首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The first high-accuracy CCDUBV RI light curves for the recently discovered eclipsing system V1176 Cas (P = 6 . d 33, V = 11 . m 1) have been obtained. A photometric solution for the light curves and physical characteristics of the component stars are derived. The orbital eccentricity is negligible, e = 0.009; both components have physical parameters similar to the Sun, but they are younger and may have an overabundance of metals. The orientation of the orbital ellipse and the low eccentricity make studies of the apsidal motion difficult. Nevertheless, the high accuracy of the available measurements of the timings of minima has enabled derivation of an upper limit for the rate of apsidal rotation, which agrees with a theoretical estimate of this effect.  相似文献   

2.
The climate effect of the solar energy flux variation in the annual cycle is discussed. The effect is considered to be the main cause of short-periodic climate change observed permanently in nature. Analytical approach to solve this problem based on application of the theory of perturbation is described.  相似文献   

3.
4.
内蒙古呼伦贝尔市阿尔布拉格地区为火山岩分布区,为研究该地区铀异常矿化特征,本次工作主要采用地面伽马能谱测量方法对该区进行初步分析研究,探讨了阿尔布拉格地区铀异常矿化分布特征,初步划分出两处铀成矿有利地段,表明该方法在铀矿找矿过程中应用效果明显,对下一步重点查证工作有一定的指导作用.  相似文献   

5.
Conclusion — Contemporary Implications According to Buddhist philosophy, men constitute just one class of living beings. As such, they have no right to unlimited use of natural resources. Also men have no right to unlimited exploitation of animal and plant life, which forms part of Nature. Until recently, Westerners or moderns tended to think that men were quite separate and different from the natural world. This assumption is ungrounded and unreasonable. It has brought about devastation. Men incur retaliation by nature.In order to deal with the difficult situation that has come about, we must seek a solution that is both objective and subjective. On the objective side, we must discard the arrogance of supposing that men are entitled to exploit the natural world at their own will, without limit and regardless of the consequences. It is not appropriate to maintain the idea of conquering nature. Nature should be met with affection. In this connection, we emphasize that the world of nature should not be monopolized by a few countries. The whole natural world should be shared by all mankind. We cannot but feel angry at the small, limited number of countries which totally control the reserves of a limited energy supply, and which are extravagantly wasting what nature has entrusted to them. Just as individual egoism must be curtailed and placed under control, so national and ethnic egoism also should be restrained in the name of justice and respect for nature.On the subjective side, there is need for correction of the opinion of moderns that the progress of mankind consists in the unlimited satisfaction of human desire for material objects. Buddhism taught satisfaction with what is given to men. To know being satisfied was thought to be the way to spiritual happiness. The key to the relationship between man and the environment may very well lie in the control of our desires according to this concept of satisfaction. For that purpose our desire should be scaled to the possibilities of nature conceived as supporting human existence. Nature is not an entity to confront us as if it were quite different from us; it is something to embrace, as we might think it as that from which we cannot separate ourselves. Admitting the disinction between man and nature, we have to think how to live with the knowledge that nature is necessary to us.  相似文献   

6.
We present high-and low-resolution spectral observations of the symbiotic Mira variable V407 Cyg obtained in 1993–2002. Both emission and absorption spectra of the star are analyzed in detail. We present the basic spectral parameters for three states of the hot component of V407 Cyg—its passive and quiescent states and an outburst in 1998—and study the evolution of the emission-line profiles during transitions from one state to another.  相似文献   

7.
Distribution and genesis of amber-type resins are discussed. The kerogen evolution diagram (atomic ratios of three key elements: carbon, hydrogen, and oxygen) has been used for comparing differentage fossil resins and refining their genesis and the results of postdiagenetic effects on them. Paleozoic and Meso-Cenozoic fossil resins occupy different areas in the mentioned diagram, suggesting a higher transformation degree of resins from the Paleozoic sediments and different types of resin-producing vegetation in the Paleozoic and Meso-Cenozoic. Distribution of data points on the plot can provide insight into postdiagenetic processes (magmatism, weathering) responsible for the transformation of some fossil resins. Epochs of intense succinosis and large-scale amber appearance are attributed to global events that impaired stable conditions for the growth of resin-generating forest vegetation.  相似文献   

8.
We present spectral observations of the red-dwarf flare star EV Lac made at the Crimean Astrophysical Observatory in 1994 and 1995, and describe a method for semi-empirical modeling of the chromospheres of red dwarfs based on their emission spectra. We have modeled the quiescent state of the chromosphere of EV Lac for the cases of a homogeneous chromosphere and of active regions covering one-half and one-third the stellar surface. All models that are consistent with the observations indicate a region with a small vertical temperature gradient, a so-called temperature plateau. The calculated structure of the stellar chromosphere is compared with that of the solar chromosphere.  相似文献   

9.
Theoretical spectral energy distributions for Sakurai's object at 300–1000 nm are derived. A model-atmosphere grid with T eff=5000–6250 K and logg=0.0–1.0 is computed for the chemical composition of Sakurai's object using opacity sampling including molecular and atomic absorption. Opacity due to absorption in 20 band systems of diatomic molecules is computed using the JOLA technique. The theoretical fluxes are compared with the observed energy distribution in a spectrum of Sakurai's object taken in April 1997. It is shown that (a) the theoretical energy distributions agree well qualitatively with the observed spectrum and depend strongly on the effective temperature; (b) C2 and CN molecular bands are dominant in the visible and near-infrared spectrum, while atomic absorption is important at UV and blue wavelengths; and (c) comparison of the observed and computed spectra yields an effective temperature for Sakurai's object in April 1997 T eff≈5250–5500 K. The dependence of the computed spectra at 300–1000 nm on the input parameters and adopted approximations is also discussed.  相似文献   

10.
This paper analyses the urban process in the oil producing countries of the Gulf. The mode of urbanization is identified as one characterized by an extreme case of primacy but with rates varying among the countries of the region. This pattern is related to the historical evolution of human settlements as affected by the local environmental qualities and the recent large scale development of urban infrastructures which favoured the already existing capital cities. The relative city growth rates are among the highest in the world but with a declining tendency which reflects expenditure patterns and the nature of the regional economies. The high growth rates are essentially due to massive foreign migration into the region and to extremely high natural increase rate — an abnormal condition in an urban process approaching saturation point. The role of these primate centres in the development of the region is undeniable and, furthermore, all indications suggest that this pattern of urban development will continue in the furture as it is, perhaps economically and politically less costly.  相似文献   

11.
Aidan Davison   《Geoforum》2008,39(3):1284-1295
The number and range of contests over the social production of nature is growing. Much environmentalist discourse, however, continues to appeal for unequivocal scientific support on clearly demarcated issues of pure, a-social nature. This paper explores the question of how participants in environmental movements view this demarcation in the context of their own lives. After introducing scholarly critique of dualistic ideas of nature and the ambivalence characteristic of environmentalist conceptions of nature, the paper draws upon a qualitative study with environmentalists in the Australian cities of Melbourne, Perth and Hobart. Inquiring into the interplay of discourse of nature and everyday worlds, interviews revealed a complex interdependence of dualistic and non-dualistic understandings of nature. This ecology of ideas was especially evident in spatial imaginaries of nature. Scientific terminology, social disaffection and pessimism were associated with abstract and mutually exclusive conceptions of society and nature. Reflections on personal experience, however, indicated more flexible and hopeful negotiations in everyday liminal spaces offering ‘the best of both worlds’. It is concluded that environmentalist resistance to dismantling of conceptual boundaries between society and nature may often stem not from failure to appreciate socionatural complexity, but from a strongly felt sense that the self can only truly be found in nature.  相似文献   

12.
Synthetic spectrum of the peculiar roAp star HD 101065 (Przybylski’s Star) have been computed in the wavelength interval 6705.8–6708.7 Å in order to describe the observed spectrum in the vicinity of the 6708 Å lithium line. Our detailed computations of the synthetic spectrum allowing for the hyperfine structure of the lithium line, lithium isotopic composition, and blending due to lines of rare-earth elements (CeII, NdII, SmII, and others) have yielded estimates of the atmospheric lithium abundance of the star and its 6Li/7Li isotopic ratio.  相似文献   

13.
CCD spectra acquired with the PFES echelle spectrograph on the 6 m telescope of the Special Astrophysical Observatory (Russian Academy of Sciences) were used to study short-term variations in the HeI-line profiles in the spectrum of HD 93521. For all the lines, the variability pattern relative to the mean profile is the same, and can be described as a sinusoidal wave passing through the profiles, from the blue to the red wings. The variability amplitudes and time scales are different for different HeI lines. We studied variations of the radial velocities at the level of 0.5 R 0 of the line residual intensity, for the absorption bisector and the blue and red halves of the absorption profile. The variation time scales and amplitudes for the line halves differ from one HeI line to another, and show good correlations with the line central depths. Going from the weak to the strong lines, the time scale of the radial-velocity variations measured for both halves of the absorption profile increases, and the amplitude decreases. The time scale of the radial-velocity variations for weak lines is, on average, twice the time scale for strong HeI lines. A variable absorption feature was detected in the profiles of strong HeI lines, which moves across the profile synchronously with the star’s axial rotation. Generally, the observed line variations are probably due to nonradial photospheric pulsations, together with the influence of the stellar wind on the profiles of the strong lines.  相似文献   

14.
青海地区盐渍土分布规律及其盐胀溶陷机制探讨   总被引:6,自引:0,他引:6       下载免费PDF全文
针对青海一些地区盐渍土当硫酸钠含量小于1%时也会产生盐胀,而超氯盐渍土却不会产生溶陷的事实,进行了较为深入细致的论证和研究。得出如下结论:建(构)筑物由于盐胀问题引起破坏,往往由其所处地质环境因素起决定性作用,而并非完全符合相关规范所给出的硫酸钠含量超过1%才应考虑盐胀性。柴达木盆地腹地超氯盐渍土却由于难溶盐及中溶盐含量偏高,导致其反常态不产生溶陷。这些认识及观点与现行理论、规范有较大出入。  相似文献   

15.
李鹏  宋二祥 《岩土力学》2012,33(7):1979-1985
目前对渗透系数取极端值情况下饱和土中两类压缩波物理本质的理解尚不够清晰,比如文献中对渗透系数无穷大情况下饱和土中两类压缩波波速的求解有不同的结果。结合Zienkiewicz给出的土动力学基本方程,深入讨论了流体运动方程的建立,推导了饱和土一维压缩弹性问题的动力控制方程及其 - 、 - 形式,进而得出渗透系数取0和取无穷大这两种极端情况下饱和土中压缩波的波速,解释了其物理意义。提出了惯性耦合力的概念,指出两相体动力分析时土骨架和孔隙水之间的相互作用包含渗透力和惯性耦合力两项,并重点讨论了衡量惯性耦合力的参数孔隙度对压缩波波速的影响。  相似文献   

16.
The image of nature in geomancy   总被引:1,自引:0,他引:1  
The art of geomancy (feng-shui in Chinese) is concerned with choosing auspicious sites from which man can benefit. Geomancy has been one of the most important ideas which influenced man's relationships with nature in East Asia and has significantly affected the location and morphology of cities, villages, houses and graves in China and Korea. In geomancy, nature is basically interpreted in terms of the following three images, namely: (1) magical, that which is produced mysterious power to influence man; (2) personified, that which is treated as functioning system of animate organism or inanimate object; (3) vulnerable, that which can be destroyed or recovered by human action.  相似文献   

17.
18.
19.
自然界中ZnS-CdS完全类质同象系列的发现和初步研究   总被引:6,自引:1,他引:6       下载免费PDF全文
过去认为在自然界中的Cd只能有限替代ZnS中的Zn。但是,近几年笔者在研究贵州牛角塘镉锌矿床时,经电子探针、扫描电镜和透射电镜等多种方法的研究,发现锌硫化物中的Cd主要以类质同象存在,其含量可从0.8%增至37.93%;镉硫化物中的Zn同样主要以类质同象存在,其含量为2.43%~38.64%。锌硫化物与镉硫化物成渐变的过渡关系,并且Zn与Cd成很好的负相关关系,相关系数达0.99以上,形成ZnS-CdS的完全类质同象系列。这一发现无论在矿物学,还是在地球化学和矿床学上都具有重要的理论意义和实用价值。  相似文献   

20.
关岭生物群——世界上罕见的化石库   总被引:9,自引:3,他引:9       下载免费PDF全文
以产保存完美海生爬行动物和海百合化石为特色,多门类脊柱动物、无脊柱动物共同繁盛,且夹带有少许古植物化石的关岭生物群是世界上极为罕见的珍衡古生物组合。其化石保存之完美,类型之多样,数量之丰富,堪称世界上少有的晚三叠世“化石库”。在该“化石库”中,海生爬行动物主要有鱼龙类(ichthyosaurs):Qianichthyosaurus zhoui Li(1999),Cymbospondylus asiaticus Li et You(2002),Panjiangsaurus epicharis Chen et Cheng gen.et sp.nov.;海龙类(thalat-tosaurs):Anshunsaurus huangguoshuensis(Liu,1999),Xinpusaurus suni(Yin et al.,2000),X.banaolinensis Cheng et Liu sp.nov.Shun齿龙类(placodonts):Sinocymodus xinpuensis Li(2000)以及某些尚待研究的类型。在所储藏的海百合化石中,以重新厘定的许氏创口海百合Traumatocrinus hsui(Mu)[?=T.caudes(Dittmar,1866);?=T.guanlingensis Yu et al.]为主,新的发现说明,此类海百合营假浮游生活方式,它们通过其网状或铰接状根簇附着在漂浮树干上而广泛分布。共存的化石还有:新近发现和重厘定的Metapolygnathus nodosus带的牙形石,少量鱼类(Asialepidotus sp.nov.),大量软骨鱼类(elas-mobranch ichthyoliths)鳞片和牙齿化石的新类型,Trachyceras multituberculatus带的菊石,Halobia-“Daonella” bifurcata组合带的双壳类,以及腕足类:Koninckina guizhouensis,K.zhengfengensis等以及古植物化石:Equisetites arennaceus,Ctenozamites sarrani等。系统调查、科学发掘和对上述各门类化石时代综合分析后指,了这个珍稀生物群形成于晚三叠世卡尼期早-中期,主要产在新铺乡黄土塘、小凹、毛凹、巴毛林和岗乌乡白岩一带小凹组下段,距5-11m的地层间隔中,其分布面积约200km^2。构造古地理及层序、生态、化学地层的综合研究说明,关岭生物群可能是伴随晚三叠世卡尼期早中期的海侵在南盘江裂陷槽盆西北角活动外陆棚边缘所形成的“避难所”中形成和发展起来的。随着海侵的扩大,海水的加深和有机质的过盛贮存所诱发的缺氧和海水的咸化事件,可能是导致该生物群的集群绝灭,并形成完好保存埋藏群落的主要原因。  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号