全文获取类型
收费全文 | 13630篇 |
免费 | 1721篇 |
国内免费 | 966篇 |
专业分类
电工技术 | 636篇 |
综合类 | 761篇 |
化学工业 | 2856篇 |
金属工艺 | 3064篇 |
机械仪表 | 590篇 |
建筑科学 | 71篇 |
矿业工程 | 141篇 |
能源动力 | 358篇 |
轻工业 | 1245篇 |
水利工程 | 7篇 |
石油天然气 | 152篇 |
武器工业 | 144篇 |
无线电 | 1352篇 |
一般工业技术 | 2264篇 |
冶金工业 | 1110篇 |
原子能技术 | 1364篇 |
自动化技术 | 202篇 |
出版年
2024年 | 49篇 |
2023年 | 313篇 |
2022年 | 596篇 |
2021年 | 656篇 |
2020年 | 597篇 |
2019年 | 592篇 |
2018年 | 583篇 |
2017年 | 615篇 |
2016年 | 541篇 |
2015年 | 508篇 |
2014年 | 683篇 |
2013年 | 914篇 |
2012年 | 821篇 |
2011年 | 936篇 |
2010年 | 653篇 |
2009年 | 733篇 |
2008年 | 675篇 |
2007年 | 931篇 |
2006年 | 799篇 |
2005年 | 664篇 |
2004年 | 641篇 |
2003年 | 496篇 |
2002年 | 362篇 |
2001年 | 322篇 |
2000年 | 275篇 |
1999年 | 239篇 |
1998年 | 180篇 |
1997年 | 176篇 |
1996年 | 154篇 |
1995年 | 103篇 |
1994年 | 88篇 |
1993年 | 93篇 |
1992年 | 74篇 |
1991年 | 54篇 |
1990年 | 37篇 |
1989年 | 36篇 |
1988年 | 21篇 |
1987年 | 9篇 |
1986年 | 8篇 |
1985年 | 12篇 |
1984年 | 6篇 |
1983年 | 4篇 |
1982年 | 31篇 |
1981年 | 20篇 |
1979年 | 4篇 |
1978年 | 4篇 |
1977年 | 2篇 |
1976年 | 2篇 |
1959年 | 1篇 |
1951年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
等离子体煤热解与气化工艺的研究进展 总被引:11,自引:1,他引:11
介绍了煤在热等离子体中转化为小分子化合物的2个重要过程,即等离子体煤热解和气化的基本原理、应用及发展状况。在非氧化性气氛中,煤热解生成的气体产物主要是乙炔、氢气、一氧化碳,此外还有甲烷和乙烯等小分子烃,乙炔的收率与煤种、粉煤粒度、反应器结构、粉煤进料方式、进料速度及操作条件密切相关,等离子体中氢的存在有利于乙炔的产生;在氧化性气氛中,煤气化产物主要是一氧化碳和氢气,煤中碳的转化率达95%,合成气体积分数约85%,二氧化碳体积分数低于5%。指出等离子体应用于煤转化过程是煤洁净利用的有效方式,具有潜在的工业化应用前景。 相似文献
102.
High‐density polyethylene (HDPE) beads were successfully surface‐crosslinked in a modified plasma reactor. The modified plasma reactor treats large amounts of beads, which are uniformly surface‐crosslinked. In this study, effects of the gas pressure, radio‐frequency (RF) power, and the treatment time on the degree of surface crosslinking were systematically investigated. Degree of surface crosslinking was measured by solvent extraction method (boiling xylene method, BXM). The gel content of plasma‐treated HDPE increases from 0.0 to 1.05% within 10 min at 100 mTorr, 200 W. FTIR and DSC analyses show that the crosslinked layer after plasma treatment is limited only at HDPE surface without changing the bulk thermal property of HDPE. Through the analysis of FTIR, it was confirmed that main peaks corresponding to CH2 bands were decreased and two peaks corresponding to CF2 and CF3 were observed after plasma surface modification. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 2921–2929, 2002; DOI 10.1002/app.10295 相似文献
103.
Low-temperature catalytic growth of carbon nanotubes under microwave plasma assistance 总被引:4,自引:0,他引:4
Various carbon nanotubes (CNTs) including aligned arrays, Y-branching and some other novel morphologies have been catalytically grown on anodic porous alumina template (APAT) and on the alumina-supported catalysts with methane (or benzene) as carbon source under microwave plasma assistance below 520 °C. The growth process could be simply operated since neither heating nor bias-voltage was applied to the catalysts or APAT. The results presented in this paper not only greatly richened the nanostructures of carbon family but also provided with a new technique path for synthesizing CNTs or some other nanostructures with the characteristics of low-temperature which has some special advantages or applications. 相似文献
104.
The problem of Langmuir probe data deformation due to RF pickup by the probe is treated through a computer simulation method. It is pointed out that proper RF compensations can be obtained by treatment of the Langmuir probe raw data through the use of computer software. It is demonstrated that correct, RF unaffected probe I–V characteristics can be accurately reproduced from the RF contaminated data. This eliminates the need for the use of any filters or other hardware procedures. User friendly matlab based software is presented. The software automatically retrieves the correct RF I–V characteristics for single Langmuir probe data which consequently allows for proper evaluation of plasma parameters such as the plasma electron temperature, electron number density and the electron energy distribution function (EEDF) 相似文献
105.
从等离子体的基本特性出发,综述了等离子体技术在氨气合成、有机物合成、高分子合成以及纳米碳管的合成等方面的应用和最新进展,并展望了等离子体技术在化学合成方面的应用前景. 相似文献
106.
人血浆蛋白C的纯化与鉴定 总被引:1,自引:0,他引:1
目的 建立人血浆蛋白C的纯化与鉴定方法。方法 利用DEAE SephadexA 5 0代替氯化钡 ,对血浆进行预处理 ,再经DEAE SepharoseFF离子交换和肝素 SepharoseCL 6B亲和层析进行分离纯化 ,用活化的部分凝血活酶时间 (APTT)测定组分活性 ,非还原型SDS PAGE测定其相对分子质量 ,Westernblot鉴定其特异性。结果获得相对分子质量为 6 2 0 0 0的蛋白条带 ,此条带可与人蛋白C单克隆抗体发生特异性反应。结论 已成功地从血浆中分离到蛋白C ,为其规模化生产奠定了基础。 相似文献
107.
108.
109.
110.
Dilip Chandra Ghimire Sudip Adhikari Hideo Uchida Masayoshi Umeno 《Diamond and Related Materials》2006,15(11-12):1792
We report the effects of gas composition pressure (GCP) on the optical, structural and electrical properties of thin amorphous carbon (a-C) films grown on p-type silicon and quartz substrates by microwave surface wave plasma chemical vapor deposition (MW SWP CVD). The films, deposited at various GCPs ranging from 50 to 110 Pa, were studied by UV/VIS/NIR spectroscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and current–voltage characteristics. The optical band gap of the a-C film was tailored to a relatively high range, 2.3–2.6 eV by manipulating GCPs from 50 to 110 Pa. Also, spin density strongly depended on the band gap of the a-C films. Raman spectra showed qualitative structured changes due to sp3/sp2 carbon bonding network. The surfaces of the films are found to be very smooth and uniform (RMS roughness < 0.5 nm). The photovoltaic measurements under light illumination (AM 1.5, 100 mW/cm2) show that short-circuit current density, open-circuit voltage, fill factor and photo-conversion efficiency of the film deposited at 50 Pa were 6.4 μA/cm2, 126 mV, 0.164 and 1.4 × 10− 4% respectively. 相似文献