全文获取类型
收费全文 | 28722篇 |
免费 | 1386篇 |
国内免费 | 698篇 |
专业分类
电工技术 | 980篇 |
综合类 | 1166篇 |
化学工业 | 5204篇 |
金属工艺 | 1698篇 |
机械仪表 | 1289篇 |
建筑科学 | 1324篇 |
矿业工程 | 570篇 |
能源动力 | 526篇 |
轻工业 | 1656篇 |
水利工程 | 627篇 |
石油天然气 | 1865篇 |
武器工业 | 131篇 |
无线电 | 2046篇 |
一般工业技术 | 5799篇 |
冶金工业 | 2574篇 |
原子能技术 | 1001篇 |
自动化技术 | 2350篇 |
出版年
2022年 | 444篇 |
2021年 | 703篇 |
2020年 | 586篇 |
2019年 | 560篇 |
2018年 | 697篇 |
2017年 | 743篇 |
2016年 | 758篇 |
2015年 | 820篇 |
2014年 | 988篇 |
2013年 | 1319篇 |
2012年 | 1274篇 |
2011年 | 1330篇 |
2010年 | 1145篇 |
2009年 | 1146篇 |
2008年 | 1050篇 |
2007年 | 1091篇 |
2006年 | 957篇 |
2005年 | 786篇 |
2004年 | 707篇 |
2003年 | 718篇 |
2002年 | 877篇 |
2001年 | 767篇 |
2000年 | 536篇 |
1999年 | 432篇 |
1998年 | 342篇 |
1997年 | 306篇 |
1996年 | 295篇 |
1995年 | 245篇 |
1989年 | 277篇 |
1988年 | 249篇 |
1986年 | 260篇 |
1985年 | 268篇 |
1984年 | 286篇 |
1983年 | 273篇 |
1982年 | 258篇 |
1981年 | 255篇 |
1980年 | 258篇 |
1979年 | 282篇 |
1978年 | 360篇 |
1977年 | 334篇 |
1976年 | 348篇 |
1975年 | 330篇 |
1974年 | 394篇 |
1973年 | 372篇 |
1972年 | 357篇 |
1971年 | 329篇 |
1970年 | 280篇 |
1969年 | 277篇 |
1968年 | 267篇 |
1967年 | 249篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
21.
The low energy density of supercapacitors, especially supercapacitors based on aqueous electrolytes, is the main factor limiting their application, and the energy density is closely related to the operating potential window of the supercapacitor. The polymer electrolyte is the main contributor to the safe operation and good ion conductivity of the supercapacitor. In this study, a crosslinked quaternized poly(arylene ether sulfone) (PAES) membrane was prepared via crosslinking during membrane formation with a thermal-only treatment and applied in an electric double-layer capacitor (EDLC). The pre-prepared PAES membrane formed a polymer electrolyte with 1 mol/L Li2SO4 and was then fabricated into an EDLC single cell. The properties of both the membrane and ELDC were investigated. The preferred cPAES-N-0.2 polymer electrolyte showed an ionic conductivity of 1.18 mS/cm. The optimized EDLC exhibited a single-electrode gravimetric capacitance of 104.92 F/g at a current density of 1.0 A/g and a high operating potential window (1.5 V); it, thereby, achieved a high energy density of 8.20 W h/kg. The EDLC also exhibited excellent cycling properties over 3000 charge–discharge cycles. The crosslinked structures promoted the tensile strength and thermal stability of the PAES membranes; this was accompanied by a slight decrease in the ionic conductivity. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47759. 相似文献
22.
Xiangrong Ma Rui Dang Ning Yang Xiao Li Ya zhang Ying Gong Zhipan Liu Wei Guo Yuanyuan Zhang Chunyan Li 《International Journal of Hydrogen Energy》2021,46(44):22842-22851
The high cost of noble metal catalysts has been a great bottleneck for the catalyst industry. Using the noble metal at a single-atom level for catalytic applications could dramatically decrease the cost. The impacts of single Pt atoms on the photocatalytic performance of Ag3VO4 have been investigated and reported. In this report, single Pt atoms were anchored on the surface of Ag3VO4 (AVO) as a cocatalyst, and the resultant composite photocatalyst has been studied for photocatalytic H2 production from water driven by visible light. The as-prepared AVO particles are hollow nanospheres in the monoclinic phase with a bandgap of 2.20 eV. The light absorption edge of AVO/Pt is slightly red-shifted compared to that of the pristine AVO, indicating more visible light absorption of AVO/Pt. The XPS peaks of Ag, V, and Pt exhibit a significant shift after AVO and Pt get into contact, suggesting the strong interaction between the surface Ag and V atoms, and single Pt atoms. After 3-h illumination, the photocatalytic H2 evolution amount from AVO/Pt is improved up to 1400 μmol, which is 2.8 times that on the bare AVO. Such efficient photocatalytic H2 evolution on AVO/Pt is still maintained after five reaction cycles. The better photocatalytic performance of AVO/Pt has been attributed to the more efficient visible light utilization and the lower interfacial charge transfer resistance, as demonstrated in the DRS and EIS spectra. The presence of the surface Pt atoms also leads to a higher amount of reactive radicals, which could efficiently promote the surface redox reactions. 相似文献
23.
A. Yu. Pustynnikov V. G. Ryabov D. T. Kalimullin A. N. Nechaev Ya. A. Treskov 《Chemistry and Technology of Fuels and Oils》2006,42(3):188-191
Paving-and roofing-grade asphalts were obtained at LUKOIL-Permnefteorgsintez Ltd. by mixing peroxidized asphalt and a number
of high-boiling unoxidized petroleum products in certain ratios. The asphalts obtained have improved performance characteristics:
high plasticity and low brittleness temperature.
__________
Translated from Khimiya i Tekhnologiya Topliv i Masel, No. 2, pp. 26–28, May–June, 2006. 相似文献
24.
中国石化北京燕山分公司(简称燕山分公司)为增产高附加值产品、提升效益,对炼油系统进行了流程协同优化。中压加氢裂化装置掺炼催化裂化柴油,由加氢裂化方案改为加氢改质方案运行,将改质柴油送入三号催化裂化装置(简称三催化装置)的提升管进行回炼;同时,将焦化蜡油改入加氢裂化装置进行加工,而蜡油加氢装置不再加工焦化蜡油以改善催化裂化原料。协同优化后,中压加氢改质装置的柴油产品十六烷值提高7个单位;三催化装置的液化气收率提高1.96百分点,汽油收率增加0.88百分点,总液体收率增加2.28百分点;高压加氢裂化装置喷气燃料产品的密度(20 ℃)降低至806 kg/m3,烟点为23.8 mm,尾油BMCI由11.8降低至10.8;蜡油加氢装置精制蜡油的饱和分质量分数提高4.68百分点,芳香分质量分数降低5.96百分点,氮质量分数降低0.06百分点,使催化裂化原料性质得以改善。通过将中压加氢改质装置的喷气燃料馏分抽出送催化裂化装置回炼,与回炼改质柴油相比,催化裂化汽油的研究法辛烷值(RON)增加1.0个单位,改质柴油十六烷值提高4.8个单位。通过全炼油板块系统性优化,燕山分公司车用柴油产品的十六烷值由53.5降低至51.5,解决了质量过剩问题。 相似文献
25.
26.
27.
28.
Yu. V. Baldokhin V. V. Vavilova P. Ya. Kolotyrkin Yu. K. Kovneristyi N. A. Palii A. S. Solomatin 《Inorganic Materials》2003,39(6):562-567
Mössbauer effect measurements and physicochemical analysis demonstrate that annealing of amorphous Fe–P–Mn alloys leads to the formation of a nanocrystalline structure. 相似文献
29.
用CMOS工艺实现非接触IC卡天线的集成化设计 总被引:2,自引:0,他引:2
论述了用CMOS工艺实现非接触式IC卡天线的集成化需要考虑的各个方面,建立了集成天线的模型,给出了合理的设计方案,并通过实验验证了模型和设计方案.实验结果表明,采用片上天线完全可以提供非接触式IC卡工作所需要的能量.在频率为2 2 .5 MHz、感应强度为6×10 - 4 T的磁场中,面积为2 m m×2 mm的集成天线可以为10 kΩ的负载提供1.2 2 5 m W的能量. 相似文献
30.
R. K. Melekhov A. V. Vasylyk E. I. Palashchuk H. M. Krutsan Ya. D. Onyshchak 《Materials Science》2004,40(5):668-675
We study the process of degradation and damage for superheater tubes of the pressure boilers of power plants made of austenitic chromium-nickel steel. The role of sensitization and partial sigmatization of austenitic steel in the embrittlement of the tubes is analyzed.__________Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 4, pp. 81–86, July–August, 2004. 相似文献