全文获取类型
收费全文 | 1444篇 |
免费 | 39篇 |
国内免费 | 31篇 |
专业分类
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 |
出版年
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.
孙华 《单片机与嵌入式系统应用》2014,(7):72-75
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.
Keshun Liu 《Journal of the American Oil Chemists' Society》2021,98(12):1115-1129
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.
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.
Psang Dain Lin Chian Sheng Tzeng 《International Journal of Machine Tools and Manufacture》2007,47(15):2218-2229
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.
28.
Taneli Rantaharju Neil J. Mansfield Jussi M. Ala-Hiiro Thomas P. Gunston 《Ergonomics》2015,58(7):1071-1087
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.
《Information Security Journal: A Global Perspective》2013,22(6):343-350
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.