全文获取类型
收费全文 | 29064篇 |
免费 | 1598篇 |
国内免费 | 850篇 |
专业分类
电工技术 | 2413篇 |
技术理论 | 1篇 |
综合类 | 1438篇 |
化学工业 | 3795篇 |
金属工艺 | 653篇 |
机械仪表 | 1058篇 |
建筑科学 | 3730篇 |
矿业工程 | 921篇 |
能源动力 | 6257篇 |
轻工业 | 1013篇 |
水利工程 | 519篇 |
石油天然气 | 794篇 |
武器工业 | 80篇 |
无线电 | 1847篇 |
一般工业技术 | 1859篇 |
冶金工业 | 1984篇 |
原子能技术 | 425篇 |
自动化技术 | 2725篇 |
出版年
2024年 | 73篇 |
2023年 | 467篇 |
2022年 | 804篇 |
2021年 | 1006篇 |
2020年 | 899篇 |
2019年 | 748篇 |
2018年 | 716篇 |
2017年 | 812篇 |
2016年 | 1073篇 |
2015年 | 1062篇 |
2014年 | 1899篇 |
2013年 | 1742篇 |
2012年 | 2036篇 |
2011年 | 2918篇 |
2010年 | 2124篇 |
2009年 | 1917篇 |
2008年 | 1638篇 |
2007年 | 1769篇 |
2006年 | 1311篇 |
2005年 | 1032篇 |
2004年 | 838篇 |
2003年 | 744篇 |
2002年 | 596篇 |
2001年 | 513篇 |
2000年 | 451篇 |
1999年 | 357篇 |
1998年 | 324篇 |
1997年 | 237篇 |
1996年 | 227篇 |
1995年 | 191篇 |
1994年 | 150篇 |
1993年 | 132篇 |
1992年 | 106篇 |
1991年 | 80篇 |
1990年 | 64篇 |
1989年 | 54篇 |
1988年 | 48篇 |
1987年 | 39篇 |
1986年 | 30篇 |
1985年 | 67篇 |
1984年 | 55篇 |
1983年 | 45篇 |
1982年 | 58篇 |
1981年 | 14篇 |
1980年 | 21篇 |
1979年 | 6篇 |
1978年 | 6篇 |
1976年 | 2篇 |
1974年 | 2篇 |
1973年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
61.
2005年11月份邯郸钢铁厂8万煤气柜外送煤气加压机采用高压变频技术改造。其原因是该加压机外送量波动较大,采用普通阀门调节打回流,将会浪费大量电能,采用变频技术改造后,节能效果非常明显。 相似文献
62.
63.
The influence of raw material characteristics on the industrial pelletizing process and pellet quality 总被引:1,自引:0,他引:1
Mehrdad Arshadi Rolf Gref Paul Geladi Sten-Axel Dahlqvist Torbjörn Lestander 《Fuel Processing Technology》2008
Industrial pelletizing of sawdust was carried out as a designed experiment in the factors: sawdust moisture content, fractions of fresh pine, stored pine and spruce. The process parameters and response variables were energy consumption, pellet flow rate, pellet bulk density, durability and moisture content. The final data consisted of twelve industrial scale runs. Because of the many response variables, data evaluation was by principal component analysis of a 12 × 9 data matrix. The two principal component model showed a clustering of samples, with a good reproducibility of the center points. It also showed a positive correlation of energy consumption, bulk density and durability all negatively correlated to flow rate and moisture content. The stored pine was more related to high durability and bulk density. The role of the spruce fraction was unclear. The design matrix, augmented with the process parameters was a 12 × 6 matrix. Partial least squares regression showed excellent results for pellet moisture content and bulk density. The model for durability was promising. A 12 × 21 data matrix of fatty- and resin acid concentrations measured by GC–MS showed the differences between fresh and stored pine very clearly. The influence of the spruce fraction was less clear. However, the influence of the fatty- and resin acids on the pelletizing process could not be confirmed, indicating that other differences between fresh and stored pine sawdust have to be investigated. This work shows that it is possible to design the pelletizing process for moderate energy consumption and high pellet quality. 相似文献
64.
A. N. Karapetyan I. A. Gribova A. P. Krasnov Yu. N. Studnev A. K. Pogosyan K. V. Oganesyan 《Journal of Friction and Wear》2007,28(6):546-550
The results of investigation of the modification of the Armenian minerals with fluorine-containing oligomers show that a modified product appears when the mineral fillers are treated with fluoroalkanes. The product preserves the structure of the fillers with a “grafted” fluoroalkane layer in which chlorine atoms locate mainly over their periphery. The composite materials based on heterochained polymers and the modified fillers possess a stronger wear resistance and a low friction coefficient. 相似文献
65.
66.
67.
To meet Turkey’s growing energy demand, the installed electric power capacity of 27.8 GW in 2001 has to be doubled by 2010 and increased fourfold by 2020. The difference between Turkey’s total primary energy supply (TPES) of from its own sources and total final consumption (TFC) is projected grow from 1 quad (1.06–2.06) in 1999 to 5.71 quads (2.79–8.5) in 2020 (1 QUAD=293.071 TWh). Turkey’s limited amount of fossil fuels has a present average ratio of proved reserves of 97.38 quads to production rate of 3.2 quads yr−1 of about 30 years. Turkey’s reliance on fossil fuel-based energy systems to meet the growing demand is most likely to exacerbate the issues of energy insecurity, national environmental degradation, and global climate change in increasing proportions. Economically-feasible renewable energy potential in Turkey is estimated at a total of ca. 1.69 quads yr−1 (495.4 TWh yr−1) with the potential for 0.67 quads yr−1 (196.7 TWh yr−1) of biomass energy, 0.42 quads yr−1 (124 TWh yr−1) of hydropower, 0.35 quads yr−1 (102.3 TWh yr−1) of solar energy, 0.17 quads yr−1 (50 TWh yr−1) of wind energy, and 0.08 quads yr−1 (22.4 TWh yr−1) of geothermal energy. Pursuit and implementation of sustainability-based energy policy could provide about 90 and 35% of Turkey’s total energy supply and consumption projected in 2010, respectively. Utilization of renewable energy technologies for electricity generation would necessitate about 23.2 Mha (29.8%) of Turkey’s land resources. 相似文献
68.
随着系统芯片(SoC)集成更多的功能并采用更先进的工艺,它所面临的高性能与低功耗的矛盾越来越突出.动态电压调整(DVS)技术可以在不影响处理器性能的前提下,通过性能预测软件根据处理器的繁忙程度调整处理器的工作电压和工作频率,达到降低芯片功耗的目的.文中讨论了DVS技术降低功耗的可能性,介绍了如何利用两种不同的DVS技术让处理器根据当前的工作负荷运行在不同的性能水平上,以节省不必要的功耗. 相似文献
69.
本文介绍了“四低一高”(低电解温度、低分子比、低氧化铝浓度、低阳极效应系数、高工作电压)工艺技术条件在85kA预焙槽上的应用与优化,实验证明“四低一高”工艺需要针对具体槽型进行优化设计,适宜的技术条件对提高电流效率、降低直流电耗,节能效果显著。 相似文献
70.
����Ȼ��Ϊ��Դ��ѹ��ʽ������ϵͳ 总被引:2,自引:0,他引:2
以天然气为能源,用燃气机代替电动机驱动压缩机并充分利用发动机废热、工业余热以及低品位环境热量的采暖、空调装置——燃气压缩式热泵近年来发展迅速。美国燃气设备的总装机容量已达到1.2GW,日本燃气机热泵占全部燃气制冷设备的29%,总装机容量大约1GW,燃气机热泵在英国、法国、德国、瑞士等都得到了较快的发展与应用。中研究了以天然气为驱动能源的压缩式热泵的特点及能量利用率,分析并测试了该系统的运行特性及交工况特性,进行了各种工况及转速下的实验研究。结果表明,该系统具有较好的部分负荷特性、一次能源利用率及交工况特性,为一种绿色高效的供热空调系统。 相似文献