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排序方式: 共有203条查询结果,搜索用时 15 毫秒
31.
K. -L. Kratz H. Ohm H. Gabelmann G. I. Crawford G. Jung B. Pfeiffer 《Zeitschrift für Physik A Hadrons and Nuclei》1982,305(1):93-94
Beta-delayed neutron measurements on95Rb have indicated evidence for two heretofore unknown excited O+ states in94Sr which are not fed by ß -decay from the Jπ = 3? ground state of94Rb. 相似文献
32.
A. Baas-May J. V. Kratz N. Trautmann 《Zeitschrift für Physik A Hadrons and Nuclei》1985,322(3):457-462
We have searched for beta-delayed fission in the decay of 2.3 min238Pa produced in the238U(n,p) reaction with 14.7 MeV neutrons. Through microprocessor-controlled chemical separations of protactinium about 109 atoms of238Pa were isolated and exposed to fission track detectors. From the absence of fission tracks an upper limit for the betadelayed fission probability of238Pa, i.e.P βf <2.6 10?8, is obtained at 95% confidence level. This rules out positive evidence for this decay mode of238Pa reported elsewhere. Simple theoretical estimates ofP βf range from 10?7 to 10?9. 相似文献
33.
Dr. Werner Kratz 《Monatshefte für Mathematik》1974,78(3):223-228
Ohne Zusammenfassung 相似文献
34.
K.-L. Kratz H. Ohm K. Sümmerer M. Zendel G. Jung K.D. Wünsch C. Ristori J. Crançon S.G. Prussin 《Physics letters. [Part B]》1979,86(1):21-23
Experimental β?-strength functions (Sβ) are presented for the odd-mass Rb isotope sequence A=89to97. As expected from general nuclear structure considerations, but in contrast to present purely statistical concepts, these strength functions exhibit well separated “pygmy” resonances and a systematic behaviour as a function of mass number and β-decay energy. 相似文献
35.
36.
Linear self-eliminating (LSE) systems are oligomers of branched self-eliminating linkers that disassemble upon a single triggering event under complete degradation of the linear backbone, accompanied by the release of side-chain bound effector molecules. Enabling a controlled and almost simultaneous release of different effectors (drugs) in defined ratios, LSE systems may gain importance for the development of novel combination therapeutics. On the basis of the well-known self-eliminating p-aminobenzyloxycarbonyl (PABC) linker, 2,4-bis(hydroxymethyl)aniline was considered a suitable branched linker for building LSE systems that degrade by 1,6- and 1,4-benzyl elimination reactions. A first LSE model system based on this linker was prepared in a simple procedure and was shown to release its effector payload efficiently after activation. In addition, elimination model compounds were synthesized to study the release behavior of LSE systems based on 2,4-bis(hydroxymethyl)aniline. It was found that chain degrading 1,6-benzyl elimination occurs much faster than the effector releasing 1,4-elimination. 相似文献
37.
Kulkarni A Reiche J Kratz K Kamusewitz H Sokolov IM Lendlein A 《Langmuir : the ACS journal of surfaces and colloids》2007,23(24):12202-12207
The hydrolytic and enzymatic degradation behavior of poly(epsilon-caprolactone) (PCL) is investigated using the Langmuir monolayer technique, and an improved data acquisition and data reduction procedure is presented. Hydrolytic and enzymatic monolayer degradation experiments of PCL with various molecular weights by Pseudomonas cepacia lipase have been carried out to analyze the influence of subphase pH, subphase temperature, enzyme concentration, and the packing density of polymer chains on the degradation kinetics. The enzymatic monolayer degradation results in an exponential increase in the number of dissolved degradation fragments with increasing degradation time, which confirms random chain scission to be the dominant scission mechanism. The increase in the enzymatic scission rate constant with decreasing initial average molecular weight of the polymers is assigned to the influence of the area density of polar terminal groups on the substrate-enzyme complex formation. 相似文献
38.
T. Kautzsch W.B. Walters M. Hannawald K.-L. Kratz V.I. Mishin V.N. Fedoseyev W. Böhmer Y. Jading P. Van Duppen B. Pfeiffer A. Wöhr P. Möller I. Klöckl V. Sebastian U. Köster M. Koizumi J. Lettry H.L. Ravn the ISOLDE Collaboration 《The European Physical Journal A - Hadrons and Nuclei》2000,9(2):201-206
A chemically selective laser ion source has been used in a β-decay study of heavy Ag isotopes into even-even Cd nuclides.
Gamma-spectroscopic techniques in time-resolving event-by-event and multiscaling modes have permitted the identification of
the first 2+ and 4+ levels in 126Cd78, 128Cd80, and tentatively the 2+ state in 130Cd82. From a comparison of these new states in 48Cd with the E(2+) and E(4+)/E(2+) level systematics of 46Pd and 52Te isotopes and several recent model predictions, possible evidence for a weakening of the spherical N = 82 neutron-shell below double-magic 132Sn is obtained.
Received: 13 July 2000 / Accepted: 12 October 2000 相似文献
39.
N. Erdmann J.-V. Kratz N. Trautmann G. Passler 《Analytical and bioanalytical chemistry》2009,395(6):1911-1918
Micro-particles containing actinides are of interest for risk assessments of contaminated areas, nuclear forensic analyses,
and IAEA as well as Euratom safeguards programs. For their analysis, secondary ion mass spectrometry (SIMS) has been established
as the state-of-the-art standard technique. In the case of actinide mixtures within the particles, however, SIMS suffers from
isobaric interferences (e.g., 238U/238Pu, 241Am/241Pu). This can be eliminated by applying resonance ionization mass spectrometry which is based on stepwise resonant excitation
and ionization of atoms with laser light, followed by mass spectrometric detection of the produced ions, combining high elemental
selectivity with the analysis of isotopic compositions. This paper describes the instrumental modifications for coupling a
commercial time-of-flight (TOF)-SIMS apparatus with three-step resonant post-ionization of the sputtered neutrals using a
high-repetition-rate (kHz) Nd:YAG laser pumped tunable titanium:sapphire laser system. Spatially resolved ion images obtained
from actinide-containing particles in TOF-SIMS mode demonstrate the capability for isotopic and spatial resolution. Results
from three-step resonant post-ionization of bulk Gd and Pu samples successfully demonstrate the high elemental selectivity
of this process. 相似文献
40.
We review structure data obtained by decay spectroscopy of neutron-rich nuclei of mass close to 100. Emphasis is put on the contribution of experiments at IGISOL in the nineties. They confirmed the earlier postulated shape coexistence in the fast shape-transition region between N = 58 (spherical ground states and low collectivity) and N = 60 (strong axial deformation). A detailed spectroscopic study of the A = 99 chain established the upper-Z limit of the N = 56 shell closure region with 99Nb, owing to striking similarities with 97Y. A consequence of the N = 56 closure is that the s 1/2 odd-neutron becomes the ground state of the most neutron-rich N = 57 isotones, starting with 99Mo, instead of the degenerated d 5/2 and g 7/2 subshells familiar in the tin region. Consequences on the change of spin on astrophysical r-process calculations are briefly discussed. Finally, we say a few words about neutron-rich rhodium and palladium isotopes near the neutron midshell where regular and intruder states coexist very close to each other. 相似文献