全文获取类型
收费全文 | 5027篇 |
免费 | 583篇 |
国内免费 | 261篇 |
专业分类
电工技术 | 255篇 |
综合类 | 405篇 |
化学工业 | 893篇 |
金属工艺 | 250篇 |
机械仪表 | 233篇 |
建筑科学 | 403篇 |
矿业工程 | 160篇 |
能源动力 | 146篇 |
轻工业 | 475篇 |
水利工程 | 112篇 |
石油天然气 | 256篇 |
武器工业 | 41篇 |
无线电 | 625篇 |
一般工业技术 | 645篇 |
冶金工业 | 226篇 |
原子能技术 | 41篇 |
自动化技术 | 705篇 |
出版年
2024年 | 23篇 |
2023年 | 91篇 |
2022年 | 170篇 |
2021年 | 251篇 |
2020年 | 204篇 |
2019年 | 199篇 |
2018年 | 203篇 |
2017年 | 234篇 |
2016年 | 195篇 |
2015年 | 224篇 |
2014年 | 248篇 |
2013年 | 351篇 |
2012年 | 349篇 |
2011年 | 325篇 |
2010年 | 281篇 |
2009年 | 266篇 |
2008年 | 293篇 |
2007年 | 221篇 |
2006年 | 205篇 |
2005年 | 179篇 |
2004年 | 143篇 |
2003年 | 187篇 |
2002年 | 241篇 |
2001年 | 220篇 |
2000年 | 118篇 |
1999年 | 84篇 |
1998年 | 55篇 |
1997年 | 52篇 |
1996年 | 48篇 |
1995年 | 45篇 |
1994年 | 30篇 |
1993年 | 30篇 |
1992年 | 18篇 |
1991年 | 21篇 |
1990年 | 16篇 |
1989年 | 11篇 |
1988年 | 10篇 |
1987年 | 11篇 |
1986年 | 9篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 1篇 |
1951年 | 3篇 |
排序方式: 共有5871条查询结果,搜索用时 46 毫秒
1.
Xiaozhen Li Chao Yin Si Si Liew Chun-Sing Lee Kanyi Pu 《Advanced functional materials》2021,31(46):2106154
Optical imaging has played a pivotal role in deciphering in vivo bioinformatics but is limited by shallow penetration depth and poor imaging performance owing to interfering tissue autofluorescence induced by concurrent photoexcitation. The emergence of near-infrared (NIR) self-luminescence imaging independent of real-time irradiation has timely addressed these problems. There are two main kinds of self-luminescent agents, namely inorganic and organic luminophores. Inorganic luminophores usually suffer from long-term biotoxicity concerns resulting from potential heavy-metal ions leakage and nonbiodegradability, which hinders their further translational application. In contrast, organic luminophores, especially organic semiconducting luminophores (OSLs) with good biodegradable potential, tunable design, and outstanding optical properties, are preferred in biological applications. This review summarizes the recent progress of OSLs used in NIR afterglow, chemiluminescence, and bioluminescence imaging. Molecular manipulation and nanoengineering approaches of OSLs are discussed, with emphasis on strategies that can extend the emission wavelength from visible to NIR range and amplify luminescence signals. This review concludes with a discussion of current challenges and possible solutions of OSLs in the self-luminescence field. 相似文献
2.
Nowadays, oil pollution has become more serious, which causes great threats both to the ecological environment and human life. In this study, a novel type of multifunctional deacetylated cellulose acetate/polyurethane (d-MCA:MTPU) composite nanofiber membranes for oil/water separation are successfully fabricated by electrospinning, which show super-amphiphilicity in air, super-hydrophilicity in oil, and oleophobicity in water. All the d-MCA:MTPU composite nanofiber membranes with different mass ratios can be used as water-removing, oil-removing, and emulsion separation substance only by gravity driving force. The highest separation flux for water and oil reaches up to 37 000 and 74 000 L m−2 h−1, respectively, and all the separation efficiencies are more than 99%. They have outstanding comprehensive mechanics performance, which can be controlled by simply adjusting the mass ratios. They show excellent antifouling and self-cleaning ability, endowing powerful cyclic stability and reusability. Those results show that d-MCA:MTPU composite nanofiber membranes have great application prospects in oil/water separation. 相似文献
3.
4.
雷斯 《石油化工腐蚀与防护》2006,23(5):35-37,41
文章介绍了中国石油化工股份有限公司齐鲁石化分公司胜利炼油厂第二常减压蒸馏装置的总体情况,分析总结了装置在2000-2005年期间停工闲置及开工运行过程中设备腐蚀情况和防护中所做的工作,可供相似类型、相似状态的装置借鉴。 相似文献
5.
激光熔覆Ni基SiC合金涂层组织与性能的研究 总被引:5,自引:0,他引:5
利用5kWCO2连续波激光器在16Mn钢基材表面对含20%(体积比)SiC陶瓷粉末的镍基自熔性合金粉末进行激光熔覆得到Ni基SiC合金涂层(NiSiC)。研究了合金涂层的组织形貌及相结构,并用单纯的镍基合金涂层(Ni60)进行了显微硬度及滑动磨损性能的对比试验。结果表明,NiSiC合金涂层由γ枝晶及其间的共晶组织组成,主要组成相为γ-Ni,γ-(Ni,Fe)固溶体和(Cr,Fe)7C3,Cr23C6及(Cr,Si)3Ni3Si等化合物。添加SiC的镍基合金涂层NiSiC比单纯的镍基合金涂层Ni60具有较高的硬度和耐磨性。 相似文献
6.
Abdelbaki Benamor Brahim Si Ali Mohamed Kheireddine Aroua 《Korean Journal of Chemical Engineering》2008,25(3):451-460
The absorption rates of CO2 into aqueous solutions of Diethanolamine (DEA) with varying concentrations from 0.2 to 4M and temperature range from 293
to 323 K were measured by using a laboratory stirred reactor. The CO2 partial pressure was varied in a range that the reaction would occur in pseudo first order regime. Experimental data were
analyzed and the kinetic parameters associated with the reaction were determined. The activation energy for the deprotonation
of the intermediate zwitterion was estimated at about 11.4 kcal/mol. The contribution of carbamate formation to the overall
absorbed CO2 was experimentally evaluated and found to be of the order of 100%. 相似文献
7.
8.
斯新中 《石油化工设备技术》1996,17(4):1-3
根据十万立方米浮顶油罐罐壁板应力测试的实测结果,运用应力分析程序,对罐壁板应力分布情况进行了分析和比较,通过调整罐壁板的厚度,使新设计储罐的罐壁板应力分布更加均匀、合理。 相似文献
9.
10.