首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   16篇
  免费   0篇
地球物理   5篇
地质学   7篇
海洋学   2篇
天文学   2篇
  2022年   1篇
  2015年   1篇
  2014年   1篇
  2013年   2篇
  2012年   3篇
  2011年   3篇
  2010年   1篇
  2004年   1篇
  2003年   1篇
  2002年   1篇
  1994年   1篇
排序方式: 共有16条查询结果,搜索用时 437 毫秒
1.
The possibility to apply long-term regional series to reconstruct the Earth’s global temperature in the past is considered. It is shown using symbolic analysis methods that significant (on the so-called order patterns) are relations of time series of St. Petersburg temperature with certain regional and global series. New sets of global temperature reconstructions, starting from the mid-18th century, are constructed on the basis of the previously proposed MSR and DPS methods.  相似文献   
2.
Oxyphlogopite is a new mica-group mineral with the idealized formula K(Mg,Ti,Fe)3[(Si,Al)4O10](O,F)2. The holotype material came from a basalt quarry at Mount Rothenberg near Mendig at the Eifel volcanic complex in Rhineland-Palatinate, Germany. The mineral occurs as crystals up to 4 × 4 × 0.2 mm in size encrusting cavity walls in alkali basalt. The associated minerals are nepheline, plagioclase, sanidine, augite, diopside, and magnetite. Its color is dark brown, its streak is brown, and its luster is vitreous. D meas = 3.06(1) g/cm3 (flotation in heavy liquids), and D calc = 3.086 g/cm3. The IR spectrun does not contain bands of OH groups. Oxyphlogopite is biaxial (negative); α = 1.625(3), β = 1.668(1), and γ = 1.669(1); and 2V meas = 16(2)° and 2V calc = 17°. The dispersion is strong; r < ν. The pleochroism is medium; X > Y > Z (brown to dark brown). The chemical composition is as follows (electron microprobe, mean of 5 point analyses, wt %; the ranges are given in parentheses; the H2O was determined using the Alimarin method; the Fe2+/Fe3+ was determined with X-ray emission spectroscopy): Na2O 0.99 (0.89–1.12), K2O 7.52 (7.44–7.58), MgO 14.65 (14.48–14.80), CaO 0.27 ((0.17–0.51), FeO 4.73, Fe2O3 7.25 (the range of the total iron in the form of FeO is 11.09–11.38), Al2O3 14.32 (14.06–14.64), Cr2O3 0.60 (0.45–0.69), SiO2 34.41 (34.03–34.66), TiO2 12.93 (12.69–13.13), F 3.06 (2.59–3.44), H2O 0.14; O=F2 −1.29; 99/58 in total. The empirical formula is (K0.72Na0.14Ca0.02)(Mg1.64Ti0.73Fe0.302+ Fe0.273+Cr0.04)Σ2.98(Si2.59Al1.27Fe0.143+ O10) O1.20F0.73(OH)0.07. The crystal structure was refined on a single crystal. Oxyphlogopite is monoclinic with space group C2/m; the unit-cell parameters are as follows: a = 5.3165(1), b = 9.2000(2), c = 10.0602(2) ?, β = 100.354(2)°. The presence of Ti results in the strong distortion of octahedron M(2). The strongest lines of the X-ray powder diffraction pattern [d, ? (I, %) [hkl]] are as follows: 9.91(32) [001], 4.53(11) 110], 3.300(100) [003], 3.090(12) [112], 1.895(21) [005], 1.659(12) [−135], 1.527(16) [−206, 060]. The type specimens of oxyphlogopite are deposited at the Fersman Mineralogical Museum in Moscow, Russia; the registration numbers are 3884/2 (holotype) and 3884/1 (cotype).  相似文献   
3.
Zektser  I. S.  Karimova  O. A.  Bujuoli  J.  Bucci  M. 《Water Resources》2004,31(6):595-600
Two independent methods for estimating groundwater vulnerability to pollution are described. The methods are used for regions with different geological and hydrogeological conditions. A new combined approach taking into account the physicochemical processes that take place in all parts of the protected zone is proposed.  相似文献   
4.
5.
A new mineral of the neptunite group, magnesioneptunite KNa2Li(Mg,Fe)2Ti2Si8O24, a Mg-dominant analogue of neptunite and manganoneptunite, has been found in the Upper Chegem caldera near Mount Lakargi, Kabardino-Balkaria, the North Caucasus, Russia in a xenolith of altered sandstone located between skarnified carbonate xenoliths and ignimbrite. Magnesioneptunite occurs as nearly isometric grains and aggregates up to 0.1 mm in size in the cores of some grains of a Mg-rich variety of neptunite with Mg/(Fe + Mn) = 0.7?1.0. The chemical composition of magnesioneptunite with a maximum Mg content is as follows, wt %: 3.63 K2O, 8.21 Na2O, 1.73 Li2O, 6.47 MgO, 0.04 MnO, 5.87 FeO, 0.07 Al2O3, 18.73 TiO2, 56.88 SiO2, 99.62 in total. The empirical formula is (K0.67Na0.32Ca0.01)Σ1.00Na2.06Li1.00 · (Mg1.39Fe 0.71 2+ )Σ2.10(Si7.90Al0.01)Σ7.91O24. Grains of magnesioneptunite are dark brown to red-brown, translucent, with vitreous luster. D calc = 3.15 g/cm3, and the Mohs hardness is 5–6. Cleavage parallel to the (110) is perfect. The new mineral is optically biaxial, positive, α = 1.697(2), β = 1.708 (3), γ = 1.725(3), 2V meas = 45(15)°. The mineral is associated with quartz, alkali feldspar, rutile, aegirine, and neptunite. Magnesioneptunite and the Mg-rich variety of neptunite were formed as products of ilmenite alteration. Magnesioneptunite is monoclinic, C2/c; unit-cell parameters: a = 16.327(7), b = 12.4788(4), c = 9.9666(4) Å, β = 115.6519(5)°, V = 1830.5(1) Å3, Z = 4. The type specimen is deposited at the Fersman Mineralogical Museum of the Russian Academy of Sciences, Moscow.  相似文献   
6.
Themain purpose of this paper is to describe the evolution of the magnetic field of active regions of the Sun in the context of Minkowski functionals: the Euler characteristic and perimeter calculated on the excursion set for a specified level. Themethods of geometry of random fields was applied to the MDI SOHO magnetogram, containing flaring active regions. The results demonstrated that morphological functional tracked the dynamic scenarios of the magnetic fields preceded by flares or accompanying them.  相似文献   
7.
8.
Mordvinov  A.V.  Salakhutdinova  I.I.  Plyusnina  L.A.  Makarenko  N.G.  Karimova  L.M. 《Solar physics》2002,211(1-2):241-253
We investigate the topological properties and evolution of background magnetic fields on synoptic maps from Wilcox Solar Observatory using mathematical morphology methods in terms of the Minkowski functionals. The total length of the neutral line, the total areas occupied by positive and negative polarities, and the Euler characteristics of background magnetic fields vary over an eleven-year cycle. Changes in the length of the neutral line that separates the polarities of the background magnetic field correlate well with flare activity. A time–longitude analysis of solar flare activity revealed a complicated organization and rotation of the entire flare ensemble. On the time–longitude diagram, flare activity is organized into the patterns which follow the rearrangements in background magnetic field and exhibit coexisting and alternating modes of rigid rotation. The character of rotation of the entire flare ensemble is similar to the rotation of background magnetic fields. The emergence of background magnetic fields and changes in their topology and rotation are often accompanied by enhancements in flare activity. A comparative analysis of the topological changes in background magnetic fields and flare activity reveals their causal relation.  相似文献   
9.
10.
Karimova  O. A. 《Water Resources》2003,30(1):103-108
The procedure of evaluating pesticide travel time through the aeration zone to the groundwater table is presented. It is found that the time of pollutant travel through rocks of the aeration zone depends on the thickness and composition of rocks of this zone, the porosity of rocks, distribution factor, volumetric humidity, and the infiltration recharge. As shown, the most vulnerable are the valleys of principal rivers of the area of Caucasian Mineral Water, where the Recent and Middle Quaternary aquifers confined to these valleys are intensely used for domestic and drinking needs.  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