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41.
42.
介绍一种自行设计和加工的直接雾化石墨炉进样装置的结构、工作原理和操作方法。该装置由微机控制与石墨炉加热程序同步工作,可以实现自动控制和自动测量。对雾化进样石墨炉分析的仪器参数和实验条件进行了研究和选择。结果表明,该装置与石墨炉结合具有自动化程度高、重现性好、样品利用率高和分析速度快等特点。 相似文献
43.
Gamma-ray burst remnants become trans-relativistic typically in days to tens of days, and they enter the deep Newtonian phase in tens of days to months, during which the majority of shock-accelerated electrons will no longer be highly relativistic. However, a small portion of electrons are still accelerated to ultra-relativistic speeds and are capable of emitting synchrotron radiation. The distribution function for electrons is re-derived here so that synchrotron emission from these relativistic electrons can be calculated. Based on the revised model, optical afterglows from both isotropic fireballs and highly collimated jets are studied numerically, and compared to analytical results. In the beamed cases, it is found that, in addition to the steepening due to the edge effect and the lateral expansion effect, the light curves are universally characterized by a flattening during the deep Newtonian phase. 相似文献
44.
Zhu Ge-yan 《中国海洋湖沼学报》1996,14(4):308-315
The composition and distribution of benthic, periphytic and planktonic rotifers in different habitats in Krottensee were investigated.
Sixty-five rotifer taxa were identified, their relative abundance estimated.
Classification of the data set by cluster analysis allowed the recognition of distinct habitat groups confined to acid bog
ponds, macrophytes, sediments and open water. Five groups of rotifer taxa were identified on the basis of their habitat preferences
and the occurrence of the taxa. Highest diversities were found on macrophytes and in acid bog ponds. 相似文献
45.
利用三维有限元模拟两层地球模型(包括弹性层和粘弹性层)介质的横向不均匀和断层错动的复杂性对震后地表位移场的影响,其数值结果包括弹性解和粘弹性解。结果表明,震后位移场的分布特征不仅与粘弹性层的流变特性有关,还与弹性层介质的剪切模量以及断层的同震错动有关。 相似文献
46.
1IntroductionOne of the key factors related to basin geody-namics is deep process controlling formation and evolution of sedimentary basin. Depth and tempera-ture of asthenosphere,existence of mantle plume,occurrence of mantle melting,and amounts of melts under depressurization during thinning of lithosphere are controlling factors influenced formation and characteristics of extensional basin directly (Li,1994). Rifting is probably governed by frictional forces exerted on the base of litho… 相似文献
47.
WANGWei-wu ZHULi-zhong WANGRen-chao SHIYong-jung 《中国地理科学(英文版)》2003,13(1):39-47
Urban heat environmental quality(UHEQ) is affected by the interacting of weather condition and underlying surface framework of urban area .In the last two decades,many researchers from domestic and overseas have studied many problems at the aspect of urban heat environment such as urban heat islands ,urban air temperature and their rela-tion with urban land cover,city population,air pollution etc,In the recent years,Hangzhou,acting as a center city of Zhejiang Province in China,its urbanization quantum and quantity have both changed greatly,in particular ,representing as business affairs building,resident real property and all kins of specialty market having arisen in built-up zone,Based on Landsat TM images data in 1991 and 1999,urban underlying surface temperature value and Normalized Difference Vegetation Index (NDVI) were calculated using image interpreting and supervised classification technique by remote sensing software ERDAS image 8.4,The relation model between urban underlying surface temperature (UUST )and urban air temperature was setup according to the certain correlation patten .Reference to the relational standard of assessing human comfort and other meteorology data of Hangzhou City in summer,the spatial distribution characteristic and the spatial varia-tion degree of human comfort of heat environmental quality are estimated and mapped on a middle scale,that is ,in six districts of Hangzhou City .Then the paper reveals the main characteristic of spatial variation from 1991 to 1999.Lastly,the change mechanism is analyzed and discussed from the viewpoint of city planning,construction and environmental protec-tion. 相似文献
48.
Study is made on a 45 km-long artificial ecosystem without irrigation in Tengger desert on the basis of long-term ecological monitoring and ecohydrological fundamentals. Changes in water allocation, utilization, cycle and balance patterns in more than 40-year evolution of the soil-plant system are analyzed. The formation of a drought horizon in shrub rhizosphere and its effect, ecohydrological function of the crust and its effect on the soil-plant system change are discussed. Driven by water self-regulation and water stress, the soil-plant system is going to develop towards the steppe desert to ensure more effective use and optimum collocation of water resource.
相似文献49.
In this paper, the equilibrium configurations of rapid rotating compact stars and some gravitational effects are studied within the general relativity by use of the Harrison-Wheeler equation of state and by the self-consistent field method. Numerical calculations show that the equilibrium configuration of a rotating star is a spheroid. For large spin velocities, say, ω > 3.0 × 102 sec−1 the eccentricity and mass increase very rapidly as the angular velocity increases, for the critical angular velocity of the rotating star, the eccentricity is about 0.7, the increase in mass is about 10–35%. The difference of the gravitational redshifts at the surface of the star caused by rotation, and the difference of the light bending when the beam moves in the direction of rotation or in the opposite direction are obvious. 相似文献
50.
An Example of Island-Arc Petrogenesis: Geochemistry and Petrology of the Southern Luzon Arc, Philippines 总被引:7,自引:1,他引:6
DEFANT MARC J.; MAURY REN? C.; RIPLEY EDWARD M.; FEIGENSON MARK D.; JACQUES DARIO 《Journal of Petrology》1991,32(3):455-500
Volcanism throughout the Luzon arc is associated with eastwardsubduction of the South China Sea floor along the Manila Trench.The southern section of the arc, the focus of this study, extendsfrom the Lingayen-Dingalan fault to the small islands just southof Luzon. Two segments appear to exist along this section ofthe arc the northern Bataan and southern Mindoro segments whichare separated by the Macolod Corridor. The volcanic rocks have typical arc phenocryst mineralogies:olivine, clinopyroxene, plagioclase, and titanomagnetite inthe most mafic rocks and clinopyroxene, plagioclase, orthopyroxene,titanomagnetite, ? amphibole in the more felsic samples. Complexzoning, sieve textures, and decoupling of incompatible traceelements suggest that processes such as assimilation have takenplace. The rocks from the study area range from basalts to rhyolitesand show typical calc-alkaline features. The rocks of the MacolodCorridor and Mindoro segment are particularly enriched in largeion lithophile elements (LILE), light rare earth elements (LREE),and radiogenic Sr compared with the Bataan segment. The datafall within the mantle array on Sr-Nd isotopic diagrams andgrade toward higher Sr and lower Nd isotopic values from northto south. A likely source for the volcanics of this study is either amid-ocean ridge basalt (MORB)-type mantle that undergoes higherdegrees of partial melting than regions involved in MORB generationor a previously depleted source. We suggest that the high fieldstrength element (HFSE) anomalies have been derived throughdifferential element partitioning during fluid transport fromthe subducted lithosphere to the mantle wedge. Continental crustal material seems to play a significant roleparticularly in the Macolod Corridor and the Mindoro segment,based on the high LILE, La/Sm ratios, radiogenic Sr isotopes,and 18O values. The Macolod Corridor and the Mindoro segmenthave undergone source contamination by crustal material fromthe North Palawan-Mindoro crustal block either during the collisionof this block with the Manila Trench or by subduction of sedimentsrich in this crustal material. A similar component has alsobeen detected in the Bataan segment but in minor amounts. Thetrace element and isotopic differences between the northernand southern sections of the arc are interpreted in terms ofvariable composition (i. e., variable amounts of a crustal componentintroduced from the Palawan-Mindoro crustal terrain) of themetasomatic fluids released into the source. 相似文献