全文获取类型
收费全文 | 12873篇 |
免费 | 1307篇 |
国内免费 | 604篇 |
专业分类
电工技术 | 795篇 |
综合类 | 870篇 |
化学工业 | 5830篇 |
金属工艺 | 262篇 |
机械仪表 | 285篇 |
建筑科学 | 596篇 |
矿业工程 | 732篇 |
能源动力 | 1637篇 |
轻工业 | 273篇 |
水利工程 | 627篇 |
石油天然气 | 1249篇 |
武器工业 | 24篇 |
无线电 | 60篇 |
一般工业技术 | 632篇 |
冶金工业 | 572篇 |
原子能技术 | 122篇 |
自动化技术 | 218篇 |
出版年
2024年 | 22篇 |
2023年 | 158篇 |
2022年 | 232篇 |
2021年 | 278篇 |
2020年 | 299篇 |
2019年 | 272篇 |
2018年 | 281篇 |
2017年 | 309篇 |
2016年 | 392篇 |
2015年 | 326篇 |
2014年 | 603篇 |
2013年 | 886篇 |
2012年 | 796篇 |
2011年 | 827篇 |
2010年 | 691篇 |
2009年 | 661篇 |
2008年 | 732篇 |
2007年 | 792篇 |
2006年 | 776篇 |
2005年 | 688篇 |
2004年 | 687篇 |
2003年 | 601篇 |
2002年 | 567篇 |
2001年 | 516篇 |
2000年 | 394篇 |
1999年 | 360篇 |
1998年 | 292篇 |
1997年 | 241篇 |
1996年 | 229篇 |
1995年 | 193篇 |
1994年 | 136篇 |
1993年 | 99篇 |
1992年 | 98篇 |
1991年 | 74篇 |
1990年 | 61篇 |
1989年 | 48篇 |
1988年 | 35篇 |
1987年 | 55篇 |
1986年 | 21篇 |
1985年 | 18篇 |
1984年 | 14篇 |
1983年 | 6篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1959年 | 2篇 |
1951年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
41.
The objective of this study is to determine the chemical kinetics of desulphurization of Thai limestone in an atmospheric fluidized bed combustor (AFBC). The experiments, which employed the batch technique using the limestone samples from six major sources in Thailand, were performed in a laboratory‐scale AFBC. The results obtained were analysed and correlated in the form of apparent reaction rate and deactivation rate constants as a function of operating conditions of the furnace and their properties, respectively. The formulae derived from these correlations were kept as general as possible in order that they could be used as input parameters for the selected mathematical model of desulphurization in an AFBC that is suitable for practical use. The predicted results were in good agreement with the experimental data reported in the literature. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
42.
研究了钛铁矿选择氯化制取人造金红石反应的Fe-Ti-C-O2-Cl2系平衡图,计算了氧与某些氯化物相互作用的自由能变化,采用“通氧一步选择氯化法”,解决了选择氯化“自热”反应持续进行的技术关键,对反应参数进行了实验室,半工业和工业化生产试验研究,研究证明,选择氯化过程的动力学模型是“固体颗粒粒度保持不变的缩核反应模型”,动力学区的活性能为34.33kJ/mol;扩散区的活化能为0.80kJ/mol,研究开发的无筛板沸腾氯化炉可以长期稳定地连续运转,生产出的人造金红石品位为92.10%,经摇床和磁选,品位达到95%,床层单位炉产能达12.4t/(m2.d),该工艺和设备已成功地应用于工业生产。 相似文献
43.
The thermal behaviour of a packed bed storage system charged with hot air is modelled using two partial differential equations representing the energy conservation in the air and solid phases constituting the bed. These two equations are coupled through the heat exchange process between the two phases. A fully implicit numerical scheme based on forward, upwind and central differencing for the time, first and second space derivatives, respectively, is used to solve the modelling equations. Marching technique is used for the air equation and a tri-diagonal matrix solver is employed to solve the solid equation. The solution yields the thermal structure of the bed, namely the air and solid temperature distribution inside the bed at any particular time, and the variation of total energy stored in the bed with time. The effect of bed length, solid diameter and void fraction on the thermal characteristics of the packed bed is studied. Further, the performance of the bed under variable inlet air temperature and mass flow rate is investigated. 相似文献
44.
A new catalyst loading method, in which catalyst particles are packed in a reactor with a novel internal, has been studied by measuring pressure drop, RTD, liquid holdup and mass transfer. It can be inferred from experimental results that the internal changes the conventional gas and liquid counter-current flow into a new cross-current flow, so the problems of excessive pressure drop and “flooding” are avoided. When pressure drop, liquid holdup, RTD and mass transfer coefficient are similar, the catalyst loading fraction of the new method is much higher than that of conventional methods. Furthermore, the reactive distillation reactor with the novel internal has advantages such as simple structure, low operating cost, and convenience for installation and removal of the catalyst. 相似文献
45.
46.
Athanasios Eftaxias Josep Font Agusti Fortuny Azael Fabregat Frank Stüber 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(6):677-687
The wet air oxidation of phenol over a commercial active carbon catalyst was studied in a trickle bed reactor (TBR) in the temperature and oxygen partial pressure ranges of 120–160 °C and 0.1–0.2 MPa, respectively. The performance of the active carbon was compared in terms of phenol and COD destruction. The weight change of active carbon due to reaction was also measured. Finally, oxic phenol adsorption isotherms were assessed in batch conditions at 25, 125 and 160 °C. In order to use the conversion data obtained from the TBR for a kinetic study, special care was taken to check the kinetic control in the TBR experiments. Several kinetic models including power law or Langmuir–Hinshelwood expressions were considered to describe the catalytic oxidation of phenol over active carbon. The simple power law model with first order dependence on both phenol and oxygen concentration predicted satisfactorily the experimental data not only over the entire range of operating conditions studied, but also outside its validity range. Copyright © 2005 Society of Chemical Industry 相似文献
47.
Deterministic chaos theory offers useful quantitative tools to characterize the non-linear dynamic behavior of a fluidized bed and the developed complexity theory presents a new approach to evaluate finite sequences. In this paper,the non-linear,hydrodynamic behavior of the pressure flutuation signals in a reactor was discussed by chaos parameters and complexity measures.Coherent results were achieved by our multi-scale analysis,which further exposed the behavior in a gas-solid two-phase system. 相似文献
48.
49.
50.
Combined straw–bitumen pellets have been proposed as an alternative fuel. An interesting finding is the potentiality of straw ash constituents to retain sulphur as bitumen that has relatively high sulphur content. The aim of the present work is to enhance sulphur self-retention to directly meet the environmental regulations by building-in CaO in the pellet instead of feeding sorbent separately. CaO powder has been mixed with the pellet constituents during production processes. 相似文献