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31.
de la Vaissiere C Luth V Abrams GS Amidei D Baden AR Barklow T Boyarski AM Boyer J Breidenbach M Burchat P Burke DL Butler F Dillon JW Dorfan JM Feldman GJ Gidal G Gladney L Gold MS Goldhaber G Golding LG Hanson G Haggerty J Herrup D Himel T Hollebeek RJ Innes WR Jaros JA Juricic I Kadyk JA Klein SR Lankford AJ Larsen RR LeClaire BW Levi ME Lockyer NS Matteuzzi C Nelson ME Ong RA Perl ML Richter B Ross MC Rowson PC Schaad T Schellman H Schmidke WB Sheldon PD Trilling GH Yelton JM Wood DR 《Physical review letters》1985,54(19):2071-2074
32.
The design, synthesis and evaluation of a pentacyclic scaffold, CWO-324 to mimic saframycin A is described. CWO-324 is readily synthesized in five steps from 1,4-diacetyl-piperazine-2,5-dione and 2,5-dimethoxybenzaldehyde. CWO-324 was found to scission DNA, binds to bases 69-83(5′-GCAGTCAGG CACCGT-3′) of Hind III/Rsa I from plasmid pBR322 DNA in a foot-printing study and possesses anti-tumor activity. 相似文献
33.
Salt effects on the apparent stability of the cucurbit[7]uril-methyl viologen inclusion complex 总被引:1,自引:0,他引:1
The effects of the medium ionic composition on the apparent equilibrium association constant (K) for the formation of a 1:1 inclusion complex between the guest methyl viologen (MV(2+)) and the host cucurbit[7]uril (CB7) were studied in aqueous solutions. The K values were found to decrease with increasing ionic strength, with more pronounced effects for solutions containing divalent Ca(2+) ions than for solutions containing monovalent Na(+) ions. The competing ion-dipole interactions between Ca(2+) or Na(+) and MV(2+) ions appear to be responsible for the remarkable modulation of the K values observed in this work. 相似文献
34.
G.W. Zhang Y.P. Feng C.K. Ong 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1996,37(3):241-247
We report an experimental study of energy pooling collisions involving Cs atoms in the 6P and 5D states. The 5D state was populated by a cw dye-laser tuned to the cesium dipole-forbidden transition 6S → 5D at 685.0 nm. The 6P state was populated by subsequent radiative relaxation of the 5D state. The 6P population density was determined from the absorption of a cw diode-laser probe beam. The population densities of the 5D state and the higher, by energy pooling excited states were determined by measuring the corresponding fluorescence intensities relative to the fluorescence intensity from the optically thin quasi-static wings of the cesium D 2 line. The rate coefficient for the process Cs*(6P)+Cs*(6P)→Cs**(6D)+Cs(6S) is found to be (4.2±0.13)×10?10 cm3 s?1 at T=570 K. In addition, estimates of the rate coefficients for the processes Cs*(6P)+Cs*(5D)→Cs**(7D)+Cs(6S) and Cs*(5D)+ Cs*(5D)→Cs**(7F)+Cs(6S) are given. 相似文献
35.
Multidimensional gas chromatography (MDGC) is performed in a new manner, described in this paper. The method incorporates two directly coupled columns and employs a longitudinally modulated cryogenic trap located between the columns. No heartcutting process is used, but rather a method better termed selected zone compression pulsing is used. Compared with normal MDGC, where primary column effluent has to be temporarily diverted either to a monitor detector or to the second dimension column, the new procedure in its simplest mode passes all of the first column effluent to the second column. It is simply the times at which the modulation of the trap is performed that determines which target solutes will be selected for enhanced separation. This approach allows almost instantaneous separation of selected zones on the second column, and has the potential to significantly simplify the MDGC method. Since data are presented in a time-response format, and do not require transformation as previously described for comprehensive GC when using the longitudinal modulator, quantitation and report generation are essentially the same as in any GC method and data system. Advantages also include significant sensitivity improvement. By using cryofocussing, and benefiting from the zone compression effects along with fast GC conditions on the second dimension, new possibilities for MDGC can be realised. The method is demonstrated by using a mixture of semi-volatile aromatic hydrocarbons. 相似文献
36.
Yulu Yang Mingguang Wu Xingwang Zhu Hui Xu Si Ma Yongfeng Zhi Hong Xia Xiaoming Liu Jun Pan Jie-Yinn Tang Siang-Piao Chai Leonardo Palmisano Francesco Parrino Junli Liu Jianzhong Ma Ze-Lin Wang Ling Tan Yu-Fei Zhao Yu-Fei Song Pardeep Singh Pankaj Raizada Deli Jiang Di Li R. A. Geioushy Jizhen Ma Jintao Zhang Song Hu Rongjuan Feng Gang Liu Minghua Liu Zhenhua Li Mingfei Shao Neng Li Jiahe Peng Wee-Jun Ong Nikolay Kornienko Zhenyu Xing Xiujun Fan Jianmin Ma 《中国化学快报》1990,30(12):2065-2088
This roadmap demonstrates a series of two-dimensional nanomaterials, such as graphene, black phosphorus, oxides, layered double hydroxides, chalcogenides, bismuth-based layered compounds, MXenes, metal organic frameworks, covalent organic frameworks, and others, for environmental catalysis. 相似文献
37.
38.
Virginia Lea Miller Wei-li Lee Nai-Phuan Ong 《Journal of solid state chemistry》2005,178(5):1508-1512
We report the synthesis and elementary properties of the Co7Se8−xSx (x=0-8) and Ni7Se8−xSx (x=0-7) solid solutions. Both systems form a NiAs-type structure with metal vacancies. In general, the lattice parameters decrease with increasing x, but in the Ni7Se8−xSx system c increases on going from x=5 to 7. Magnetic susceptibility measurements show that all samples exhibit temperature-independent paramagnetism from 25-250 K. Samples within the Co7Se8−xSx system, as well as Ni7Se8 and Ni7SeS7, were found to be poor metals with resistivities of ∼0.20 and ∼0.06 mΩ cm at 300 K, respectively. The Sommerfeld constant (γ) was determined from specific heat measurements to be ∼13 mJ/molCoK2 and ∼7 mJ/molNiK2 for Co7Se8−xSx and Ni7Se8−xSx, respectively. 相似文献
39.
The direct reaction of iron pentacarbonyl with diethylamidocyclohexadiene gave three isomeric tricarbonyliron complexes, 1, 2 and 3. Only 1 isomerized to give 2 under acidic conditions, whereas 3 remained unchanged. The chemical properties of the tricarbonyl(amidocyclohexadiene)iron complexes differed from those of the tricarbonyl(carboxycyclohexadiene)iron complexes. Complex 3 which underwent no hydride abstraction with triphenylmethyl hexafluorophosphate, has an exo stereochemistry. 相似文献
40.
Yeow YL McGowan KL Ong SI Leong YK 《Langmuir : the ACS journal of surfaces and colloids》2005,21(24):11241-11250
The problem of obtaining the first and second derivatives of the profile of a pendant droplet is formulated as an integral equation of the first kind. This equation is solved by Tikhonov regularization in which the method of general cross validation is used to guide the selection of the regularization parameter. These derivatives are converted into mean curvature as a function of droplet height. Surface tension is then obtained by regression computation between the mean curvature and two possible algebraic expressions suggested by the Laplace-Young equation. This way of obtaining surface tension is demonstrated by applying it to a number of published droplet profiles. Some of the problems encountered are discussed and solutions suggested. 相似文献