全文获取类型
收费全文 | 591098篇 |
免费 | 9194篇 |
国内免费 | 1682篇 |
专业分类
电工技术 | 11548篇 |
技术理论 | 3篇 |
综合类 | 1704篇 |
化学工业 | 95227篇 |
金属工艺 | 24460篇 |
机械仪表 | 20018篇 |
建筑科学 | 14180篇 |
矿业工程 | 4743篇 |
能源动力 | 15272篇 |
轻工业 | 47729篇 |
水利工程 | 7276篇 |
石油天然气 | 16017篇 |
武器工业 | 192篇 |
无线电 | 63201篇 |
一般工业技术 | 120345篇 |
冶金工业 | 96783篇 |
原子能技术 | 15003篇 |
自动化技术 | 48273篇 |
出版年
2022年 | 4303篇 |
2021年 | 6229篇 |
2020年 | 4619篇 |
2019年 | 5897篇 |
2018年 | 9859篇 |
2017年 | 10205篇 |
2016年 | 10637篇 |
2015年 | 6943篇 |
2014年 | 11383篇 |
2013年 | 27544篇 |
2012年 | 17314篇 |
2011年 | 22775篇 |
2010年 | 18334篇 |
2009年 | 20134篇 |
2008年 | 20385篇 |
2007年 | 20011篇 |
2006年 | 17582篇 |
2005年 | 15948篇 |
2004年 | 14825篇 |
2003年 | 14460篇 |
2002年 | 13956篇 |
2001年 | 13473篇 |
2000年 | 13090篇 |
1999年 | 12807篇 |
1998年 | 28323篇 |
1997年 | 20610篇 |
1996年 | 16133篇 |
1995年 | 12475篇 |
1994年 | 11204篇 |
1993年 | 10871篇 |
1992年 | 8553篇 |
1991年 | 8277篇 |
1990年 | 8126篇 |
1989年 | 7890篇 |
1988年 | 7572篇 |
1987年 | 6796篇 |
1986年 | 6583篇 |
1985年 | 7433篇 |
1984年 | 6719篇 |
1983年 | 6442篇 |
1982年 | 5789篇 |
1981年 | 5909篇 |
1980年 | 5640篇 |
1979年 | 5739篇 |
1978年 | 5666篇 |
1977年 | 6182篇 |
1976年 | 7691篇 |
1975年 | 5111篇 |
1974年 | 4904篇 |
1973年 | 4981篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
Aleksandrov A. V. 《Power Technology and Engineering (formerly Hydrotechnical Construction)》2021,55(4):477-481
Power Technology and Engineering - The work done on the test site to ensure the operational safety of the powerhouse of the Zagorsk PSP-2 after its leveling is described. The controlled... 相似文献
152.
Xiaohui Hu Li Cheng Yan Hong Zhaofeng Li Caiming Li Zhengbiao Gu 《International Journal of Food Science & Technology》2021,56(8):4149-4158
Incorporating high level of potato flour into wheat flour enhances nutritional values of bread but induces a series of problems that lead to the decline of the bread quality. To overcome the barrier, wheat gluten and carboxymethylcellulose (CMC) were added into potato–wheat composite flour to improve dough machinability and bread quality. The rheological properties, thermo-mechanical properties and microstructures of dough were investigated. The results showed that the interaction between gluten and CMC mitigated the discontinuity of gluten matrix and gluten protein aggregation caused by the addition of potato flour, which yielded a more branched and compact gluten network. The compact three-dimensional viscoelastic structure induced improvements of gas retention capacity and dough stability, making it mimic the machinability properties of wheat flour dough. Bread qualities were apparently improved with the combined use of 4% gluten and 6% CMC, of which specific volume increased by 42.86%, and simultaneously, hardness reduced by 75.93%. 相似文献
153.
Mechanical durability of extruded fish feed must be optimized to lower economic losses as well as emission of organic matter to aquatic environments. The glass transition hypothesis for viscoelastic biopolymers is demonstrated and confirmed experimentally to be valid for extruded fish feed pellets. It is proposed and demonstrated that it is important to avoid early glass transition onset, to optimize the obtained mechanical durability. From the proposed glass transition hypothesis, immediate process relevance to the pre-drying transport mechanism is demonstrated. Furthermore, measured mechanical durability is found to range from 1.5 to 5.0% loss, for different combinations of drying parameters. 相似文献
154.
Wireless Personal Communications - In this paper, cooperative communication (CC) assisted cognitive wireless sensor network (CWSN) is presented for monitoring health and activity of an end-user in... 相似文献
155.
Angelico Mendy Nervana Metwali Sarah S. Perry Elizabeth A. Chrischilles Kai Wang Peter S. Thorne 《Indoor air》2020,30(1):88-97
Endotoxin exacerbates asthma. We designed the Louisa Environmental Intervention Project (LEIP) and assessed its effectiveness in reducing household endotoxin and improving asthma symptoms in rural Iowa children. Asthmatic school children (N = 104 from 89 homes) of Louisa and Keokuk counties in Iowa (aged 5-14 years) were recruited and block-randomized to receive extensive (education + professional cleaning) or educational interventions. Environmental sampling collection and respiratory survey administration were done at baseline and during three follow-up visits. Mixed-model analyses were used to assess the effect of the intervention on endotoxin levels and asthma symptoms in the main analysis and of endotoxin reduction on asthma symptoms in exploratory analysis. In the extensive intervention group, dust endotoxin load was significantly reduced in post-intervention visits. The extensive compared with the educational intervention was associated with significantly decreased dust endotoxin load in farm homes and less frequent nighttime asthma symptoms. In exploratory analysis, dust endotoxin load reduction from baseline was associated with lower total asthma symptoms score (Odds ratio: 0.52, 95% confidence interval: 0.29-0.92). In conclusion, the LEIP intervention reduced household dust endotoxin and improved asthma symptoms. However, endotoxin reductions were not sustained post-intervention by residents. 相似文献
156.
157.
In vivo Kinetic Biodistribution of Nano‐Sized Outer Membrane Vesicles Derived from Bacteria 下载免费PDF全文
Su Chul Jang Sae Rom Kim Yae Jin Yoon Kyong‐Su Park Ji Hyun Kim Jaewook Lee Oh Youn Kim Eun‐Jeong Choi Dae‐Kyum Kim Dong‐Sic Choi Yoon‐Keun Kim Jaesung Park Dolores Di Vizio Yong Song Gho 《Small (Weinheim an der Bergstrasse, Germany)》2015,11(4):456-461
Evaluation of kinetic distribution and behaviors of nanoparticles in vivo provides crucial clues into their roles in living organisms. Extracellular vesicles are evolutionary conserved nanoparticles, known to play important biological functions in intercellular, inter‐species, and inter‐kingdom communication. In this study, the first kinetic analysis of the biodistribution of outer membrane vesicles (OMVs)—bacterial extracellular vesicles—with immune‐modulatory functions is performed. OMVs, injected intraperitoneally, spread to the whole mouse body and accumulate in the liver, lung, spleen, and kidney within 3 h of administration. As an early systemic inflammation response, increased levels of TNF‐α and IL‐6 are observed in serum and bronchoalveolar lavage fluid. In addition, the number of leukocytes and platelets in the blood is decreased. OMVs and cytokine concentrations, as well as body temperature are gradually decreased 6 h after OMV injection, in concomitance with the formation of eye exudates, and of an increase in ICAM‐1 levels in the lung. Following OMV elimination, most of the inflammatory signs are reverted, 12 h post‐injection. However, leukocytes in bronchoalveolar lavage fluid are increased as a late reaction. Taken together, these results suggest that OMVs are effective mediators of long distance communication in vivo. 相似文献
158.
159.
160.