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排序方式: 共有115条查询结果,搜索用时 328 毫秒
1.
N. N. Kolos V. D. Orlov E. K. Slobodina E. Yu. Yur'eva S. P. Korshunov Zyong van Tué 《Chemistry of Heterocyclic Compounds》1992,28(2):222-227
1,2,4-Triazolo[3,4-b]-1,3,4-thiadiazines, hydrazones, and -thio adducts were obtained by reactions of 4-amino-3-mercapto-1,2,4-triazole with -bromoacetophenones, aldehydes, and ,-unsaturated ketones. Conditions that promote the cyclocondensation of the -thio adducts to the previously undescribed 1,2,4-triazolo[3,4-b]-1,3,4-thiadiazepines were found. The chemical and spectral properties of the compounds obtained are discussed.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 267–272, February, 1992. 相似文献
2.
In the presence of trialkylamine and formic acid RuCl2(PPh3)3 selectively reduces aldehydes to the corresponding alcohols at room temperature. Other reducible groups are unaffected. 相似文献
3.
Kam Yee Yoon Wen Siang Tan Beng Ti Tey Khai Wooi Lee Kok Lian Ho 《Electrophoresis》2013,34(2):244-253
Hepatitis B core antigen (HBcAg) expressed in Escherichia coli is able to self‐assemble into large and small capsids comprising 240 (triangulation number T = 4) and 180 (triangulation number T = 3) subunits, respectively. Conventionally, sucrose density gradient ultracentrifugation and SEC have been used to separate these capsids. However, good separation of the large and small particles with these methods is never achieved. In the present study, we employed a simple, fast, and cost‐effective method to separate the T = 3 and T = 4 HBcAg capsids by using native agarose gel electrophoresis followed by an electroelution method (NAGE‐EE). This is a direct, fast, and economic method for isolating the large and small HBcAg particles homogenously based on the hydrodynamic radius of the spherical particles. Dynamic light scattering analysis demonstrated that the T = 3 and T = 4 HBcAg capsids prepared using the NAGE‐EE method are monodisperse with polydispersity values of ~15% and ~13%, respectively. ELISA proved that the antigenicity of the capsids was not affected in the purification process. Overall, NAGE‐EE produced T = 3 and T = 4 capsids with a purity above 90%, and the recovery was 34% and 50%, respectively (total recovery of HBcAg is ~84%), and the operation time is 15 and 4 times lesser than that of the sucrose density gradient ultracentrifugation and SEC, respectively. 相似文献
4.
Cyclodimerization of norbornadiene (NBD) yielding pentacyclic products of exo-trans(cis)endo-structure in the presence of the model catalytically active complex Ni(H)(η4-NBD) has been studied using the DFT/PBE method. The rate-limiting reaction step is the reductive elimination of the metallacycle, the decomposition of the latter yields the norbornadiene dimer. 相似文献
5.
6.
N. Kh. Zyong N. D. Musayev R. I. Nigmatulin 《Journal of Applied Mathematics and Mechanics》1987,51(6):749-757
Selfsimilar solutions of a system of stationary equations of heat condunction and filtration of molten material in the presence of a volume heat source generated by absorption of the energy of electromagnetic radiation, are considered. The possibility of the existence of a self-similar solution in the case of various (plane, cylindrical and spherical) spatial symmetries is studied. The existence of a selfsimilar solution is shown for the axisymmetric case when the radiation obeys a prescribed law. The influence of the surface volume heating and convective heat transfer due to filtration is studied. A solution for the case when the filtration of the molten phase is quasistationary is also investigated. 相似文献
7.
Unsteady wave processes in vapor-liquid media containing bubbles are investigated taking into account the unsteady interphase heat and mass transfer. A single velocity model of the medium with two pressures is used for this, which takes into account the radial inertia of the liquid with a change in volume of the medium and the temperature distribution in it [1]. The system of original differential equations of the model is converted into a form suitable for carrying out numerical integration. The basic principles governing the evolution of unsteady waves are studied. The determining influence of the interphase heat and mass transfer on the wave behavior is demonstrated. It is found that the time and distance at which the waves reach a steady configuration in a vapor-liquid bubble medium are considerably less than the correponding characteristics in a gas-liquid medium. The results of the calculation are compared with experimental data. The propagation of acoustic disturbances in a liquid with vapor bubbles was studied theoretically in [2]. The evolution of waves of small but finite amplitude propagating in one direction in a bubbling vapor-liquid medium is investigated in [3, 4] on the basis of the generalization of the Burgers-Korteweg-de Vries equation obtained by the authors. An experimental investigation of shock waves in such a medium is reported in [5, 6], and the structure of steady shock waves is discussed [7].Translated from Izvestiya Akademii Nauk SSSR, Hekhanika Zhidkosti i Gaza, No. 5, pp. 117–125, September–October, 1984. 相似文献
8.
9.
Comparing several population means: a parametric bootstrap method, and its comparison with usual ANOVA F test as well as ANOM 总被引:3,自引:0,他引:3
This paper deals with testing the equality of several homoscedastic normal population means. We introduce a newly developed
computational approach test (CAT), which is essentially a parametric bootstrap method, and discuss its merits and demerits.
In the process of studying the CAT’s usefulness, we compare it with the traditional one-way ANOVA’s F test as well as the analysis of means (ANOM) method. Further, the model robustness of the above three methods have been studied
under the ‘t-model’. The motivation behind the proposed CAT is to provide the applied researchers a statistical tool to carry out a comparison
of several population means, in a parametric setup, without worrying about the sampling distribution of the inherent test
statistic. The CAT can be used to test the equality of several means when the populations are assumed to be heteroscedastic
t-distributions. 相似文献
10.
Duong Minh Duc Tran Vinh Hung Nguyen Tien Khai 《Proceedings of the American Mathematical Society》2007,135(3):921-927
Using elementary differential calculus we get a version of the Morse-Palais lemma. Since we do not use powerful tools in functional analysis such as the implicit theorem or flows and deformations in Banach spaces, our result does not require the -smoothness of functions nor the completeness of spaces. Therefore it is stronger than the classical one but its proof is very simple.