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31.
The Effects of Terrain Slope and Orientation on Different Weather Processes in China under Different Model Resolutions
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Currently, short wave radiation at the ground surface (GSW) is calculated under the assumption of a
horizontal surface. This method of estimating the GSW may lead to considerable errors when the model
resolution becomes higher and the model terrain becomes steeper. In this paper, to improve the short wave solar radiation simulations, a terrain slope and orientation parameterization has been implemented into the non-hydrostatic mesoscale model GRAPES (Global/Regional Assimilation and Prediction System). The effects of the terrain slope and orientation on different short range weather processes in China under different model resolutions are simulated and discussed. In the simulations, topography height is taken from NCEP(National Centers for Environmental Prediction) with a resolution of 1 km, and the slope and orientation of terrain are calculated using different staggering schemes and under di erent weather conditions. The results show that when the model resolution is low (30 and 60 km) and the slope of terrain is not large, the influence of the slope and orientation of terrain on the GSW is not evident; otherwise, however, it is not negligible.
Under high model resolutions (3 and 6 km), the increase (decrease) of simulated precipitation corresponds to the decrease (increase) of the GSW induced by the slope effect, and the variations of precipitation are usually ranged between -5 and 5 mm. Under the high resolution, the surface temperature and heat fluxes are strongly correlated to each other and the high correlation exists mostly in the complex terrain regions. The changes of the GSW, precipitation, surface temperature, and heat fluxes induced by the e ects of the terrain slope and orientation are more obvious in mountainous regions, due to the alternations in the atmospheric circulation. It is found as well that under the weather condition of less cloud and less precipitation, the effects of the terrain slope and orientation can be more realistically seen. Therefore, the terrain slope and orientation can usually be neglected in numerical models when the horizontal model resolution is low and the slopes are moderate, but should be taken into account when the model resolution becomes high and the terrain is steep and undulating. 相似文献
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墙面太阳辐照的理论计算与模式估计——以上海为例 总被引:7,自引:0,他引:7
倾斜面和墙面的太阳辐射和日照状况对于农林生态、建筑环境工程以及城市气候研究具有重要意义。为了充分利用水平面日照与日射的丰富资料以得到倾斜面和墙面相应变量的细致分布规律,本文将理论计算与模式估计相结合的方法具体应用到一个平原城市(上海)。在倾斜面直接辐射计算中,本文以倾斜面与水平面天文辐射月值的比值(R_b)取代各月代表日的(R_(bo))在倾斜面日照时间的估计中,本文提出利用水平面日照百分率的简单方法。在倾斜面辐射与日照的时空分布规律方面主要突出其随方位与随季节(月份)的变化。 作为例子,本文计算分析了上海市每月各方位墙面上的天文辐射与可能日照时间,对相应的实际日照时间进行了估计。并在计算给出的(R_b)值的基础上,利用散射辐射各向同性与非各向同性模式研究了上海各月墙面直接辐射与总辐射随方位的变化特征。 相似文献
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U6+-phases are common alteration products, under oxidizing conditions, of uraninite and the UO2 in spent nuclear fuel. These U6+-phases are subjected to a radiation field caused by the α-decay of U, or in the case of spent nuclear fuel, incorporated actinides, such as 239Pu and 237Np. In order to evaluate the effects of α-decay events on the stability of the U6+-phases, we report, for the first time, the results of ion beam irradiations (1.0 MeV Kr2+) of U6+-phases. The heavy-particle irradiations are used to simulate the ballistic interactions of the recoil-nucleus of an α-decay event with the surrounding structure. The Kr2+-irradiation decomposed the U6+-phases to UO2 nanocrystals at doses as low as 0.006 displacements per atom (dpa). U6+-phases accumulate substantial radiation doses (∼1.0 displacement per atom) within 100,000 yr if the concentration of incorporated 239Pu is as high as 1 wt.%. Similar nanocrystals of UO2 were observed in samples from the natural fission reactors at Oklo, Gabon. Multiple cycles of radiation-induced decomposition to UO2 followed by alteration to U6+-phases provide a mechanism for the remobilization of incorporated radionuclides. 相似文献
36.
岩石的微波处理效果受诸多因素影响,其中水是一种良好的吸波介质,能提高岩石的微波吸收能力。为探索饱和度对微波照射后岩石响应特征的影响效果,以不同饱和度的玄武岩试样为研究对象,以升温特性、波速与孔隙度变化以及动态抗拉强度等为参考指标,开展了3 kW功率微波照射的破岩试验。从细观与宏观角度的分析结果表明:(1)水的存在影响了微波照射过程中岩样的升温特性,照射的前15 s内,饱和度低于75%组明显促进了升温速率,而饱和度达到100%则作用相反,升温速率低于干燥组;15~30 s随着含水率的减少与蒸发吸热,含水试样升温速率降低;30~45 s内水分蒸发完毕,含水试样的升温速率接近干燥试样。(2)饱和度差异导致玄武岩在微波照射后发生不同程度的波速与孔隙率的变化,波速降幅范围为8.18%~17%,孔隙率增长范围为18.71%~43.65%,损伤效果并未随饱和度升高而增强。(3)同样照射条件下,50%饱和度组在蒸汽压力和热应力共同作用下快速达到强度极限,试样直接发生破坏。其余组试样大多未发生明显细观损伤,最终动态抗拉强度差距不明显。 相似文献
37.
水下激光通讯发射接收系统 总被引:1,自引:0,他引:1
报导了可用于水下激光通讯的由89c51单片机控制的全双工水下激光通讯系统实验装置。系统能有效的消除水下背景光的影响,并具有3~4个数量级动态范围的自动增益放大能力以更有效地接收水下激光通讯信号。能在水下以较高的数据传输率传递信息,数据传输率可以用软件调整,最大数据传输率为19.2kBits/s。 相似文献
38.
Olive oil mill wastewater (OMW) is environmentally hazardous not only because it contains high recalcitrant and toxic compounds, but also due to its high organic load and turbidity. In this study, oxidation of OMW by microwave (MW)‐activated persulfate is investigated. Box–Behnken design is applied to investigate the effects of operating conditions on operating cost, organic matter, and color removal. Multi response optimization is performed according to minimum operating cost, maximum organic matter and color removal efficiencies. At optimum conditions (persulfate anion dose of 266 g L?1, oxidation duration of 23.58 min, MW power of 567 W, and initial pH 2), chemical oxygen demand (COD) removal of 63.38%, color removal of 94.85%, and operating cost of 0.0633 Euro/g total organic carbon (TOC) removal are found. The biochemical oxygen demand (BOD5)/COD ratio is increased from 0.144 to 0.285. Results of Pareto analysis show individual effect of MW power is 92.81% for TOC removal, 15.52% for color removal, 68.99% for operating cost, respectively. According to the results, it is not recommended to use this process as an ultimate treatment unit due to the high amount of oxidizing agent consumed. Instead, it is recommended to be used as a pre‐ or post‐treatment step. 相似文献
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40.
D. Gournis A. E. Mantaka-Marketou M. A. Karakassides D. Petridis 《Physics and Chemistry of Minerals》2000,27(7):514-521
The interaction of γ-rays with smectite clays induces noticeable changes in the structure and physicochemical properties of the minerals. For sodium-montmorillonite, Mössbauer spectra show that γ-irradiation causes a partial reduction of trivalent iron to the divalent state due to hydrogen radicals production from the radiolysis of interlayer water. The XRD results show no change in the interlayer space upon irradiation and therefore the radiolysis of interlayer water causes no measurable changes in the architectural organization of the interlayer environment. Intercalation of simple organic molecules (ethylene glycol, tert-butanol and tetraalkylammonium salts) causes partial oxidation of structural divalent iron and affects the Mössbauer parameters of the M1 and M2 ferric components. Irradiation of ethylene glycol- or tert-butanol-clay composites indicates reduction of trivalent iron to the divalent state. XRD data show that the irradiation of clay-ethylene glycol complex causes collapse of the initial double layer of glycol molecules to a single layer complex. Finally, XRD results show that the effects of γ-irradiation on clay-tetraalkylammonium complexes depend upon the chain length of the organic cations. 相似文献