全文获取类型
收费全文 | 5863篇 |
免费 | 171篇 |
国内免费 | 18篇 |
专业分类
电工技术 | 66篇 |
综合类 | 16篇 |
化学工业 | 899篇 |
金属工艺 | 86篇 |
机械仪表 | 115篇 |
建筑科学 | 247篇 |
矿业工程 | 42篇 |
能源动力 | 180篇 |
轻工业 | 568篇 |
水利工程 | 51篇 |
石油天然气 | 19篇 |
无线电 | 691篇 |
一般工业技术 | 805篇 |
冶金工业 | 1472篇 |
原子能技术 | 43篇 |
自动化技术 | 752篇 |
出版年
2023年 | 20篇 |
2022年 | 38篇 |
2021年 | 76篇 |
2020年 | 76篇 |
2019年 | 72篇 |
2018年 | 96篇 |
2017年 | 107篇 |
2016年 | 109篇 |
2015年 | 91篇 |
2014年 | 123篇 |
2013年 | 341篇 |
2012年 | 207篇 |
2011年 | 259篇 |
2010年 | 233篇 |
2009年 | 232篇 |
2008年 | 257篇 |
2007年 | 254篇 |
2006年 | 217篇 |
2005年 | 160篇 |
2004年 | 168篇 |
2003年 | 169篇 |
2002年 | 140篇 |
2001年 | 112篇 |
2000年 | 102篇 |
1999年 | 126篇 |
1998年 | 443篇 |
1997年 | 256篇 |
1996年 | 202篇 |
1995年 | 122篇 |
1994年 | 105篇 |
1993年 | 115篇 |
1992年 | 67篇 |
1991年 | 60篇 |
1990年 | 54篇 |
1989年 | 56篇 |
1988年 | 41篇 |
1987年 | 57篇 |
1986年 | 61篇 |
1985年 | 67篇 |
1984年 | 60篇 |
1983年 | 44篇 |
1982年 | 43篇 |
1981年 | 42篇 |
1980年 | 34篇 |
1979年 | 24篇 |
1978年 | 27篇 |
1977年 | 49篇 |
1976年 | 77篇 |
1975年 | 18篇 |
1973年 | 27篇 |
排序方式: 共有6052条查询结果,搜索用时 0 毫秒
991.
Shin-Kun Ryi Nong Xu Anwu Li C. Jim Lim John R. Grace 《International Journal of Hydrogen Energy》2010
This study demonstrates palladium membranes can be electrolessly plated on aluminum oxide-modified porous Hastelloy with hydrazine using an EDTA-free bath. The plating bath temperature affected the membrane surface morphology, with the palladium grain size increasing with increasing temperature. A 7.5 μm thick membrane plating was obtained at room temperature. Helium leak testing confirmed that the membrane was free of defects. Hydrogen permeation test showed that the membrane had a hydrogen permeation flux of 3.3 × 10−1 mol m−2 s−1 at a temperature of 823 K and at a pressure difference of 100 kPa. There was no measurable interdiffusion between the membrane film and the porous Hastalloy substrate at 823 K. This room temperature membrane plating method provides several advantages such as very high selectivity, stability, favorable energy efficiency and simplicity. 相似文献
992.
Teachers are in a very real sense the embodiment of leadership, providing direction, guidance, and feedback to their students in addition to acting as role models. Teachers may well thus benefit from developmental coaching that draws on theories of leadership. This study was both an experimental (randomly assigned conditions) and a quasi-experimental (pre–post) study. A randomized controlled design was used to explore the impact of coaching on goal attainment, mental health, workplace well-being, and resilience, and a quasi-experimental (pre–post) design was used to explore the impact of coaching on leadership styles. Forty-four high school teachers were randomly assigned to either coaching or a waitlist control group. The coaching used a cognitive–behavioral, solution-focused approach and was informed by theories of self-leadership and transformational leadership. Participants in the coaching group received multirater feedback on their leadership style and undertook 10 coaching sessions conducted by professional coaches over a 20-week period. Compared with randomly allocated controls, participation in coaching was associated with increased goal attainment, reduced stress, and enhanced workplace well-being and resilience. Pre–post analyses for the coaching group indicated that coaching enhanced self-reported achievement and humanistic–encouraging components of constructive leadership styles and reduced self-reported aggressive/defensive and passive/defensive leadership styles. Findings suggest that coaching, as a professional development methodology, has great potential to contribute to the development and well-being of society beyond the corporate and organizational settings with which leadership coaching and executive coaching are normally associated. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
993.
Farb Norman A. S.; Anderson Adam K.; Mayberg Helen; Bean Jim; McKeon Deborah; Segal Zindel V. 《Canadian Metallurgical Quarterly》2010,10(2):215
Reports an error in "Minding one’s emotions: Mindfulness training alters the neural expression of sadness" by Norman A. S. Farb, Adam K. Anderson, Helen Mayberg, Jim Bean, Deborah McKeon and Zindel V. Segal (Emotion, 2010[Feb], Vol 10[1], 25-33). The DOI printed in the article was incorrect. The correct DOI is presented in the erratum. (The following abstract of the original article appeared in record 2010-01983-008.) Recovery from emotional challenge and increased tolerance of negative affect are both hallmarks of mental health. Mindfulness training (MT) has been shown to facilitate these outcomes, yet little is known about its mechanisms of action. The present study employed functional MRI (fMRI) to compare neural reactivity to sadness provocation in participants completing 8 weeks of MT and wait-listed controls. Sadness resulted in widespread recruitment of regions associated with self-referential processes along the cortical midline. Despite equivalent self-reported sadness, MT participants demonstrated a distinct neural response, with greater right-lateralized recruitment, including visceral and somatosensory areas associated with body sensation. The greater somatic recruitment observed in the MT group during evoked sadness was associated with decreased depression scores. Restoring balance between affective and sensory neural networks—supporting conceptual and body based representations of emotion—could be one path through which mindfulness reduces vulnerability to dysphoric reactivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
994.
995.
996.
Extruded snacks from whole wheat supplemented with textured soy flour: Effect on instrumental and sensory textural characteristics
下载免费PDF全文
![点击此处可从《Journal of texture studies》网站下载免费的PDF全文](/ch/ext_images/free.gif)
997.
Physicochemical Changes of Connective Tissue Proteins in Jumbo Squid (Dosidicus gigas) Muscle During Ice Storage
下载免费PDF全文
![点击此处可从《Journal of Food Processing and Preservation》网站下载免费的PDF全文](/ch/ext_images/free.gif)
998.
Phylogenetic profile of gut microbiota in healthy adults after moderate intake of red wine
下载免费PDF全文
![点击此处可从《Molecular nutrition & food research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
999.
Mediterranean tomato‐based sofrito protects against vascular alterations in obese Zucker rats by preserving NO bioavailability
下载免费PDF全文
![点击此处可从《Molecular nutrition & food research》网站下载免费的PDF全文](/ch/ext_images/free.gif)
1000.
Willemijn M. Appels Susan N. Wall S. Lee Barbour M. Jim Hendry Craig F. Nichol Saidur R. Chowdhury 《Mine Water and the Environment》2017,36(4):479-494
Saline-sodic shale overburden associated with oil sand mining is a potential source of salt release to surface water and groundwater and can lead to salinization and/or sodification of reclamation covers. Weathering of shale overburden due to oxidation of sulphide minerals within the shale leads to sulphate (SO4 2?) production and increased salinity. The controls on the rates of weathering of a shale overburden dump in the oil sands region of northern Alberta were determined from soil chemistry sampling and in situ monitoring of pore gases (O2, CO2, CH4) in three shallow profiles (1.9–4.45 m deep) and one deep (25 m deep) profile under reclamation covers of varying thickness. Oxidation, defined by the depth over which O2 concentrations were depleted, reached depths of approximately 1.1 m under the reclamation soil covers over a 6 year period after dump placement. Calculations of SO4 2? production rates and weathering depths were consistent with numerical simulations of the diffusion and subsequent consumption of atmospheric O2 in the overburden. The rate of SO4 2? production during the 6 year weathering period estimated from direct measurements of solids chemistry ranged from 0.70 to 8.3 g m?2 day?1. The rates calculated from the oxygen diffusion models were within that same range, between 1.6 and 4.1 g m?2 day?1. 相似文献