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281.
S. T. Boneva V. A. Khitrov Yu. V. Kholnov Le Hong Khiem Pham Dinh Khang Yu. P. Popov A. M. Sukhovoj V. A. Bondarenko I. L. Kuvaga P. T. Prokofiev G. L. Rezvaja L. I. Simonova 《Zeitschrift für Physik A Hadrons and Nuclei》1993,346(1):35-42
The applicability of the method of summed amplitudes of coinciding pulses to determine radiative strength functions of heavy nuclei by measuring two-step cascade-ray spectra is discussed. Experiments based on thermal neutron capture in136Ba and180Hf were carried out to test this method. The values obtained for the radiative strength functions of a wide range of primary transitions were compared with the predictions of two modifications of the giant dipole resonance model. Some insight into the characteristics of the-decay of compound-states is provided by analyzing the information obtained on the two-step-decay of a number of nuclei in the mass region 137A187.Authors' thanks are due to Mrs. T.F. Drozdova and Dr. M.A. Ali for their help in the preparation of the English version of this paper. 相似文献
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Wender PA Gamber GG Hubbard RD Pham SM Zhang L 《Journal of the American Chemical Society》2005,127(9):2836-2837
Prompted by the view that intermediates of transition metal-catalyzed reactions could be intercepted by one or more additional components, studies in our laboratory have led to the design and development of new three-component [5+2+1], [4+2+1], and [2+2+1] cycloadditions. These continuing studies have now led to the identification of a fundamentally new four-component [5+1+2+1] cycloaddition reaction of vinylcyclopropanes, alkynes and CO, yielding hydroxyindanone products in generally good yields. Terminal alkynes bearing aryl or alkyl groups are tolerated well. Substitution at any position of the VCP leads predictably to substituted hydroxyindanone products. Using a bis-alkynyl substrate, the reaction can be carried out bi-directionally, forming 10 C-C bonds and four new rings from seven components in a single, operationally simple process. 相似文献
284.
Vo Dac Bang Tran Dai Nghiep Tran Duc Thiep Sh. Gerbish Phan Thu Huong Pham Thi Nam 《Journal of Radioanalytical and Nuclear Chemistry》1984,86(5):291-302
The combination of photon and neutron activation provides an effective method of analysis of rare earths and other elements. A mixed -neutron field is obtained with electron-to-gamma /e/ and gamma-to-neutron /n/ converters combined with a lucite moderator. The samples are activated simultaneously. The sensitivities of this method have been compared with neutron activation in a graphite moderator cube using the same microtron. The advantages and shortcomings of the method are discussed.Dedicated to Prof. V.D. Nefedov on the occasion of his 70th birthday 相似文献
285.
Some symptoms of excessive seepage of water were observed at the earthfill dam of the 400 MW Tri An hydropower plant in South Viet Nam. To provide experimental information for assessing the situation, isotope tracer experiments were performed using 24 existing piezometric boreholes encompassing a 1100 m long middle section of the dam. Filtration velocities measured were in the ranges (0.2–30) cm d–1 in the dam body and (0.5–75) cm d–1 in subsurface strata. No abnormally permeable horizons were detected. Permeability coefficients were calculated and compared with that obtained in pre-project hydrogeological surveys and by field tests during dam construction. Tracer experiments yielded permeability of the same range for the subsurface aquifer but from one to two orders of magnitude higher for the dam body. Such a dramatic change of permeability of the dam body me dia is interpreted as a result of interaction with seeping water after reservoir impoundment. A transient erosion process took place during several years. The losses of water by seepage through the dam body and infiltration to underground water were estimated as 1100 m3 d–1 and 15,000 m3 d–1 respectively, less than 1/2000 of the quantity of water consumed for power generation. A multi-well interconnection experiment was performed to determine the velocity and direction of subsurface flows. 相似文献
286.
In this paper, we give sufficient conditions for the existence of efficient solutions of a generalized vector quasi-equilibrium problem in topological vector spaces. The motivations for introducing this problem come from practical problems in traffic networks and the optimal control theory for discrete-time dynamical systems. The main results of the paper are proven with the help of a strongly monotonic function which can be constructed from the data of the problem under consideration. Some notions of cone-semicontinuity of set-valued maps, weaker than the usual concepts of semicontinuity, are also used in our study. As applications, we obtain existence results in vector quasi-optimization problems, Stampacchia set-valued vector quasi-variational inequality problems and Pareto vector quasi-saddle point problems. All these results are different from the corresponding ones in the literature. 相似文献
287.
Pham Huu Anh Ngoc 《Nonlinear dynamics》2018,93(2):385-393
By a novel approach, we give some explicit criteria for global exponential stability of singular nonlinear differential equations with delays. An application to electrical networks containing lossless transmission lines is presented. 相似文献
288.
Phan Van Kiem Chau Van Minh Nguyen Xuan Nhiem Nguyen Thi Cuc Ngo Van Quang Hoang Le Tuan Anh Bui Huu Tai Pham Hai Yen Nguyen Thi Hoai Kim Young Ho Nanyoung Kim SeonJu Park Seung Hyun Kim 《Magnetic resonance in chemistry : MRC》2014,52(1-2):51-56
Seven new muurolane‐type sesquiterpenes, (4R,5R)‐muurol‐1(6),10(14)‐diene‐4,5‐diol (1), (4R,5R)‐muurol‐1(6)‐ene‐4,5‐diol (2), (4R,5R,10R)‐10‐methoxymuurol‐1(6)‐ene‐4,5‐diol (3), (4S)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (4), (4R)‐4‐hydroxy‐1,10‐seco‐muurol‐5‐ene‐1,10‐dione (5), (6S,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (6), and (6R,10S)‐6,10‐dihydroxy‐7,8‐seco‐2,8‐cyclo‐muurol‐4(5),7(11)‐diene‐12‐oic acid (7) were isolated from the marine sponge Dysidea cinerea. Their structures were determined by the combination of spectroscopic and chemical methods, including 1D‐NMR, 2D‐NMR, and CD spectra as well as by comparing the NMR data with those reported in the literature. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
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