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Search Results: 1 - 10 of 132081 matches for " 沈元林? "
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再评宫体诗

天府新论 , 2000,
Abstract: 本文对宫体诗作了客观的认识和重新评价,指出宫体虽格调不高,但也拓展了诗歌的描写领域,并对乐府民歌有所师承,不宜一概否定
侧风环境下高速列车外部流场数值模拟方法研究
,许建,赵鹤群,
工程力学 , 2012, DOI: 10.6052/j.issn.1000-4750.2010.08.0578
Abstract: 该文基于有限体积法的CFD软件以及块结构化和四面体非结构化网格,采用三维常物性定常不可压缩流动N-S方程的SIMPLE算法,利用国外典型模型试验数据对ICE2高速列车侧风环境下的空气绕流进行了数值模拟方法研究。结果表明:四面体非结构化和块结构化网格一样均能得到较好的结果,同时采用二次非线性高雷诺数k-ε模型和MARS差分格式的数值结果与试验数据吻合较好,从而验证了数值方法的正确性。在此基础上进行了四面体非结构化网格的独立性研究,得出适宜的网格总数和固壁法向第一层网格厚度合理的取值。该文确定的数值计算方法和四面体非结构化网格划分方法可用于复杂几何外形高速列车的数值模拟。
大别山北缘中生代火山―侵入岩锶―钕同位素组成特征及其物质来源
杨祝良,,渭洲,谢方贵,陶奎
矿物岩石 , 2002,
Abstract: 报道了大别山北缘中生代(早白垩世)不同成因系列火山-侵入岩的14个Rb-Sr,Sm-Nd同位素分析数据,其中正长岩类ISr值为0.70943-0.71014,εNd值为-14.7-15.8,亏损地幔两阶段模式年龄TDM为2.12-2.20Ga;高钾钙碱性系列岩石ISr值为0.70750-0.71054,εNd值为-17.2--19.1,TDM为2.32-2.48Ga,橄榄安粗岩系列岩石ISr值为0.70873-0.70912,εNd值为-20.7-21.7,TDM为2.60-2.68Ga。通过与基底变质岩Sm-Nd同位素组成对比,认为高钾钙碱性系列主要由类似于大别群的地壳岩石衍生而成,正长岩类是由大别群和少量较年轻地壳岩石(卢镇关群和佛子岭群?)衍生而成的,而橄榄安粗岩系列则来源于富集地幔并可能混入少量更古老的类似于泰山群的地壳组分。
北淮阳中生代火山―侵入岩同位素年代学研究
杨祝良,,渭洲,陶奎,谢芳贵
地质论评 , 1999,
Abstract: 北淮阳(大别山北缘)中生代火山―侵入岩带西起河南信阳东至安徽舒城,早期为偏中性和偏碱性的火山碎屑岩、熔岩及相应侵入岩,晚期出现酸性火山岩及相应侵入岩。关于该带的年代学工作前人已做了较多的研究,但所用方法仅局限于全岩KAr法和单矿物????40?Ar????39?Ar法。本文以全岩及全岩―矿物RbSr等时线法为主,辅以单矿物????40?Ar????39?Ar法和单颗粒锆石UPb稀释法,较系统地测定了该带火山―侵入岩的时代,结果表明主期活动在130~140Ma,晚期酸性活动在117Ma左右,基本上均属于早白垩世。
香蕉多糖的分离纯化及其性质研究
,余龙江,金文闻,,朱涛
食品科学 , 2004,
Abstract: ??本文建立了香蕉多糖的提取纯化方法,并对提取的香蕉多糖进行了理化性质分析。香蕉多糖经40%乙醇分级得到的组分len5,用seohadexg-150凝胶柱层析得到单一峰,len5的酸性水解液经纸层析和薄层层析分析,其单糖组成为葡萄糖和木糖,用sephadexg-150凝胶柱层析法测得其分子量为43000道尔顿。
A NEW CONFIGURATION OF THE LASER CAVITY FOR SIMULTANEOUS DUAL WAVELENGTH Q-SWITCH PULSED Nd
一种新型结构的Nd∶YAlO3双波长调Q脉冲激光器

LIN WEN-XIONG,SHEN HONG-YUAN,
文雄
,鸿

物理学报 , 1999,
Abstract: 从Nd∶YAlO3 (Nd∶YAP)的双波长速率方程出发,提出了一种新型的腔型,使两种波长的运行腔长与其跃迁截面成正比.在这种条件下使得两种波长的竞争能力相同,从而可以实现双波长调Q脉冲在能量积分最大值时两种波长脉冲峰峰值同步,而且做为双波长最佳输出判据的两波长光子密度乘积的积分值比采用其它方法约大一个量级.
Slope Irradiance Scheme in GRAPES and its Effect on Simulation of Short-Range Weather Processes
GRAPES模式中的坡地辐射方案及其对短期天气过程模拟的影响

SHEN Yuan-Fang,HU Jiang-Lin,
,胡江

大气科学 , 2006,
Abstract: Solar radiation is obviously an important factor in many aspects of surface forcing.Currently short wave radiation scheme in GRAPES(Global/Regional Assimilation and PrEdiction System) is based on Dudhia(1989)and taken from MM5.It is a simple downward integration of solar flux,accounting for clear-air scattering(Lacis and Hansen 1974),water vapor absorption,cloud albedo and absorption,and uses look-up tables for clouds from Stephens(1978).Short wave radiation at the ground surface(GSW) is originally calculated under the assumption of horizontal surface.This method of estimating the GSW may lead to considerable errors when the model resolution becomes high and the model terrain steep.To improve solar short wave radiation parameterization,slope irradiance has been implemented into nonhydrostatic mesoscale model GRAPES.Topography height is taken from NCEP with a resolution of 1 km,and the slope and orientation of terrain are calculated by the staggered difference scheme.The focus of this paper is slope irradiances and the effect on the simulation for short range weather processes in the different resolutions,especially on the simulation of a Meiyu front precipitation process.The result shows that the influence of slope and orientation of terrain on the calculations of GSW is large.The radiation minima's are reduced up to 60%,and the maximums are up to 60% larger compared to the reference run,which are much larger than at other time during the day and the 12 or 24 h average.The impact of model resolution on GSW patterns has been investigated,the areas where the differences of GSW between two schemes are larger mostly occur in undulating mountains for high resolution(6 km),but there is no such connection for lower resolution(60 km).The result also shows that during a Meiyu front process in the Yangtze River and Huaihe River valleys the increase or decrease of precipitation accords with the decrease or increase of GSW due to slope irradiance,but it is difficult to see such relations with the complex terrain at a lower resolution(60 km).At a higher resolution(6 km) the increase or decrease of precipitation not only occurs in the areas where GSW changes are larger,but also has better correlation with the complex terrain,which indicates that the slope irradiance has the obvious effect on the simulation of precipitation.To investigate the effect of GSW on meteorological conditions in the planetary boundary layer,the surface energy budget has been studied.The heating or cooling takes place whenever net incoming fluxes are positive or negative,and the surface heat flux(SHF) is thus naturally important in the energy budge.The result shows that the changes of surface temperature due to the slope and orientation of topography accord with the SHF,there is better correlation between them,and also occur in undulating mountains at a higher resolution(6 km).Therefore,slope irradiance can normally be neglected in numerical models when the horizontal model resolution i
饱和冻结粉土的动弹模与动强度
何平,,张家懿,忠言,俞祁浩
冰川冻土 , 1993,
Abstract: 通过对饱和冻结粉土(兰州黄土)在不同温度(-10,-5和-2℃)、不同频率(0.1,1和5HZ)及不同动荷载下进行的大量振动试验表明,动弹模随冻土应变的增长而减小,随温度降低而增大,随频率增快而增大。最大应力对动弹模的影响可忽略。冻土的强度随温度降低而增大,频率对动强度的影响取决于冻土的固有频率。最小应力对强度影响可忽略。本文给出了动弹模及动强度随各种因素而变化的相关方程。
冰芯与其它记录所揭示的中国全新世大暖期变化特征
,姚檀栋,永平,张忠,陈拓,章典
冰川冻土 , 2003,
Abstract: 冰芯、孢粉、黄土、湖泊和海平面变化记录揭示出,在全新世时,我国曾发生过多次气候冷暖波动事件,其中最重要的事件是全新世大暖期.由于青藏高原的存在,造成了中亚地区大气环流的改变,形成了中国大陆复杂的气候条件和独特的季风气候,从而导致全国各地大暖期在起讫时间、变化幅度和持续时间上都存在着较大的差异.中国西部高海拔地区大暖期起讫时间较早、持续时间较短、变化幅度较大;反之,在中国东部,大暖期起讫时间较晚、持续时间较长、变化幅度较小,反映出西部高海拔区域对气候变化的响应度和敏感度都比东部低海拔区域强.此外,不同区域的冰芯记录也有差异,古里雅冰芯记录反映了全球气候变化的趋势,而敦德冰芯记录则与我国季风气候变化的趋势比较接近.
冻土的单轴压缩本构关系
,张家懿,彭万巍,忠言,苗丽娜
冰川冻土 , 1992,
Abstract: 根据大量的冻土单轴压缩试验资料,本文提出可将冻土的应力-应变性状分为9种类型,并分别给出了相应的应力-应变方程。试验结果表明,对一定土质及含水量的冻土,其应力-应变性状主要取决于应变率及温度。根据9种类型应力-应变性状的应变率及温度范围,作者首次提出了冻土单轴压缩本构关系类型图。
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