首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   1735篇
  免费   34篇
  国内免费   40篇
电工技术   31篇
综合类   69篇
化学工业   244篇
金属工艺   166篇
机械仪表   523篇
建筑科学   13篇
矿业工程   14篇
能源动力   26篇
轻工业   46篇
水利工程   2篇
石油天然气   465篇
武器工业   4篇
无线电   8篇
一般工业技术   111篇
冶金工业   82篇
原子能技术   1篇
自动化技术   4篇
  2024年   2篇
  2023年   11篇
  2022年   19篇
  2021年   29篇
  2020年   26篇
  2019年   39篇
  2018年   36篇
  2017年   44篇
  2016年   50篇
  2015年   42篇
  2014年   65篇
  2013年   62篇
  2012年   71篇
  2011年   107篇
  2010年   76篇
  2009年   86篇
  2008年   58篇
  2007年   105篇
  2006年   126篇
  2005年   134篇
  2004年   128篇
  2003年   86篇
  2002年   80篇
  2001年   60篇
  2000年   43篇
  1999年   52篇
  1998年   31篇
  1997年   30篇
  1996年   34篇
  1995年   27篇
  1994年   12篇
  1993年   5篇
  1992年   4篇
  1991年   7篇
  1990年   3篇
  1989年   2篇
  1988年   3篇
  1987年   3篇
  1986年   1篇
  1985年   2篇
  1984年   3篇
  1983年   3篇
  1982年   2篇
排序方式: 共有1809条查询结果,搜索用时 265 毫秒
41.
平整废液是带钢冷精轧过程中产生的一种废液,是一种较难处理的高浓度有机废水,其生化性较差,传统的生物处理难以奏效,对于此类废水,国内外尚无成熟的处理工艺。采用芬顿(Fenton)氧化工艺对某公司生产的平整液进行了试验研究,研究了初始pH值、硫酸亚铁投加量、H2O2投加量以及混凝pH值等因素对COD去除效果的影响。通过试验研究,确定了反应温度、初始pH值、FeSO4和H2O2投加量等最佳处理工艺条件。在最佳处理条件下,COD去除率可达56%,同时BOD5/COD由0.17提高到0.48,废水的可生化性得到明显改善,可以满足后续生化处理的进水要求。  相似文献   
42.
等温压缩过程理论上可大幅降低制冷压缩机的功耗,通过对压缩机分别进行绝热压缩过程和近似等温压缩过程的数值模拟,明确了等温压缩可以节省的压缩机输入功耗。研究了通过润滑油系统冷却压缩机实现近似等温的工程方法,并通过润滑油冷却系统的试验确定最优的注油量,为提高压缩机的性能和节能减耗提供有价值的参考。  相似文献   
43.
阐述了润滑油真空分离与聚结分离脱水的工作原理及试验方法,选取L-TSA46汽轮机油作为试验对象,在相同条件下进行了对比试验,结果表明:当含水量高于约2×10-4采用聚结分离比采用真空分离效率高、能耗低;当含水量低于约2×10-4采用真空分离比采用聚结分离效率高、能耗低;当含水量低于6×10-5则只能采用真空分离。  相似文献   
44.
简单介绍了润滑油监测技术,润滑油监测技术正向在线监控,微型化,多功能,可视化,无损检测,智能化和远程诊断的方向发展.  相似文献   
45.
Wen-Tien Tsai 《Energy》2011,36(7):4333-4339
Utilizing used lubricants as energy sources has been currently demonstrated to be one of the best available waste management methods. In this regard, used lubricants for use as energy sources in Taiwan thus became popular in recent years. The objective of this study was to present a comprehensive analysis of used lubricant-to-energy in Taiwan, which includes status of lubricant consumption, and used lubricant generation and its recycling (i.e., collection & treatment) management system. It was found that a major market for utilizing used lubricants in Taiwan (over 90%) was reused as fuel oils or auxiliary fuels in the cogeneration system. Under the regulatory authorization of the Waste Management Act and the Petroleum Administration Act, the central competent authorities encouraged the energy-intensive industries in the waste-to-energy through the excess electricity purchase and subsidiary incentives. Based on the certified volume of collected used lubricant and its energy use proportion in 2009, the total energy potential and the environmental benefit of mitigating CO2 emissions in place of fuel oils were preliminarily calculated to be around 9.4 × 102 TJ and 7.3 × 107 kg, respectively.  相似文献   
46.
47.
Abstract

White etching cracking (WEC) is a subsurface bearing failure mechanism influenced by a number of factors, including lubricant composition. Certain metal-containing lubricants have been reported to promote WEC-induced failure; however, the exact mechanisms linking lubricant effects on WEC propensity are still not fully understood. An interesting field that has not been elucidated is the influence of additive concentration and tribofilm growth on WEC initiation, propagation, and failure. The investigations conducted in this work involved two series of oil formulations: one with additives that give rise to WEC (WEC oils) in different combinations and concentrations and another with additives that do not cause WEC (non-WEC oils). A mini traction machine (MTM) in combination with a spacer layer imaging machine (SLIM) was employed to study the growth of tribofilms and their influence on friction response. Insights from the MTM-SLIM study allowed for better interpretation of FE8 bearing tests. When using oils that contribute to WEC formation, the tribofilm-induced WEC mechanism was confirmed, with cracks initiating as early as after 20 h of FE8 testing. Metal-containing additives were found to favor the formation of WECs by generating a high-friction tribofilm and increasing the water content in the lubricant. Furthermore, the source of subsurface H associated with WEC failure is investigated using heavy water (D2O)-saturated oil. A mechanism of water dissociation induced in tribofilm growth (incubation period) is proposed in this article.  相似文献   
48.
四辊冷轧机第三倍频程颤振   总被引:5,自引:1,他引:4  
林鹤  岳海龙 《钢铁》1999,34(12):56-59
四辊冷轧机有时会出现一种不稳定的高频自激振动,严重妨碍生产及安全。它既与轧制工艺相关,又与振动理论有联系,必须将二者结合起来进行研究,才能解决问题。  相似文献   
49.
车用发动机磨合油研究   总被引:2,自引:0,他引:2  
郭文杰 《化工时刊》2001,15(7):15-18
超精细金刚石(UDD)粉是利用爆炸法人工合成的具有使用价值的纳米材料,它具有一系列特殊的物理及化学特性,针对车用内燃机磨合特点,并利用UDD的特殊性能,研制一种高效专用内燃机磨合油。  相似文献   
50.
This paper investigates the cooling and lubrication properties of supercritical carbon dioxide (scCO2) sprays as potential substitutes for aqueous emulsions and straight oils used in the metalworking industry today. Sprays of rapidly expanding scCO2 act to cool and lubricate machining and forming processes by delivering a mixture of dry ice and lubricant deep into the cutting/forming zone. In this work, experiments with turning, milling, drilling, thread cutting, and thread forming were performed with scCO2 and other metalworking fluids (MWFs) to evaluate their relative performance with respect to tool wear and machining torque. Observations reveal that scCO2–MWFs are more effective in removing heat from the tool-workpiece interface than conventionally delivered (flood) aqueous MWFs as well as other gas-based MWF sprays. In addition, scCO2–MWFs delivered in lubricant-expanded phase, where scCO2 is used to increase volume of lubricant in the spray field, are shown to provide better lubricity than straight oils and oil-in-air minimum quantity lubrication (MQL) sprays. As a result, scCO2–MWFs can reduce tool wear and improve machining productivity in a wide range of manufacturing operations leading to appreciable improvements in the economics of manufacturing. Also given that CO2 is a recovered waste gas that is non-toxic, scCO2–MWFs can improve the environmental and worker health performance of manufacturing operations.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号