全文获取类型
收费全文 | 3137篇 |
免费 | 113篇 |
国内免费 | 20篇 |
专业分类
电工技术 | 55篇 |
综合类 | 16篇 |
化学工业 | 706篇 |
金属工艺 | 47篇 |
机械仪表 | 70篇 |
建筑科学 | 52篇 |
矿业工程 | 3篇 |
能源动力 | 145篇 |
轻工业 | 291篇 |
水利工程 | 20篇 |
石油天然气 | 14篇 |
无线电 | 327篇 |
一般工业技术 | 631篇 |
冶金工业 | 467篇 |
原子能技术 | 25篇 |
自动化技术 | 401篇 |
出版年
2023年 | 31篇 |
2022年 | 68篇 |
2021年 | 120篇 |
2020年 | 78篇 |
2019年 | 80篇 |
2018年 | 102篇 |
2017年 | 89篇 |
2016年 | 109篇 |
2015年 | 61篇 |
2014年 | 102篇 |
2013年 | 176篇 |
2012年 | 145篇 |
2011年 | 164篇 |
2010年 | 120篇 |
2009年 | 105篇 |
2008年 | 121篇 |
2007年 | 122篇 |
2006年 | 97篇 |
2005年 | 92篇 |
2004年 | 59篇 |
2003年 | 57篇 |
2002年 | 48篇 |
2001年 | 29篇 |
2000年 | 44篇 |
1999年 | 41篇 |
1998年 | 163篇 |
1997年 | 104篇 |
1996年 | 90篇 |
1995年 | 57篇 |
1994年 | 63篇 |
1993年 | 54篇 |
1992年 | 38篇 |
1991年 | 33篇 |
1990年 | 23篇 |
1989年 | 25篇 |
1988年 | 25篇 |
1987年 | 16篇 |
1986年 | 21篇 |
1985年 | 26篇 |
1984年 | 32篇 |
1983年 | 14篇 |
1982年 | 20篇 |
1981年 | 19篇 |
1980年 | 19篇 |
1978年 | 19篇 |
1977年 | 17篇 |
1976年 | 31篇 |
1975年 | 15篇 |
1974年 | 20篇 |
1972年 | 13篇 |
排序方式: 共有3270条查询结果,搜索用时 15 毫秒
101.
Lee Spencer Martin Jakobsen Sunay Shah Graham Cairns 《Journal of the Society for Information Display》2013,21(8):352-360
There has been a rapid increase in the resolution of small‐sized and medium‐sized displays. This study determines an upper discernible limit for display resolution. A range of resolutions varying from 254–1016 PPI were evaluated using simulated display by 49 subjects at 300 mm viewing distance. The results of the study conclusively show that users can discriminate between 339 and 508 PPI and in many cases between 508 and 1016 PPI. 相似文献
102.
在油井管特殊扣产品的加工过程中,拧接是一个重要工序,而拧接设备是否具有自动判定的功能,自动判定方法合适与否,都会对生产节奏和质量控制产生影响。本文介绍了一种自动判定的方法,通过对拐点的扭矩数值、圈数的判断,再加上一些防错手段,实现对特殊扣拧接曲线的自动判定。 相似文献
103.
Mohammed Saleh Zeynep Bilici Merve Kaya Mutlu Yalvac Hudaverdi Arslan H. Cengiz Yatmaz Nadir Dizge 《Advanced Powder Technology》2021,32(4):1264-1275
The use of naturally present heterogeneous catalysts has recently been an essential issue in the Fenton and photo-Fenton processes. In this study, the uses of basalt as a catalyst for the Fenton and photo-Fenton reactions for methylene Blue (MB) and Basic Red 18 (BR18) degradations were investigated. Basalt was selected because of the presence of the iron (III) oxide in the structure. Basalt was characterized by X-Ray Fluorescence (XRF) and X-Ray Diffraction (XRD) analysis to obtain the chemical composition and the crystalline phase. The surface charge and the surface area were obtained by zeta potential and Brunauer Emmett-Teller (BET) analysis. Fourier Transform Infrared Spectroscopy (FTIR) and scanning electron microscope (SEM) were utilized to explore the functional group and the surface morphology. Fenton and photo-Fenton processes were applied to explore the best degradation method. Adsorption was also tested and the adsorption process had minimum removal efficiency (12% for MB and 17% for BR18). The removal efficiencies for MB and BR18 by the Fenton process were 87% and 28%, respectively. The photo-Fenton process had maximum removal efficiency with 100% for MB and 70% for BR18. The optimum conditions were 70 mg/L dye concentration, 5 mM H2O2, 1.0 g/L basalt loading and pH 2. Basalt has shown reuse capability as a catalyst for three consecutive cycles. 相似文献
104.
105.
The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW?1 h?1 and the high cost of stored electricity of ≈ The commercial development and current economic incentives associated with energy storage using redox flow batteries (RFBs) are summarised. The analysis is focused on the all‐vanadium system, which is the most studied and widely commercialised RFB. The recent expiry of key patents relating to the electrochemistry of this battery has contributed to significant levels of commercialisation in, for example, Austria, China and Thailand, as well as pilot‐scale developments in many countries. The potential benefits of increasing battery‐based energy storage for electricity grid load levelling and MW‐scale wind/solar photovoltaic‐based power generation are now being realised at an increasing level. Commercial systems are being applied to distributed systems utilising kW‐scale renewable energy flows. Factors limiting the uptake of all‐vanadium (and other) redox flow batteries include a comparatively high overall internal costs of $217 kW?1 h?1 and the high cost of stored electricity of ≈ $0.10 kW?1 h?1. There is also a low‐level utility scale acceptance of energy storage solutions and a general lack of battery‐specific policy‐led incentives, even though the environmental impact of RFBs coupled to renewable energy sources is favourable, especially in comparison to natural gas‐ and diesel‐fuelled spinning reserves. Together with the technological and policy aspects associated with flow batteries, recent attempts to model redox flow batteries are considered. The issues that have been addressed using modelling together with the current and future requirements of modelling are outlined. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
106.
107.
108.
109.
110.