全文获取类型
收费全文 | 1165篇 |
免费 | 125篇 |
国内免费 | 102篇 |
学科分类
工业技术 | 1392篇 |
出版年
2024年 | 3篇 |
2023年 | 19篇 |
2022年 | 27篇 |
2021年 | 51篇 |
2020年 | 34篇 |
2019年 | 38篇 |
2018年 | 52篇 |
2017年 | 37篇 |
2016年 | 48篇 |
2015年 | 50篇 |
2014年 | 63篇 |
2013年 | 99篇 |
2012年 | 75篇 |
2011年 | 70篇 |
2010年 | 49篇 |
2009年 | 47篇 |
2008年 | 56篇 |
2007年 | 58篇 |
2006年 | 55篇 |
2005年 | 50篇 |
2004年 | 45篇 |
2003年 | 32篇 |
2002年 | 52篇 |
2001年 | 34篇 |
2000年 | 33篇 |
1999年 | 27篇 |
1998年 | 28篇 |
1997年 | 21篇 |
1996年 | 15篇 |
1995年 | 21篇 |
1994年 | 17篇 |
1993年 | 11篇 |
1992年 | 11篇 |
1991年 | 14篇 |
1990年 | 9篇 |
1989年 | 5篇 |
1988年 | 7篇 |
1987年 | 5篇 |
1986年 | 5篇 |
1985年 | 4篇 |
1984年 | 2篇 |
1983年 | 2篇 |
1982年 | 9篇 |
1981年 | 2篇 |
排序方式: 共有1392条查询结果,搜索用时 15 毫秒
1.
根据剪切解络-超滤过程中金属离子的动态浓度关系和质量守恒定律,采用CodeBlocks17.12软件编写程序,建立了剪切解络-超滤工艺关键指标预测模型,实现了金属离子浓度、回收率、体积稀释倍数等指标的预测,并用实验加以验证。依次在转速800 r/min、1 400 r/min、3 000 r/min下回收模拟废水中43 μg/L的Co2+、995 μg/L的Ni2+和88 μg/L的La3+,3种金属的回收率均达99.8%以上时,超滤过程体积稀释倍数的预测值分别为7.0、7.5、5.75,实验值分别为7.5、7.25、6.25,可见预测值与实验值基本一致。本模型对研究方案制定和调整有实际指导意义。 相似文献
2.
3.
Simulation of producer gas flameless combustion with fresh reactant diluted by hot flue gas 下载免费PDF全文
Lemthong Chanphavong Zainal Alimuddin Zainal Tsuneyoshi Matsuoka Yuji Nakamura 《国际能源研究杂志》2018,42(10):3218-3227
Flameless combustion is considered as a flexible and efficient combustion process for low heating value gas fuel. This paper presents numerical simulations of premixed flameless combustion using producer gas as a fuel. Different initial conditions of the premixed fresh reactant (air/fuel mixture) and dilution levels are taken into account for the investigation. The numerical simulations were investigated using a network of chemical reactor models with the detailed reaction mechanism of GRI‐Mech 3.0. A threshold dilution level for flameless combustion fuelled by producer gas was determined. The numerical results show that dilution of the fresh reactant with hot combustion products and initial fresh reactant temperature play important roles in flameless combustion formation and its auto‐ignition behaviour, rather than equivalence ratio of the fresh reactant. In the flameless combustion regime, temperature and chemical concentrations were reduced while chemical kinetics process was decelerated, resulting in delay of the auto‐ignition process. 相似文献
4.
Unplanned dilution and ore-loss are the most critical challenges in underground stoping operations. These problems are the main cause behind a mine closure and directly influencing the productivity of the underground stope mining and the profitability of the entire operation. Despite being aware of the significance of unplanned dilution and ore-loss, prediction of these phenomena is still unexplained as they occur through complex mechanisms and causative factors. Current management practices primarily rely on similar stope reconciliation data and the intuition of expert mining engineers. In this study, an innovative unplanned dilution and ore-loss (uneven break: UB) management system is established using a neuro-fuzzy system. The aim of the proposed decision support system is to overcome the UB phenomenon in underground stope blasting which provides quantitative prediction of unplanned dilution and ore-loss with practical recommendations simultaneously. To achieve the method proposed, an uneven break (UB) prediction system was developed by an artificial neural network (ANN) considering 1076 datasets covering 10 major UB causative factors collected from three underground stoping mines in Western Australia. In succession, the UB consultation system was established via a fuzzy expert system (FES) in reference to surveyed results of fifteen underground-mining experts. The UB prediction and consultation system were combined as one concurrent neuro-fuzzy system that is named the ‘uneven break optimiser’. Because the current UB prediction systems in investigated mines were highly unsatisfactory with correlation coefficient (R) of 0.088 and limited to only unplanned dilution, the performance of the proposed UB prediction system (R of 0.719) is a remarkable achievement. The uneven break optimiser can be directly employed to improve underground stoping production, and this tool will be beneficial not only for underground stope planning and design but also for production management. 相似文献
5.
Yuyan Li Rongpei Jiang Yuan Chen Kaiming Zhang Lifeng Xie 《Journal of Energetic Materials》2018,36(3):352-361
The flame propagation behavior of premixed N2O–NH3/N2O–NH3–C3H8 was experimentally investigated in elongated vented cylindrical vessels with central ignition. The effect of vessel diameter and propane concentration ([C3H8] = 1.96–7.41 wt.%) on the process of flame acceleration was studied and discussed. The results revealed that the maximum value of flame acceleration rate was found in the cylindrical vessel with an inner diameter of 7 mm, followed by 5 mm, 10 mm, and 15 mm. At a constant vessel diameter, the rate of flame acceleration was noticeably improved by adding propane ([C3H8] = 1.96–3.85 wt.%) to the premixed N2O–NH3. However, a further increase in the propane fraction up to 5.66%, caused a decline in the flame acceleration rate, probably as a consequence of a combined effect between the reduction of oxygen and greater dilution of the ammonia in the total concentration. 相似文献
6.
随着国家对矿产资源开采的不断深入,富矿石、易选矿石逐渐枯竭,入选的贫矿石和难选矿石比例不断上升,导致生产处理成本增加。人工智能、智能光电选矿技术,可以甄别和分拣矿石,实现提前抛废,对矿石进行预富集,提高矿石的入选品位,提升矿石综合利用率,成为解决经济增长中矿产资源短缺重要手段,确保矿产资源安全和矿业经济稳定发展的研究方向。 相似文献
7.
8.
9.
10.
Natasha Luckovitch Enea Pagliano 《International Journal of Food Science & Technology》2020,55(3):1110-1118
A novel method for the determination of nitrite and nitrate in meat products is presented. The samples were ground and extracted in hot water with the presence of and internal standards. The solution was buffered with sodium bicarbonate and reacted with triethyloxonium tetrafluoroborate to convert nitrite and nitrate into EtNO2 and EtONO2. Such derivatives could be detected by headspace GC/MS in positive chemical ionisation mode with 0.05 µg g−1 and 1.0 µg g−1 LOD. The method was used for and quantitation in the 0.5-300 and 2.5-300 µg g−1 ranges. The method was applied for the analysis of fifteen meat products. Despite minimal sample preparation, the headspace sampling ensured a clean chromatography for over 135 analyses (throughput ten samples per hour). The proposed method offers selective GC/MS detection combined with high-precision isotope dilution calibration, it is suitable for metrological applications and can support regulations on meat safety (European Commission, 2011). 相似文献