全文获取类型
收费全文 | 1163篇 |
免费 | 92篇 |
国内免费 | 2篇 |
专业分类
电工技术 | 16篇 |
化学工业 | 340篇 |
金属工艺 | 24篇 |
机械仪表 | 38篇 |
建筑科学 | 28篇 |
矿业工程 | 1篇 |
能源动力 | 61篇 |
轻工业 | 138篇 |
水利工程 | 8篇 |
石油天然气 | 3篇 |
无线电 | 90篇 |
一般工业技术 | 218篇 |
冶金工业 | 43篇 |
原子能技术 | 4篇 |
自动化技术 | 245篇 |
出版年
2024年 | 1篇 |
2023年 | 18篇 |
2022年 | 77篇 |
2021年 | 77篇 |
2020年 | 36篇 |
2019年 | 64篇 |
2018年 | 52篇 |
2017年 | 54篇 |
2016年 | 58篇 |
2015年 | 48篇 |
2014年 | 43篇 |
2013年 | 76篇 |
2012年 | 90篇 |
2011年 | 99篇 |
2010年 | 73篇 |
2009年 | 73篇 |
2008年 | 61篇 |
2007年 | 66篇 |
2006年 | 25篇 |
2005年 | 27篇 |
2004年 | 30篇 |
2003年 | 13篇 |
2002年 | 13篇 |
2001年 | 8篇 |
2000年 | 2篇 |
1999年 | 8篇 |
1998年 | 8篇 |
1997年 | 4篇 |
1996年 | 9篇 |
1995年 | 3篇 |
1994年 | 4篇 |
1993年 | 3篇 |
1992年 | 5篇 |
1991年 | 3篇 |
1990年 | 2篇 |
1989年 | 1篇 |
1988年 | 3篇 |
1987年 | 4篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 3篇 |
1982年 | 3篇 |
1981年 | 3篇 |
1979年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1972年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有1257条查询结果,搜索用时 14 毫秒
1.
Leonardo Setti Pier Giorgio Pifferi Gaetano Lanzarini 《Journal of chemical technology and biotechnology (Oxford, Oxfordshire : 1986)》1995,64(1):41-48
A new mathematical model for n-alkane biodegradation in crude oil, heavy oil and paraffinic mixtures is described. The pattern of n-alkane degradation as a function of the inverse of hydrocarbon chain length reported in this paper can be considered as general behaviour for many aerobic n-alkane biodegradation processes. A new interpretation of n-alkane biodegradation as a function of surface tension, is given. A mathematical expression was obtained starting from the degradation values of n-alkane and relative surface tension, which is a parameter independent of fermentation conditions. An interesting parameter, b, was identified which represented the accelerating conversion factor for n-alkane biodegradation. The findings suggested that the n-alkane biodegradation. The findings suggested that he n-alkane biodegradation rate may be affected by the fermentation condition (agitation, aeration, etc.) and by the strain of microorganism, while the behaviour pattern of n-alkane degradation was essentially linked to the substrate characteristics (molecular structure, molecular weight and density). 相似文献
2.
[1-14C]Heptane was aromatized under 5 atm pressure over a “nonacidic” 3% platinum on alumina catalyst maintained at 500 °C. The reactant was pumped in at a HLSV of 0.88, and the hydrogen-to-heptane mole ratio was 5.1. The samples of product were collected (one during the first 90 min and another during the next 90 min), the toluene was separated from the respective samples, and the radioactivity in each position of the toluene was determined by a degradation sequence. The distribution of radioactivity in sample 1 was as follows: in position 1–2.6%, 2–38.6%; 3–14.5%; 4–4.2%, and in the methyl group—40.1%. Approximately similar distribution of radioactivity was found in sample 2. 1,6-Ring closure is the most important pathway leading to the formation of toluene from [1-14C]heptane; lesser amounts of repetitive, 1,5-ring closure and hydrogenolysis, and bond shift reactions followed by 1,6-ring closure and dehydration can explain the distribution of radioactivity. The participation of 1,7-ring closure in the reaction is also indicated. 相似文献
3.
Finkbeiner Bernd Mariani Leonardo 《International Journal on Software Tools for Technology Transfer (STTT)》2021,23(4):545-546
International Journal on Software Tools for Technology Transfer - 相似文献
4.
Aniello Leonardo Halak Basel Chai Peter Dhall Riddhi Mihalea Mircea Wilczynski Adrian 《International Journal of Information Security》2021,20(3):445-460
International Journal of Information Security - The complexity of today’s integrated circuit (IC) supply chain, organised in several tiers and including many companies located in different... 相似文献
5.
Pardo Diego Fichera Loris Caldwell Darwin Mattos Leonardo S. 《Neural Processing Letters》2015,41(1):55-69
Neural Processing Letters - This paper presents an approach to determine a model of superficial tissue temperature dynamics during continuous wave CO $$_2$$ laser irradiation. The main contribution... 相似文献
6.
Rosamaria W.C. Leonardo Jonas Yoshio Lilian R.F. 《Sensors and actuators. B, Chemical》2008,131(2):646-651
A novel poly(p-xylylene), PPX, derivative bearing alkoxyphenyl side groups was electrochemically synthesized in 87% yield. The polymer, poly(4′-hexyloxy-2,5-biphenyleneethylene) (PHBPE), presented a fraction (92%) soluble in common organic solvents. It showed to be thermally resistant up to 185 °C. UV–vis analysis revealed an Egap of 3.5 eV. Gas sensors made from thin films of 10-camphorsulfonic acid-doped PHBPE deposited on interdigitated electrodes exhibited significant changes in electrical conductance upon exposure to five VHOCs: 1,2-dichloroethane, bromochloromethane, trichloromethane, dichloromethane and tetrachloromethane. The conductance decreased after exposure to tetrachloromethane and increased after exposure to all the other VHOCs. Three-dimensional plots of relative response versus time of half response versus time of half recovery showed good discrimination between the five VHOCs tested. 相似文献
7.
Leonardo?F.?Peiretti Nuria?Navascués Inés?S.?TiscorniaEmail author Eduardo?E.?Miró 《Journal of Materials Science》2016,51(8):3989-4001
CeO2 and Co3O4–CeO2 nanoparticles were synthesized, thoroughly characterized, and evaluated in the COPrOx reaction. The CeO2 nanoparticles were synthesized by the diffusion-controlled precipitation method with ethylene glycol. A notably higher yield was obtained when H2O2 was used in the synthesis procedure. For comparison, two commercial samples of CeO2 nanoparticles (Nyacol®)—one calcined and the other sintered—were also studied. Catalytic results of bare CeO2 calcined at 500 °C showed a strong influence of the method of synthesis. Despite having similar BET area values, the CeO2 synthesized without H2O2 was the most active sample. Co3O4–CeO2 catalysts with three different Co/(Co + Ce) atomic ratios, 0.1, 0.3, and 0.5, were prepared by the wet impregnation of the CeO2 nanoparticles. TEM and STEM observations showed that impregnation produced mixed oxides composed of small CeO2 nanoparticles located both over the surface and inside the Co3O4 crystals. The mixed oxide catalysts prepared with a cobalt atomic ratio of 0.5 showed methane formation, which started at 200 °C due to the reaction between CO2 and H2. However, above 250 °C, the reaction between CO and H2 became important, thus contributing to CO elimination with a small H2 loss. As a result, CO could be totally eliminated in a wide temperature range, from 200 to 400 °C. The methanation reaction was favored by the reduction of the cobalt oxide, as suggested by the TPR experiments. This result is probably originated in Ce–Co interactions, related to the method of synthesis and the surface area of the mixed oxides obtained. 相似文献
8.
Insight into In Situ Amphiphilic Functionalization of Few‐Layered Transition Metal Dichalcogenide Nanosheets 下载免费PDF全文
9.
10.