全文获取类型
收费全文 | 324378篇 |
免费 | 3340篇 |
国内免费 | 1275篇 |
专业分类
电工技术 | 5956篇 |
综合类 | 260篇 |
化学工业 | 46564篇 |
金属工艺 | 18426篇 |
机械仪表 | 13119篇 |
建筑科学 | 6379篇 |
矿业工程 | 3136篇 |
能源动力 | 6748篇 |
轻工业 | 19217篇 |
水利工程 | 4509篇 |
石油天然气 | 10132篇 |
武器工业 | 61篇 |
无线电 | 32928篇 |
一般工业技术 | 73559篇 |
冶金工业 | 49435篇 |
原子能技术 | 9507篇 |
自动化技术 | 29057篇 |
出版年
2021年 | 2656篇 |
2019年 | 2602篇 |
2018年 | 11455篇 |
2017年 | 11902篇 |
2016年 | 9227篇 |
2015年 | 3403篇 |
2014年 | 5094篇 |
2013年 | 11784篇 |
2012年 | 9617篇 |
2011年 | 16199篇 |
2010年 | 14225篇 |
2009年 | 14007篇 |
2008年 | 14168篇 |
2007年 | 15643篇 |
2006年 | 7414篇 |
2005年 | 9407篇 |
2004年 | 7801篇 |
2003年 | 7486篇 |
2002年 | 6296篇 |
2001年 | 5685篇 |
2000年 | 5418篇 |
1999年 | 5337篇 |
1998年 | 13217篇 |
1997年 | 9228篇 |
1996年 | 7011篇 |
1995年 | 5491篇 |
1994年 | 4802篇 |
1993年 | 5039篇 |
1992年 | 3805篇 |
1991年 | 3880篇 |
1990年 | 3781篇 |
1989年 | 3688篇 |
1988年 | 3619篇 |
1987年 | 3181篇 |
1986年 | 3256篇 |
1985年 | 3579篇 |
1984年 | 3310篇 |
1983年 | 3163篇 |
1982年 | 2841篇 |
1981年 | 2816篇 |
1980年 | 2866篇 |
1979年 | 2883篇 |
1978年 | 2882篇 |
1977年 | 3136篇 |
1976年 | 3711篇 |
1975年 | 2652篇 |
1974年 | 2513篇 |
1973年 | 2609篇 |
1972年 | 2327篇 |
1971年 | 2118篇 |
排序方式: 共有10000条查询结果,搜索用时 78 毫秒
101.
Chao Peng Tian Zhang Deliris N Ortiz‐Ortiz Apoorva Vishwakarma Hazel A Barton Abraham Joy 《Polymer International》2019,68(7):1255-1262
Each year, thousands of patients die from antimicrobial‐resistant bacterial infections that fail to respond to conventional antibiotic treatment. Antimicrobial polymers are a promising new method of combating antibiotic‐resistant bacterial infections. We have previously reported the synthesis of a series of narrow‐spectrum peptidomimetic antimicrobial polyurethanes that are effective against Gram‐negative bacteria, such as Escherichia coli; however, these polymers are not effective against Gram‐positive bacteria, such as Staphylococcus aureus. With the aim of understanding the correlation between chemical structure and antibacterial activity, we have subsequently developed three structural variants of these antimicrobial polyurethanes using post‐polymerization modification with decanoic acid and oleic acid. Our results show that such modifications converted the narrow‐spectrum antibacterial activity of these polymers into broad‐spectrum activity against Gram‐positive species such as S. aureus, however, also increasing their toxicity to mammalian cells. Mechanistic studies of bacterial membrane disruption illustrate the differences in antibacterial action between the various polymers. The results demonstrate the challenge of balancing antimicrobial activity and mammalian cell compatibility in the design of antimicrobial polymer compositions. © 2019 Society of Chemical Industry 相似文献
102.
Sleptsov V. V. Kukushkin D. Yu. Kulikov S. N. Diteleva A. O. Tsyrkov R. A. 《Russian Engineering Research》2021,41(12):1175-1178
Russian Engineering Research - Theoretical principles are outlined for the use of thin-film technology in producing electrode materials for hybrid capacitors. The materials are based on a carbon... 相似文献
103.
Dobrydnev S. V. Alexandrova O. A. Rezvov Yu. G. 《Theoretical Foundations of Chemical Engineering》2022,56(3):362-366
Theoretical Foundations of Chemical Engineering - The reaction of nickel(II) hydroxide and a mixed ammonia–carbonate solution to form nickel(II) aqua–ammonia complexes is studied in the... 相似文献
104.
Zinov’eva I. V. Fedorov A. Ya. Milevskii N. A. Zakhodyaeva Yu. A. Voshkin A. A. 《Theoretical Foundations of Chemical Engineering》2021,55(4):663-670
Theoretical Foundations of Chemical Engineering - A choline chloride–sulfosalicylic acid deep eutectic solvent (DES) is proposed for dissolving the oxides Co(II), Cu(II), Zn(II), Fe(III),... 相似文献
105.
Dolmatov O. Yu. Kuznetsov M. S. Semenov A. O. Shamanin I. V. Verkhoturova V. V. 《Atomic Energy》2021,130(1):1-5
Atomic Energy - An implementation assessment of PSKD-600 type power reactors was made. It was established that the readiness level of all PSKD-600 nuclear fuel cycle technologies is no lower than... 相似文献
106.
Volkovich A. G. Kolyadin V. I. Lemus A. V. Pavlenko V. I. Potapov V. N. Semenov S. G. Simirskii Yu. N. Chesnokov A. V. Shisha A. D. 《Atomic Energy》2021,129(6):349-355
Atomic Energy - The results of the dismantling of the active drain system and the decontamination of technological enclosures of the loop installations of the MR reactor, which is being... 相似文献
107.
Andrew N. Kuhn Haidong Zhao Uzoma O. Nwabara Xiaofei Lu Mingyan Liu Yung-Tin Pan Wenjin Zhu Paul J. A. Kenis Hong Yang 《Advanced functional materials》2021,31(26):2101668
Copper catalysts are widely studied for the electroreduction of carbon dioxide (CO2) to value-added hydrocarbon products. Controlling the surface composition of copper nanomaterials may provide the electronic and structural properties necessary for carbon-carbon coupling, thus increasing the Faradaic efficiency (FE) towards ethylene and other multi-carbon (C2+) products. Synthesis and catalytic study of silver-coated copper nanoparticles (Cu@Ag NPs) for the reduction of CO2 are presented. Bimetallic CuAg NPs are typically difficult to produce due to the bulk immiscibility between these two metals. Slow injection of the silver precursor, concentrations of organic capping agents, and gas environment proved critical to control the size and metal distribution of the Cu@Ag NPs. The optimized Cu@Ag electrocatalyst exhibited a very low onset cell potential of −2.25 V for ethylene formation, reaching a FE towards C2+ products (FEC2+) of 43% at −2.50 V, which is 1.0 V lower than a reference Cu catalyst to reach a similar FEC2+. The high ethylene formation at low potentials is attributed to enhanced C C coupling on the Ag enriched shell of the Cu@Ag electrocatalysts. This study offers a new catalyst design towards increasing the efficiency for the electroreduction of CO2 to value-added chemicals. 相似文献
108.
R.N. Maksimov V.A. Shitov V.V. Platonov A.S. Yurovskikh G. Toci B. Patrizi M. Vannini A. Pirri 《Ceramics International》2021,47(4):5168-5176
Yb3+-doped Lu2O3 nanoparticles produced by laser ablation were used to fabricate transparent ceramics by a combination of pressureless sintering in vacuum (PS) followed by a hot isostatic pressing (HIPing). The samples were subjected to various PS and HIPing conditions and the microstructure evolution and its correlation with the transmittance were investigated. Relative densities of over 97% were achieved after PS at the temperatures of 1250–1700 °C. Rapid grain growth occurred within PS and HIPing temperatures above 1500 °C leading to formation of intragranular porosity which is deleterious for optical quality. Higher transmittance (81.7% at λ = 1080 nm) and ultrafine microstructure with an average grain size of 0.35 μm were obtained by PS at 1250 °C followed by HIPing at 1400 °C for 5 h under 207 MPa. Output power of 2.02 W with a slope efficiency of 46.5% was obtained under a quasi-continuous wave end pumping at 929.4 nm. 相似文献
109.
Chertkov Yu. B. Anikin M. N. Lebedev I. I. Naimushin A. G. Smol’nikov N. V. 《Atomic Energy》2021,131(1):42-45
Atomic Energy - The results of calculations and experimental determination of the neutronics characteristics of the IRT-T research reactor are presented. The IRT-T reactor is a pool reactor with... 相似文献
110.
Val’kov A. V. Igumnov S. N. Ovchinnikov K. V. 《Theoretical Foundations of Chemical Engineering》2021,55(4):821-828
Theoretical Foundations of Chemical Engineering - The features of distribution are studied and a complex technology for the separation of samarium, europium, and gadolinium is proposed. This... 相似文献