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A study on the allocation of productive factors of Chinese agriculture

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Journal of Geographical Sciences 2000年第1期10卷 59-65页

作者： LIU Yan-li (Institute of Rural Development, china Agricultural University, beijing 100094, china) 中国农业大学北京

Chinese agriculture is undergoing a transformation process from traditional agriculture into modern *** article discusses how land. labor, fertilizer, machinery etc. are used in agricultural production of different regions. reveals the influence of natural conditions and economic level on the utilization of modern agricultural factors. It proposes a system of allocation hoes of regional agricultural productive factors and points out the development stage and tendency of allocation of agricultural productive factors in different regions.

关键词： agricultural productive factor, innovative productive factor,traditional allocation technological allocation

THE RIEMANN-HILBERT BOUNDARY VALUE PROBLEM FOR FIRST ORDER COMPLEX EQUATIONS OF MIXED TYPE

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Systems Science and Mathematical Sciences 1999年第4期12卷 357-365页

作者： WEN Guochun(Department of Mathematics, Peking University, beijing 100871, china) 北京大学数学系北京

In this Paper the Riemann--Hilbert boundary value problem for first orderquasilinear complex equations of mixed (elliptic- hyperbolic ) type is discussed. Firstly, therepresentation theorem is given, afterwards by using the method of successive iterations,the existence and uniqueness of solutions for the above problem are proved. In [1], *** discussed the Tricomi problem for some linear mixed equation of second order,which can be derived from the results of the present paper.

关键词： Riemann-Hilbert problem mixed complex equations uniqueness and existence.

The　concentration　of　total　dissolved　CO_2　in　surface　water　in　ENSO　event──The　results　of　investigation　during　TOGA　expeditions

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Acta Oceanologica Sinica 1995年第2期14卷 208-224页

作者： Ma Liming Zhang Bin and Qiao Ran (National Research center for Marine Environmental Forecasts, State Oceanic Administration, beijing 100081, china)

The observations of total dissolved CO2 (TCO2) in surface water on the range from 115°E to 165°E,from 10°S to 20°N from Dec. 1986 to Jun. 1990, present following results: There was distinguished difference of distribution of TCO2 between during El Nino and La Nina, especially on east of 155° E and equator. During El Nino TCO2 was the lowest (TCO2, 1 900 μmol/kg) in seven cruises and proportional to salinity, the dominant effect of current was from North Equatorial Current (NEC). During La Nina the value of TCO2 became the highest (TCO2 >1 900 μmol/kg) in range of Equatorial Upwelling, the dominant effect was from South Equatorial Current. The effect of air-sea exchange and biological activity increased. The types of distribution and interannual variations of TCO2 in 110 single stations and 23.small areas, the characteristics of relationship among TCO2, PCO2, S, SST during El Nino and La Nina are discussed in this *** above results it is clear that TCO2 is a useful observational quantity, which reflects the alteration of atmosphere-sea system and the change of surface currents, air-sea exchange and biological activity caused by this alteration.

关键词： ENSO event investigation

DISTRIBUTION MODEL OF FATIGUE LIFEAND ITS GOODNESS-OF-FIT TEST

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Chinese Journal of Aeronautics 1995年第3期8卷 185-190页

作者： Dong Cong Rong Haiwu Xia Renwei(Department of Aircraft Engineering, beijing University ofAeronautics and Astronaulies, beijing, china, 100081)

ＤＩＳＴＲＩＢＵＴＩＯＮＭＯＤＥＬＯＦＦＡＴＩＧＵＥＬＩＦＥＡＮＤＩＴＳＧＯＯＤＮＥＳＳ－ＯＦ－ＦＩＴＴＥＳＴＤｏｎｇＣｏｎｇ；ＲｏｎｇＨａｉｗｕ；ＸｉａＲｅｎｗｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＡｉｒｃｒａｆｔＥｎｇｉ... 详细信息

ＤＩＳＴＲＩＢＵＴＩＯＮＭＯＤＥＬＯＦＦＡＴＩＧＵＥＬＩＦＥＡＮＤＩＴＳＧＯＯＤＮＥＳＳ－ＯＦ－ＦＩＴＴＥＳＴＤｏｎｇＣｏｎｇ；ＲｏｎｇＨａｉｗｕ；ＸｉａＲｅｎｗｅｉ（ＤｅｐａｒｔｍｅｎｔｏｆＡｉｒｃｒａｆｔＥｎｇｉｎｅｅｒｉｎｇ，ＢｅｉｊｉｎｇＵｎ...

关键词： fatigue life distnbution goodness of fit

SPECIAL HIGH-ORDER BENDING CRACK TIP FINITE ELEMENT FOR THE REISSNER PLATE

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Chinese Journal of Aeronautics 1997年第4期10卷 31-37页

作者： Jiang Chiping (Department of Flight Vehicle Design and Applied Mechanics, beijing University of Aeronautics and Astronautics. beijing, 100083. china) Liu Chuntu (Institute of Mechanics, Chinese Academy of Sciences, beijing, 100080, china)

Based on the crack tip field expansion of the Reissner plate, a special high order bending crack tip element is developed, and the element stiffness matrix is given in the explicit form, which is especially convenient for engineering analyses. A numerical example is presented and compared with previous results to demonstrate the efficiency and accuracy of the special element.

关键词： Reissner theory plates fracture mechanics stress intensity factors finite element method bending crack tip element

A　GENERALIZED　GRADIENT　METHOD　FOR　NONLINEAR　CONSTRAINTS　AND　ITS　CONVERGENT　PROPERTIES

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Systems Science and Mathematical Sciences 1996年第2期9卷 140-144页

作者： GAO Ziyou (Northern Jiaotong University, beijing 100044, china) 北方交通大学北京 100044

ＡＧＥＮＥＲＡＬＩＺＥＤＧＲＡＤＩＥＮＴＭＥＴＨＯＤＦＯＲＮＯＮＬＩＮＥＡＲＣＯＮＳＴＲＡＩＮＴＳＡＮＤＩＴＳＣＯＮＶＥＲＧＥＮＴＰＲＯＰＥＲＴＩＥＳＧＡＯＺｉｙｏｕ（ＮｏｒｔｈｅｒｎＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉ... 详细信息

ＡＧＥＮＥＲＡＬＩＺＥＤＧＲＡＤＩＥＮＴＭＥＴＨＯＤＦＯＲＮＯＮＬＩＮＥＡＲＣＯＮＳＴＲＡＩＮＴＳＡＮＤＩＴＳＣＯＮＶＥＲＧＥＮＴＰＲＯＰＥＲＴＩＥＳＧＡＯＺｉｙｏｕ（ＮｏｒｔｈｅｒｎＪｉａｏｔｏｎｇＵｎｉｖｅｒｓｉｔｙ，Ｂｅｉｊｉｎｇ１０００４４，...

关键词： Constrained optimization generalized gradient projection method degencracy convergent properties.

Modeling Study of the Particle Pinning Effect on the Grain Boundary Movement

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Journal of Iron and Steel Research International 2011年第S1期18卷 342-345页

作者： WANG Xue-lun 1,FU Li-ming 2,WANG Wei 3.JIA Zhi-xin 1 (1.Rizhaosteel Technology center,Rizhao Iron and Steel Co Ltd.Rizhao 276806,china 2.School of Materials Science and Engineering,Shanghai Jiaotong University,Shanghai 200240 china 3.Department of Structural Steels,Baosteel Research Institute,Shanghai 201900,china) Rizhao Iron & Steel Co Ltd Rizhaosteel Technol Ctr Rizhao 276806 Peoples R China Shanghai Jiao Tong Univ Sch Mat Sci & Engn Shanghai 200240 Peoples R China Baosteel Res Inst Dept Struct Steels Shanghai 201900 Peoples R China

In this work,based on the classical grain boundary (GB) formula and the principle of work-energy conversion,a new physically-based model has been developed to predict the particle pinning force concerning the interaction between second phase particles (SPPs) and the moving *** effect of particles pinning on the GB movement is *** modeling results can be applied to quantitatively determine the critical numbers of SPPs required for complete pining the grain growth,such as the critical SPPs number of the unit GB area,the critical number for single grain stagnation,the critical volume fraction of particles at a given particle *** predictions are in good agreement with the experimental results by Gladman.

关键词： the second-phase particle pinning force physical-based model

FREQUENCY SELECTIVITY OF PRIMARY AUDITORY NEURONS IN THE BUSHCRICKET GAMPSOCIEIS GRATIOSA

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Chinese Journal of Acoustics 1989年第1期8卷 80-85页

作者： SHEN Junxian(Institute of Biophysics, Academia Sinica, beijing) Acad Sinica China

Sound is one of the information carriers often used in animal communication. Sound produced by animals is useful not only in intraspecific communication,but also in alarm or *** basic problems in hearing should be resolved i. e. frequency selectivity, pattern recognition and sound direction. With intracellular recording and single cell staining techniques, frequency selectivity of primary auditory neurons in the bushcricket has been studied. Each neuron has its characteristic best frequency (BF) and tuning curve in response to sound. The central projections of their axons in the prothoracic ganglion are unikteral, non - transsegmental and of some corresponding relation to their BFs. Neural mechanisms for frequency analysis in species - specific song recognition of the bushcricket are discussed.

关键词： FREQUENCY SELECTIVITY OF PRIMARY AUDITORY NEURONS IN THE BUSHCRICKET GAMPSOCIEIS GRATIOSA kHz

Intrinsic ultracontractivity on Riemannian manifolds with infinite volume measures

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Science china Mathematics 2010年第4期53卷 895-904页

作者： WANG FengYu 1,2 1 School of Mathematical Sciences,beijing Normal University,beijing 100875,china 2 Department of Mathematics,Swansea University,Singleton Park,Swansea SA2 8PP,UK 1. School of Mathematical Sciences Beijing Normal University Beijing 100875 China2. Department of Mathematics Swansea University Singleton Park Swansea SA2 8PP UK

By establishing the intrinsic super-Poincar'e inequality,some explicit conditions are presented for diffusion semigroups on a non-compact complete Riemannian manifold to be intrinsically *** conditions,as well as the ... 详细信息

关键词： intrinsic ultracontractivity intrinsic super-Poincar’e inequality Riemannian manifold diffusion semigroup