检索结果-南通市图书馆

在线全文

学校读者我要写书评

暂无评论

中国科学院黄河三角洲滨海湿地生态试验站

中国科学院院刊 2020年第2期35卷 229-231页

作者： Yantai Institute of Coastal Zone Research chinese academy of sciences 中国科学院烟台海岸带研究所烟台264003

中国科学院黄河三角洲滨海湿地生态试验站(以下简称"黄河三角洲站")位于山东省东营市黄河三角洲国家级自然保护区内,隶属于中国科学院烟台海岸带研究所。2009年4月由中国科学院烟台海岸带研究所和东营市人民政府共同筹建,2011年8月获中... 详细信息

中国科学院黄河三角洲滨海湿地生态试验站(以下简称"黄河三角洲站")位于山东省东营市黄河三角洲国家级自然保护区内,隶属于中国科学院烟台海岸带研究所。2009年4月由中国科学院烟台海岸带研究所和东营市人民政府共同筹建,2011年8月获中国科学院资源环境科学与技术局批复,属于中国科学院院级野外站,纳入中国科学院生态系统研究网络(CERN)管理,是唯一的院级滨海湿地研究站。

关键词：黄河三角洲中国科学院生态试验站山东省东营市滨海湿地环境科学与技术

INFLUENCE OF CAPILLARITY ON NANO-LITER FLOWRATE MEASUREMET WITH DISPLACEMET METHOD

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第5期19卷 594-600页

作者： GUO Qiang CHENG Rui SILBER-LI Zhan-hua State Key Laboratory of Nonlinear Mechanics Institute of Mechanics Chinese Academy of Sciences Beijing 100080 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200072 China

Nanoqiter flowrate measurements in micro-tubes with displacement method were performed and the effect of capillarity force on the accuracy was investigated through lab experiments and theoretical analysis in this article. The experiments were conducted under the pressure drops ranging from 1 kPa to 10 kPa in a circular pipe with a diameter of 50 pm, to give the pressure-flowrate （P-Q） relation and verify the applicability of the classical Hagen-Poiseuille （HP） formula. The experimental results showed that there existed a discrepancy between the experimental data and the theoretical values predicted by the HP formula if the capillary effect was not considered, which exceeded obviously the limit of the system error. And hence a modified formula for the relation, taking the capillary effect into account, was presented through theoretical deduction, and after the HP formula had been modified the error was proved to be less than 3%, which was permitted in comparison with the system error. It was also concluded that only by eliminating the effect of the capillary force in experiments could the original HP formula be employed to predict the pressure-flowrate relation in the Hagen-Poiseuille flow in the micro-tube.

关键词： nano-liter flowrate measurement,Hagen-Poiseuille (HP) formula displacement method,capillarity force

中国经济发展的机遇与挑战——学习中央经济工作会议精神座谈会综述

在线全文

学校读者我要写书评

暂无评论

中国工业经济 2024年第1期 5-16页

作者：中国社会科学院工业经济研究所课题组史丹不详中国社会科学院工业经济研究所

2023年12月11—12日,中央经济工作会议在北京举行。习近平总书记出席会议并发表重要讲话,全面总结2023年经济工作,深刻分析当前经济形势,系统部署2024年经济工作。会议要求,2024年要坚持稳中求进、以进促稳、先立后破,多出有利于稳预期... 详细信息

2023年12月11—12日,中央经济工作会议在北京举行。习近平总书记出席会议并发表重要讲话,全面总结2023年经济工作,深刻分析当前经济形势,系统部署2024年经济工作。会议要求,2024年要坚持稳中求进、以进促稳、先立后破,多出有利于稳预期、稳增长、稳就业的政策,在转方式、调结构、提质量、增效益上积极进取,不断巩固稳中向好的基础。要强化宏观政策逆周期和跨周期调节,继续实施积极的财政政策和稳健的货币政策,加强政策工具创新和协调配合。为深入解读2023年中央经济工作会议精神,中国社会科学院工业经济研究所“我国发展的新战略机遇与风险挑战研究”课题组邀请7位专家学者交流学习体会,立足当前经济走势,回应当下经济热点问题,为推动高质量发展建言献策。

关键词：高质量发展宏观政策科技创新城乡融合绿色低碳

THE CALCULUS OF GENERATING FUNCTIONS AND THE FORMAL ENERGY FOR HAMILTONIAN ALGORITHMS

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1998年第6期16卷 481-498页

作者： Feng K.(ICMSEC, chinese academy of sciences) chinese Acad Sci ICMSEC Beijing 100864 Peoples R China

In [2-4], symplectic schemes of arbitrary order are constructed by generating functions. However the construction of generating functions is dependent on the chosen coordinates. One would like to know that under what circumstance the construction of generating functions will be independent of the coordinates. The generating functions are deeply associated with the conservation laws, so it is important to study their properties and computations. This paper will begin with the study of Darboux transformation, then in section 2, a normalization Darboux transformation will be defined naturally. Every symplectic scheme which is constructed from Darboux transformation and compatible with the Hamiltonian equation will satisfy this normalization condition. In section 3, we will study transformation properties of generator maps and generating functions. Section 4 will be devoted to the study of the relationship between the invariance of generating functions and the generator maps. In section 5, formal symplectic erengy of symplectic schemes are presented.

关键词： generating function calculus of generating functions Darboux transformation cotangent bundles Lagrangian submanifold invariance of generating function formal energy

THE STEP-TRANSITION OPERATORS FOR MULTI-STEP METHODS OF ODE'S

在线全文

学校读者我要写书评

暂无评论

Journal of Computational Mathematics 1998年第3期16卷 193-202页

作者： Feng K.(ICMSEC, chinese academy of sciences) 中科院计算数学与科学工程计算所北京

In this paper, we propose a new definition of symplectic multistep methods. This definition differs from the old ones in that it is given via the one step method defined directly on M which is corresponding to the m step scheme defined on M while the old definitions are given out by defining a corresponding one step method on M × M ×…× M = Mm with a set of new variables. The new definition gives out a steptransition operator g: M → M. Under our new definition, the Leap-frog method is symplectic only for linear Hamiltonian systems. The transition operator g will be constructed via continued fractions and rational approximations.

关键词： Multi-step methods Explike and loglike function Fractional and rational approximation Simplecticity of LMM Nonexistence of SLMM.

Preliminary Response of Soil Fauna to Simulated N Deposition in Three Typical Subtropical Forests

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2006年第5期16卷 596-601页

作者： XU Guo-Liang MO Jiang-Ming ZHOU Guo-Yi FU Sheng-Lei Institute of Ecology South China Botanical Garden Chinese Academy of Sciences Guangzhou 510650 （China） Graduate School of the chinese academy of sciences Beijing 100039 （China）

A field-scale experiment arranged in a complete randomized block design with three N addition treatments including a control (no addition of N), a low N (5 g m-2 year-1), and a medium N (10 g m-2 year-1) was performed in each of the three typical forests, a pine (Pinus massoniana Lamb.) forest (PF), a pine-broadleaf mixed forest (MF) and a mature monsoon evergreen broadleaf forest (MEBF), of the Dinghushan Biosphere Reserve in subtropical China to study the response of soil fauna community to additions of N. Higher NH4+ and NO3- concentrations and a lower soil pH occurred in the medium N treatment of MEBF, whereas the NO3- concentration was the lowest in PF after the additions of N. The response of the density, group abundance and diversity index of soil fauna to addition of N varied with the forest type, and all these variables decreased with increasing N under MEBF but the trend was opposite under PF. The N treatments had no significant effects on these variables under MF. Compared with the control plots, the medium N treatment had significant negative effect on soil fauna under MEBF. The group abundance of soil fauna increased significantly with additions of higher N rates under PF. These results suggested that the response of soil fauna to N deposition varied with the forest type and N deposition rate, and soil N status is one of the important factors affecting the response of soil fauna to N deposition.

关键词： Dinghushan Biosphere Reserve N deposition soil fauna subtropical China

在线全文

学校读者我要写书评

暂无评论

中国科学院海北高寒草甸生态系统定位站

中国科学院院刊 2018年第10期33卷 1127-1129页

作者： Northwest Institute of Plateau Biology,chinese academy of sciences 中国科学院西北高原生物研究所

中国科学院海北高寒草甸生态系统定位站（以下简称为＂海北站＂）,始建于1976年,地处青藏高原东北隅祁连山区门源县境内。1978年,该站成为中国科学院院属台站,2000年成为国家科技部野外观测试点站,2002年加入中国陆地生态系统通量观测... 详细信息

中国科学院海北高寒草甸生态系统定位站（以下简称为＂海北站＂）,始建于1976年,地处青藏高原东北隅祁连山区门源县境内。1978年,该站成为中国科学院院属台站,2000年成为国家科技部野外观测试点站,2002年加入中国陆地生态系统通量观测研究网络（ChinaFLUX）,2006年成为国家科技部野外观测研究站,2013年加入中国荒漠-草地生态系统观测研究野外站联盟和高寒网。

关键词：高寒草甸生态系统中国科学院定位站国家科技部野外观测陆地生态系统草地生态系统祁连山区

Effect of Long-Term Application of Chemical Fertilizers on Microbial Biomass and Functional Diversity of a Black Soil

在线全文

学校读者我要写书评

暂无评论

Pedosphere 2008年第6期18卷 801-808页

作者： KONG Wei-Dong ZHU Yong-Guan FU Bo-Jie HAN Xiao-Zeng ZHANG Lei HE Ji-Zheng Research Center for Eco-Environmental sciences Chinese Academy of Sciences Beijing 100085 （China） Northeast Institute of Geography and Agricultural Ecology Chinese Academy of Sciences Harbin 150040 （China） Institute of Microbiology Chinese Academy of Sciences Beijing 100080 （China）

An experiment with seven N, P, K-fertilizer treatments, i.e., control (no fertilizer), NP, NK, PK, NPK, NP2K, and NPK2 where P2 and K2 indicate double amounts of P and K fertilizers respectively, was conducted to examine the effect of long-term continuous application of chemical fertilizers on microbial biomass and functional diversity of a black soil (Udoll in the USDA Soil Taxonomy) in Northeast China. The soil microbial biomass C ranged between 94 and 145 mg kg-1, with the NK treatment showing a lower biomass; the functional diversity of soil microbial community ranged from 4.13 to 4.25, with an increasing tendency from control to double-fertilizer treatments, and to triple-fertilizer treatments. The soil microbial biomass, and the microbial functional diversity and evenness did not show any significant differences among the different fertilizer treatments including control, suggesting that the long-term application of chemical fertilization would not result in significant changes in the microbial characteristics of the black soil.

关键词： Biolog black soil chemical fertilizer microbial biomass microbial functional diversity

A NUMERICAL STUDY ON MECHANISM OF S-STARTS OF NORTHERN PIKE (ESOX LUCIUS)

在线全文

学校读者我要写书评

暂无评论

Journal of Hydrodynamics 2007年第2期19卷 135-142页

作者： HU Wen-rong TONG Bing-gang LIU Hao Department of Engineering Mechanics Shanghai Jiaotong University Shanghai 200240 China Laboratory for Biomechanics of Animal Locomotion Graduate University of the Chinese Academy of Sciences Beijing 100039 China Laboratory for Biomechanics of Animal Locomotion Graduate University of the Chinese Academy otSciences Beijing 100039 China Department of Electronics and Mechanical Engineering Chiba University Japan

Northern pike is regarded as a specialist in swimming acceleration. The force production mechanism of northern pike, Esox lucius, during its predation S-starts was numerically studied in this article. The problem was reasonably simplified to a loose-coupling problem of fish swimming dynamics and hydrodynamics just in the swimming direction. The approach involved the simulation of the flow by solving the two-dimensional unsteady incompressible Navier-Stokes equations and decribing the fish motion dynamics based on Newton＇s Second Law. Visualizations of flow fields and vortex structures were performed. The results show that the large acceleration is obtained mainly in the first undulatory cycle in which the amplitude increases. In the second cycle, a couple of vortices are generated and induce a jet. In the third cycle, the jet is strengthened by the mergence of the vortices in the same direction. Through discussing the effects of various controllable factors on the swimming performance, it is found that the actual locomotion mode of the northern pike in nature is just the best choice.

关键词： S-starts of fish swimming Navier-Stokesequations mechanism of force production