全文获取类型
收费全文 | 5964篇 |
免费 | 657篇 |
国内免费 | 9篇 |
专业分类
电工技术 | 49篇 |
综合类 | 8篇 |
化学工业 | 1659篇 |
金属工艺 | 163篇 |
机械仪表 | 291篇 |
建筑科学 | 100篇 |
矿业工程 | 1篇 |
能源动力 | 230篇 |
轻工业 | 679篇 |
水利工程 | 6篇 |
石油天然气 | 7篇 |
武器工业 | 2篇 |
无线电 | 1017篇 |
一般工业技术 | 1414篇 |
冶金工业 | 365篇 |
原子能技术 | 67篇 |
自动化技术 | 572篇 |
出版年
2023年 | 68篇 |
2022年 | 44篇 |
2021年 | 197篇 |
2020年 | 160篇 |
2019年 | 202篇 |
2018年 | 221篇 |
2017年 | 223篇 |
2016年 | 289篇 |
2015年 | 242篇 |
2014年 | 340篇 |
2013年 | 416篇 |
2012年 | 414篇 |
2011年 | 543篇 |
2010年 | 401篇 |
2009年 | 383篇 |
2008年 | 352篇 |
2007年 | 246篇 |
2006年 | 208篇 |
2005年 | 201篇 |
2004年 | 174篇 |
2003年 | 163篇 |
2002年 | 132篇 |
2001年 | 102篇 |
2000年 | 98篇 |
1999年 | 100篇 |
1998年 | 133篇 |
1997年 | 119篇 |
1996年 | 94篇 |
1995年 | 62篇 |
1994年 | 36篇 |
1993年 | 48篇 |
1992年 | 28篇 |
1991年 | 30篇 |
1990年 | 29篇 |
1989年 | 17篇 |
1988年 | 16篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 7篇 |
1984年 | 6篇 |
1983年 | 7篇 |
1981年 | 5篇 |
1980年 | 4篇 |
1978年 | 4篇 |
1977年 | 5篇 |
1976年 | 10篇 |
1975年 | 7篇 |
1973年 | 4篇 |
1969年 | 3篇 |
1967年 | 5篇 |
排序方式: 共有6630条查询结果,搜索用时 125 毫秒
1.
Multimedia Systems - The preferences of Web information purchasers are changing. Cost-effectiveness (i.e., an emphasis on performance with respect to price) is becoming less regarded than... 相似文献
2.
Eui Dae Jung Amit Kumar Harit Do Hui Kim Chung Hyeon Jang Jong Hyun Park Shinuk Cho Myoung Hoon Song Han Young Woo 《Advanced materials (Deerfield Beach, Fla.)》2020,32(30):2002333
A series of anionic conjugated polyelectrolytes (CPEs) is synthesized based on poly(fluorene-co-phenylene) by varying the side-chain ionic density from two to six per repeat units (MPS2-TMA, MPS4-TMA, and MPS6-TMA). The effect of MPS2, 4, 6-TMA as interlayers on top of a hole-extraction layer of poly(bis(4-phenyl)-2,4,6-trimethylphenylamine (PTAA) is investigated in inverted perovskite solar cells (PeSCs). Owing to the improved wettability of perovskites on hydrophobic PTAA with the CPEs, the PeSCs with CPE interlayers demonstrate a significantly enhanced device performance, with negligible device-to-device dependence relative to the reference PeSC without CPEs. By increasing the ionic density in the MPS-TMA interlayers, the wetting, interfacial defect passivation, and crystal growth of the perovskites are significantly improved without increasing the series resistance of the PeSCs. In particular, the open-circuit voltage increases from 1.06 V for the PeSC with MPS2-TMA to 1.11 V for the PeSC with MPS6-TMA. The trap densities of the PeSCs with MPS2,4,6-TMA are further analyzed using frequency-dependent capacitance measurements. Finally, a large-area (1 cm2) PeSC is successfully fabricated with MPS6-TMA, showing a power conversion efficiency of 18.38% with negligible hysteresis and a stable power output under light soaking for 60 s. 相似文献
3.
4.
5.
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
6.
7.
8.
Bioactive compounds and antioxidant activities of the Korean lotus leaf (Nelumbo nucifera) condiment: volatile and nonvolatile metabolite profiling during fermentation 下载免费PDF全文
Recent studies have shown that lotus (Nelumbo nucifera) leaf has various pharmacological effects. However, there have been no scientific investigations into these leaves as a fermented crude liquid. This study compared the in vitro antioxidant capacity of lotus leaf‐fermented broth (LLFB) with that of 57° Brix sugar broth (SB) as a control over a period of 6 months based on 1,1‐diphenyl‐2‐picrylhydrazyl radical scavenging activity, ferric ion reducing power, superoxide dismutase‐like activity, tyrosinase inhibition and nitrite scavenging activity. The dominant species during fermentation process were Leuconostoc lactis and Saccharomyces cerevisiae for LLFB. A total of thirty‐six metabolites such as alkaloids, fatty acids, organic acids, phenolics, sugar and sugar derivatives, ethyl esters and monoterpenoids differed between SB and LLFB using gas chromatography–mass spectrometry. Meanwhile, nine volatile compounds in LLFB contributed pleasant, slightly sweetish and fruity odour of condiment and sensory evaluation score of 4.06 ± 1.52 in the proportion of 1:9 LLFB/water. 相似文献
9.
10.
Chun Dong Hyun Rhim Geun Bae Youn Min Hye Deviana Deviana Lee Ji Eun Park Ji Chan Jeong Heondo 《Topics in Catalysis》2020,63(9-10):793-809
Topics in Catalysis - Fischer–Tropsch synthesis (FTS) is a promising way to produce clean liquid fuels and high value-added chemicals from low-value carbon-containing resources such as coal,... 相似文献