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71.
依据岩性组合、古生物特征及地震事件层研究,对胶辽鲁西徐淮地区新元古代地层可作如下多重划分对比:鲁西黑山官组、二青山组分别与辽东的钓鱼台组,南芬组相当,胶东豹山口组可与南芬组对比,它们同属青白口系。辽东南关岭组下部、鲁西石旺庄组下部、苏皖北部贾园组、淮南九里桥组皆为一套砂灰岩组合,都发育第一期地震事件层,并开始含有后生动物化石,为等时地层单位,与其以上各前寒武岩石地层单位同属灯影峡阶,鲁西的佟家庄组、浮来山组可分别与辽东桥头组、长岭子组、胶东辅子夼组、南庄组、苏皖北部兰陵组一城山组、淮南伍山组一四十里长山组对比,归属《中国区域年代地层(地质年代)表》新划分的陡山陀阶。 相似文献
72.
Cold water in the deep Pacific can be drawn up to the surface (or west warm water drifts eastwards ) because strong tide increases the mixing of seawater both in vertical and horizontal. In this way greenhouse effect is decreased or increased by means of absorbing (or releasing) CO2. Therefore, La Nina cold event (or El Nino warm event) may occur,which is caused by wanning - up or cooling - down air above the ocean. Volcanic action at sea bottom is also controlled by strong tide. 相似文献
73.
K. Iwasawa A.C. Fabian S.W. Allen S. Ettori 《Monthly notices of the Royal Astronomical Society》2001,328(1):L5-L10
We report on the metal distribution in the intracluster medium around the radio galaxy 4C+55.16 observed with the Chandra X-ray Observatory . The radial metallicity profile shows a dramatic change at 10 arcsec (∼50 kpc) in radius from half solar to twice solar at inner radii. Also found was a plume-like feature located at ∼3 arcsec to the south-west of the centre of the galaxy, which is mostly accounted for by a strong enhancement of iron L emission. The X-ray spectrum of the plume is characterized by the metal abundance pattern of Type Ia supernovae (SNeIa), i.e. large ratios of Fe to α elements, with the iron metallicity being unusually high at solar (90 per cent error). How the plume has been formed is not entirely clear. The inhomogeneous iron distribution suggested in this cluster provides important clues to understanding the metal enrichment process of the cluster medium. 相似文献
74.
张敏先 《成都信息工程学院学报》2001,16(3):209-212
文献[1][2]认为M-PN空间是局部凸的。通过定理说明这个结论对t-模T(a,b)≥min(a,b)时成立。又通过反例表明,当t-模型T(a,b)=max(a b-1,0)时无论邻域Nθ(ε,λ)概率有界还是概率半有界结论均不成立。还讨论了Takahashi凸性并对S-凸和K-凸作了比较。 相似文献
75.
周发贵 《地球科学与环境学报》2001,23(1):63-65
路基施工中保证路基填筑密实度,通常沙土路基采用水夯;普通路基采用振动碾、羊角碾等重型机具振密夯实。但在缺电、缺水,高气温、大风沙的沙漠气候等恶劣的施工条件下,风沙路基的施工如何保证路基填筑的密实度和施工机械在风沙路基上作业而不陷车的问题,就目前没有合适的经验可借鉴,也没有规范可参考。因此把在包西线神木北至延安北段的铁路工程建设中风沙路基施工所取得的经验和施工技术作一介绍。 相似文献
76.
77.
1 INTRODUCTIONIn the previous paper (on et al. 1999, hereafter Paper I), we investigated the wavelength-dependence of four colltribution functions (CFs) derived from dmerent formal solutions andreferring to different emergellt quantities in the unpolarized case. Because one cannot generallyassign a single formation region to the whole line band in a real stellar atmosphere, e.g., the solaratmosphere, instead, the line formation region can be defined as the layers deviating farthestfrom t… 相似文献
78.
A. Del Popolo 《Monthly notices of the Royal Astronomical Society》2001,326(2):667-674
I discuss the effect of non-radial motions on the small-scale peculiar pairwise velocity dispersions (PVD) of galaxies in a cold dark matter (CDM) model and calculate the PVD for the SCDM model by means of the refined cosmic virial theorem (CVT), taking account of non-radial motions by means of the Del Popolo & Gambera model. I compare the results of the present model with the data from Davis & Peebles, the IRAS value at 1 h −1 Mpc of Fisher et al. and Marzke et al. I show that while the SCDM model disagrees with the observed values, as pointed out by several authors, taking account of non-radial motions produces smaller values for the PVD. At r ≤1 h −1 Mpc the result is in agreement with Bartlett & Blanchard. In the light of this last paper, the result may be also read as a strong dependence of the CVT prediction on the model chosen to describe the mass distribution around galaxies, suggesting that the CVT cannot be taken as a direct evidence for a low-density Universe. Similarly to what is shown by Del Popolo & Gambera and Del Popolo et al., the agreement of our model to the observational data is because of a scale-dependent bias induced by the presence of non-radial motions. As the assumptions on which CVT is based have been questioned by several authors, I also calculated the PVD using the redshift distortion in the redshift-space correlation function, ξ z ( r p , π), and compared it with the PVD measured from the Las Campanas Redshift Survey by Jing et al. The result confirms that non-radial motions influence the PVD making them agree better with the observed data. 相似文献
79.
Z. Balog † A. J. Delgado ‡ A. Moitinho G. Frész † G. Kaszás † J. Vinkó E. J. Alfaro 《Monthly notices of the Royal Astronomical Society》2001,323(4):872-886
CCD photometry in Johnson UBV and Strömgren uvby systems and medium-resolution spectroscopy of the galactic open cluster NGC 7128 are presented. Spectral types of the brightest 12 stars in the cluster field were determined based on equivalent widths of the H α and the He i 6678-Å line. The spectroscopic observations also revealed two obvious and one probable Be-type stars showing H α emission. The analysis of the photometric diagrams gave a colour excess of E ( B − V )=1.03±0.06 mag, a distance modulus DM =13.0±0.2 mag and an age above 10 Myr. Time-resolved photometric observations obtained on one night resulted in the detection of short time-scale light variations of seven new and three already known variable stars in the cluster field. 相似文献
80.
P. B. Tissera R. Domínguez-Tenreiro C. Scannapieco A. Sáiz 《Monthly notices of the Royal Astronomical Society》2002,333(2):327-338
We use cosmological smooth particle hydrodynamical (SPH) simulations to study the effects of mergers in the star formation history of galactic objects in hierarchical clustering scenarios. We find that during some merger events, gaseous discs can experience two starbursts: the first one during the orbital decay phase, owing to gas inflows driven as the satellite approaches, and the second one when the two baryonic clumps collide. A trend for these first induced starbursts to be more efficient at transforming the gas into stars is also found. We detect that systems that do not experience early gas inflows have well-formed stellar bulges and more concentrated potential wells, which seem to be responsible for preventing further gas inward transport triggered by tidal forces. The potential wells concentrate owing to the accumulation of baryons in the central regions and of dark matter as the result of the pulling in by baryons. The coupled evolution of the dark matter and baryons would lead to an evolutionary sequence during which systems with shallower total potential wells suffer early gas inflows during the orbital decay phase that help to feed their central mass concentration, pulling in dark matter and contributing to build up more stable systems. Within this scenario, starbursts triggered by early gas inflows are more likely to occur at early stages of evolution of the systems and to be an important contributor to the formation of stellar bulges. Our results constitute the first proof that bulges can form as the product of collapse, collisions and secular evolution in a cosmological framework, and they are consistent with a rejuvenation of the stellar population in bulges at intermediate z with, at least, 50 per cent of the stars (in SCDM) being formed at high z . 相似文献