全文获取类型
收费全文 | 32101篇 |
免费 | 3111篇 |
国内免费 | 1601篇 |
学科分类
工业技术 | 36813篇 |
出版年
2024年 | 160篇 |
2023年 | 578篇 |
2022年 | 955篇 |
2021年 | 1197篇 |
2020年 | 1152篇 |
2019年 | 1025篇 |
2018年 | 971篇 |
2017年 | 1097篇 |
2016年 | 1229篇 |
2015年 | 1073篇 |
2014年 | 1851篇 |
2013年 | 2021篇 |
2012年 | 2243篇 |
2011年 | 2184篇 |
2010年 | 1648篇 |
2009年 | 1659篇 |
2008年 | 1329篇 |
2007年 | 1956篇 |
2006年 | 1851篇 |
2005年 | 1592篇 |
2004年 | 1503篇 |
2003年 | 1319篇 |
2002年 | 1167篇 |
2001年 | 975篇 |
2000年 | 873篇 |
1999年 | 662篇 |
1998年 | 462篇 |
1997年 | 398篇 |
1996年 | 286篇 |
1995年 | 266篇 |
1994年 | 246篇 |
1993年 | 179篇 |
1992年 | 187篇 |
1991年 | 125篇 |
1990年 | 89篇 |
1989年 | 70篇 |
1988年 | 50篇 |
1987年 | 35篇 |
1986年 | 22篇 |
1985年 | 35篇 |
1984年 | 23篇 |
1983年 | 17篇 |
1982年 | 15篇 |
1981年 | 5篇 |
1980年 | 8篇 |
1979年 | 12篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1973年 | 1篇 |
1951年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
1.
热镀锌板(卷)工程设计中的环境保护问题 总被引:1,自引:0,他引:1
对热镀锌板(卷)的生产工艺、主要生产设备进行了简要介绍,并就其污染源(工序)、生产过程中产生的污染物及其控制措施进行了评述,同时就设计和生产中宜注意的几个环保问题进行了分析。 相似文献
2.
3.
美国固体照明技术进展概况 总被引:2,自引:0,他引:2
介绍了美国能源部于2002年开始实施的固体照明(SSL)技术的"下一代照明计划".同时对美国SSL技术的研发、生产和使用现状以及召开学术会议的情况做了叙述. 相似文献
4.
实体造型中的几何约束 总被引:5,自引:0,他引:5
实体造型是一个基于约束的过程,完成从功能约束到几何约束、再到代数约束的转化而得到实体模型。本文讨论了几何约束的层次性及其表示,并且对几何约束同设计意图的关系进行了研究,提出了基于CSG/GCG/B-rep的模型表示。 相似文献
5.
Muralidhar N. Ingale Vijaykumar V. Mahajani 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):80-86
The effectiveness of the hybrid system sonication followed by wet oxidation (SONIWO) to treat otherwise refractory waste has been demonstrated. In such a hybrid system homogeneous CuSO4 catalyst was found to be very efficient. 相似文献
6.
7.
8.
One of the new physical methods that provides much information about the processes going on in a friction contact zone in real time is acoustic emission (AE). Basic experimental results of AE in friction are presented and analysed. Using AE signals we can get an indication about the state of the friction processes, about the quality of solid and liquid layers on the contacting surfaces in real time, sometimes about intensity of wear, changing of wear and friction regimes and so on. The influence of sliding velocity, load, roughness and some physical and mechanical properties of the body on the parameters of AE are also given. Some attention to the practical implementation of these techniques for control of capability for work of friction pairs in real conditions are given. Modern methods and devices enable condition monitoring of sliding and rolling bearings. 相似文献
9.
Tomi Gominek Andrej Lubej Ciril Pohar 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》2005,80(8):939-947
Precipitation of calcium sulfate dihydrate, gypsum, from (i) a pure sulfuric acid/lime suspension and (ii) a waste sulfuric acid/lime suspension in a continuous pilot plant in the temperature range from 40 °C to 80 °C was studied. It was observed that in the case of waste sulfuric acid with a high content of Mg2+ and Fe2+ ions, several hours after the beginning of the precipitation, partial dissolution of the product and modification of the crystals from needle‐ and plate‐like to agglomerated structures occurred. It is suggested that the secondary changes occur due to the increased concentration of Mg2+ and Fe2+ ions in the reactor. Below 60 °C, and above 70 °C plate‐like and needle‐like single crystals respectively were formed. The mean size (d50) of the crystals was found to increase with increasing temperature and decrease with the initial concentration of lime. Gypsum produced between 70 °C and 80 °C is suitable for further processing for construction plaster. In a precipitation process with pure sulfuric acid only single perfect needle‐like crystals occurred. Copyright © 2005 Society of Chemical Industry 相似文献
10.
This is the first time an extensive investigation has been carried out regarding the effects of riser exit geometry on pressure drop and solid behaviour inside the Internal Circulating Fluidized Bed (ICFB) riser, using different riser exit geometries at several operating conditions.The Radioactive Particle-Tracking (RPT) technique was used for solid concentration measurements and solid residence time distribution at the exit zone. Experiments were conducted using Geldart B particles, in the gas superficial velocity range of 4 to 10 m/s. Axial solid hold-up, solid residence time distribution in the exit zone, and the reflux ratio factor km, (defined earlier by [E.H. Van der Meer, R.B. Thorpe, J.F. Davidson, Flow patterns in the square cross-section riser of a circulating fluidized bed and the effect of riser exit design, Chem. Eng. Sc. 55 (19) (2000) 4079-4099]), were the main criteria used to investigate the impact of gas-solid separator devices implemented at the ICFB riser exit.Solid residence time distribution results and axial solid hold-up profiles provided clear evidence that the separator device at the riser exit strongly influences the hydrodynamic structure of the ICFB riser. The V-shaped riser exit geometry was found to be the optimum of all the configurations studied. 相似文献