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排序方式: 共有384条查询结果,搜索用时 250 毫秒
91.
Lucas C. Moore Anna Lo Jason S. Fell Matthew R. Duong Jose A. Moreno Barry E. Rich Martin Bravo Dr. James C. Fettinger Lucas W. Souza Prof. Marilyn M. Olmstead Prof. Kendall N. Houk Prof. Jared T. Shaw 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(52):12214-12220
Diastereoselective Lewis acid-mediated additions of nucleophilic alkenes to N-sulfonyl imines are reported. The canonical polar Felkin–Anh model describing additions to carbonyls does not adequately describe analogous additions to N-sulfonyl imines. Herein, we describe the development of conditions to produce both syn and anti products with high diastereoselectivity and good yields. A stereoelectronic model consistent with experimental outcomes is also proposed. 相似文献
92.
93.
94.
Tran Thi-Minh-Dinh Duong Thuc-Huy Tran Thanh-Nha Nguyen Thi-Hang Nguyen Ngoc-Phuong Nguyen Ngoc-Hong Dinh Minh-Hiep Nguyen Thi-Anh-Tuyet 《Chemistry of Natural Compounds》2021,57(2):388-389
Chemistry of Natural Compounds - 相似文献
95.
The scaling limit and Schauder bounds are derived for a singular integral operator arising from a difference equation approach
to monodromy problems.
Research supported in part by National Science Foundation grants DMS-02-45371 and DMS-04-05519. 相似文献
96.
D. Verney L. Cabaret J. E. Crawford H. T. Duong B. Fricke J. Genevey G. Huber F. Ibrahim M. Krieg F. Le Blanc J. K. P. Lee G. Le Scornet D. Lunney J. Obert J. Oms J. Pinard J. C. Puteaux K. Rashid B. Roussière J. Sauvage V. Sebastian 《The European Physical Journal A - Hadrons and Nuclei》2006,30(3):489-518
Laser spectroscopy measurements have been performed on neutron-deficient and stable Ir isotopes using the COMPLIS experimental
setup installed at ISOLDE-CERN. The radioactive Ir atoms were obtained from successive decays of a mass-separated Hg beam
deposited onto a carbon substrate after deceleration to 1kV and subsequently laser desorbed. A three-color, two-step resonant
scheme was used to selectively ionize the desorbed Ir atoms. The hyperfine structure (HFS) and isotope shift (IS) of the first
transition of the ionization path 5d
76s
24
F
9/2 → 5d
76s6p
6
F
11/2 at 351.5nm were measured for 182-189Ir, 186Ir
m
and the stable 191, 193Ir. The nuclear magnetic moments μI and the spectroscopic quadrupole moments Qs were obtained from the HFS spectra and the change of the mean square charge radii from the IS measurements. The sign of μI was experimentally determined for the first time for the masses 182≤A≤189 and the isomeric state 186Ir
m
. The spectroscopic quadrupole moments of 182Ir and 183Ir were measured also for the first time. A large mean square charge radius change between 187Ir and 186Ir
g
and between 186Ir
m
and 186Ir
g
was observed corresponding to a sudden increase in deformation: from β2 ≃ + 0.16 for the heavier group A = 193, 191, 189, 187 and 186m to β2≥ + 0.2 for the lighter group A = 186g, 185, 184, 183 and 182. These results were analyzed in the framework of a microscopic treatment of an axial rotor plus one
or two quasiparticle(s). This sudden deformation change is associated with a change in the proton state that describes the
odd-nuclei ground state or that participates in the coupling with the neutron in the odd-odd nuclei. This state is identified
with the π3/2+[402] orbital for the heavier group and with the π1/2-[541] orbital stemming from the 1h
9/2 spherical subshell for the lighter group. That last state seems to affect strongly the observed values of the nuclear moments. 相似文献
97.
We give an example of a group action on Euclidean space for which each map in the action is compactly supported, and such that the action is chaotic in the sense that it is topologically transitive and the set of points with finite orbit is dense. This resolves a conjecture of Naolekar and Sankaran. 相似文献
98.
Graphs with Prescribed Mean Curvature on Poincare Disk 总被引:1,自引:0,他引:1
We establish the existence and uniqueness of a solution of aquasilinear elliptic equation in the unit disk of R2. Usingthis result, we obtain the existence of graphs with prescribedcurvature on the Poincaré disk. 相似文献
99.
Duong Duc La Anuradha Anuradha Amanpreet Kaur Hundal Sidhanath V. Bhosale Lathe A. Jones 《Supramolecular chemistry》2018,30(1):1-8
The fabrication of well-defined nanostructures with luminescent properties in the solid or aggregated state is of intense interest due to their applications in nano- and biotechnology. We report the synthesis of water-soluble tetraphenylethylene bearing four sulfonate groups as a sodium salt (Su-TPE), and investigations concerning its AIE characteristics by the addition of organic solvent into the aqueous solution, which is the reverse procedure to conventional AIE-active TPE derivatives. The resultant compound is weakly emissive in pure water, however, emits strongly upon addition of THF solvent (with THF fraction > 60%). The emission properties and the morphologies of the aggregates were greatly dependent upon the solution pH. Su-TPE self-assembled into variety of structures in water/THF mixture with pH control, for the first time. Well-defined uniform nanorods with a width of about 200 nm and a length of up to 10 μm were obtained at solution pH of 1. The Su-TPE showed very good mechanochromic properties were observed during the process of grounding and fuming. 相似文献
100.