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991.
丰度关系法估算分离结晶岩浆岩系原始岩浆成分 总被引:3,自引:0,他引:3
幔源原始岩浆是分离结晶过程的起点,又是地幔的平衡或分离部分熔融的产物,在这种原始岩浆岩中元素丰度关系既遵守分离结晶规律,又遵守地幔部分熔融规律。根据原始岩浆的元素丰度关系的这种双重特性,以安底斯山脉火山岩系的稀土元素为例,阐明了由分离结晶的岩浆岩岩系成分恢复原始岩浆成分的原理,并厘定出原始岩浆元素丰度的估算方法。 相似文献
992.
Tintinnid ciliates are important pelagic microplankton.Most studies previously conducted in the Amundsen Sea have covered a relatively small latitude range and provided minimal information about tintinnid species composition and distribution.The present study was conducted to investigate tintinnid assemblages from the Antarctic zone(AZ)northward through the polar front(PF)to the subantarctic zone(SAZ).A total of 17 tintinnid species belonging to seven genera were collected,and 16 were identified.Results show that nine of the species are endemic to the Southern Ocean and they mainly inhabit the AZ near Antarctic continent with an abundant proportion exceeding 60%of total tintinnid.According to the tintinnid abundance distribution,the species were divided into four groups:Group I includes Acanthostomella norvegica,Codonellopsis glacialis,C.pusilla and Cymatocylis antarctica and mainly occurs in the northern boundary of the PF;Group II includes Cymatocylis convallaria forma calyciformis,an unidentified species,and Amphorellopsis quinquealata and mainly inhabits the PF;Group III includes Salpingella costata,Cymatocylis vanhoeffeni,C.convallaria forma cristallina,C.convallaria forma drygalskii,C.convallaria,Codonellopsis gaussi,and Laackmanniella naviculaefera and mainly occurs in the AZ near the Antarctic continent;and Group IV,which comprises Salpingella sp.and inhabits all zones.The new species of tintinnid(belonging to Group II)primarily inhabit the AZ but also are distributed in the PF,and they have large lorica-oral-diameter(LOD).The distribution ranges of tintinnid assemblages from the AZ to PF were determined,in addition to the different assemblages mixed in the PF.The information provided in this study increases our understanding of tintinnid assemblages from the Antarctic continent in the Antarctic Circumpolar Current and Antarctic waters. 相似文献
993.
994.
YAN Chunyan LIU Qiang NIU Zheng WANG Jihua HUANG Wenjiang & LIU Liangyun . State Key Laboratory of Remote Sensing Science Jointly Sponsored by the Institute of Remote Sensing Applications of Chinese Academy of Sciences Beijing Normal University Beijing China . National Engineering Research Center for Information Technology in Agriculture Beijing China 《中国科学D辑(英文版)》2005,48(10)
Vegetation is an important component of the eco-system, and to estimate accurately the biochemical component content is very helpful to understanding the ecosystem functions at different scales. While the method to retrieve biochemical component content using leaf scale spectral measurements is applicable, to retrieve biochemical component content from can-opy spectra is still a challenging problem. Because canopy spectra are the combined results of leaf bio-chemical component content, soil ba… 相似文献
995.
996.
Summary The presence of solid carbon monoxide (CO) on interstellar grains was confirmed observationally in 1984 with the detection of infrared absorption at 4.67m wavelength in several molecular clouds. Subsequent observations suggest that solid CO is ubiquitous in the quiescent molecular cloud environment. In some lines of sight, the degree of frosting on to grains is sufficient to reduce appreciably the abundance of CO remaining in the gas, a result of considerable astrophysical significance: in addition to its importance as a tracer of molecular material, CO is vital to the production of many polyatomic molecules by gas phase reaction schemes, and its depletion could have a dramatic effect on the abundances of more complex carbon-bearing molecules. The infrared spectrum of solid CO provides an important diagnostic of the chemical composition and thermal evolution of grain mantles, leading to the prediction that CO2 is also present in solid form.As it is now some six years since observations of interstellar solid CO were first reported, this is an appropriate time to review the topic and to suggest some directions for future research. The introduction (Sect. 1) attempts to place the subject in its broader astrophysical context. The infrared observations and their implications are discussed in detail in Sect. 2. The question of the degree of CO depletion implied by the observations of both solid state and gas phase CO is re-examined in Sect. 3. We assess the possibility of CO detection by means of solid state absorption or luminescence in the ultraviolet in Sect. 4. Future prospects are summarised in the final section.This article was processed by the author using the Springer-Verlag TEX Theaar macro package 1988. 相似文献
997.
Abstract Bacterial numbers and production were measured in the upper water column in the winter and spring of 1993 in five water masses surrounding the South Island of New Zealand. Average bacterial numbers and production were found to be higher in spring (8.5 × 105 cells ml?1 and 0.20 mg m3 h?1, respectively) than winter (5.5 × 105 cells ml?1 and 0.05 mg C m3 h?1 respectively). Bacterial production was strongly correlated with chlorophyll a and primary production (P < 0.001) in spring but not in winter. Spring bacterial production and at 10 m depth averaged across 28 stations was 23% of primary production, and with a growth efficency of 40%, may have consumed up to 57% of primary production. Bacterial biomass was greater than phytoplankton biomass for 75% of the 10 m depth comparisons during winter sampling and 44% during the spring sampling. The bacterial biomass was found to represent 24.6–33.5% of the nitrogen in particulate organic matter (<200 μm) supporting the concept that in New Zealand oceanic water masses bacteria are of significant biogeochemical importance. 相似文献
998.
利用夜间热红外数据求取玉米冠层孔隙率 总被引:1,自引:0,他引:1
孔隙率是光线透过冠层未被拦截到达地表的概率,是描述冠层结构和生物量空间分布的关键变量。已有研究证明,在夜间热红外图像上,玉米地各亮温组分比较稳定,并且温度均值有明显差异,易于区分。本研究的目的是利用2005年8月23日在怀来测得的夜间热红外数据求取中等密度的玉米冠层(LA I=3.64)在不同角度下的孔隙率。结果表明,在沿垄行方向,孔隙率随着天顶角变化缓慢;而在其他方向(45°和90°)变化较快,且变化趋势相似。将测得结构参数代入余涛的热红外方向辐射性模型,模拟出不同方向下的孔隙率。将测量值与模拟值进行对比,二者有一定的相似性,模型能较好地抓住玉米冠层孔隙率的主要特征。针对二者间的差异,初步分析是由测量中观测目标不完全一致、角度控制不精确、测量高度过低以及投影函数和丛生参数的选择等原因引起的。 相似文献
999.
本文分析了长城湾夏季作为异养微型浮游生物主要类群的领鞭毛类(choanoflagelates)的生态分布和丰度。共记述7个属的11个种。领鞭毛类是长城湾夏季的一个丰富的类群,其总丰度在5.1×103-5.3×104细胞/升范围。但其最大丰度和最大叶绿素a浓度不在表层,而分别在20米和30米水层。在垂直丰度上领鞭毛类显现随叶绿素a浓度而增减的趋势。根据对40组数据的回归分析表明:长城湾夏季领鞭毛类总丰度和叶绿素a浓度之间存在着正相关关系。长城湾夏季领鞭毛类四个优势种Bicostaspinifera,Crinolinaaperta,Diaphanoecamultiannulata和Parvicorbiculacircularis广泛地分布于自表到底的各水层中,占各水层领鞭毛类总丰度的90%以上。B.spinifera是表层最丰富的种类,占表层领鞭毛类总丰度平均值的41%。D.multiannu-lata在1991年1月25日的20米水层达到2.2×104细胞/升的单种最大丰度 相似文献
1000.
Standing stock and community structure of photosynthetic picoplankton in the northern South China Sea 总被引:1,自引:0,他引:1
1 Introduction Forthe lastm ore than 20 a,ow ing to the develop-m ent of observation and experim ent technologies form arine m icroorganism s,m arine biologistshave discov-ered m any m icroorganism s w hich are difficult to beobserved by com m on m icroscope before. T hus, thecognition to the m arine phytoplankton com m unitiesand the structure of food chains has achieved im por-tantprogress.E specially,w ith the developm entand ap-plication of epifluorescence m icroscopy and flow cy-tom etry… 相似文献