全文获取类型
收费全文 | 374篇 |
免费 | 1篇 |
国内免费 | 1篇 |
专业分类
综合类 | 5篇 |
化学工业 | 233篇 |
金属工艺 | 3篇 |
机械仪表 | 5篇 |
建筑科学 | 3篇 |
能源动力 | 68篇 |
轻工业 | 1篇 |
石油天然气 | 14篇 |
一般工业技术 | 42篇 |
冶金工业 | 1篇 |
自动化技术 | 1篇 |
出版年
2023年 | 3篇 |
2022年 | 8篇 |
2021年 | 4篇 |
2020年 | 11篇 |
2019年 | 4篇 |
2018年 | 1篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 6篇 |
2014年 | 12篇 |
2013年 | 12篇 |
2012年 | 6篇 |
2011年 | 24篇 |
2010年 | 25篇 |
2009年 | 43篇 |
2008年 | 21篇 |
2007年 | 26篇 |
2006年 | 18篇 |
2005年 | 25篇 |
2004年 | 11篇 |
2003年 | 20篇 |
2002年 | 13篇 |
2001年 | 10篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 8篇 |
1997年 | 1篇 |
1996年 | 17篇 |
1995年 | 1篇 |
1994年 | 6篇 |
1993年 | 2篇 |
1992年 | 1篇 |
1991年 | 3篇 |
1984年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有376条查询结果,搜索用时 15 毫秒
1.
《International Journal of Hydrogen Energy》2022,47(45):19916-19934
In the present study, non-premixed combustion and NOx emission of H2, NH3, C3H8, and CH4 fuels have been studied in a combustion test unit under lean mixture conditions (λ = 4) at 8.6 kW thermal capacity. Furthermore, the combustion and NOx emission of the H2, C3H8, and CH4 fuels have been investigated for various NH3 enrichment ratios (5, 10, 20, and 50%) and excess air coefficients (λ = 1.1, 2, 3, and 4) at the same thermal capacity. The obtained results have been compared for each fuel. Numerical simulation results show that H2 emits intense energy through the reaction zone despite the lowest fuel consumption in mass, among others, due to its high calorific value. Therefore, it has a higher flame temperature than others. At the same time, C3H8 has the lowest flame temperature. Besides, NH3 has the shortest flame length among others, while C3H8 has the most extended flame form. The highest level of NOx is released from the NH3 flame in the combustion chamber, while the lowest NOx is released from the CH4. However, the lowest NOx emission at the combustion chamber exit is obtained in NH3 combustion, while the highest NOx emission is obtained with H2 combustion. It results from the shortest flame length of NH3, short residence time, and backward NOx reduction to N2 for NH3. As for H2, high flame temperature and relatively long flame, and high residence time of the products trigger NOx formation and keep the NOx level high. On the other hand, excess air coefficient from 1.1 to 2 increases NOx for H2, CH4, and NH3 due to their large flame diameters, unlike propane. Then, NOx emission levels decrease sharply as the excess air coefficient increases to 4 for each fuel. NH3 fuel also emits minimum NOx in other excess air coefficients at the exit, while H2 emits too much emission. With NH3 enrichment, the NOx emissions of H2, CH4, and C3H8 fuels at the combustion chamber exit decrease gradually almost every excess air coefficient apart from λ = 1.1. As a general conclusion, like renewable fuels, H2 appears to be a source of pollution in terms of NOx emissions in combustion applications. In contrast, NH3 appears to be a relatively modest fuel with a low NOx level. In addition, the high amount of NOx emission released from H2 and other fuels during the combustion can be remarkably reduced by NH3 enrichment with an excess air combustion. 相似文献
2.
Marcia Cristina Kaezer Fran a Rosane Aguiar da Silva San Gil Jean-Guillaume Eon 《Catalysis Today》2003,78(1-4):105-115
γ-Al2O3 supported vanadium oxides were modified by tungsten and molybdenum oxides in order to improve dispersion and selectivity towards olefins in propane oxidative dehydrogenation (ODH). Both vanadium–tungsten and vanadium–molybdenum catalysts were obtained by adsorption of mixed isopolyanions (VW5O195−, V2W4O194−, VMo5O195− and V2Mo4O194−) from aqueous solutions. The isopolyanion solutions were characterized by UV-Vis and 51V NMR spectroscopy. Vanadium, vanadium–tungsten and vanadium–molybdenum precursors and catalysts were also characterized by UV-Vis (diffuse reflectance) and solid state 51V NMR spectroscopy. An improved selectivity to propene in the presence of tungsten and molybdenum in VOx/γ-Al2O3 was observed and attributed to dilution of vanadium by tungsten or molybdenum oxides on the γ-Al2O3 surface. 相似文献
3.
The role of Nb2O5 and γ-Al2O3 oxide supports on the ammoxidation of propane on supported mixed Sb–V oxide at different Sb+V surface coverages is studied. Sb and V oxide species on alumina and on niobia support show different structural features that reflect in different performance during the ammoxidation of propane to acrylonitrile. Niobia-supported catalysts are much more selective to acrylonitrile than alumina-supported ones. Alumina interacts weakly with the supported oxides while niobia forms new phases through solid state reactions with the supported oxides during catalytic operation that must account for its higher selectivity values towards acrylonitrile and higher specific rate of acrylonitrile formation per vanadium site. 相似文献
4.
Burcu Selen alayan Ahmet K. Avc Z. lsen
nsan A. Erhan Aksoylu 《Applied Catalysis A: General》2005,280(2):181-188
Indirect partial oxidation (IPOX) of propane was studied over bimetallic 0.2 wt.% Pt–15 wt.% Ni/δ-Al2O3 catalyst in the 623–743 K temperature range. The unreduced and reduced forms of the catalyst were characterized by ESEM–EDAX and X-ray diffraction (XRD). In the IPOX tests, the effects of steam to carbon ratio (S/C), carbon to oxygen ratio (C/O2) and residence time (W/F (gcat h/mol HC)) on the hydrogen production activity, selectivity and product distribution were studied in detail. The effect of temperature program applied (increasing from 623 to 743 K, ITP; decreasing from 743 to 623 K, DTP) during reaction was also tested. The results showed that the Pt–Ni bimetallic system has superior performance characteristics compared to the monometallic catalysts reported in literature. The reason is thought to be the utilization of the catalyst particles as micro heat exchangers during IPOX; the heat generated by Pt sites during exothermic total oxidation (TOX) being readily transferred through the catalyst particles acting as micro heat exchangers to the Ni sites, which promote endothermic steam reforming (SR). The optimal conditions were found as S/C = 3, C/O2 = 2.70 and W/F = 0.51 gcat h/mol HC for IPOX of propane on the basis of high hydrogen productivity and selectivity between 623 and 748 K for the experimental conditions tested. The thermo-neutral points obtained showed the sustainability of reaction in terms of energy. 相似文献
5.
Selective catalytic reduction of nitric oxide by propane over vanadia-titania aerogels 总被引:1,自引:0,他引:1
An investigation has been carried out of the effect of vanadia loading on the activity and selectivity ofV2O5TiO2 aerogel catalysts, prepared by a two-step procedure, for the reduction of NO by propane. The structure of catalysts have been characterized by laser Raman spectroscopy and XRD measurements. At vanadia loading levels below ca. 4.4 wt%, the vanadia is present in the form of coordinated polymeric species, whereas crystallites of V2O5 are formed at higher vanadia contents. At this critical level of 4.4 wt% V2O5, the kinetic measurements showed also a maximum in the activity per mass of catalyst which very likely indicated that the coordinated polymeric surface species are more active than crystalline V2O5. The selectivity towards the formation of dinitrogen decreased as the loading increased, presumably because of the formation of larger polymeric species and V2O5 crystallites, below and above the critical loading level, respectively. For the reduction of NO by propane, titania supported vanadia aerogel catalysts are significantly more active, per mass of catalyst, and more selective towards N2 formation than conventionalV2O5TiO2 and V2O5Al2O3 aerogel catalysts, at vanadia loading levels below ca. 11 wt%. 相似文献
6.
Tony Maillet Jacques Barbier Jr. Daniel Duprez 《Applied catalysis. B, Environmental》1996,9(1-4):251-266
A 1% Pd catalyst (38% dispersion) was prepared by impregnating a γ-alumina with palladium acetylacetonate dissolved in acetone. The behaviour of this catalyst in oxidation and steam reforming (SR) of propane was investigated. Temperature-programmed reactions of C3H8 with O2 or with O2 + H2O were carried out with different stoichiometric ratios S(S =[O2]/5[C3H8]). The conversion profiles of C3H8 for the reaction carried out in substoichiometry of O2 (S < 1) showed two discrete domains of conversion: oxidation at temperatures below 350°C and SR at temperatures above 350°C. The presence of steam in the inlet gases is not necessary for SR to occur: there is sufficient water produced in the oxidation to form H2 and carbon oxides by this reaction. Contrary to what was observed with Pt, an apparent deactivation between 310 and 385°C could be observed with Pd in oxidation. This is due to a reduction of PdOx into Pd0, which is much less active than the oxide in propane oxidation. Steam added to the reactants inhibits oxidation while it prevents the reduction of PdOx into Pd0. Compared to Pt and to Rh, Pd has a higher thermal resistance: no deactivation occurred after treatment up to 700°C and limited deactivation after treatment up to 900°C, provided that the catalyst is maintained in an oxygen-rich atmosphere during the cooling. 相似文献
7.
掺炼糠醛抽出油生产高质量沥青 总被引:3,自引:0,他引:3
掺炼糠醛抽出油,改变了丙烷脱沥青装置原料性质,通过调整部分操作参数,可提高轻脱油和重脱油的收率,改善脱油沥青质量,直接生产出合格的高标号道路沥青。 相似文献
8.
Mitsuhiro Fukuta Tadashi Yanagisawa Hiroaki Iwata Kazutaka Tada 《International Journal of Refrigeration》2002,25(7)
This paper discusses the feasibility of a vapor compression/absorption hybrid refrigeration cycle for energy saving and utilization of waste heat. The cycle employs propane as a natural refrigerant and a refrigeration oil as an absorbent. A prototype of the cycle is constructed, in which a compressor and an absorption unit are combined in series. The performance of the cycle is examined both theoretically and experimentally. Although the solubility of the propane with the oil is not enough as a working pair in the absorption unit, the theoretical calculation shows that the hybrid cycle has a potential to achieve a higher performance in comparison with a simple vapor compression cycle by using the waste heat. In the experiment, the prototype cycle is operated successfully and it is found that an improvement of an absorber is necessary to achieve the good performance close to the theoretical one. The application of an AHE (absorber heat exchanger) can reduce the heat input to a generator. Further examinations on some other combinations of refrigerant/refrigeration oil and additives are desirable. 相似文献
9.
The activation of propane using zeolite H-Y and Ga3+ exchanged zeolite Y indicates that in the presence of Ga3+ the mechanism of propane activation is changed from a cracking pathway to a dehydrogenation pathway. The presence of both Ga3+ and H+ are required to achieve this effect. 相似文献
10.
L. Savary J. Saussey G. Costentin M. M. Bettahar M. Gubelmann-Bonneau J. C. Lavalley 《Catalysis Today》1996,32(1-4):57-61
A VPO/TiO2 catalyst tested in the oxydehydrogenation reaction (ODH) of propane between 300 and 400°C shows satisfactory performances (up to 80% of propene selectivity at 2% of propane conversion at 300°C or 56% of propene selectivity at 9% of propane conversion at 400°C). Addition of water or pyridine in the feed gas tends to decrease the propane conversion and enhances the propene selectivity. It is shown that water increases the number of Brönsted surface acid sites by dissociative adsorption which, in turn, enhances propene selectivity at the expense of the COx selectivity. These results are in good agreement with spectroscopic IR observations performed under catalytic conditions showing that the Lewis acid sites are linked to COxformation, whereas it seems that Brönsted sites would rather be linked to propene formation. 相似文献