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Effects　of　Zn^（2＋）　on　root　growth，cell　division，and　nucleoli　of　Allium　cepa　L．

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Journal of Environmental Sciences 1996年第1期8卷 21-27页

作者： Liu Donghua Jiang Wusheng Wang Chunli (Department of Biology, tianjin Normal University,tianjin 300074,china)Zhai Lin (Xinhua High School , tianjin 300204,china)

The effects of different concentrations of Zn￣(2+)ion on root growth,cell division,and nucleoli of Allium cepa were studied. The test Zn￣(2+) ion concentration was made up from zinc sulphate (ZnSO4. 7H2O) ranging from 10￣(-7) to 10￣(-2) mol/L. The solutions were prepared in tap water (pH =6. 5).The results indicated that Zn￣(2+) could obviously inhibit root growth at concentrations from 10￣(-4)to 10￣(-2) mol/*** treated with zinc sulphate showed the presence of c-mitosis, anaphase bridges,including sticky and fluidized bridges (at 10￣(-3) to 10￣(-2) mol/L) , chromosome stickiness, irregularly shaped nuclei, broken nuclei and micronuclei. A toxicity effect was also observed on the nucleoli using silver staining technique after 48h of treatment with 10￣(-4)to 10￣(-2) mol/L Zn￣(2+), e. g,the nucleolar particulate material scattered around the nucleoli in the nucleus of root tip cells.

关键词： Allium cepa mitosis chromosome aberration nucleoli silver staining technique.

COMBINED LEGENDRE SPECTRAL-FINITE ELEMENTMETHOD FOR THE TWO-DIMENSIONAL UNSTEADYNAVIER-STOKES EQUATION

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Journal of Computational Mathematics 1999年第5期17卷 495-508页

作者： Song-man He Cai-ping Yang(Department of Basic Courses, Civil Aviation University of china, tianjin 300300, china) 中国民用航空学院天津

A combined Legendre spectral-finite element approximation is proposed for solving two-dimensional unsteady Navier-Stokes equation. The artificial compressibility is used. The generalized stability and convergence are ... 详细信息

关键词： Navier-Stokes equation combined Legendre spectral-finite element approximation

Integrated modeling of nitrogen oxides formation in diesel engines

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Progress in Natural Science:Materials International 2007年第12期17卷 1476-1481页

作者： Song Jinou, Yao Chunde and Wang Hongfu(State Key Laboratory of Engine, tianjin University, tianjin 300072, china) State Key Laboratory of Engine Tianjin University Tianjin 300072 China

To account for the effects of both chemistry and flow turbulence, the present study proposes an integrated NO sub-model that combines the extended Zel’dovich mechanism and engine CFD computations to simulate the NO histories in a diesel engine. NOx sub-model parameters and pollutant formation mechanisms can be more easily investigated by solving the NOx sub-model. The new NO formation model incorporating the effects of both chemical kinetics and turbulent mixing was applied to simulate a diesel engine with a quiescent combustion chamber, and one with a re-entrant combustion chamber; the premise of the model being the reaction rate is mainly determined by a kinetic timescale and a turbulent timescale. The results indicate that the predicted NO formulation from the new model agrees well with the measured data. As the utilization of fossil fuels continues to increase, the control of NOx emissions is a worldwide concern; and it is imperative to understand fully the NOx reaction processes in combustion systems. This technology has the potential to enhance the application of various combustion techniques used to reduce NOx emissions from practical combustion systems.

关键词： nitrogen oxides (NOx) combustion turbulence diesel.

Inherent mechanism of breakdown in laminar-turbulent transition of plane channel flows

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Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 228-236页

作者： LUO Jisheng, WANG Xinjun & ZHOU Heng Department of Mechanics, tianjin University Liu-Hui Center of Mathematics, Nankai and tianjin University, tianjin 300071, china Department of Mechanics Tianjin University Tianjin China Liu-Hui Center of Mathematics Nankai and Tianjin University Tianjin China

Laminar-turbulent transition is an old yet unsolved problem. Notwithstanding the great effort made, there is an important question that seems not to have been addressed yet, that is, what is the inherent mechanism of breakdown that eventually leads to transition? The conventional idea is that the transition starts from the amplification of disturbances, and when the disturbances become larger, higher harmonics will be generated due to nonlinear effect, making the flow more and more complicated, and finally turbulent. Though the scenario seems clear, yet there is a missing link, that is, what happens in the breakdown process. Here we show by analyzing the results from direct numerical simulations that the change of stability characteristics of the mean flow profile plays a key role in the breakdown process.

关键词： laminar-turbulent transition, breakdown, plane channel flow.

1. 32μm Nd3+: YAG Pulse Laser

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Chinese Journal of Lasers 2002年第2期11卷 3-5页

作者： WANG Zhaoying WU Xing(College of Precision Instrument and Optoelectronics Engineering, tianjin University, tianjin 300072, china) Precision Instrument and Optoelectronics Engineering Tianjin University 天津 300072

Using specially coated mirrors, an output energy of 0.97 J at 1.32 μm from a Nd3+: YAG pulse laser is obtained with pumping energy of 66 J. The repetition rate is 1 pulse/sec and the slope efficiency is 1.7%. The rep... 详细信息

关键词： 1.32 μm specially coated mirrors pulse repetition

Laser glazing study of Co-based alloy and Ni-Nb-Cr alloy coating

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Chinese Journal of Lasers 1994年第4期B3卷 377-384页

作者： TIAN Nailiang(Department of Applied Physics,tianjin Institute of Science and Technology, tianjin 300191,china)YANG Yongqiang(Department of Mechanics, tianjin Institute of Textile Science and Technology,tianjin 300160, china) tianjin Inst of Science and Technology Tianjin China

ＬａｓｅｒｇｌａｚｉｎｇｓｔｕｄｙｏｆＣｏ－ｂａｓｅｄａｌｌｏｙａｎｄＮｉ－Ｎｂ－Ｃｒａｌｌｏｙｃｏａｔｉｎｇ￥ＴＩＡＮＮａｉｌｉａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＰｈｙｓｉｃｓ，ＴｉａｎｊｉｎＩｎｓｔｉ... 详细信息

ＬａｓｅｒｇｌａｚｉｎｇｓｔｕｄｙｏｆＣｏ－ｂａｓｅｄａｌｌｏｙａｎｄＮｉ－Ｎｂ－Ｃｒａｌｌｏｙｃｏａｔｉｎｇ￥ＴＩＡＮＮａｉｌｉａｎｇ（ＤｅｐａｒｔｍｅｎｔｏｆＡｐｐｌｉｅｄＰｈｙｓｉｃｓ，ＴｉａｎｊｉｎＩｎｓｔｉｔｕｔｅｏｆＳｃｉｅｎｃｅａｎｄＴ...

关键词： Metallic glass cladding layer Co-based

Homotopy type of smooth weighted complete intersections

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Science china Mathematics 2010年第6期53卷 1583-1594页

作者： WANG JianBo1,& WANG YuYu2 1Department of Mathematics,tianjin University,tianjin 300072,china 2College of Mathematical Science,tianjin Normal University,tianjin 300387,china Department of Mathematics Tianjin University Tianjin China College of Mathematical Science Tianjin Normal University Tianjin China

If the total degree d has no prime divisors less than(n+3)/2,then we prove that the homotopy type of complex odd dimensional smooth weighted complete intersection Xn(d;w) is determined by the dimension n,the total degree d,the Euler characteristic and the Kervaire invariant,provided that the weights w =(ω0,...,ωn+r) is pairwise relatively prime.

关键词： weighted projective space weighted complete intersection homotopy type connected sum

The mechanism of breakdown in laminar-turbulent transition of a supersonic boundary layer on a flat plate-temporal mode

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Science china(Physics,Mechanics & Astronomy) 2005年第5期48卷 614-625页

作者： HUANG Zhangfeng 1, CAO Wei 1,2 & ZHOU Heng 1,2 1. Department of Mechanics, tianjin University, tianjin 300072, china 2. Liu-Hui Center of Applied Mathematics, Nankai University and tianjin University, tianjin 300072, china Department of Mechanics Tianjin University Tianjin China Liu-Hui Center of Applied Mathematics Nankai University and Tianjin University Tianjin China

Temporal mode direction numerical simulation has been done for the transition of a supersonic boundary layer on a flat plate with Mach number 4.5. Analysis of the result showed that during the breakdown process in laminar-turbulent transition, the mechanism causing the mean flow profile to evolve swiftly from laminar to turbulent was that the modification of mean flow profile by the disturbances,when they became larger,led to a remarkable change of its stability characteristics. Though the most unstable T-S wave was of second mode for laminar flow, the first mode waves played the key role in the breakdown process in laminar-turbulent transition.

关键词： supersonic boundary layer, transition, breakdown.

On homotopy regular monomorphisms

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Chinese Science Bulletin 1998年第1期43卷 27-30页

作者： CHEN Jixiang Department of Mathematics, Nankai University, tianjin 300071, china Department of Mathematics Nankai University Tianjin China

A concept of homotopy regular monomorphism is introduced which is strictly between homotopy monomorphism and homotopy equivalence. And it characterizes homotopy equivalence in some sense.

关键词： homotopy monomorphism homotopy equalizer homotopy regular monomorphism homotopy pull back.