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1.
The effects of oxidation/reduction regeneration treatments, with and without 1,2-dichloropropane present as a chlorinating agent, on the structure of Pt(3%)–Sn(4.5%)/Al2O3 catalysts have been correlated with selectivities for butane/H2 reactions. Particles of Pt0 fin Cl-free catalysts were partly covered by Sn0, but retained exposed ensembles of Pt atoms which were active for isomerisation, hydrogenolysis and dehydrogenation reactions, the latter becoming dominant at high reaction temperatures. Coking reduced Pt ensemble size and, hence, also favoured high selectivities for dehydrogenation as hydrogenolysis and isomerisation sites became poisoned. In contrast, the addition of 1,2-dichloropropane in an oxychlorination step before reduction promoted 1:1 Pt0–Sn0 alloy formation after reduction, the proportion of the total Pt in alloy being enhanced by increasing 1,2-dichloropropane concentration and oxychlorination temperature. The alloy surfaces were inactive for isomerisation and hydrogenolysis reactions, giving dehydrogenation as the sole catalytic reaction. 相似文献
2.
FTIR spectra are reported of CO2 and CO2/H2 on a silica-supported caesium-doped copper catalyst. Adsorption of CO2 on a “caesium”/silica surface resulted in the formation of CO2
− and complexed CO species. Exposure of CO2 to a caesium-doped reduced copper catalyst produced not only these species but also two forms of adsorbed carboxylate giving
bands at 1550, 1510, 1365 and 1345 cm−1. Reaction of carboxylate species with hydrogen at 388 K gave formate species on copper and caesium oxide in addition to methoxy
groups associated with caesium oxide. Methoxy species were not detected on undoped copper catalyst suggesting that caesium
may be a promoter for the methanol synthesis reaction. Methanol decomposition on a caesium-doped copper catalyst produced
a small number of formate species on copper and caesium oxide. Methoxy groups on caesium oxide decomposed to CO and H2, and subsequent reaction between CO and adsorbed oxygen resulted in carboxylate formation. Methoxy species located at interfacial
sites appeared to exhibit unusual adsorption properties. 相似文献
3.
G.J. Hutchings R. Wells S. Feast M.R.H. Siddiqui D.J. Willock F. King C.H. Rochester D. Bethell P.C.B. Page 《Catalysis Letters》1997,46(3-4):249-254
Modification of zeolite H-Y by dithiane oxides (2-R-1,3-dithiane 1-oxide, R = H, CH3, C6H5) is shown to enhance significantly its activity for the acid-catalysed gas phase dehydration of butan-2-ol. The rate enhancement
is observed for catalysts that are prepared using two commercial samples of zeolite H-Y. The origin of this effect is examined
using in situ FTIR spectroscopy and 27Al and 29Si MAS NMR spectroscopy studies of the modified zeolite. The rate enhancement is considered to result from a specific interaction
between the dithiane oxide modifier with both the extra-framework and framework aluminium in the zeolite.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Family physicians who provide obstetric care may periodically encounter a patient with a history of epilepsy, which may manifest before or after pregnancy. In either case, several issues need to be addressed. Pregnant women with epilepsy may have an increased frequency of seizures, with the potential for resultant maternal and fetal morbidity and mortality. Teratogenic effects of antiepileptic drugs include craniofacial abnormalities and neural tube defects. Management strategies include the prenatal use of folic acid and vitamin K, monotherapy with a single antiepileptic drug, and obtaining at least monthly free serum drug levels. Fortunately, with close monitoring and proper management, more than 90 percent of pregnancies in women with epilepsy will be uncomplicated. 相似文献
5.
H Yamamoto WB Atwood PH Baillon BC Barish GR Bonneaud A Courau GJ Donaldson R Dubois MM Duro EE Elsen SG Gao YZ Huang GM Irwin R Johnson H Kichimi J Kirkby DE Klem DE Koop J Ludwig GB Mills A Ogawa T Pal D Perret-Gallix R Pitthan DL Pollard CY Prescott LZ Rivkin LS Rochester W Ruckstuhl M Sakuda S Sherman EJ Siskind R Stroynowski SQ Wang SG Wojcicki WG Yan CC Young 《Canadian Metallurgical Quarterly》1985,32(11):2901-2910
6.
Evaldas Bal
inas Sara J Baldock Nadeda Drei Monika Grubliauskait Sarah Coultas David L Rochester Mindaugas Valius John G Hardy Daiva Baltriukien 《Polymer International》2019,68(11):1928-1940
Materials with microscale structures are gaining increasing interest due to their range of technical and medical applications. Additive manufacturing approaches to such objects via laser two‐photon polymerization, also known as multiphoton fabrication, enable the creation of new materials with diverse and tunable properties. Here, we investigate the properties of 3D structures composed of organometallic polymers incorporating aluminium, titanium, vanadium and zirconium. The organometallic polymer‐based materials were analysed using a variety of techniques including SEM, energy‐dispersive X‐ray spectroscopy, X‐ray photoelectron spectroscopy analysis and contact angle measurements and their biocompatibility was tested in vitro. Cell viability and mode of death were determined by 3‐(4,5‐dimethyl‐2‐thiazolyl)‐2,5‐diphenyl‐2H‐tetrazolium bromide (MTT) assay and acridine orange/ethidium bromide staining. Polymers incorporating Al, Ti and Zr supported cell adhesion and proliferation, and showed low toxicity in vitro, whereas the organometallic polymer incorporating V was shown to be cytotoxic. Inductively coupled plasma optical emission spectrometry suggested that leaching of the V from the organometallic polymer is the likely cause of this. The preparation of the organometallic polymers is straightforward and both simple 2D and complex 3D structures can be fabricated with ease. Resolution tests of the newly developed organometallic polymer incorporating Al show that suspended lines with widths down to 200 nm can be fabricated. We believe that the materials described in this work show promising properties for the development of objects with sub‐micron features for biomedical applications (e.g. biosensors, drug delivery devices, tissue scaffolds etc.). © 2019 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. 相似文献
7.
In this paper we present a preliminary study on a new technique for forecasting iceberg motion. The technique is based on using the past motions of icebergs to generate the currents required by a model for predicting those past observed motions. These currents are then used to forecast the motions of other icebergs passing through the same area at a later time. In addition, consideration — within the limits of our data set — is given the relationship between the currents obtained from the models and the actual currents present in the ocean. Of particular interest is the spatial variability of the derived currents and the implications of this variability for predicting future iceberg motions. 相似文献
8.
DE Klem WB Atwood BC Barish GR Bonneaud A Courau GJ Donaldson R Dubois MM Duro EE Elsen SG Gao YZ Huang GM Irwin RP Johnson H Kichimi J Kirkby DE Koop J Ludwig GB Mills A Ogawa T Pal R Pitthan DL Pollard CY Prescott LS Rochester W Ruckstuhl M Sakuda SS Sherman R Stroynowski SQ Wang SG Wojcicki H Yamamoto WG Yan CC Young 《Canadian Metallurgical Quarterly》1988,37(1):41-51
9.
C.H. Rochester 《Catalysis Letters》1998,52(1-2):121-121
This note rectifies serious omissions from the references included in a recent paper by Fujitani et al. concerned with methanol
synthesis over Cu/SiO2 containing ZnO.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
10.
KL Carlson MA Helvie MA Roubidoux CG Kleer HA Oberman TE Wilson EW Pollak AB Rochester 《Canadian Metallurgical Quarterly》1999,172(2):313-317
We have explored the nature of the sudden viral amplification observed during the ageing of P22-infected lysogenic colonies of Salmonella typhimurium [Ramírez, E, and Villaverde, A. (1997) Gene 202, 147-149]. By a comparative analysis of the wild-type P22 and a P22 integration mutant, it has been shown that the conditions promoting prophage induction occur in only a small portion of the bacterial population and briefly during the transition between the exponential growth and the stationary phase. The viral burst is RecA-dependent and cannot be reproduced in continuous culture by a mere decrease of the growth rate. This suggests that the limited viral propagation in colonies is probably linked to heterogeneous physiological conditions within colonial populations, distinct from those of the homogeneous liquid cultures. 相似文献