶金工业 | 791篇 |
原子能技术 | 104篇 |
自动化技术 | 4050篇 |
出版年
2024年 | 43篇 |
2023年 | 213篇 |
2022年 | 446篇 |
2021年 | 522篇 |
2020年 | 578篇 |
2019年 | 467篇 |
2018年 | 503篇 |
2017年 | 610篇 |
2016年 | 645篇 |
2015年 | 739篇 |
2014年 | 1040篇 |
2013年 | 1075篇 |
2012年 | 1268篇 |
2011年 | 1347篇 |
2010年 | 1048篇 |
2009年 | 1042篇 |
2008年 | 1027篇 |
2007年 | 1208篇 |
2006年 | 1053篇 |
2005年 | 845篇 |
2004年 | 673篇 |
2003年 | 592篇 |
2002年 | 523篇 |
2001年 | 437篇 |
2000年 | 340篇 |
1999年 | 286篇 |
1998年 | 227篇 |
1997年 | 192篇 |
1996年 | 142篇 |
1995年 | 117篇 |
1994年 | 108篇 |
1993年 | 75篇 |
1992年 | 55篇 |
1991年 | 46篇 |
1990年 | 20篇 |
1989年 | 25篇 |
1988年 | 17篇 |
1987年 | 8篇 |
1986年 | 12篇 |
1985年 | 13篇 |
1984年 | 11篇 |
1983年 | 7篇 |
1982年 | 4篇 |
1980年 | 5篇 |
1979年 | 3篇 |
1965年 | 4篇 |
1964年 | 3篇 |
1963年 | 3篇 |
1961年 | 3篇 |
1959年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
Alexander Babich Konstantinos Mavrommatis Dieter Senk Heinrich Wilhelm Gudenau 《国际钢铁研究》2004,75(7):428-432
This contribution deals with advanced educational technologies needed to equip customers from higher education institutions, research and industry with efficient tools supporting their work and operating new skills‐training methods. The challenges are reducing the training costs, improving quality and increasing the number of graduates in engineering departments. The concept of a Virtual Lab based on the combination of various teaching methods and tools is presented. Principles of mathematisation in metallurgical education and training are discussed. An example of online course designed in the form of Virtual Lab is demonstrated. 相似文献
103.
A. Campillo J. I. Farran M. J. Pisabarro 《Applicable Algebra in Engineering, Communication and Computing》2007,18(1-2):191-203
We use the special geometry of singular points of algebraic differential equations on the affine plane over finite fields
to study the main features and parameters of error correcting codes giving by evaluating functions at sets of singular points.
In particular, one gets new methods to construct codes with designed minimum distance.
This work was partially supported by MCyT BFM2001-2251. 相似文献
104.
105.
We propose subspace distance measures to analyze the similarity between intrapersonal face subspaces, which characterize the variations between face images of the same individual. We call the conventional intrapersonal subspace average intrapersonal subspace (AIS) because the image differences often come from a large number of persons. An intrapersonal subspace is referred to as specific intrapersonal subspace (SIS) if the image differences are from just one person. We demonstrate that SIS varies significantly from person to person, and most SISs are not similar to AIS. Based on these observations, we introduce the maximum a posteriori (MAP) adaptation to the problem of SIS estimation, and apply it to the Bayesian face recognition algorithm. Experimental results show that the adaptive Bayesian algorithm outperforms the non-adaptive Bayesian algorithm as well as Eigenface and Fisherface methods if a small number of adaptation images are available. 相似文献
106.
喷雾沉积快速凝固技术的发展与展望 总被引:2,自引:0,他引:2
喷雾沉积是制取大体积快凝材料的一种新工艺。本文综述了它的产生和发展,概述了其基本原理和过程控制。对该领域今后的发展动向,提出了一些新看法。 相似文献
107.
介绍了电熨斗底板真空静电喷涂的工作原理。说明了电晕放电在底板真空静电喷涂中的作用。分析了氟涂料微粒的带电过程及影响因素。这个工艺对产品质量提高的作用进行了分析。 相似文献
108.
Zinc dust and manganese powder as pigments were incorporated in epoxy-polyamide and butyl titanate medium, with different pigment volume concentration (PVC) ranging from 20 to 74. These protective coatings were coated on sand blasted mild steel substrates and immersed in 3 wt.% sodium chloride solution and the corrosion current was measured by the Tafel extrapolation method. From the corrosion current produced by these primers, the optimum level of the pigments in these binders was identified. Thus the protective performance of optimised primers was evaluated on a sand blasted mild steel surface by the Tafel polarisation method in 3 wt.% sodium chloride solution, over different periods of time. The results were found to be comparable with the salt spray test and galvanic current measurements. The manganese powder used for this investigation showed that it could be used as an alternative to zinc powder for metal rich primers. 相似文献
109.
“To understand and protect our home planet, to explore the universe and search for life, and to inspire the next generation of explorers” is NASA's mission. The Systems Management Office at Johnson Space Center (JSC) is searching for methods to effectively manage the Center's resources to meet NASA's mission. D-Side is a group multi-criteria decision support system (GMDSS) developed to support facility decisions at JSC. D-Side uses a series of sequential and structured processes to plot facilities in a three-dimensional (3-D) graph on the basis of each facility's alignment with NASA's mission and goals, the extent to which other facilities are dependent on the facility, and the dollar value of capital investments that have been postponed at the facility relative to the facility's replacement value. A similarity factor rank orders facilities based on their Euclidean distance from Ideal and Nadir points. These similarity factors are then used to allocate capital improvement resources across facilities. We also present a parallel model that can be used to support decisions concerning allocation of human resources investments across workforce units. Finally, we present results from a pilot study where 12 experienced facility managers from NASA used D-Side and the organization's current approach to rank order and allocate funds for capital improvement across 20 facilities. Users evaluated D-Side favorably in terms of ease of use, the quality of the decision-making process, decision quality, and overall value-added. Their evaluations of D-Side were significantly more favorable than their evaluations of the current approach. 相似文献
110.
Bar-Anan Yoav; Liberman Nira; Trope Yaacov; Algom Daniel 《Canadian Metallurgical Quarterly》2007,136(4):610
A picture-word version of the Stroop task was used to test the automatic activation of psychological distance by words carrying various senses of psychological distance: temporal (tomorrow, in a year), social (friend, enemy), and hypotheticality (sure, maybe). The pictures implied depth, with the words appearing relatively close to or distant from the observer. The participants classified the spatial distance of words faster when the word's implicit psychological distance matched its spatial distance (e.g., a geographically close word was classified faster when it was "friend" than when it was "enemy"). The findings are consistent with the idea that psychological distance is accessed automatically, even when it is not directly related to people's current goals, and suggest that psychological distance is an important dimension of meaning, common to spatial distance, temporal distance, social distance, and hypotheticality. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献