Editorial     

C. De Jager  Z. Švestka 《Solar physics》1968,5(3):259-259

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On the abundance of calcium in the solar corona     

K. S. De Boer  S. R. Pottasch 《Solar physics》1972,23(2):406-409

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PCDD and PCDF intake through consumption of locally produced seafood by Venice lagoon residents: elements for risk management     

Miniero R  Ceretti G  Cherin E  Dellatte E  De Luca S  Ferri F  Fulgenzi AR  Grim F  Iacovella N  Iamiceli AL  Ingelido AM  Vio P  di Domenico A 《Marine pollution bulletin》2005,50(12):1727-1732

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Diffuse Component Spectra of Solar Active Regions at Submillimeter Wavelengths     

Adriana?V.?R.?SilvaEmail author  Tatiana?F.?Laganá  C.?Guillermo?Gimenez?De?Castro  Pierre?Kaufmann  Joaquim?E.?R.?Costa  Hugo?Levato  Marta?Rovira 《Solar physics》2005,227(2):265-281

Solar maps at 212 and 405 GHz obtained by the Solar Submillimetric Telescope (SST) show regions of enhanced brightness temperature, which coincide with the location of active regions. A statistical study of the radio emission from these active regions was performed for the first time at such high frequencies during 23 days on June and July 2002, when the atmospheric opacity was low. The brightest regions on the maps were chosen for this study, where the brightness excess observed varies from 3 to 20% above quiet Sun levels (i.e., 200–1000 K) at both wavelengths. Sizes of the regions of enhanced emission calculated at half the maximum value were estimated to be between 2′ and 7′. These sizes agree with observed sizes of active regions at other wavelengths such as Hα and ultraviolet. An important result is that the flux density spectra of all sources increase toward submillimeter frequencies, yielding flux density spectral index with an average value of 2.0. The flux density of the active region sources were complemented with that from maps at 17 and 34 GHz from the Nobeyama Radio Heliograph. The resulting spectra at all four frequencies were fit considering the flux density to be due to thermal bremsstrahlung from the active region. In the calculations, the source radius was assumed to be the mean of the measured values at 212 and 405 K. The effective temperatures of the radio emitting source, assumed homogeneous, obtained from this fit were 0.6–2.9 × 10⁴ K, for source diameters of 2′–7′.  相似文献   

Single Particle Analysis of Aerosols, Observed in the Marine Boundary Layer during the Monterey Area Ship Tracks Experiment (MAST), with Respect to Cloud Droplet Formation     

L. A. De Bock  P. E. Joos  K. J. Noone  R. A. Pockalny  R. E. Van Grieken 《Journal of Atmospheric Chemistry》2000,37(3):299-329

The chemical composition of individual particles >0.2 m sampled duringthe MAST-experiment wereanalysed by SEM-EDX, in combination with multivariatetechniques. The objective of this experiment was toidentify the mechanisms responsible for themodification of marine stratocumulus clouds byemissions from ships and in a wider sense to provideinformation on the global processes involved inatmospheric modification of cloud albedo. Aerosolswere examined under different MBL pollution levels(clean, intermediately polluted and moderatelypolluted) in five different reservoirs: backgroundbelow-cloud and above-cloud aerosol; background clouddroplet residual particles; below-cloud ship plumeaerosol and ship track cloud droplet residualparticles.In this study a relation was provided between theaerosol emitted from the ship's stack to an effect incloud. Additionally, a large fraction of the ambientaerosol was found to be composed of organic materialor other compounds, consisting of low Z-elements,associated with chlorine. Their number fraction waslargest in clean marine boundary layers, and decreasedwith increasing pollution levels. The fraction of`transformed sea salt' (Na, Cl, S), on the other hand,increased with the pollution level in the MBL. Only20% of the particles fell within the detectable rangeof the analysis.  相似文献   

Approximate Solutions For The Obukhov Length And The Surface Fluxes In Terms Of Bulk Richardson Numbers     

H. A. R. De Bruin  R. J. Ronda  B. J. H. Van De Wiel 《Boundary-Layer Meteorology》2000,95(1):145-157

Simple analytic approximate solutions arepresented for the set of equations that follows fromthe Monin–Obukhov flux-profile relationships using thestability functions of Dyer (unstable case) andBeljaars–Holtslag (stable case). Several publicationsare devoted to the same subject, however the currentapproach contains some new features, namely: (a) itappears to be more accurate for unstable situationsand (b) it applies also to the general case where windspeed (u) and potential temperature() are given at different levels. In order toillustrate the accuracy of the approach a comparisonwith the actual solutions is presented for someselected combinations of and u levelstypical for various practical applications.  相似文献   

二安替比林对羟基苯乙烯基甲烷与钒的高灵敏显色反应   总被引：1，自引：1，他引：0  

周世萍  段德良  杨光宇  尹家元  杨文凡 《岩矿测试》2000,19(2):116-118

合成了试剂二安替比林对羟基苯乙烯基甲烷 (DApHVM) ,研究了它与V(Ⅴ )的显色反应。在H3PO4介质中 ,Mn(Ⅱ )和Tween 2 0协同作用下 ,DApHVM与V(Ⅴ )生成红色产物 ,λmax为 540nm ,ε=1 0 3× 1 0 6 L·mol-1 ·cm-1 ,V(Ⅴ )的质量浓度在 0～ 50 μg/L内符合比尔定律。方法用于中草药及钢样中V(Ⅴ )的测定 ,结果与原子吸收法一致 ,加标回收率在 96%～ 1 0 5 % ,5次测定结果的RSD <3 5 %。  相似文献   

Measurement of a Peak in the Cosmic Microwave Background Power Spectrum from the North American Test Flight of Boomerang     

Mauskopf PD  Ade PA  de Bernardis P  Bock JJ  Borrill J  Boscaleri A  Crill BP  DeGasperis G  De Troia G  Farese P  Ferreira PG  Ganga K  Giacometti M  Hanany S  Hristov VV  Iacoangeli A  Jaffe AH  Lange AE  Lee AT  Masi S  Melchiorri A  Melchiorri F  Miglio L  Montroy T  Netterfield CB  Pascale E  Piacentini F  Richards PL  Romeo G  Ruhl JE  Scannapieco E  Scaramuzzi F  Stompor R  Vittorio N 《The Astrophysical journal》2000,536(2):L59-L62

We describe a measurement of the angular power spectrum of anisotropies in the cosmic microwave background (CMB) at scales of 0&fdg;3 to 5 degrees from the North American test flight of the Boomerang experiment. Boomerang is a balloon-borne telescope with a bolometric receiver designed to map CMB anisotropies on a long-duration balloon flight. During a 6 hr test flight of a prototype system in 1997, we mapped more than 200 deg(2) at high Galactic latitudes in two bands centered at 90 and 150 GHz with a resolution of 26&arcmin; and 16&farcm;5 FWHM, respectively. Analysis of the maps gives a power spectrum with a peak at angular scales of 1 degrees with an amplitude 70 μK(CMB).  相似文献   

Author Index     

R. De La Fuente Marcos  A. Nissar 《Earth, Moon, and Planets》2000,88(4):249-249

Authors Index

Author Index  相似文献   

基于SSA-MGF的BP神经网络多步预测模型   总被引：3，自引：2，他引：3  

李永华  金龙  缪启龙  刘德  高阳华 《南京气象学院学报》2005,28(4):549-555

采用奇异谱分析（Singular Spectrum Analysis，SSA）方法对标准化样本序列进行准周期信号分量重建，将重建序列构造均值生成函数（Mean Generating Function．MGF）延拓矩阵作为输入因子，原样本序列作为输出因子，构建BP神经网络多步预测模型。通过实际建模并与逐步回归等方法进行对比预测试验，结果表明，基于SSA-MGF的BP神经网络多步预测模型预测效果优于其他3种模型，说明SSA的去噪及BP神经网络预报模型对于提高预测准确率是相对有效的，是一种具有较高应用价值的多步预测方法。  相似文献