全文获取类型
收费全文 | 5314篇 |
免费 | 51篇 |
国内免费 | 6篇 |
专业分类
电工技术 | 33篇 |
综合类 | 5篇 |
化学工业 | 298篇 |
金属工艺 | 32篇 |
机械仪表 | 37篇 |
建筑科学 | 83篇 |
矿业工程 | 5篇 |
能源动力 | 31篇 |
轻工业 | 89篇 |
水利工程 | 36篇 |
石油天然气 | 3篇 |
无线电 | 235篇 |
一般工业技术 | 337篇 |
冶金工业 | 3949篇 |
原子能技术 | 22篇 |
自动化技术 | 176篇 |
出版年
2022年 | 20篇 |
2021年 | 27篇 |
2019年 | 14篇 |
2018年 | 24篇 |
2017年 | 17篇 |
2016年 | 21篇 |
2015年 | 25篇 |
2014年 | 28篇 |
2013年 | 59篇 |
2012年 | 47篇 |
2011年 | 78篇 |
2010年 | 53篇 |
2009年 | 56篇 |
2008年 | 73篇 |
2007年 | 69篇 |
2006年 | 63篇 |
2005年 | 49篇 |
2004年 | 62篇 |
2003年 | 60篇 |
2002年 | 42篇 |
2001年 | 43篇 |
2000年 | 54篇 |
1999年 | 143篇 |
1998年 | 1197篇 |
1997年 | 649篇 |
1996年 | 500篇 |
1995年 | 274篇 |
1994年 | 241篇 |
1993年 | 254篇 |
1992年 | 38篇 |
1991年 | 54篇 |
1990年 | 71篇 |
1989年 | 71篇 |
1988年 | 63篇 |
1987年 | 70篇 |
1986年 | 70篇 |
1985年 | 43篇 |
1984年 | 25篇 |
1983年 | 28篇 |
1982年 | 28篇 |
1981年 | 34篇 |
1980年 | 51篇 |
1979年 | 15篇 |
1978年 | 22篇 |
1977年 | 98篇 |
1976年 | 216篇 |
1975年 | 16篇 |
1974年 | 11篇 |
1972年 | 9篇 |
1971年 | 13篇 |
排序方式: 共有5371条查询结果,搜索用时 15 毫秒
191.
Pai-shan PA Digital Content Design Graduate School of Toy Game Design National Taipei University of Education Taipei City China 《中国有色金属学会会刊》2011,(Z1)
Color filters are produced using semiconductor production techniques although problems with low yield remain to be addressed. This study presents a new means of selective removal using excimer irradiation, chemical etching, or electrochemical machining on the fifth generation TFT LCDs. The selective removal of microstructure layers from the color filter surface of an optoelectronic flat panel display, as well as complete removal of the ITO thin-films, RGB layer, or resin black matrix (BM) layer from the sub... 相似文献
192.
Di Bias A. Dahle D.M. Diekhans M. Grate L. Hirschberg J. Karplus K. Keller H. Kendrick M. Mesa-Martinez F.J. Pease D. Rice E. Schultz A. Speck D. Hughey R. 《Parallel and Distributed Systems, IEEE Transactions on》2005,16(1):80-92
The architectural landscape of high-performance computing stretches from superscalar uniprocessor to explicitly parallel systems, to dedicated hardware implementations of algorithms. Single-purpose hardware can achieve the highest performance and uniprocessors can be the most programmable. Between these extremes, programmable and reconfigurable architectures provide a wide range of choice in flexibility, programmability, computational density, and performance. The UCSC Kestrel parallel processor strives to attain single-purpose performance while maintaining user programmability. Kestrel is a single-instruction stream, multiple-data stream (SIMD) parallel processor with a 512-element linear array of 8-bit processing elements. The system design focuses on efficient high-throughput DNA and protein sequence analysis, but its programmability enables high performance on computational chemistry, image processing, machine learning, and other applications. The Kestrel system has had unexpected longevity in its utility due to a careful design and analysis process. Experience with the system leads to the conclusion that programmable SIMD architectures can excel in both programmability and performance. This work presents the architecture, implementation, applications, and observations of the Kestrel project at the University of California at Santa Cruz. 相似文献
193.
M. R. Gafurov V. A. Ivanshin I. N. Kurkin M. P. Rodionova H. Keller M. Gutmann U. Staub 《Journal of Superconductivity》2000,13(6):895-897
The first observation of electron paramagnetic resonance (EPR) of Tb3+ doped into YBa2Cu3O6 is reported. EPR is used to determine the local symmetry of the rare-earth ion and to study the effect of suppression of high-T
c superconductivity by doping. The distance between the lowest singlets of Tb3+ ion 7.1 GHz 0.24 cm–1 and g-factor g
17.9 have been estimated from measurements. Both these parameters are in a good agreement with the corresponding calculated values. No evidence of Tb4+ ions was found. 相似文献
194.
195.
Influence of the preparation conditions on the synthesis of high surface area SiC for use as a heterogeneous catalyst support 总被引:2,自引:0,他引:2
N. Keller C. Pham-Huu S. Roy M. J. Ledoux C. Estournes J. Guille 《Journal of Materials Science》1999,34(13):3189-3202
The influence of different parameters (temperature, duration and SiO source) on the synthesis of silicon carbide SiC according to the gas-solid reaction between SiO vapors and activated charcoal was investigated. The material obtained retained the general shape of the activated charcoal, which is an advantage because of the difficulty in post shaping SiC, due to the high strength of the material. High temperature (>1250 °C) and long reaction duration led to a high C* SiC conversion but with a relatively low surface area (20–25 m2 · g–1) due to sintering via the surface diffusion phenomenon. The combination of a lower reaction temperature (1200 °C), longer reaction duration (15 h) and high (Si + SiO2)/C* weight ratio allowed SiC to be obtained with a surface area of around 50 m2 · g–1, which can be used as a support material for heterogeneous catalysis. 相似文献
196.
197.
The spirochete Borrelia burgdorferi Johnson, Schmid, Hyde, Steigerwalt & Benner is transmitted by Ixodes scapularis Say, a vector of Lyme disease. As a 1st step into investigating the possibility of biocontrol of the tick, we identified the microbiota associated with the ticks. We collected, identified, and determined the sex of ticks from foliage and deer. Seventy-three initial bacterial isolates were recovered from 43 ticks (27 adults and 16 nymphs). The bacteria isolated from nymphs were qualitatively different (mainly gram-negative cocci) from the bacteria isolated from adult ticks (gram-negative and gram-positive rods). To determine long-term viability, these isolates were stored for 6 mo under laboratory conditions. After storage, 63 surviving bacterial isolates were characterized using the Biology System of identification by substrate utilization. Forty-four isolates were identified to the species level. Our characterization efforts focused on the 40 spore-forming bacteria, which could prove useful in the biocontrol of ticks. Eleven species of Bacillus were identified. Bacillus thuringiensis-B. cereus was the predominant species group isolated. Six isolates from this group formed crystals. 相似文献
198.
R Wikaningrum J Highton A Parker M Coleman PA Hessian PJ Roberts-Thompson MJ Ahern MD Smith 《Canadian Metallurgical Quarterly》1998,41(10):1783-1797
OBJECTIVE: To investigate the production of proinflammatory cytokines and expression of cell adhesion molecules in the rheumatoid nodule. METHODS: Cytokine content (tumor necrosis factor alpha [TNFalpha], interleukin-1beta [IL-1beta], and IL-1 receptor antagonist [IL-1Ra]), at the messenger RNA (mRNA) and protein levels, and cell adhesion molecule expression were studied in 16 rheumatoid nodules and 6 synovial membranes. RESULTS: Macrophages in the rheumatoid nodules contained TNFalpha, IL-1beta, and IL-1Ra mRNA and protein, particularly in perivascular cells of the stroma and in the palisading layer. All cell adhesion molecules studied were expressed in both the rheumatoid nodules and synovial membranes, with increased expression of E-selectin in the rheumatoid nodule compared with the synovial membrane, and with the absence of vascular cell adhesion molecule 1 expression on cells of the palisading layer in the rheumatoid nodule. CONCLUSION: The presence of similar proinflammatory cytokines and cell adhesion molecules in the rheumatoid nodule and synovial membrane suggests that similar pathogenic processes result in the chronic inflammation and tissue destruction in these lesions. 相似文献
199.
OBJECTIVES: To identify the reasons for non-compliance with fecal occultblood test in the screening programme for colorectal cancer. DESIGN AND SETTING: The people who had never participated in the screening programme for colorectal cancer served as the subjects of this study. A structured questionnaire which included the reasons for rejection was sent to each of non-compliers. They were requested to choose two major reasons which were described in a best way that why they did not participate in the programme. The frequency of the stated reasons were analysed from the viewpoint of both sex and age effects. MAIN RESULTS:A total of 439 people was identified as non-compliers, and 356 (81.1%) people completed the questionnaire. No significant difference was noted in response to the questionnaire between male and female as well as aged 40-59 and those 60-79. The most commonest reason was felt well (47.8%) in male, fear or shyness of further examination (40.2%) in female, and also felt well (48.5%) in aged 40-59, fear or shyness of further examination (40.1%) in aged 60-79. Significant differences were observed in the frequencies of felt well (p<0.01), fear or shyness of further examination (p<0. 01), busy for work (p<0.01) and fear of cancer (p<0.01) between male and female, and also felt well (p<0.01), fear or shyness of further examination (p<0.01), busy for work (p<0.01) and coexistent disease (p<0.01) between aged 40-59 and those 60-79. CONCLUSIONS: These results suggest that public education about the concept of asymptomatic illness, the benefits of early detection, the safety and painless colonoscopy, and the effective treatment should be emphasised to increase compliance with screening for fecal occult blood. 相似文献
200.