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41.
Elucidation of the structures of olivoretin B and C 总被引:2,自引:0,他引:2
Y Hitotsuyanagi K Yamaguchi K Ogata N Aimi S Sakai Y Koyama Y Endo K Shudo A Itai Y Iitaka 《Chemical & pharmaceutical bulletin》1984,32(9):3774-3778
42.
Itai Massad Heiko Sommer Ilan Marek 《Angewandte Chemie (International ed. in English)》2020,59(36):15549-15553
An in situ generated cationic Ir‐catalyst isomerizes simple allylic silyl ethers into valuable, fully substituted aldehyde‐derived silyl enol ethers. Importantly, by judicious choice of substrate, either of the two possible stereoisomers of a given enolate derivative is accessible with complete stereoselectivity. One‐pot isomerization‐aldol and isomerization‐allylation processes illustrate the synthetic utility of this method. 相似文献
43.
Let
\mathfraka \mathfrak{a} be a finite-dimensional Lie algebra and
Y( \mathfraka ) Y\left( \mathfrak{a} \right) the
\mathfraka \mathfrak{a} invariant subalgebra of its symmetric algebra
S( \mathfraka ) S\left( \mathfrak{a} \right) under adjoint action. Recently there has been considerable interest in studying situations when
Y( \mathfraka ) Y\left( \mathfrak{a} \right) may be polynomial on index
\mathfraka \mathfrak{a} generators, for example if
\mathfraka \mathfrak{a} is a biparabolic or a centralizer
\mathfrakgx {\mathfrak{g}^x} in a semisimple Lie algebra
\mathfrakg \mathfrak{g} . 相似文献
44.
Prof. Dr. Kimihiro Komeyama Yuuhei Itai Prof. Dr. Ken Takaki 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(27):9130-9134
A practical and scalable nickel‐catalyzed allylic stannylation of allyl acetates with Bu3SnOMe is described. A variety of acyclic and cyclic allyl acetates, even with base‐sensitive moieties, undergoes the stannylation by using NiBr2/4,4′‐di‐tert‐butylbipyridine (dtbpy)/Mn catalyst system to afford highly functionalized allyl stannanes with excellent regioselectivity and yields. Furthermore, the scope of protocol is also extended by the reaction of propargyl acetates, giving rise to propargyl or allenyl stannanes. Additionally, a unique diastereoselectivity using the nickel catalyst different from the palladium was demonstrated for the stannylation of cyclic allyl acetates. In the reaction, inexpensive and stable nickel complexes, abundant reductant (Mn), and atom‐economical stannyl source were used. 相似文献
45.
In this paper a simple DLA type model is analyzed. In (Benjamini and Yadin in Commun. Math. Phys. 279:187–223, [2008]) the standard DLA model from (Witten and Sander in Phys. Rev. B 27:5686–5697, [1983]) was considered on a cylinder and the arm growing phenomena was established, provided that the section of the cylinder has
sufficiently fast mixing rate. When considering DLA on a cylinder it is natural to ask how many particles it takes to clog
the cylinder, e.g. modeling clogging of arteries. In this note we formulate a very simple DLA clogging model and establish
an exponential lower bound on the number of particles arriving before clogging appears. In particular we possibly shed some
light on why it takes so long to reach the bypass operation. 相似文献
46.
The degree of bitterness of clarithromycin (CAM) dry syrup was evaluated using several methods. Using the inversion method, shaking method, and paddle method, a reasonable correlation between the bitter taste and the amount dissolved was not observed. A mini-column with inner diameter of 0.76 cm and height of 5 cm packed with CAM dry syrup was used for the release test. The release rate of CAM in test solution, which passed through the mini-column, was then measured to evaluate bitterness. The release rate of CAM in the release test using the mini-column correlated well with the results of a sensory test for the bitterness of CAM dry syrup. The dissolution rate constant, defined as the percentage of CAM dissolved from the unit void surface multiplied by the void volume, was inversely proportional to the linear velocity of the test solution. The critical factors affecting evaluation of bitterness were the void volume of the column and linear velocity of the test solution. The optimum linear velocity and void volume were 0.048-0.021 cm/min and 0.27-0.12 cm3, respectively. In addition, the threshold of bitterness of CAM dry syrup was defined as the concentration at which half of the volunteers recognized bitterness in the sensory test. This threshold was found to be 135 microg/ml using the mini-column. 相似文献
47.
48.
(Accepted July 23, 1996) 相似文献
49.
We establish recurrence criteria for sums of independent random variables which take values in Euclidean lattices of varying dimension. In particular, we describe transient inhomogeneous random walks in the plane which interlace two symmetric step distributions of bounded support.Research partially supported by the U.S. Army Research Office through the Mathematical Sciences Institute of Cornell University.Research supported in part by National Science Foundation Grant No. DMS 9300191, by a Sloan Foundation Fellowship, and by a Presidential Faculty Fellowship. 相似文献
50.
Changes in the liver parenchyma after proton beam radiotherapy: evaluation with MR imaging 总被引:2,自引:0,他引:2
Onaya H Itai Y Yoshioka H Ahmadi T Niitsu M Okumura T Akine Y Matsuzaki Y Doi M Tsuji H Tsujii H 《Magnetic resonance imaging》2000,18(6):707-714
The objective of this study was to describe magnetic resonance (MR) findings with a 1.5T imager for hepatic parenchymal changes after proton beam radiotherapy. Thirty-two patients who received proton radiotherapy with doses of 50-87 Gy underwent MR imaging 1-75 months (mean 22 months) after the start of irradiation. Axial T(2), T(1)-weighted imaging, and a dynamic study after a gadolinium injection were performed. The irradiated areas showed hypointense in T(1)-weighted images, hyperintense in T(2)-weighted images, and intense and prolonged enhancement on the dynamic study (maximum relative enhancement 441.8%+/-263.3 vs. surrounding liver 145.6%+/-67.7, p<0.0001). T(2) values of the irradiated areas were 50.6 to 65.8 msec greater than in the surrounding liver (p<0.005). The values increased with time, being significantly greater 13 months or longer after the beginning of the therapy than after a period of less than 3 months (p<0.05). Pathologic examinations (n = 3) indicated that the irradiated areas were composed of collapsed lobules with hepatic small vein occlusions, and rich extracellular matrices which retained extracellular fluid. MR imaging can demonstrate hepatic parenchymal changes after proton beam radiotherapy, and show the changes are irreversible. 相似文献