全文获取类型
收费全文 | 30380篇 |
免费 | 2884篇 |
国内免费 | 1280篇 |
专业分类
电工技术 | 1757篇 |
综合类 | 1523篇 |
化学工业 | 5199篇 |
金属工艺 | 1864篇 |
机械仪表 | 2088篇 |
建筑科学 | 1804篇 |
矿业工程 | 794篇 |
能源动力 | 1131篇 |
轻工业 | 2290篇 |
水利工程 | 455篇 |
石油天然气 | 1329篇 |
武器工业 | 179篇 |
无线电 | 3987篇 |
一般工业技术 | 4750篇 |
冶金工业 | 1559篇 |
原子能技术 | 296篇 |
自动化技术 | 3539篇 |
出版年
2024年 | 128篇 |
2023年 | 566篇 |
2022年 | 998篇 |
2021年 | 1421篇 |
2020年 | 1065篇 |
2019年 | 917篇 |
2018年 | 1051篇 |
2017年 | 1035篇 |
2016年 | 1085篇 |
2015年 | 1215篇 |
2014年 | 1586篇 |
2013年 | 1883篇 |
2012年 | 2003篇 |
2011年 | 2250篇 |
2010年 | 1959篇 |
2009年 | 1836篇 |
2008年 | 1719篇 |
2007年 | 1472篇 |
2006年 | 1358篇 |
2005年 | 1251篇 |
2004年 | 919篇 |
2003年 | 903篇 |
2002年 | 873篇 |
2001年 | 771篇 |
2000年 | 653篇 |
1999年 | 636篇 |
1998年 | 582篇 |
1997年 | 460篇 |
1996年 | 394篇 |
1995年 | 340篇 |
1994年 | 273篇 |
1993年 | 187篇 |
1992年 | 153篇 |
1991年 | 100篇 |
1990年 | 97篇 |
1989年 | 84篇 |
1988年 | 55篇 |
1987年 | 40篇 |
1986年 | 36篇 |
1985年 | 26篇 |
1984年 | 27篇 |
1983年 | 19篇 |
1982年 | 15篇 |
1981年 | 27篇 |
1980年 | 15篇 |
1979年 | 8篇 |
1978年 | 9篇 |
1977年 | 8篇 |
1976年 | 12篇 |
1973年 | 5篇 |
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
101.
疏水缔合型聚丙烯酰胺的合成与性能评价 总被引:1,自引:0,他引:1
为了提高高相对分子质量的聚丙烯酰胺的抗温抗盐性能,利用自制的两亲表面活性单体与丙烯酰胺共聚合成了疏水缔合型聚丙烯酰胺并进行室内评价。结果表明,在高温、高盐、高钙条件下,合成的疏水缔合型聚丙烯酰胺具有良好的增粘性和较强的热稳定性;克服了疏水缔合型聚合物在盐水中溶解性差的问题,可用各种矿化度的盐水和油田产出污水配制;具有良好的无机盐增粘性能和抗温性能。 相似文献
102.
后浇带质量控制的措施 总被引:1,自引:0,他引:1
后浇带起着超长建筑的温度伸缩、高层建筑高层部分与裙房间沉降缝的作用,已普遍采用,但有些工程由于施工不当,设了后浇带起不到应有作用,本文就施工中如何采取有效措施,对后浇带的质量进行控制,作了探讨,以期能真正发挥后浇带的作用。 相似文献
103.
The fabrication of functional textiles able to provide thermal regulation and comfort for the body has attracted increasing interest in recent years. This research investigated fabric coatings containing energy absorbing, temperature stabilizing, phase‐change material microcapsules (PCMMcs), and their methods of application. Specifically, a coated fabric was directly prepared by a dual‐type coating method, in which the PCMMcs were dispersed in a polyurethane coating solution with no binder. The thermal performances of the dual‐coated samples were evaluated by differential scanning calorimetry, and their physical characteristics were examined by scanning electron microscopy, thermal vision camera, porosity, water vapor transmission rate (WVTR), and water entry pressure (WEP) analyses. Furthermore, the microclimate characteristics of the thermally enhanced fabrics were investigated under experimental conditions using a human‐clothing‐environment (HCE) simulator system. The study results confirmed the superior performance of the dual‐coated fabrics in terms of thermal regulation and body comfort, compared with those coated by the dry or wet coating method, because of the improved WEP, WVTR, and thermal performance. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
104.
105.
106.
107.
108.
S. Toita D. Kang K. Kobayashi H. Kawamoto K. Kojima M. Tachibana 《Diamond and Related Materials》2008,17(7-10):1389-1393
DNA-wrapped single-wall carbon nanotubes (DNA-SWNT hybrids) prepared from different diameter HiPco- and Arc-SWNTs were investigated by atomic force microscopy. The mean diameter of DNA-HiPco-SWNT hybrids is 1.94 nm that is consistent with one HiPco-SWNT (~ 0.9 nm) wrapped by DNA (~ 1 nm). On the other hand, the mean diameter of DNA-Arc-SWNT hybrids is 3.74 nm that can correspond to one Arc-SWNT (~ 1.4 nm) wrapped by several layers of DNA. It is suggested that the DNA-wrapping mechanism for large diameter Arc-SWNTs is different from that for small diameter HiPco-SWNTs. 相似文献
109.
This paper highlighted the use of X-ray diffraction, scanning electron microscopy and X-ray fluorescence spectroscopy to investigate the changes on the surface composition of high-sulfur coal and pyrite before and after ultrasonic conditioning. The results showed that ultrasonic conditioning resulted in a decrease in the contents of iron and sulfur in coal, an increase in the content of element carbon, and an increase in the purity of the coal. Conversely, ultrasonic conditioning led to an increase in the content of iron and sulfur in pyrite, a decrease in the impure content of calcium, and a relative increase in the purity of the pyrite after ultrasonic conditioning. This study verified that on the one hand, ultrasonic conditioning can promote the pyrite separation from the high-sulfur coal, with the separated pyrite taking the form of FeS; on the other hand, it can produce a cleaning effect on the surface of coal and pyrite with the consequent increase both in hydrophobicity of coal and hydrophilicity of pyrite. The paper introduced ultrasonic pre-treatment of the slurry and stepped froth removal tests of high-sulfur coal and the study on the yield, ash and sulfur content of clean coal in different phases. The results gave further evidence of the increases both in the rate and the selectivity of flotation. This study shows that ultrasonic conditioning can enhance the performance of de-sulphurization of high-sulfur coal flotation. 相似文献
110.
In a mobile ad hoc network, difficulties exist in supporting address autoconfiguration and naming resolution due to the lack of centralized servers. This letter presents a novel approach, called name‐based autoconfiguration (NBA), which uses host names to determine IP addresses and provides address autoconfiguration and name resolution as a single protocol. 相似文献