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101.
Five cellulase components were identified and purified in one step from Streptomyces strain A20 using electroendosmotic preparative electrophoresis. By this procedure up to 18 mg of protein mixture could be loaded on the column, with an estimated recovery of 60-70% of total activity; activity and protein recovery could be estimated 32% and 47% respectively, if only activity peaks were considered. In comparison to other purification methods, this technique results in high protein recovery and resolution of applied samples. 相似文献
102.
103.
F. Frontera D. Dal Fiume T. Franceschini G. Landini E. Morelli M. Pamini A. Rubini S. Silvestri G. Spada E. Costa D. Cardini A. Emanuele 《Il Nuovo Cimento C》1984,7(6):656-672
Summary We describe a balloon experiment, currently in the marking, devoted to the observation of celestial X-ray sources. The main
features of the X-ray telescope are summarized as follows. It operates in the energy band from 20 to 300 keV. Its energy resolution
is about 17% at 60 keV. Under the hypothesis of 104 s of observing time, 3 mbar of residual atmospheric pressure and 3σ of statistical significance, the expected sensitivity
of the instrument is 2·10−6 photons/cm2 s keV in the (20÷200) keV energy band, corresponding to about 1 milliCrab. Its high sensitivity allows us to detect both
time variability in the flux and cyclotron lines in the spectra of X-ray sources. It has a field of view of 3° FWHM and has
the possibility of resolving complex fields by using multipitch modulation collimators. With such a configuration its angular
resolution is about 10′.
Paper presented at the 2° Convegno Nazionale di Fisica Cosmica, held at L'Aquila, 29 May–2 June 1984. 相似文献
104.
105.
C. Dal Cappello J. Langlois M. C. Dal Cappello B. Joulakian A. Lahmam-Bennani A. Duguet R. Tweed 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,23(4):389-396
Electron-impact double ionization of noble gases is investigated theoretically for the case of high incident energies (5 keV). An ab initio calculation is made including partial correlation in the initial state as well as in the final state. The results of the calculations are compared with those of other theories and with the first available (e, 3e) experimental data on krypton 4p 6. 相似文献
106.
Jack A. A. Van der Veen René van Dal 《The Journal of the Operational Research Society》1991,42(11):971-980
The no-wait flow-shop scheduling problem (NWFSSP) with a makespan objective function is considered. As is well known, this problem is ????-hard for three or more machines. Therefore, it is interesting to consider special cases, i.e. special structured processing time matrices, that allow polynomial time solution algorithms. Furthermore, it is well known that the NWFSSP with a makespan objective function can be formulated as a travelling salesman problem (TSP). It is observed that special structured processing time matrices for the NWFSSP lead to special structured distance matrices for which the TSP is polynomially solvable. Using this observation, it is shown that some NWFSSPs with fixed processing times on all except two machines are well solvable while the others are conjectured to be ????-hard. Also, it is shown that NWFSSPs with a mean completion time objective function restricted to semi-ordered processing time matrices are easily solvable. 相似文献
107.
If Au = - div(a(x, Du)) is a monotone operator defined on the Sobolev space W1,P(R
n, 1 < p < + , with a(x,0) = 0 for a.e. x Rn, the capacity C_A(E,F) relative to A can be defined for every pair (E,F) of bounded sets in Rn with E F. The main properties of the set function CA(E,F) are investigated. In particular it is proved that CA(E,F) is increasing and countably subadditive with respect to E, decreasing with respect to F, and continuous, in a suitable sense, with respect to E and F. 相似文献
108.
R. F. Cretella R. A. Lukaszew J. Dal Fávero R. Servant 《Journal of Radioanalytical and Nuclear Chemistry》1990,144(5):379-386
A technique for isotopic submicrosample analysis of uranium by TIMS is presented. The heating pattern, used was modified in order to improve the precision for microsample analysis of SRM U-500 /NBS/ The technique was applied to submicrosample isotopic analysis of SRM U-150 /NBS/ and found satisfactory.Thermal Ionization Mass Spectrometry. 相似文献
109.
Electrospray ionization mass spectrometry for identification and structural characterization of pregnane glycosides 总被引:1,自引:0,他引:1
Dal Piaz F De Leo M Braca A De Simone F Morelli I De Tommasi N 《Rapid communications in mass spectrometry : RCM》2005,19(8):1041-1052
Pregnane glycosides are a class of naturally occurring substances characterized by some interesting biological activities and widely distributed in the plant kingdom and in some marine organisms. Their toxicity and use in herbal drugs and folk medicines has generated great interest in the chemical characterization of these molecules. In the study reported here the potential of electrospray ionization mass spectrometry (ESI-MS) in the identification and structural characterization of pregnane glycosides was examined. ESI-MS/MS and ESI-MS(n) analyses were performed on 27 different compounds employing two mass spectrometers equipped with a triple-quadrupole or an ion-trap analyzer. The data illustrate the ability of the ESI techniques in the identification of pregnane glycosides, including the nature of the pregnane core, the kind of ester substituents, the types of sugar residues (hexose, deoxyhexose, dideoxyhexose, O-methyldeoxyhexose and O-methyldideoxyhexose), and the primary structure of the saccharide chain. From these data, a generalized fragmentation pathway was proposed by comparing the spectra acquired for all the compounds. Interestingly, similar results were obtained from the two instruments, thus demonstrating that detailed analyses of product ion spectra obtained using a triple-quadrupole mass spectrometer led to structural information comparable to those obtainable in MSn experiments using an ion trap. Different and complementary information was deduced by fragmenting the [M+H]+ or the [M+Na]+ ions, or the protonated aglycone [Agl+H]+ generated by in-source fragmentation. The present evidence clearly suggests that, in order to obtain a complete characterization of pregnane glycosides by MS, all three of these species should be accurately analyzed. 相似文献
110.
J. Gulens H.D. Herrington J.W. Thorpe G. Mainprize M.G. Cooke P.Dal Bello S. Macdougall 《Analytica chimica acta》1982
A commercial prototype monitor, in which a sulfide-selective electrode detects hydrogen sulfide with a pH electrode used as the reference electrode in a sample acidified to pH <5, is compared to a monitor in which a solid-state sensor detects hydrogen sulfide stripped from the sample by an air—CO2 mixture. Each monitor has a detection limit of ?0.005 mg kg-1 and both monitors performed well over a six-month period in the field, sampling a heavy water plant effluent. Both monitors are simple to operate, calibrate, and maintain, but their accuracies are affected by oil and particulates in the sample. Advantages of using the suifide/glass electrode detection system in acidic solutions are presented. 相似文献