全文获取类型
收费全文 | 11864篇 |
免费 | 1079篇 |
国内免费 | 103篇 |
专业分类
电工技术 | 309篇 |
综合类 | 179篇 |
化学工业 | 2798篇 |
金属工艺 | 436篇 |
机械仪表 | 555篇 |
建筑科学 | 276篇 |
矿业工程 | 97篇 |
能源动力 | 439篇 |
轻工业 | 1070篇 |
水利工程 | 71篇 |
石油天然气 | 70篇 |
武器工业 | 8篇 |
无线电 | 1947篇 |
一般工业技术 | 2577篇 |
冶金工业 | 823篇 |
原子能技术 | 117篇 |
自动化技术 | 1274篇 |
出版年
2024年 | 13篇 |
2023年 | 154篇 |
2022年 | 260篇 |
2021年 | 409篇 |
2020年 | 292篇 |
2019年 | 275篇 |
2018年 | 381篇 |
2017年 | 406篇 |
2016年 | 501篇 |
2015年 | 462篇 |
2014年 | 601篇 |
2013年 | 836篇 |
2012年 | 823篇 |
2011年 | 1037篇 |
2010年 | 772篇 |
2009年 | 703篇 |
2008年 | 635篇 |
2007年 | 534篇 |
2006年 | 494篇 |
2005年 | 379篇 |
2004年 | 359篇 |
2003年 | 329篇 |
2002年 | 297篇 |
2001年 | 260篇 |
2000年 | 228篇 |
1999年 | 213篇 |
1998年 | 299篇 |
1997年 | 196篇 |
1996年 | 155篇 |
1995年 | 103篇 |
1994年 | 95篇 |
1993年 | 71篇 |
1992年 | 59篇 |
1991年 | 57篇 |
1990年 | 35篇 |
1989年 | 36篇 |
1988年 | 29篇 |
1987年 | 16篇 |
1986年 | 25篇 |
1985年 | 10篇 |
1984年 | 19篇 |
1983年 | 24篇 |
1982年 | 14篇 |
1981年 | 14篇 |
1980年 | 12篇 |
1979年 | 13篇 |
1977年 | 10篇 |
1976年 | 21篇 |
1974年 | 10篇 |
1970年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
2.
Sangmin Lee Biao Che Meiling Tai Wanzhao Li Shin-Hyun Kim 《Advanced functional materials》2021,31(42):2105477
Hydrogel shells that compartmentalize the water core from the aqueous surrounding provide molecular selectivity on size and charge in transmembrane transport. It is highly demanding to produce thin hydrogel shells to minimize diffusion length and maximize core volume. Here, internal osmosis in water-in-oil-in-water-in-oil (W/O/W/O) triple-emulsion droplets is used to produce thin hydrogel shells enclosing a large water core. The triple-emulsion droplets are prepared to have an ultrathin middle oil layer using a capillary microfluidic device. The innermost water droplet has a higher osmolarity than the outer water layer containing photopolymerizable hydrogel precursors, which pumps water from the outer layer to the core through the ultrathin oil layer by the osmosis. Therefore, the outer layer gets thinner and hydrogel precursors are enriched while the size of the triple-emulsion droplets remains unchanged. Through photopolymerization of precursors and phase transfer from oil to water, hydrogel shells enclosing water core are produced in the water environment; the oil layer is ruptured for molecular exchange through the shells. The thickness and composition of the hydrogel shells are precisely controllable by the osmotic conditions. The shells show a high permeation rate due to the thinness as well as controlled cut-off threshold of permeation for neutral and charged molecules. 相似文献
3.
Young Been Kim Sung Hyeon Jung Dong Su Kim Nishad G. Deshpande Hee Won Suh Hak Hyeon Lee Ji Hoon Choi Ho Seong Lee Hyung Koun Cho 《Advanced functional materials》2021,31(38):2102439
Antimony triselenide (Sb2Se3) nanoflake-based nitrogen dioxide (NO2) sensors exhibit a progressive bifunctional gas-sensing performance, with a rapid alarm for hazardous highly concentrated gases, and an advanced memory-type function for low-concentration (<1 ppm) monitoring repeated under potentially fatal exposure. Rectangular and cuboid shaped Sb2Se3 nanoflakes, comprising van der Waals planes with large surface areas and covalent bond planes with small areas, can rapidly detect a wide range of NO2 gas concentrations from 0.1 to 100 ppm. These Sb2Se3 nanoflakes are found to be suitable for physisorption-based gas sensing owing to their anisotropic quasi-2D crystal structure with extremely enlarged van der Waals planes, where they are humidity-insensitive and consequently exhibit an extremely stable baseline current. The Sb2Se3 nanoflake sensor exhibits a room-temperature/low-voltage operation, which is noticeable owing to its low energy consumption and rapid response even under a NO2 gas flow of only 1 ppm. As a result, the Sb2Se3 nanoflake sensor is suitable for the development of a rapid alarm system. Furthermore, the persistent gas-sensing conductivity of the sensor with a slow decaying current can enable the development of a progressive memory-type sensor that retains the previous signal under irregular gas injection at low concentrations. 相似文献
4.
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
5.
6.
Choi Paul Santos Christian Ariane Kim Min-Kun Jung Hyunsook Hong Do-Young Koo Junemo 《Journal of Mechanical Science and Technology》2021,35(11):5007-5022
Journal of Mechanical Science and Technology - This study delivers equations useful for low-height pleated fibrous filter design: two pressure drop equations and one set of optimum design equations... 相似文献
7.
Ming-Puu Chen Asta Y. Z. Lord Yu-Yao Cheng Ku-Chou Tai Wen-Harn Pan 《Journal of Computer Assisted Learning》2020,36(3):383-396
Reflective judgement is crucial for medical-related practitioners in dealing with controversial issues. However, the conformity phenomenon is likely to occur and interfere with reflective judgement learning during interactive activities. Effective strategies are required to moderate the conformity behaviour tendency (CBT) and improve reflective judgement performance (RJP). This study demonstrates two significant results: (a) Compared with the guided self-reflection learning strategy, the online collective reflection (OCR) learning strategy effectively weakened the learners' general CBT while dealing with professional controversial issues; and (b) a significantly negative correlation between the RJP achieved and the change of CBT in online environment was detected in the OCR group. The implications and potential applications in higher education were discussed. Further studies are needed to confirm the long-term effects and the extending application to other professional studies. 相似文献
8.
9.
10.