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61.
62.
63.
Bouška M Dostál L Padělková Z Lyčka A Herres-Pawlis S Jurkschat K Jambor R 《Angewandte Chemie (International ed. in English)》2012,51(14):3478-3482
The step-wise oxidation of an organotin(I) compound with elemental tellurium gave a variety of unprecedented organotin tellurides containing tin atoms in the oxidation states +II and +IV. 相似文献
64.
Mazen Bou Khuzam 《Geometriae Dedicata》2013,163(1):45-59
A Knot ${K\subset S^{3}}$ is said to satisfy the G-property if for every ${r \in \mathbb{Q}}$ the manifold M(K, r) obtained by rational surgery on K with surgery coefficient r is the boundary of a Stein domain. The problem of finding which knots satisfy the G-property is still wide open. This paper introduces this problem and presents some techniques used to prove that certain infinite families of knots satisfy the G-property. 相似文献
65.
P. Vermaercke F. Farina L. Sneyers M. Bruggeman J. G. Bouças 《Journal of Radioanalytical and Nuclear Chemistry》2009,281(1):35-39
Several recent intercomparisons and certification exercises have shown that the determination of tin in e.g. food samples
and plastics is not straightforward. k
0-Instrumental Neutron Activation Analysis (k
0-INAA) offers some intrinsic quality control opportunities for the determination of the tin content in samples since several
monitoring radioisotopes are formed. In this work we will discuss the validation of the determination of tin by k
0-INAA using different reference materials. The results show that only few of these radioisotopes are reliable in terms of
accuracy and that from a survey of the tin content in a range of canned foods detection limits as low as 2 mg/kg can be achieved. 相似文献
66.
Detailed specific heat C(p) measurements of delta-Pu stabilized by Am (8%-20%) were performed in the temperature range 4.5-300 K. The coefficient of the electronic specific heat gamma, which reflects the quasiparticle density of states at the Fermi level E(F), is smaller than originally assumed and, depending on the estimate of phonon contributions, a value between 35 and 55 mJ/mol K2 can be deduced for Pu-8% Am. For higher Am concentrations, which expand the lattice, gamma decreases slightly with the Am content. An applied magnetic field of 9 T had no effect on C(p). The results strongly suggest that itinerant 5f states at E(F) are not appropriate for describing delta-Pu. 相似文献
67.
Guy Blanchard Boué Jean Brice Boti Zanahi Félix Tonzibo Ange Bighelli 《Natural product research》2019,33(19):2795-2800
Root and flower essential oils of Cyanthillium cinereum (L.) H. Rob. (Synonym Vernonia cinerea (L.) Less.) (Asteraceae) collected in Southern Côte d’Ivoire was investigated using a combination of chromatographic and spectroscopic techniques. The root oil composition was dominated by trans–β–bergamotene (20.7%), β–elemene (19.0%), cyperene (10.6%), germacrene A (7.1%) and β–pinene (3.8%), whereas γ–humulene (31.0%), (E)–β–caryophyllene (17.0%), trans–β–bergamotene (7.7%), β–pinene (7.5%) and (E)–β–farnesene (6.0%) were the major components of flower oil. Two new compounds bearing the trans–β–bergamotene framework were identified: trans–β–bergamotenone and (E)–trans–β–bergamotenol. 相似文献
68.
Aqueous solutions of a well-defined poly(N-isopropylacrylamide-co-sodium 2-acrylamido-methylpropanesulfonate) (NIPAM/NaAMPS in a 95/5 molar ratio) have been investigated by means of small-angle
neutron scattering (SANS) and rheological experiments as a function of temperature ( 25°
C
T
60°
C) and polymer concentration ( 0.5wt%
C
12wt%). The solutions remain optically transparent and isotropic over the whole temperature range, in contrast with the homopolyNIPAM
which precipitates above its lower critical solution temperature (LCST = 32°
C). Upon addition of salt, the systems undergo a micro-macrophase separation. At temperatures above 45°
C, the SANS spectra exhibit a sharp peak at a scattering wave vector, q
max, which increases slightly with temperature. At high temperature ( T∼ 60°
C), the scattered intensity follows a power law I(q) ∼q
-4 in the asymptotic regime, characteristic of two-density media with sharp interfaces, and q
max is found to vary with polymer concentration as q
max∼C
0.22. Estimates of the typical sizes give values between 40 ? and 200 ?. These results provide a strong evidence of a thermally
induced microphase separation, which is corroborated by the very sharp increases of the viscosity (over 2 decades) and of
the stress relaxation time of the solutions, occurring in the temperature range where the scattering peak is observed. The
results are discussed and compared with the theoretical models proposed for weakly charged polyelectrolytes in a poor solvent.
Received 1 October 2001 相似文献
69.
Experimental tests were conducted to control the flow around a cylinder by means of unsteady blowing (synthetic jet) through a single slot disposed on the wall of the model. The flow Reynolds number (based on the diameter of the model) wasR D=105. The efficiency of the synthetic jet is quantified in terms of delaying separation and modifying the drag coefficient. The investigations were of three types: measurements of the mean pressure distribution, wall visualizations of the separation line position and measurements of the mean flow-field in the wake. 相似文献