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81.
Luo Zhiguo Shen JianhuaDept. of Math. Hunan Normal Univ. Changsha . E mail: luozg@mail. hunnu.edu.cn 《高校应用数学学报(英文版)》2000,(4)
§ 1 IntroductionDelay differential equations with piecewise constant arguments repressenta hybrid ofcontinuous and discrete dynamical systems and combine the properties of both differentialand difference equations.They have particular importance in control theory and certainbiomedical problems.Recently there has been a lot of activities concerning the oscillatoryproperties of solutions of such equations.See,for example[1~ 4 ] and the comprehensivesurvey paper[5] .Consider the linear delay … 相似文献
82.
石墨炉原子吸收法直接测定啤酒中铝 总被引:1,自引:0,他引:1
采用高速枪弹射击猪单后肢软组织,观察伤后远离原发伤道的血管内皮细胞的形态学变化,为远达效应的血流扰动学说提供实验资料。动物伤后6h解剖,大体见双肺下叶、左室后壁以及大脑的痛、腹侧面均有不同程度的血管破裂、出血,或毛细血管充血。光镜见猪主动脉弓内皮细胞有水肿,或脱落呈“鞋钵样”垂直悬吊在血管腔内;连续切片见内皮层有剥脱现象。 相似文献
83.
SI Shi-Hui CHEN Jin-Hua HE Feng-Jiao NIE Li-Hua YAO Shou-ZhuoNew Material Research Institute Hunan University Changsha Hunan China 《中国化学》1996,14(3):222-227
Electropolymerized o-phenylenediamine film is used as a functional coating for the immobilization of anti-S. aureus antibody on the surface of a gold-plated piezoelectric crystal, and this piezoelectric immunosensor is applied to detect S. aureus. The frequency shift (F = F20s - F380s, Hz) between the frequency at the 20th second (after the addition of sample, F20s) and that at 380 seconds later (F380s) was introduced to construct a calibration graph, and shortening of assay time was achieved. The S. aureus concentrations in the range of 105-109 cells/mL can be detected by this system. 相似文献
84.
Combustion instability of O2/kerosene, O2/kerosene/hydrogen, and O2/kerosene/hydro-gen spray flame is numerically studied. The numerical results of combustion self-oscillation are consistent with the historical experiments. Hydrogen is helpful to stabilizing oxygen/hydrocarbon combustion. High gas injecting velocity of the coaxial injector would increase the combustion stability. Contrary to the former expectation, the most sensitive region for combustion instability is not where the heat releases most intensely but is the low-temperature premixed region near the injectors. According to the simulation, the technology steps, such as adding catalyzer to decrease the reaction activity energy, or improving the injector design to reduce the premixed low temperature region, would improve the combustion stability. 相似文献
85.
Carbon dioxide was found as a selective agent to promote the palladium-catalyzed cyclotrimerization of alkynes in water. Both aryl and alkylacetylenes afforded the corresponding cyclotrimerization products regioselectively in high yields using PdCl2, CuCl2, and CO2 as the catalytic system. However, tert-butylacetylene bearing a bulky group gave a dimerization product. Mechanism of this reaction was also discussed. 相似文献
86.
Liang Ximing Li Fei Xu Chengxian College of Information Science Engineering Central South Univ. Changsha . School of Science Xi''''an Jiaotong Univ. Xi''''an . 《高校应用数学学报(英文版)》2000,(4)
§ 1 IntroductionThe problem of finding a point x* ∈S such that〈F(x* ) ,x -x* 〉≥ 0 for all x∈ S,(VIP)where S is a nonempty closed convex subset of Rn,F is a mapping from Rninto itself,and〈.,.〉denotes the inner productin Rn,is called the variational inequality problem and hasbeen widely used to study various equilibrium models arising in economic,operations re-search,transportation and regional sciences[1 ,2 ] .Many iterative methods for (VIP) havebeen developed,for example,project… 相似文献
87.
STRENGTH CRITERION FOR PLAIN CONCRETE UNDER MULTIAXIAL STRESS BASED ON DAMAGE POISSON’S RATIO 总被引:1,自引:0,他引:1
Ding Faxing School of Civil Engineering Architecture Central South University Changsha China
YU Zhiwu School of Civil Engineering Architecture Central South University Changsha China 《Acta Mechanica Solida Sinica》2006,(4)
A new unified strength criterion in the principal stress space has been proposedfor use with normal strength concrete (NC) and high strength concrete (HSC) in compression-compression-tension, compression-tension-tension, triaxial tension, and biaxial stress states. Thestudy covers concrete with strengths ranging from 20 to 130 MPa. The conception of damagePoisson's ratio is defined and the expression for damage Poisson's ratio is determined basically.The failure mechanism of concrete is illustrated, which points out that damage Poisson's ratiois the key to determining the failure of concrete. Furthermore, for the concrete under biaxialstress conditions, the unified strength criterion is simplified and a simplified strength criterion inthe form of curves is also proposed. The strength criterion is physically meaningful and easy tocalculate, which can be applied to analytic solution and numerical solution of concrete structures. 相似文献
88.
SI Shi-Hui NIE Li-Hua YAO Shou-ZhuoNew material Research Institute Hunan University Changsha Hunan China 《中国化学》1994,12(5):432-439
Based on the impedance behavior of red cell at high frequency, the frequency response of series piezoelectric crystal sensor in the red cell suspension was derived and verified experimentally. A method of using piezoelectric crystal sensor to determine the conductivity of the interior of the cell was proposed. The experimental results show that the mean conductivity of rabbit red cell cytoplasm was 0.269 S/m and the mean shape factor of red cell was 2.05. 相似文献
89.
1 IntroductionConsider one-dimellsional parabolic problem in fl = (0, 1)and its weak formulatioll: find u(t) E S0 = {v 6 H'(fl), v(0) = 0} 8uch thatwhere the coefficients a(x) and b(x) are independent of t, Au = --(au')' ha, a(x) 2 ao > 0, b 20, and bilinear fOrm A(u, v) = fol(au'V' buv)dx i8 So-coercive, i.e. A(u, v) 2 ullu1li, u ESO, u > 0.Make in n = (0, 1) a subdivision: xo = 0 < x1 < x2 <.' < xn = 1. Set an elenlentry = (xj--l, xj), nddpoint xj--1/2 = (ry n--1)/2 and steplengt… 相似文献