全文获取类型
收费全文 | 20700篇 |
免费 | 1815篇 |
国内免费 | 797篇 |
专业分类
电工技术 | 1038篇 |
综合类 | 926篇 |
化学工业 | 3628篇 |
金属工艺 | 1099篇 |
机械仪表 | 1264篇 |
建筑科学 | 1162篇 |
矿业工程 | 408篇 |
能源动力 | 723篇 |
轻工业 | 1329篇 |
水利工程 | 374篇 |
石油天然气 | 598篇 |
武器工业 | 127篇 |
无线电 | 2973篇 |
一般工业技术 | 3362篇 |
冶金工业 | 1385篇 |
原子能技术 | 236篇 |
自动化技术 | 2680篇 |
出版年
2024年 | 88篇 |
2023年 | 338篇 |
2022年 | 616篇 |
2021年 | 836篇 |
2020年 | 683篇 |
2019年 | 629篇 |
2018年 | 654篇 |
2017年 | 681篇 |
2016年 | 696篇 |
2015年 | 807篇 |
2014年 | 1034篇 |
2013年 | 1396篇 |
2012年 | 1420篇 |
2011年 | 1492篇 |
2010年 | 1183篇 |
2009年 | 1171篇 |
2008年 | 1075篇 |
2007年 | 1021篇 |
2006年 | 892篇 |
2005年 | 807篇 |
2004年 | 572篇 |
2003年 | 545篇 |
2002年 | 581篇 |
2001年 | 519篇 |
2000年 | 392篇 |
1999年 | 430篇 |
1998年 | 434篇 |
1997年 | 332篇 |
1996年 | 292篇 |
1995年 | 242篇 |
1994年 | 190篇 |
1993年 | 165篇 |
1992年 | 133篇 |
1991年 | 116篇 |
1990年 | 84篇 |
1989年 | 92篇 |
1988年 | 78篇 |
1987年 | 65篇 |
1986年 | 60篇 |
1985年 | 63篇 |
1984年 | 55篇 |
1983年 | 34篇 |
1982年 | 51篇 |
1981年 | 40篇 |
1980年 | 30篇 |
1979年 | 27篇 |
1977年 | 27篇 |
1976年 | 32篇 |
1974年 | 20篇 |
1973年 | 18篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
Hong Sae Jin Park Nam Il Hwang Dae Keun Yi Tae Gyu Eum Hyang Lan 《Food science and biotechnology》2022,31(6):669-679
Food Science and Biotechnology - Various hilling materials (rice hulls, pine sawdust, and perlite) were compared to produce sprout vegetables using beach silvertop (Glehnia littoralis Fr. Schm. ex... 相似文献
2.
3.
4.
5.
The effect of charge on the dihydrogen storage capacity of Sc2–C6H6 has been investigated at B3LYP-D3/6-311G(d,p) level. The neutral system Sc2–C6H6 can store 8H2 with gravimetric density of 8.76 wt %, and one H2 dissociates and bonds atomically on the scandium atom. The adsorption of 8H2 on Sc2–C6H6 is energetically favorable below 155 K. The atom-centered density matrix propagation (ADMP) molecular dynamics simulations show that Sc2–C6H6 can adsorb 3H2 within 1000 fs at 300K. Compared with Sc2–C6H6, the charged systems can adsorb more hydrogen molecules with higher gravimetric density, and all the H2 are adsorbed in the molecular form. The gravimetric densities of Sc2–C6H6+ and Sc2–C6H62+ are 9.75 and 10.71 wt%. Moreover, the maximum adsorption of charged systems are favorable in wider temperature range. Most importantly, the ADMP-MD simulations indicate that Sc2–C6H62+ can adsorb 6 hydrogen molecules within 1000 fs at 300K. It can be found that the gravimetric density (6.72 wt%) of Sc2–C6H62+ still exceeds the target of US Department of Energy (DOE) under ambient conditions. 相似文献
6.
Environmental concerns continue to pose the challenge to replace petroleum-based products with renewable ones completely or at least partially while maintaining comparable properties. Herein, rigid polyurethane (PU) foams were prepared using soy-based polyol for structural and thermal insulation applications. Cell size, density, thermal resistivity, and compression force deflection (CFD) values were evaluated and compared with that of petroleum-based PU foam Baydur 683. The roles of different additives, that is, catalyst, blowing agent, surfactants, and different functionalities of polyol on the properties of fabricated foam were also investigated. For this study, dibutyltin dilaurate was employed as catalyst and water as environment friendly blowing agent. Their competitive effect on density and cell size of the PU foams were evaluated. Five different silicone-based surfactants were employed to study the effect of surface tension on cell size of foam. It was also found that 5 g of surfactant per 100 g of polyol produced a foam with minimum surface tension and highest thermal resistivity (R value: 26.11 m2·K/W). However, CFD values were compromised for higher surfactant loading. Additionally, blending of 5 g of higher functionality soy-based polyol improved the CFD values to 328.19 kPa, which was comparable to that of petroleum-based foam Baydur 683. 相似文献
7.
Yang Yueyi Wang Lide Chen Huang Wang Chong 《Analog Integrated Circuits and Signal Processing》2021,107(3):605-616
Analog Integrated Circuits and Signal Processing - Fault diagnosis of analog circuit is critical to improve safety and reliability in electrical systems and reduce losses. Traditional fault... 相似文献
8.
9.
Lai-Ying Leong Teck-Soon Hew Keng-Boon Ooi Alain Yee Loong Chong Voon-Hsien Lee 《Information & Management》2021,58(2):103416
This paper examines what influences trust in mobile social commerce environment. Drawing on trust-based acceptance model (i.e. cognitive and emotional trust) and online review features (i.e. profile photo, linguistic style, and reported experience), we examine how these factors affect trust in mobile social commerce. Hypotheses were tested using survey data. The results of our model showed that there are significant influences of profile photo, reported experience, cognitive, and emotional trust towards trust in ms-commerce. This work contributes to existing literature by examining the roles of previous trust in mobile payments and online reviews on trust in mobile social commerce. 相似文献
10.