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861.
同位素方法已广泛用于矿床成因研究:确定矿床的形成年代,研究含矿热液的来源和地质过程。但是针对具体矿床,这方面研究仍存在许多不确定性或多解性。湘西南石英脉型金矿的成矿流体来源,是一个颇有争议的问题,有人认为成矿流体主要有变质水,后期可能有大气降水加入[... 相似文献
862.
Xu Liang Eric F. Wood Dennis P. Lettenmaier Dag Lohmann Aaron Boone Sam Chang Fei Chen Yongjiu Dai Carl Desborough Robert E. Dickinson Qingyun Duan Michael Ek Yeugeniy M. Gusev Florence Habets Parviz Irannejad Randy Koster Kenneth E. Mitchell Olga N. Nasonova Joel Noilhan John Schaake Adam Schlosser Yaping Shao Andrey B. Shmakin Diana Verseghy Kirsten Warrach Peter Wetzel Yongkang Xue Zong-Liang Yang Qing-cun Zeng 《Global and Planetary Change》1998,19(1-4)
The energy components of sixteen Soil-Vegetation Atmospheric Transfer (SVAT) schemes were analyzed and intercompared using 10 years of surface meteorological and radiative forcing data from the Red-Arkansas River basin in the Southern Great Plains of the United States. Comparisons of simulated surface energy fluxes among models showed that the net radiation and surface temperature generally had the best agreement among the schemes. On an average (annual and monthly) basis, the estimated latent heat fluxes agreed (to within approximate estimation errors) with the latent heat fluxes derived from a radiosonde-based atmospheric budget method for slightly more than half of the schemes. The sensible heat fluxes had larger differences among the schemes than did the latent heat fluxes, and the model-simulated ground heat fluxes had large variations among the schemes. The spatial patterns of the model-computed net radiation and surface temperature were generally similar among the schemes, and appear reasonable and consistent with observations of related variables, such as surface air temperature. The spatial mean patterns of latent and sensible heat fluxes were less similar than for net radiation, and the spatial patterns of the ground heat flux vary greatly among the 16 schemes. Generally, there is less similarity among the models in the temporal (interannual) variability of surface fluxes and temperature than there is in the mean fields, even for schemes with similar mean fields. 相似文献
863.
根据大量资料分析和实地考察,对我国塑料大棚小气候开发利用进行了综述,并对蔬菜大棚气象服务进行探讨,为塑料大棚应用于农业产业化,取得更好经济效益,提供参考。 相似文献
864.
滇西耿马盆地位于三江褶皱系保山褶皱带的耿马—澜沧复背斜,面积195km2,接受广泛的河湖相沉积,为典型的第三系小型陆相盆地。盆地内沉积受构造控制明显,沿边界断层主要发育冲积扇、近岸水下扇沉积,远离断层发育深湖相或半深湖相沉积。耿马盆地的构造样式与沉积展布在滇西具有极好的代表性,故从构造-沉积相互作用角度对其分析,对于指导滇西其他第三系盆地的勘探有重要意义。 相似文献
865.
实际中的测井参数反演是一个多参数、非线性优化问题,所采用的目标函数,即度量由参数化的理论模型得出的预测值与观测值的吻合程度,往往存在多解的现象。针对这种状况我们提出了模拟退火与变尺度综合反演方法用于参数计算,经过实际试算证明该方法效果很好。 相似文献
866.
Gamma-ray burst afterglows: effects of radiative corrections and non-uniformity of the surrounding medium 总被引:2,自引:0,他引:2
The afterglow of a gamma-ray burst (GRB) is commonly thought to be the result of continuous deceleration of a relativistically expanding fireball in the surrounding medium. Assuming that the expansion of the fireball is adiabatic and that the density of the medium is a power-law function of shock radius, i.e. n ext ∝ R − k , we study the effects of the first-order radiative correction and the non-uniformity of the medium on a GRB afterglow analytically. We first derive a new relation among the observed time, the shock radius and the Lorentz factor of the fireball: t ⊕ = R /4(4− k ) γ2 c, and also derive a new relation among the comoving time, the shock radius and the Lorentz factor of the fireball: t co = 2 R /(5− k ) γc. We next study the evolution of the fireball by using the analytic solution of Blandford &38; McKee. The radiation losses may not significantly influence this evolution. We further derive new scaling laws both between the X-ray flux and observed time and between the optical flux and observed time. We use these scaling laws to discuss the afterglows of GRB 970228 and GRB 970616, and find that if the spectral index of the electron distribution is p = 2.5, implied from the spectra of GRBs, the X-ray afterglow of GRB 970616 is well fitted by assuming k = 2. 相似文献
867.
Scientific objectives and payloads of Chang’E-1 lunar satellite 总被引:1,自引:0,他引:1
Sun Huixian Dai Shuwu Yang Jianfeng Wu Ji Jiang Jingshan 《Journal of Earth System Science》2005,114(6):789-794
China plans to implement its first lunar exploration mission Chang’E-1 by 2007. The mission objectives are
To achieve the above mission goals, five types of scientific instruments are selected as payloads of the lunar craft. These
include stereo camera and spectrometer imager, laser altimeter, microwave radiometer, gamma and X-ray spectrometers and space
environment monitor system. In order to collect, process, store and transmit the scientific data of various payloads a special
payload data management system is also included. In this paper the goals of Chang’E-1 and its payloads are described 相似文献
– | • to obtain a three-dimensional stereo image of the lunar surface, |
– | • to determine distribution of some useful elements and to estimate their abundance |
– | • to survey the thickness of lunar soil and to evaluate resource of3He and |
– | • to explore the environment between the Moon and Earth. |
868.
Cai Bingji Lian fiuangshan Lin Yuhui Lin Mao Dai Yanyu Liu Jinghong Chen Ruixiang 《海洋学报(英文版)》1996,15(1):139-144
ThebasicfeaturesofzooplanktoninthewesternwatersofTaiwanStraitINTRODUCTIONTheessayusesthedatafromacomprehensivesurveycarriedou... 相似文献
869.
本文计算在极高温度 (非共振能量情况 )下 1 7O(p,α) 1 4N与 1 7O(p,γ) 1 8F两反应道分支比。在 (2~ 3)× 10 7K温度范围内其分支比 R约为 5 .4× 10 - 8。这表明在 CN O循环中 ,核反应 1 7O(p,α) 1 4N可以忽略 相似文献
870.
CytochalasinBinducedtriploidyinPenaeuschinensis¥BaoZhenmin,ZhangQuanqi,WangHaiandDaiJixun(ReceivedApril5,1993;acceptedAugust1... 相似文献