全文获取类型
收费全文 | 577篇 |
免费 | 81篇 |
国内免费 | 25篇 |
专业分类
电工技术 | 50篇 |
技术理论 | 2篇 |
综合类 | 41篇 |
化学工业 | 68篇 |
金属工艺 | 11篇 |
机械仪表 | 9篇 |
建筑科学 | 25篇 |
矿业工程 | 15篇 |
能源动力 | 16篇 |
轻工业 | 40篇 |
水利工程 | 19篇 |
石油天然气 | 26篇 |
武器工业 | 5篇 |
无线电 | 88篇 |
一般工业技术 | 60篇 |
冶金工业 | 18篇 |
原子能技术 | 23篇 |
自动化技术 | 167篇 |
出版年
2024年 | 4篇 |
2023年 | 24篇 |
2022年 | 37篇 |
2021年 | 36篇 |
2020年 | 24篇 |
2019年 | 12篇 |
2018年 | 19篇 |
2017年 | 22篇 |
2016年 | 17篇 |
2015年 | 31篇 |
2014年 | 40篇 |
2013年 | 36篇 |
2012年 | 47篇 |
2011年 | 45篇 |
2010年 | 12篇 |
2009年 | 27篇 |
2008年 | 23篇 |
2007年 | 12篇 |
2006年 | 19篇 |
2005年 | 28篇 |
2004年 | 25篇 |
2003年 | 23篇 |
2002年 | 29篇 |
2001年 | 13篇 |
2000年 | 7篇 |
1999年 | 10篇 |
1998年 | 12篇 |
1997年 | 12篇 |
1996年 | 11篇 |
1995年 | 10篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 1篇 |
1990年 | 1篇 |
1989年 | 1篇 |
1988年 | 1篇 |
1987年 | 1篇 |
排序方式: 共有683条查询结果,搜索用时 15 毫秒
31.
32.
33.
34.
将硅烷偶联剂KH⁃560和硫化促进剂CZ共改性煤粉(Coal)作为增强填料加入到丁苯橡胶(SBR)中制备改性SBR/ Coal复合材料,通过设置不同的共改性Coal的添加量,寻找KH⁃560、CZ共改性Coal增强丁苯橡胶的最佳实验配比。结果表明,KH⁃560的最佳添加量为Coal质量的5 %,此时SBR/ Coal⁃KH560复合材料的力学性能最佳; KH⁃560和CZ改性Coal可以明显减少Coal团聚现象,在丁苯橡胶中均匀分散。当Coal⁃KH560⁃CZ添加量为40 %时,与纯SBR相比,拉伸强度由1.66 MPa升高至2.9 MPa,断裂伸长率由295 %升高至390 %,撕裂强度由7.1 N/mm增加至11.6 N/mm,复合材料的力学性能和热稳定性能得到改善,加工性能也得到较大提升。 相似文献
35.
In order to enhance oil recovery from high‐salinity reservoirs, a series of cationic gemini surfactants with different hydrophobic tails were synthesized. The surfactants were characterized by elemental analysis, infrared spectroscopy, mass spectrometry, and 1H‐NMR. According to the requirements of surfactants used in enhanced oil recovery technology, physicochemical properties including surface tension, critical micelle concentration (CMC), contact angle, oil/water interfacial tension, and compatibility with formation water were fully studied. All cationic gemini surfactants have significant impact on the wettability of the oil‐wet surface, and the contact angle decreased remarkably from 98° to 33° after adding the gemini surfactant BA‐14. Under the condition of solution salinity of 65,430 mg/L, the cationic gemini surfactant BA‐14 reduces the interfacial tension to 10?3 mN/m. Other related tests, including salt tolerance, adsorption, and flooding experiments, have been done. The concentration of 0.1% BA‐14 remains transparent with 120 g/L salinity at 50 °C. The adsorption capacity of BA‐14 is 6.3–11.5 mg/g. The gemini surfactant BA‐14 can improve the oil displacement efficiency by 11.09%. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46086. 相似文献
36.
Novel eco-friendly sulfonated polyurethane/polyacrylate (SPUA) emulsions were synthesized by surfactant-free emulsion polymerization method using PU as seeds. The sodium sulfonate modified polyester polyol (SDNP) was used as internal emulsifier to make the PU emulsion disperse in deionized water. Effects of the SDNP content on the properties of the emulsions and membranes were studied. Dynamic light scattering (DLS) result showed that the average particle sizes of SPUA emulsions decreased first from 124.1 nm to 102 nm when the SDNP content was lower than 40 wt% and then increased to 138 nm. Transmission electron microscopy (TEM) morphology showed that the particle sizes were all spherical and an apparent core-shell structure was observed. Fourier transform infrared spectroscopy (FT-IR) result ascertains that SPUA was successfully prepared. X-ray photoelectron spectroscopy (XPS) analysis demonstrates that the carbon, oxygen, nitrogen, sulfur, and sodium peaks were all revealed and the polyurethane component was rich in the upper surface. Thermo gravimetric analysis (TGA) of the membranes showed that the thermal stability of the SPUA membranes was enhanced by increasing the SDNP content. Scanning electron micrograph (SEM) results demonstrates that the coexistence of a dual phase. The SPUA could be used as adhesives in footwear industry, and the T-peel strength of the SPUA membranes increased from 5.98 N/mm to 12.06 N/mm when the SDNP content was up to 40 wt%. The wettability of SPUA emulsions on the rubber surface results showed that the emulsions could wet the rubber surface well. 相似文献
37.
分别采用"两步法"和"三步法"两种不同工艺方法制备植物纤维纸蜂窝芯材,通过测试压缩性能、剪切性能研究两种工艺方法所制得芯材的力学性能;测试水迁移和垂直燃烧研究芯材的物理阻燃性能;比较芯材的力学性能和物理性能,选出两种方法中效果较好的工艺方法。结果表明,三步法工艺中芯材的压缩强度比两步法增加了52%;L向剪切强度增加了47.6%,W向剪切强度增加了72%。水迁移测试中两步法水迁移孔格数平均值为5,三步法平均值为0,垂直燃烧测试中两步法平均烧焦长度为41.8 mm,比"三步法"烧焦长度长12.8 mm。通过扫描电子显微镜测试分析了三步法力学性能较好的原因。综合比较芯材的力学性能和物理性能,三步法工艺好。 相似文献
38.
利用梧州市4个空气质量监测站点网上公开发布的2015~2016年连续两年的颗粒物及气态污染物在线观测数据对该市大气污染状况进行分析,结果表明:梧州市2015~2016年环境空气质量达标率为93.3%,空气质量总体良好;大气污染以颗粒物为主,2015~2016年梧州市PM2.5年均浓度分别为36μg/m~3、39μg/m~3,均超出国家二级标准(35μg/m~3);梧州市颗粒物浓度的空间分布并无明显差异;PM2.5季节变化规律为冬季秋季春季夏季,PM10季节变化规律为冬季春季秋季夏季;PM2.5/PM10逐年增加,梧州市颗粒物污染逐渐由粗颗粒物污染向细颗粒物污染转变。 相似文献
39.
Jing Cai Xiaoyong Yang Ruimin Jiao Xiaofang He Xinxin Cao Fuqin Xu Zhaoyang Hou Zhihui Ma Xinyang Zhang 《应用聚合物科学杂志》2024,141(19):e55363
Pulverized coal (coal) possesses a layered structure similar to graphite and is a potential reinforcing filler. In this paper, ball milling is used to reduce the particle diameter of coal. The coal is modified with KH-560 to obtain K-COAL and prepared K-COAL/styrene-butadiene rubber (SBR) composites. In addition, carbon black (CB) is modified to obtain CB-Si69, K-COAL and CB-Si69 are added to SBR in different ratios to prepare COAL/CB/SBR composites. The results show that the addition of K-COAL can improve the vulcanization performance, thermal stability, and mechanical properties of SBR composites, but the reinforcing effect is weak. In the COAL/CB/SBR composites, the vulcanization and mechanical properties of the composites gradually increase with the increase of CB, while those of the thermal stability decrease. The tensile strength of the 10 phr COAL/30 phr CB/SBR composite is 24.1 MPa, which is elevated by 1105% and 205% compared with the pure SBR and 40 phr K-COAL/SBR composites, respectively. The composites maintain high elasticity while the tensile strengths are greatly improved, and the mechanical properties are significantly enhanced. In conclusion, this paper provides a reference for the clean utilization of coal and shows new possibilities for finding new fillers to replace CB. 相似文献
40.