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   1444篇
  免费   39篇
  国内免费   31篇
电工技术   46篇
综合类   84篇
化学工业   96篇
金属工艺   51篇
机械仪表   140篇
建筑科学   98篇
矿业工程   41篇
能源动力   36篇
轻工业   135篇
水利工程   22篇
石油天然气   46篇
武器工业   3篇
无线电   212篇
一般工业技术   143篇
冶金工业   73篇
原子能技术   4篇
自动化技术   284篇
  2024年   1篇
  2023年   1篇
  2022年   9篇
  2021年   19篇
  2020年   18篇
  2019年   27篇
  2018年   22篇
  2017年   30篇
  2016年   28篇
  2015年   26篇
  2014年   70篇
  2013年   79篇
  2012年   59篇
  2011年   89篇
  2010年   84篇
  2009年   97篇
  2008年   86篇
  2007年   102篇
  2006年   101篇
  2005年   67篇
  2004年   60篇
  2003年   84篇
  2002年   108篇
  2001年   60篇
  2000年   42篇
  1999年   33篇
  1998年   22篇
  1997年   21篇
  1996年   24篇
  1995年   12篇
  1994年   6篇
  1993年   8篇
  1992年   2篇
  1991年   5篇
  1990年   4篇
  1989年   3篇
  1986年   2篇
  1985年   1篇
  1984年   2篇
排序方式: 共有1514条查询结果,搜索用时 15 毫秒
21.
本文设计一种基于NXP公司的LPC812微控制器和SLRC610射频芯片的RFID模块方法。该模块采用内置天线,预留串口与外部通信。该模块性能优良、易于集成到RFID系统中,使用户更专注于系统功能方面的设计。  相似文献   
22.
基于ISO9001、ISO14001和GB/T28001标准,分析施工组织设计中存在的可操作性差、缺乏理论依据等问题,把ISO9001、ISO14001和GB/T28001标准理念应用于施工组织设计的编制和实施,并进行动态管理,对外提供环境保护及职业健康安全保证,对内指导施工,以加强对建设工程项目的安全管理,预防工程质量事故、环境污染及伤亡事故的发生.  相似文献   
23.
For measuring trypsin inhibitor activity (TIA), there are two major official methods: American Oil Chemists Society (AOCS) method Ba 12a-2020 and International Organization for Standardization (ISO) 14902:2001. The former was recently approved. The two methods differ in sample preparation, extraction, colorimetric assay systems and TIA calculations. In this study, the two methods were symmetrically compared using three unique sets of samples: assorted protein products of soybeans, pulses, and grains; soybeans boiled for varied durations; and soy white flakes toasted for varied durations. For given samples, significant differences existed in TIA measured by the two methods, resulting from effects related to the assay systems and TIA calculations, not from the difference in sample preparation and extraction. When the same trypsin was used, TIA (in mg trypsin inhibited/g sample) measured by the two methods were highly correlated (r = 0.9973, n = 27), giving an equation of y = 0.5464x − 0.4887, where y represents ISO values and x for AOCS values. The line connecting ratios of ISO/AOCS in TIA and AOCS values remained relatively flat around 0.53 but started to curve down when TIA approached the lowest. Furthermore, for the same samples, TIA values measured by the ISO method decreased with increasing specific activity of trypsin used, while AOCS values remained consistent, leading to decreasing ratios of ISO/AOCS. Therefore, accurate and direct comparison of the two methods was impossible. It could not be resolved by simply changing ISO method's calculations as hypothesized earlier. Regardless, for most samples, ISO values were roughly about 55% of AOCS values.  相似文献   
24.
研究探讨了PLIB实体的构造原理,并结合螺母零件族进行了说明。  相似文献   
25.
论文针对我国质量体系审核现状,分析了质量体系审核系统的需求,设计了质量体系审核系统的体系结构,阐述了系统的主要功能方法,介绍了系统开发的质量审核数据集成、审核流程等技术实现.最后介绍了一个系统应用实例.  相似文献   
26.
Traditionally, twist drills are reconditioned by thinning the web so the correct chisel edge length is restored. Recently, thinning has been included in the original design of drills so as to reduce torque and tool force. Because the International Standards Organization (ISO) has a system which can comprehensively model conventional twist drills but cannot model thinning specifications, this paper presents a system for precise mathematical modeling and CNC control of a 6-axis grinding workstation for drill thinning. The presented method determines the position and orientation of the grinding wheel based on the evaluated rake and clearance angles of ISO standards for 2-flute twist drills. The mathematical model and background are discussed. For verification and demonstration, two experimental drills are produced to the identical ISO standard except that one is thinned. The modeling herein is of value to industry and research if incorporated into computer software for drill design and manufacture. It is suitable for linear notch-type cutting with controlled variable rake angle along the secondary cutting edge for purposes of thinning, notching, dubbing and advanced drill research.  相似文献   
27.
阐述了ISO14000系列标准产生的背景、已发布的5个标准简况、ISO/TC207正在起草的国际标准及其发展趋势;介绍了实施ISO14000系列标准的作用和意义以及我国推行ISO14000系列标准的原则和计划;指出了ISO14000系列标准与ISO9000族标准的关系。  相似文献   
28.
In this paper, alternative assessment methods for whole-body vibration and shocks are compared by means of 70 vibration samples measured from 13 work vehicles, deliberately selected to represent periods containing shocks. Five methodologies (ISO 2631-1:1997, BS 6841:1987, ISO 2631-5:2004, DIN SPEC 45697:2012 and one specified by Gunston [2011], ‘G-method’) were applied to the vibration samples. In order to compare different evaluation metrics, limiting exposures were determined by calculating times to reach the upper limit thresholds given in the methods. Over 10-fold shorter times to exposure thresholds were obtained for the tri-axial VDV (BS 6841) than for the dominant r.m.s. (ISO 2631-1) when exposures were of high magnitude or contained substantial shocks. Under these exposure conditions, the sixth power approaches (ISO 2631-5, DIN SPEC, G-method) are more stringent than a fourth power VDV method. The r.m.s. method may lead to misleading outcomes especially if a lengthy measurement includes a small number of severe impacts. In conclusion, methodologies produce different evaluations of the vibration severity depending on the exposure characteristics, and the correct method must be selected.  相似文献   
29.
ABSTRACT

Today's businesses being IT enabled, the complexity of risks affecting the business has increased manifold and the need to gauge the Information Technology risks acting on the business operations has become paramount. The business managers who run business operations need to operate securely and seamlessly leveraging Information Technology and ability to recover and resume the business without any loss of confidentiality, integrity and availability of business information/data in any event of a security incident.

There is a need to quantify the impact of the IT security risk on the critical business processes, and provide the business-level insight at the management level. It is critical to classifying the Risk Ratings as per the impact on the business operations. This approach allows the organizations to understand and prioritize the security risk management activities that make the most sense for their organization to secure the business operations instead of trying to protect against every conceivable threat.  相似文献   
30.
程序的引导装载功能是嵌入式系统的一个必备功能.针对发动机电控单元的特点,设计出基于车辆标准传输总线CAN总线和标准诊断协议ISO15765协议的电控单元引导加载功能.实现了控制软件和标定数据的自动下载和更新,电控单元内部程序的跳转控制功能,提高了电控单元的生产和维护的效率.  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