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排序方式: 共有398条查询结果,搜索用时 15 毫秒
101.
A. Djouadi W. Kilian M. Mühlleitner P.M. Zerwas 《The European Physical Journal C - Particles and Fields》1999,10(1):45-49
The reconstruction of the Higgs potential in the Standard Model or supersymmetric theories demands the measurement of the
trilinear Higgs couplings. These couplings affect the multiple production of Higgs bosons at high energy colliders. We present
a systematic overview of the cross sections for the production of pairs of (light) neutral Higgs bosons at the LHC. The analysis
is carried out for the Standard Model and its minimal supersymmetric extension.
Received: 30 March 1999 / Published online: 28 May 1999 相似文献
102.
Andrew A. Gurtovenko Yuli Ya. Gotlib Hanns‐Georg Kilian 《Macromolecular theory and simulations》2000,9(7):388-397
A dynamic model of a heterogeneous polymer network system is proposed. A polymer network is presented as an ensemble of cross‐linked regions (domains) of different sizes, the domains have similarly regular internal structures. To a first approximation, these domains are treated independently of each other. Relaxation modulus, storage modulus, and loss modulus of the heterogeneous polymer network are calculated. For the purpose of averaging over all network domains the exponential number distribution of chain segments in domains is used. This type of distribution has been previously proposed by one of the authors in the frame of the aggregation model. It is shown that a structure heterogeneity introduced into a network model according to the above domain approach leads, at long times, to the stretched exponential type of time dependence of relaxation modulus instead of the power‐law dependence predicted by the theories dealing with regular networks. The network heterogeneity also leads to a more rapid decrease in the storage modulus in the region of low frequencies, as compared with regular polymer networks. It is shown that the loss modulus in the region of its maximum is very slightly sensitive to the “long‐range” network heterogeneity considered. 相似文献
103.
Pasture vegetation plays an important role in the air-surface exchange and food chain transfer of polycyclic aromatic hydrocarbons (PAHs). Therefore, considerable research has been focused towards measuring PAHs in vegetation using different analytical methods. However, in most cases information on the efficiencies of the different extraction methods employed is missing. This complicates data interpretation and inter-study comparisons. To address this deficiency, the extraction efficiencies of two commonly used pasture vegetation extraction techniques (sonication and soxhlet) and different solvents (hexane, DCM and hexane:acetone [4:1, v/v]) were compared. The completeness of the extraction was investigated using alkaline saponification in methanol. Soxhlet extraction was able to access between 60 and 90% of the total amount of PAHs in the pasture vegetation. Sonication was less efficient, only being able to extract between 10 and 50% of the PAHs. Extraction efficiencies were found to increase with increasing PAH molecular weight. The implications of these findings on data interpretation are discussed. 相似文献
104.
Reaction of the triamidostannates(II) MeSi{SiMe2N(3,5‐xyl)}3SnLi(OEt2) ( 2a ) and MeSi{SiMe2N(p‐tol)}3SnLi(OEt2) ( 2b ) with [IrCl(CO)(PPh3)2] gave the IrI‐Sn complex [MeSi{SiMe2N(3,5‐xyl)}3SnIr(PPh3)2(CO)] ( 3a ) for the former. In contrast, for the tolyl stannate CH‐activation occurred to give the IrIII compound [MeSi{SiMe2N(p‐tol)}2{SiMe2N(2‐C6H3‐4‐CH3)}SnIr(H)(PPh3)2(CO)] ( 3b ). The latter is thus avoided by introduction of suitably placed substituents in the peripheral aryl groups of the triamidostannate ligand. 相似文献
105.
106.
Villar A Hövelmann CH Nieger M Muñiz K 《Chemical communications (Cambridge, England)》2005,(26):3304-3306
Conditions for a first oxidative conversion of alkenes into 2-amino ketones are described, which yield racemic products within a direct oxidation pathway and 2-amino ketones with up to 99% enantiomeric excess from the corresponding enantiopure amino alcohols. 相似文献
107.
M. Abdel-Bary S. Abdel-Samad R. Bilger K.-Th. Brinkmann H. Clement S. Dshemuchadse E. Dorochkevitch H. Dutz W. Eyrich A. Erhardt D. Filges A. Filippi H. Freiesleben M. Fritsch R. Geyer A. Gillitzer D. Hesselbarth B. Jakob L. Karsch K. Kilian H. Koch J. Kreß E. Kuhlmann S. Marcello S. Marwinski S. Mauro W. Meyer P. Michel K. Möller H. P. Morsch L. Naumann N. Paul M. Richter E. Roderburg M. Rogge A. Schamlott M. Schmitz P. Schönmeier M. Schulte-Wissermann W. Schroeder T. Sefzick F. Stinzing G.Y. Sun G.J. Wagner M. Wagner A. Wilms P. Wintz S. Wirth P. Zupranski 《The European Physical Journal A - Hadrons and Nuclei》2003,16(1):127-137
The reaction pp → ppη was measured at excess energies of 15 and 41 MeV at an external target of the Jülich Cooler Synchrotron COSY with the time-of-flight
spectrometer. About 25000 events were measured for the excess energy of 15 MeV and about 8000 for 41 MeV. Both protons of
the process ppη were detected with an acceptance of nearly 100% and the η was reconstructed by the missing-mass technique. For both excess
energies the angular distributions are found to be nearly isotropic. In the invariant-mass distributions strong deviations
from the pure phase space distributions are seen.
Received: 24 May 2002 / Accepted: 20 September 2002 / Published online: 17 January 2003
RID="a"
ID="a"e-mail: e.roderburg@fz-juelich.de
Communicated by M. Gar?on 相似文献
108.
Streuff J Hövelmann CH Nieger M Muñiz K 《Journal of the American Chemical Society》2005,127(42):14586-14587
Intramolecular diamination reactions are described which yield cyclic ureas as direct products of an oxidative alkene transformation in the presence of palladium acetate and iodosobenzene diacetate as terminal oxidant. The reaction is truly catalytic in metal catalyst and represents the proof of principle for this elusive type of alkene oxidation. 相似文献
109.
Isobaric state diagrams of various binaryn-alkane mixtures have been derived from DTA-measurements. They can be described by means of proper thermodynamic relations which are essentially taking into consideration the disparity in chain lengths. The discussion of the thermodynamic parameters is elucidating the physical situation in the longitudinal boundaries of extended mixed crystals such that stability conditions in binaryn-alkane systems can be developed. Occurrence of eutectical crystallization in the binary mixtures can fairly well be predicted dependend upon the relative disparity in chain lengths.Dedicated to Prof. Dr. F. H. Müller. 相似文献
110.
H. -G. Kilian 《Colloid and polymer science》1981,259(12):1151-1160
Summary A novel equation of state for bimodal networks with extremely short chains as solid intrusions is developed proceeding from the van der Waals theory of molecular networks. Stress-strain and thermoelastic measurements on bimodal end-linked polydimethylsiloxane model networks can satisfactorily be described. The physical reasons behind that representation will be discussed.Dedicated to Professor Dr. K. Ueberreiter on his 70th birthday. 相似文献