全文获取类型
收费全文 | 151936篇 |
免费 | 1890篇 |
国内免费 | 656篇 |
专业分类
电工技术 | 3115篇 |
综合类 | 188篇 |
化学工业 | 24085篇 |
金属工艺 | 5781篇 |
机械仪表 | 4943篇 |
建筑科学 | 4425篇 |
矿业工程 | 377篇 |
能源动力 | 3927篇 |
轻工业 | 17307篇 |
水利工程 | 1140篇 |
石油天然气 | 620篇 |
武器工业 | 5篇 |
无线电 | 20519篇 |
一般工业技术 | 28851篇 |
冶金工业 | 23764篇 |
原子能技术 | 2341篇 |
自动化技术 | 13094篇 |
出版年
2019年 | 835篇 |
2018年 | 1082篇 |
2017年 | 1132篇 |
2016年 | 1269篇 |
2015年 | 1064篇 |
2014年 | 1798篇 |
2013年 | 6584篇 |
2012年 | 3195篇 |
2011年 | 4611篇 |
2010年 | 3595篇 |
2009年 | 4153篇 |
2008年 | 4648篇 |
2007年 | 4914篇 |
2006年 | 4353篇 |
2005年 | 4112篇 |
2004年 | 4005篇 |
2003年 | 3904篇 |
2002年 | 3933篇 |
2001年 | 3982篇 |
2000年 | 3742篇 |
1999年 | 3696篇 |
1998年 | 6635篇 |
1997年 | 5231篇 |
1996年 | 4461篇 |
1995年 | 3714篇 |
1994年 | 3358篇 |
1993年 | 3185篇 |
1992年 | 2783篇 |
1991年 | 2691篇 |
1990年 | 2628篇 |
1989年 | 2614篇 |
1988年 | 2459篇 |
1987年 | 2167篇 |
1986年 | 2115篇 |
1985年 | 2557篇 |
1984年 | 2317篇 |
1983年 | 2195篇 |
1982年 | 2068篇 |
1981年 | 1991篇 |
1980年 | 1860篇 |
1979年 | 1874篇 |
1978年 | 1771篇 |
1977年 | 2086篇 |
1976年 | 2563篇 |
1975年 | 1583篇 |
1974年 | 1430篇 |
1973年 | 1453篇 |
1972年 | 1196篇 |
1971年 | 1115篇 |
1970年 | 948篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
Herzog K. Schulte E. Atmanand M. A. Schwarz W. 《Automation Science and Engineering, IEEE Transactions on》2007,4(2):282-286
Tracked vehicles capable of locomotion in the deep sea are used for manganese nodule mining. This requires specific technical solutions in various respects. Locomotion in the soft sea bed is one of them. For the Crawler to safely maneuver, an automatic drive mode with slip control of the driving tracks is essential. Based on experimental studies at IKS, University of Siegen, slip control for the NIOT-IKS mining machine has been developed and implemented. The experimental setup for the development of the slip control along with the logic of the automatic driving mode is described. The system is critically discussed and the test results and future work are briefly outlined. Note to Practitioners-The work is carried out as part of the polymetallic nodule mining program of the Government of India. The technique of slip control is a specific requirement for a tracked vehicle used in the deep sea. Slip is common in many vehicles-tracked and otherwise. Examples are steam engines in the early days and ordinary cars while negotiating slush or snow/ice and dozers working in soft soil. While these are manually controlled by drivers who have firsthand knowledge of the environmental conditions, in the case of a mining machine in deep sea, it has to be completely automatic and, hence, is challenging. The knowledge generated in this work could be effectively used by practitioners in other related areas of automobile engineering for updating their expertise. Also, similar techniques may be used for maneuvering vehicles sent to other planets 相似文献
173.
The US Centers for Disease Control and Prevention (CDC) created the Public Health Information Network to advance fully capable, interoperable information systems in public health organizations. PHIN prioritizes public health information systems' functional requirements, capabilities, performance measures, and operational characteristics while letting the architects of those systems choose enabling approaches, methods, and concepts to meet the requirements. PHIN also provides a certification process for public health administrators to evaluate their information infrastructure's quality. The certification process is important because affected organizations often depend on certification for continued funding. 相似文献
174.
175.
176.
The IBM RISC System/6000, a superscalar microprocessor, is presented. The architecture of this processor has its instruction set specifically designed for a superscalar machine containing three independent units-branch, fixed-point, and floating-point. The design also emphasizes high-performance floating-point operations. The design principles are to offer maximum overlap of the three functional units, avoid dead cycles, and define instructions that can (for the most part) be completed at a rate of one per cycle. The branch cycle, fixed- and floating-point units, cache management, and performance are described. Benchmark results are given 相似文献
177.
178.
A Rate-Control vaginal device was developed which overcomes the low bioavailability and unpredictable Q - t1/2 type release and absorption rate profiles of flurogestone acetate delivered by the currently marketed Syncro-Mate pessary.
The in vitro release and vaginal absorption profiles from the Rate-Control vaginal device were run simultaneously, a linear Q - t relationship was obtained with a significant improvement in bioavailability. A mathematical model was developed to correlate the in vitro drug release and the vaginal absorption profiles of flurogestone acetate from the vaginal devices.
The design, development and the simultaneous release and absorption profiles of flurogestone acetate from this new vaginal device were outlined and discussed. 相似文献
The in vitro release and vaginal absorption profiles from the Rate-Control vaginal device were run simultaneously, a linear Q - t relationship was obtained with a significant improvement in bioavailability. A mathematical model was developed to correlate the in vitro drug release and the vaginal absorption profiles of flurogestone acetate from the vaginal devices.
The design, development and the simultaneous release and absorption profiles of flurogestone acetate from this new vaginal device were outlined and discussed. 相似文献
179.
180.
Ion-beam sputter-deposited alloy films of Co/sub 74/Fe/sub 6/B/sub 15/Si/sub 5/ and Fe/sub 75/Ni/sub 5/B/sub 15/Si/sub 5/ were examined for their magnetic and structural properties. Films were characterized by ferromagnetic resonance, vibrating sample magnetometry, and extended X-ray absorption fine structure (EXAFS) analysis. Using atomic parameters deduced from EXAFS modeling and fitting procedures, magnetic properties were calculated with no adjustable parameters. Correlation between perpendicular FMR measurements and EXAFS first-shell modeling suggests a low-temperature formation of cobalt-borides in the Co/sub 74/Fe/sub 6/B/sub 15/Si/sub 5/ alloy. Annealed Fe/sub 75/Ni/sub 5/B/sub 15/Si/sub 5/ samples did not display evidence of structural and/or magnetic instabilities until the onset of long-range crystallization near T/sub ann/=400 degrees C.<> 相似文献