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   1331篇
  免费   43篇
  国内免费   33篇
电工技术   42篇
综合类   106篇
化学工业   54篇
金属工艺   104篇
机械仪表   361篇
建筑科学   107篇
矿业工程   25篇
能源动力   49篇
轻工业   21篇
水利工程   7篇
石油天然气   54篇
武器工业   16篇
无线电   36篇
一般工业技术   168篇
冶金工业   46篇
自动化技术   211篇
  2024年   6篇
  2023年   13篇
  2022年   21篇
  2021年   39篇
  2020年   52篇
  2019年   28篇
  2018年   19篇
  2017年   32篇
  2016年   31篇
  2015年   44篇
  2014年   108篇
  2013年   90篇
  2012年   126篇
  2011年   110篇
  2010年   94篇
  2009年   71篇
  2008年   60篇
  2007年   73篇
  2006年   60篇
  2005年   68篇
  2004年   43篇
  2003年   70篇
  2002年   28篇
  2001年   20篇
  2000年   21篇
  1999年   18篇
  1998年   13篇
  1997年   12篇
  1996年   17篇
  1995年   4篇
  1994年   3篇
  1993年   4篇
  1991年   1篇
  1990年   3篇
  1988年   2篇
  1987年   1篇
  1986年   1篇
  1983年   1篇
排序方式: 共有1407条查询结果,搜索用时 0 毫秒
1.
《Oil and Energy Trends》2020,45(1):56-58
Currency exchanges rates – updated monthly. Economic indicators of industrial production. Countries included: France, Germany, Italy, the United Kingdom, the United States, Canada, Japan (Total G-7), Eurozone and Total EU-28 (Total OECD). Updated monthly. Economic indicators of car registration in the United States, Canada, France, Germany, Italy, Poland, Spain, Turkey, the United Kingdom, Japan, Republic of Korea and Other OECD (Total OECD-30). Updated monthly. Monthly averages of crude steel production in thousand metric tons for the United States, Canada, Brazil, Mexico, Austria, Belgium, Czech Republic, France, Germany, Italy, Netherlands, Poland, Spain, Sweden, Turkey, the United Kingdom, Russia, Ukraine, South Africa, Iran, China, India, Japan, Republic of Korea, Taiwan and Australia.  相似文献   
2.
《Oil and Energy Trends》2020,45(5):56-58
Currency exchanges rates – updated monthly. Economic indicators of industrial production. Countries included: France, Germany, Italy, the United Kingdom, the United States, Canada, Japan (Total G-7), Eurozone and Total EU-28 (Total OECD). Updated monthly. Economic indicators of car registration in the United States, Canada, France, Germany, Italy, Poland, Spain, Turkey, the United Kingdom, Japan, Republic of Korea and Other OECD (Total OECD-30). Updated monthly. Monthly averages of crude steel production in thousand metric tons for the United States, Canada, Brazil, Mexico, Austria, Belgium, Czech Republic, France, Germany, Italy, Netherlands, Poland, Spain, Sweden, Turkey, the United Kingdom, Russia, Ukraine, South Africa, Iran, China, India, Japan, Republic of Korea, Taiwan and Australia.  相似文献   
3.
《Oil and Energy Trends》2019,44(8):58-60
Currency exchanges rates – updated monthly. Economic indicators of industrial production. Countries included: France, Germany, Italy, the United Kingdom, the United States, Canada, Japan (Total G-7), Eurozone and Total EU-28 (Total OECD). Updated monthly. Economic indicators of car registration in the United States, Canada, France, Germany, Italy, Poland, Spain, Turkey, the United Kingdom, Japan, Republic of Korea and Other OECD (Total OECD-30). Updated monthly. Monthly averages of crude steel production in thousand metric tons for the United States, Canada, Brazil, Mexico, Austria, Belgium, Czech Republic, France, Germany, Italy, Netherlands, Poland, Spain, Sweden, Turkey, the United Kingdom, Russia, Ukraine, South Africa, Iran, China, India, Japan, Republic of Korea, Taiwan and Australia.  相似文献   
4.
With the advent of future vehicles, passengers expect to travel in comfort, and the free leg space between facing-seats could be an issue due to the unsuitability for all people, according to their anthropometric variability. A previous investigation survey showed the need to increase the leg-space between facing seats and, if installed, to improve the surface of the table placed in between. So, four different distances between seat-pans front edges of facing seats have been set-up and tested (44 cm, 51 cm, 58 cm, 65 cm) with a table in between. 13 couples of participants with different heights took part to experiments. The aim was to investigate the relationship between facing-seat distances and passenger wellbeing in terms of postural comfort and social interaction. Postural comfort has been analysed through optical tracking (for postural angles overtime) and questionnaires (perceived comfort). Social interaction feelings have been investigated with questionnaires. Experiment results showed the suitable distance could be 51 cm keeping the same table surface; otherwise, the 65 cm one could be ideal changing the table surface.Relevance to industryWith the advent of autonomous driving, vehicle manufacturers and designers are working hard to define new paradigms of public transportation in terms of seat layout, passenger wellbeing and interiors’ design. This paper contributes to increasing the general knowledge on the effects of distance between facing seats on postural comfort and social interaction.  相似文献   
5.
魏军 《油气井测试》2003,12(6):48-49
机械锁定式测试技术操作简单,测试一次成功率高,资料录取准确全面,且测试结束后可直接进行封堵作业;解封时,机械锁紧产生一个向上的震击力,有利于解封,没有换位机构的测试阀在关井期间使管柱处于自由拉伸状态,有利于保护油管。在N阀上部管柱中加1-2根伸缩接头,便可用于海洋井测试。  相似文献   
6.
概述了国外粉末冶金气门阀座的制造工艺特点,简要介绍了国外柴油机用粉末冶金气门阀座材料的性能水平。  相似文献   
7.
从机车驾驶座椅设计的人机工程学原则出发,对TZY1型驾驶座椅的主要技术参数选择进行了详细的论述,同时还对TZY1型驾驶座椅关键部件的结构设计进行了分析。  相似文献   
8.
汽车振动噪声测试的阶次跟踪方法   总被引:1,自引:0,他引:1  
俞明  柳文斌  吴庆宏 《机床与液压》2003,(6):277-278,319
汽车振动和噪声是影响舒适性的主要因素,如何采用有效的技术手段测量分析汽车的振动、噪声,日益受到人们重视。本文应用PULSE多分析系统中的阶次跟踪分析方法,测试分析了车内司机座位处振动、噪声随发动机转速变化的关系,结果发现,对于试验车在测试工况下1.5倍发动机转速时,车内振动和噪声都有一个峰值。文中通过阶次分析,对发动机运转稳定性进行了测试。为降低车内噪声和振动响应提供了分析依据和参考。  相似文献   
9.
采用液态挤压代替压力铸造及热模锻生产轿车铝合金油泵壳体,不仅克服了压铸件内部容易形成气孔和氧化夹杂的缺陷,而且减少了热模锻的投资及提高了材料利用率。本文介绍了铝合金油泵壳体液态挤压的模具结构及设计参数、技术经济分析。  相似文献   
10.
Musculoskeletal pain is commonly reported by police officers. A potential cause of officer discomfort is a mismatch between vehicle seats and the method used for carrying appointments. Twenty-five police officers rated their discomfort while seated in: (1) a standard police vehicle seat, and (2) a vehicle seat custom-designed for police use. Discomfort was recorded in both seats while wearing police appointments on: (1) a traditional appointments belt, and (2) a load-bearing vest/belt combination (LBV). Sitting in the standard vehicle seat and carrying appointments on a traditional appointments belt were both associated with significantly elevated discomfort. Four vehicle seat features were most implicated as contributing to discomfort: back rest bolster prominence; lumbar region support; seat cushion width; and seat cushion bolster depth. Authorising the carriage of appointments using a LBV is a lower cost solution with potential to reduce officer discomfort. Furthermore, the introduction of custom-designed vehicle seats should be considered.  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