全文获取类型
收费全文 | 759篇 |
免费 | 36篇 |
专业分类
电工技术 | 4篇 |
综合类 | 1篇 |
化学工业 | 209篇 |
金属工艺 | 10篇 |
机械仪表 | 8篇 |
建筑科学 | 21篇 |
矿业工程 | 5篇 |
能源动力 | 23篇 |
轻工业 | 173篇 |
水利工程 | 4篇 |
石油天然气 | 3篇 |
无线电 | 41篇 |
一般工业技术 | 97篇 |
冶金工业 | 87篇 |
原子能技术 | 5篇 |
自动化技术 | 104篇 |
出版年
2023年 | 6篇 |
2022年 | 5篇 |
2021年 | 33篇 |
2020年 | 12篇 |
2019年 | 13篇 |
2018年 | 13篇 |
2017年 | 21篇 |
2016年 | 26篇 |
2015年 | 15篇 |
2014年 | 18篇 |
2013年 | 48篇 |
2012年 | 60篇 |
2011年 | 51篇 |
2010年 | 50篇 |
2009年 | 49篇 |
2008年 | 35篇 |
2007年 | 44篇 |
2006年 | 36篇 |
2005年 | 20篇 |
2004年 | 31篇 |
2003年 | 28篇 |
2002年 | 23篇 |
2001年 | 10篇 |
2000年 | 13篇 |
1999年 | 7篇 |
1998年 | 17篇 |
1997年 | 15篇 |
1996年 | 16篇 |
1995年 | 9篇 |
1994年 | 15篇 |
1993年 | 6篇 |
1992年 | 9篇 |
1991年 | 6篇 |
1990年 | 2篇 |
1989年 | 3篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 2篇 |
1983年 | 4篇 |
1982年 | 2篇 |
1981年 | 5篇 |
1980年 | 1篇 |
1979年 | 2篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1976年 | 3篇 |
排序方式: 共有795条查询结果,搜索用时 46 毫秒
21.
The study objective was to describe the perceptions of airplane assemblers on job demand for the back and how back pain modulated these perceptions. One hundred and seventy-six workers answered two questionnaires concerning back pain and the perception of work related difficulties (work activities, work contexts, tools, work positions, efforts). Results show that positions and work contexts are perceived as greater sources of difficulty than efforts or dynamic activities. The duration of a given position is more important than its frequency. Back pain has a significant but complex impact on the perception of difficulty. Assemblers appear to integrate several factors when evaluating their difficulties as opposed to individual aspects, as it is often measured in ergonomic studies. The results have important implications for the measurement of ergonomic factors in the genesis of back pain and illustrates the potential for misclassification and biases in current epidemiologic studies. 相似文献
22.
Diguer Louis; Pelletier Sylvie; Hébert étienne; Desc?teaux Jean; Rousseau Jean-Pierre; Daoust Jean-Philippe 《Canadian Metallurgical Quarterly》2004,21(2):259
This study examined the hypothesis that psychotic, borderline, and neurotic personality organizations (POs) present a progressive differentiation between self and object representations and an increasing integration of their bad and good aspects. Fifty patients participated in the study. Measures included scales of self and object representations (S. J. Blatt, S. A. Bers, & C. E. Schaffer, 1993; S. J. Blatt, H. Wiseman, E. Prince-Gibson, & C. Gatt, 1991), as well as the Personality Organization Diagnostic Form (L. Diguer & L. Normandin, 1997) and estimations of psychiatric severity. Results showed that PO groups differed in terms of the integration of the object and its valence. It was also observed that although object and self representations were closely intertwined, the latter showed more discrimination between POs than the former. Psychiatric severity was shown to correlate more with object representations than self representations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
23.
24.
Sonia Djaziri-Larbi Awatef Zaien Sylvie Sevestre-Ghalila 《Multimedia Tools and Applications》2016,75(8):4559-4575
GIF animations are silent image sequences widely used on the web thanks to their wide support and portability. In this work, we propose an original technique based on data hiding, to add sound tracks in GIF animations. Data hiding is usually used to embed security codes in a host medium to prevent from illegal copying or to protect copyrights (watermarking) or to send secret messages to a dedicated receiver (steganography). We propose to use host GIF images as a “transmission channel” to convey “hidden” sound bits with lowest perceptual image distortion and without altering the wide portability of the GIF format, by means of data hiding. The inserted bits are neither secret nor intended for security issues. They are intended to be played by an audio player synchronously with the GIF player to add sound to the GIF animation. The embedding process is a low complexity, luminance based steganography algorithm, that slightly modifies the pixels colors of the GIF images to insert the sound bits. The extraction of the inserted audio is completely blind: the audio is directly extracted from the pixels of each cover image. The proposed GIF voicing was tested with different GIF sequences (cartoons and real scenes) and no audio degradation was reported while a slight, most imperceptible, color modification was noticed in case of an important amount of inserted data. The cover images have undergone objective quality criteria and informal subjective evaluation and has proved to be of good quality. 相似文献
25.
Mohammed Nabil El Korso Rémy Boyer Alexandre Renaux Sylvie Marcos 《Signal processing》2012,92(2):547-552
In this fast communication, we derive the statistical resolution limit (SRL), characterizing the minimal parameter separation, to resolve two closely spaced known near-field sources impinging on a linear array. Toward this goal, we conduct on the first-order Taylor expansion of the observation model a Generalized Likelihood Ratio Test (GLRT) based on a Constrained Maximum Likelihood Estimator (CMLE) of the SRL. More precisely, the minimum separation between two near-field sources, that is detectable for a given probability of false alarm and a given probability of detection, is derived herein. Finally, numerical simulations are done to quantify the impact of the array geometry of the signal sources power distribution and of the array aperture on the statistical resolution limit. 相似文献
26.
27.
Rositi Hugo Appadoo Owen Kevin Mestre Daniel Valarier Sylvie Ombret Marie-Claire Gadea-Deschamps Émilie Barret-Grimault Christine Lohou Christophe 《Multimedia Tools and Applications》2021,80(2):1945-1967
Multimedia Tools and Applications - Microsoft has recently released a mixed reality headset called HoloLens. This semi-transparent visor headset allows the user who wears it to view the projection... 相似文献
28.
Earth to air heat exchanger (EAHE) is a well‐known technique used to preheat or precool outdoor air before blowing it into a building. However, its geometry is often very simple as it consists in one or multiple straight pipes, while more complex arrangements can be found in heat exchangers design. In this paper, we explore the advantage of designing an EAHE as a network through the Constructal law point of view. A methodology is first proposed to design a single pipe EAHE when the need is defined in terms of cooling power, overall efficiency and enthalpy difference between the inlet air and the ground. Next, the single pipe EAHE is used as a reference for designing a tree‐shaped network under the constraint of identical fluid volume and cooling power. The geometrical features are allowed to change for the different branches of the network. The network coefficient of performance is found to increase significantly with the bifurcation level, illustrating the superior performances of the network. This approach was found to be robust as the improvements were not depending on the cooling demand or the environmental conditions. However, further work is needed to move from this theoretical result to practical considerations. 相似文献
29.
Elvis Maujean Stéphane Desobry Guillaume Gillet Nicolas Poupard Isabelle Desjardins-Lavisse Sylvie Desobry-Banon 《International Journal of Food Science & Technology》2021,56(5):2443-2451
In this study, preservation of spirulina using the new pressurised cryogenic nitrogen technology (PCN) was compared to classical methods used in laboratories and industry. Spirulina morphology was better preserved by PCN compared to unpressurised cryogeny and classical freezing at −20 °C that led to cells fragmentation. A 25% loss of Phycocyanin-C content against 60% were measured after 98 days storage for 6-Bar PCN process and frozen samples, respectively. The Total AntiOxidant Power (PAOT Liquid Technology®) was used for determination of total antioxidant and oxidant power of spirulina extracts. PAOT value of PCN samples was 50% higher than the frozen sample. From ABTS measurements on PCN spirulina fractions sonicated or not, it was suggested that pressurisation at 6 bars allowed a better preservation of free antioxidants (outside the cells) due to replacement of oxygen by nitrogen in the frozen beads. After dehydration, phycocyanin-C content variation during storage at 20 °C and 33% RH showed higher loss for freeze-dried spirulina treated at 0 compared to 6 Bars. 相似文献