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排序方式: 共有217条查询结果,搜索用时 15 毫秒
1.
中国石化海南炼油化工有限公司0.2 Mt/a C5/C6烷烃异构化装置以连续重整装置的拔头油为原料,使用NNI-1催化剂,采用一次通过流程,不设脱异戊烷塔和稳定塔,经设在连续重整装置内的脱丁烷塔稳定处理后作为汽油调合组分。该装置于2006年9月开工投产,截至2015年3月已连续运行3个周期。长周期运行分析结果表明:前两个周期中NNI-1催化剂具有较高的异构化活性及选择性,C5异构化率为60%左右,C6异构化率为80%左右,C6选择性为15%左右,产品辛烷值基本达到技术指标要求(RON≥78);而在第三周期运行中,催化剂积炭增加等原因导致其异构化活性及选择性降低,异构化产品辛烷值提升能力呈现逐步衰减的趋势,提高反应苛刻度已不能弥补催化剂活性下降造成的产品辛烷值降低。为保证装置长周期运行,建议择机停工对催化剂进行再生,或是直接换用与装置原料性质匹配的异构化催化剂。 相似文献
2.
The saturation capacity of n-alkanes in CHA, AFX and ERI zeolites, that consist of cages separated by windows, decreases with increasing carbon number. The major aim of the present communication is to demonstrate the possibility of separating n-alkane mixtures relying on differences in saturation capacities. To investigate this possibility, Configurational-Bias Monte Carlo simulations for adsorption of C3–nC6, nC4–nC6, and nC5–nC6 mixtures in CHA, AFX and ERI were carried out for equimolar bulk fluid phase. These mixture simulations show that for operation at fluid phase fugacities below about 1 MPa, the adsorbed phase in equilibrium with the bulk vapor phase is predominantly the alkane with the longer chain length, i.e. nC6. However, for operation at pressures in excess of 1 MPa, the adsorbed phase in equilibrium with the bulk liquid phase is richer in the component with the smaller chain length. In some cases, the nC6 is practically excluded from the zeolite. 相似文献
3.
N. Ilayaraja A. Manivel D. Velayutham M. Noel 《Journal of Applied Electrochemistry》2008,38(2):175-186
Electrochemical perfluorination (ECPF) of n-hexanoyl, n-heptanoyl, n-octanoyl, n-nonanoyl and n-decanoyl chlorides was carried out under identical experimental conditions in liquid HF. The product distribution among perfluorinated
carboxylic acids, perfluoro ethers, perfluoroalkanes, isomerised and fragmented products containing less number of carbon
atoms was identified using 19F NMR. The selectivity of C6–C10 perfluoro carboxylic acid varied between 29 and 36%. The alkali insoluble perfluoro cyclic ether and perfluoro alkane fractions
increased with increasing chain length. The increase of perfluoroalkane fractions is mainly due to decarboxylation. Cyclic
ether fractions also decreased slightly with increase in chain length. Among the cyclic ethers α substituted oxolanes were
the predominant products. Six membered cyclic ethers were always found to contain β substitution. The possible pathways for
these products are also indicated.
An erratum to this article can be found at 相似文献
4.
A generalized equation for surface tension from the triple point to the critical point 总被引:1,自引:0,他引:1
G. R. Somayajulu 《International Journal of Thermophysics》1988,9(4):559-566
A three-parameter generalized equation is proposed for surface tension from the triple point to the critical point. This equation not only fits the data well but also is good for interpolation between the normal boiling point and the critical point. This equation is also good for extrapolation to the triple point. This equation has been tested using the surface tension of water from the triple point to the critical point. The constants of this equation obtained using orthobaric surface tensions are given for a number of compounds. The isobaric surface tensions determined at a pressure of 1 atm do not differ significantly from the orthobaric surface tensions. Such data also have been used in obtaining equations from the triple to the critical point.Nomenclature
T
c
Critical temperature, K
-
T
t
Triple point, K
-
T
m
Melting point, K
-
T
r
Reduced temperature, K
-
X
(T
c-T)/T
c
-
Surface tension, dyne · cm–1;10–3N · m–1
-
m
Surface tension at the melting point
-
f
Surface tension at T
r=0.9
-
t
Surface tension at the triple point
- Relative deviation
100[
obsd–
calcd]/
obsd
- Standard deviation
[(
obsd–
calcd)2/(No. points—No. parameters)]0.5 相似文献
5.
The direct catalytic conversion of alkanes into aromatics has found potentially important industrial applications. Initially only alkanes with 6 and more carbon atoms in the chain were concerned. Supported platinum catalysts were found active for the aromatization of alkanes; the drawbacks of these catalysts were their deactivation with time on stream and the existence of simultaneous parallel reactions. Much discussion has been published on the aromatization of C6+ alkanes. A bifunctional mechanism which involves both the metal and the acid sites of the support and a monofunctional mechanism involving only the metallic sites operate over, respectively, Pt supported on acidic support and Pt supported on nonacidic support. In the present review the mechanisms proposed for the aromatization of alkanes are described. Over monofunctional Pt catalysts two possible mechanisms prevail: 1,6 ring closure on the Pt surface involving primary and secondary C-H bond rupture, followed by dehydrogenation of the cycloalkanes into aromatics (1,5 ring closure to a lesser extent also contributes to aromatic production); or dehydrogenation of the alkanes into olefins, dienes, and trienes followed by thermal ring closure. Zeolites were found most suitable as support for preparing catalysts more active and more selective in the alkane aromatization. In addition catalysts based on noble metals supported on zeolite appeared more resistant against deactivation by coke. In this review the aromatization of hexane, heptane, and octane over Pt-zeolite catalysts is discussed in detail. Comparisons between different zeolite structures and different dehydrogenation sites are given. In particular a critical analysis of the results and interpretation concerning Pt-KL catalysts strongly suggests that the exceptional high selectivity towards aromatization of n-hexane exhibited by Pt-KL could not be explained by only the nest or constraint effect exerted by the channel dimension and morphology, not by only the terminal cracking properties, not by only the partial electron transfer from the zeolite support to the Pt particles, and not by only the Pt particle size. Zeolite structure also affects the aromatic product distribution, in particular when the alkane contains more than 7 carbon atoms. It is shown how Pt on medium-pore zeolites such as In-ZSM-5, silicalites will favor the aromatization of C8 alkane isomers into ethylbenzene-styrene with respect to other C8 aromatics. Aromatization of light alkanes, C2-C5, requires the increase of the hydrocarbon chain length up to 6 carbon atoms and higher, followed by cyclization reaction. Recently new processes to convert C2-C5 alkanes into aromatics have been disclosed, M2-forming from Mobil, Cyclar from BP-UOP, and Aroforming from IFP-Saluted. In general these processes use bifunctional catalysts possessing a dehydrogenating and an acid function. The catalysts consist of a metal ion or metal oxide supported on a microporous acid solid. In this review we analyze the results concerning mainly platinum supported on pentasil-type zeolite. It is shown that althoug Pt has better dehydrogenating properties as compared with gallium and zinc, the efficiency of catalysts based on Pt-ZSM-5 for light alkane aromatization is less because undersirable reactions such as hydrogenolysis and ethene (olefins) hydrogenation occur on the platinum surface, resulting in the production of unreactive alkanes, CH2, C2H6. These drawbacks could be partially suppressed by alloying Pt and by increasing the reaction temperature. 相似文献
6.
Dehydrogenation of Light Alkanes Over Rhenium Catalysts on Conventional and Mesoporous MFI Supports 总被引:1,自引:0,他引:1
Anne Krogh Rovik Anke Hagen Iver Schmidt Søren Dahl Ib Chorkendorff Claus Hviid Christensen 《Catalysis Letters》2006,109(3-4):153-156
Recently, Re/HZSM-5 (Si/Al = 15) was shown to be an efficient catalyst for ethane dehydrogenation and aromatization at 823 K
and atmospheric pressure. In this reaction, the major initial products were benzene, toluene and xylene (BTX), but increasing
amounts of ethene were produced with time on stream due to deactivation of the catalyst. We show that by use of rhenium impregnated
MFI supports with very few or no acidic sites (Si/Al > 500), highly selective ethane dehydrogenation catalysts are obtained
with ethene selectivities of 98%. By use of mesoporous MFI supports (Si/Al >500) the lifetime of the catalyst appears to be
slightly improved compared to conventional MFI crystals. The beneficial effect of a mesoporous MFI support is convincingly
demonstrated in propane dehydrogenation, where both conversion and selectivities on the mesoporous MFI (Si/Al > 500) impregnated
with Re are significantly higher than on Re supported on a comparable conventional MFI support. 相似文献
7.
Dmitri V. Besedin Leila Yu. Ustynyuk Yuri A. Ustynyuk Valerij V. Lunin 《Topics in Catalysis》2005,32(1-2):47-60
The model reactions of ethylene polymerization and hydrogenolysis of linear alkanes (propane, n-butane, and n-pentane) on the silica-supported zirconium hydrides (Si–O)3ZrIVH, (Si–O)2ZrIVH2, and (Si–O)2ZrIIIH were studied using the DFT approach. Catalytic processes under study were shown to occur involving different surface hydrides. The ethylene polymerization was found to proceed at comparable rates on the zirconium monohydrides, (Si–O)3ZrH, and dihydrides, (Si–O)2ZrH2. Cleavage of linear alkanes on the monohydrides (Si–O)3ZrH is thermodynamically unfavorable; however, the dihydrides (Si–O)2ZrH2 can act as catalysts of the process under mild conditions. Hydrides of the trivalent zirconium, (Si–O)2ZrIIIH, can also contribute to the hydrogenolysis reaction. A feature of all the systems studied is low regioselectivity of the corresponding processes. 相似文献
8.
Felix Schmutzler Christopher Zschiesche Juliane Titus David Poppitz Jens Freiding Rainer Rakoczy Andreas Reitzmann Roger Gläser 《化学,工程师,技术》2021,93(6):981-989
The hydroisomerization of two long-chain n-alkane mixtures was investigated over bifunctional Pt/H-ZSM-5 catalysts before and after dealumination of preshaped zeolite/binder pellets. The hydroisomerization over the dealuminated catalysts leads to more isomers and less cracking products. Consequently, higher ratios of multi- to mono-branched isomerization products are formed as expected for large- rather than medium-pore zeolites. This indicates a higher availability of space in the vicinity of the active sites and provides an attractive route to make medium-pore zeolites suitable for upgrading higher boiling hydrocarbon feeds. 相似文献
9.
采用脉冲微型反应器和小型固定流化床催化裂解装置,研究了直馏石脑油中不同结构烃分子的裂解反应性能,考察了链烷烃与环烷烃的相互作用,以及催化材料对烃分子裂解性能的影响。结果表明:随着烷烃分子支链度的增加,C8烷烃的反应性能降低,丙烯选择性提高;链烷烃和具有烷基侧链的环烷烃是丙烯的主要来源,双环环烷烃对丙烯也有部分贡献,而芳香烃不易生成低碳烯烃;环烷烃的竞争吸附抑制了链烷烃的转化,而链烷烃在催化裂解过程中生成的碳正离子或烯烃提高了环烷烃的反应性能;与Beta分子筛相比,ZRP分子筛具有较狭窄孔道和较多的Brønsted酸中心,有利于正辛烷的质子化裂解,裂解产物中乙烯和丙烯产率高。 相似文献
10.