全文获取类型
收费全文 | 138篇 |
免费 | 1篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 6篇 |
地球物理 | 19篇 |
地质学 | 57篇 |
海洋学 | 9篇 |
天文学 | 45篇 |
自然地理 | 1篇 |
出版年
2022年 | 1篇 |
2020年 | 5篇 |
2019年 | 3篇 |
2018年 | 6篇 |
2017年 | 5篇 |
2016年 | 2篇 |
2015年 | 1篇 |
2014年 | 3篇 |
2013年 | 7篇 |
2012年 | 7篇 |
2011年 | 7篇 |
2010年 | 11篇 |
2009年 | 14篇 |
2008年 | 10篇 |
2007年 | 9篇 |
2006年 | 11篇 |
2005年 | 1篇 |
2004年 | 3篇 |
2003年 | 7篇 |
2002年 | 6篇 |
2001年 | 10篇 |
2000年 | 2篇 |
1998年 | 1篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1994年 | 1篇 |
1993年 | 1篇 |
1990年 | 1篇 |
1985年 | 1篇 |
1982年 | 1篇 |
排序方式: 共有139条查询结果,搜索用时 0 毫秒
41.
In volcanic tuffs, dredged during Cruise 23 of the R/V Akademik Nikolaj Strakhov, accessory zircon was found; except for the mineral-forming components, there were ∼2% of ThO2 and 0.75% of Ce2O3 in zircon. During rapid uplift of magmatic masses to the ocean bottom surface, admixture elements isolated into specific
minerals. As a result, destruction structures were formed in the rim parts of primary zircon crystals, and the new-formed
association of zircon + thorite + cerite + thoriante + baddeleyite appeared. 相似文献
42.
The dynamical stability of 38 observed hierarchical triple stars with known orbital elements of the internal and external binary subsystems and component masses is considered. Four different criteria of dynamical stability are used. The observed stability parameters and their critical values are calculated by taking into account errors in the orbital elements and component masses. Most triple systems are stable. According to some criteria, several triple stars (ADS 440, ξ Tau, λ Tau, ADS 3358, VV Ori, ADS 10157, HZ Her, Gliese 795, ADS 15971, and ADS 16138) may be dynamically unstable. This result is probably associated with unreliability of the empirical stability criteria and/or with errors in the observed quantities. 相似文献
43.
Geochemistry of polycyclic aromatic hydrocarbons in the bottom sediments of the eastern Arctic shelf
V. I. Petrova G. I. Batova A. V. Kursheva I. V. Litvinenko V. M. Savinov T. N. Savinova 《Oceanology》2008,48(2):196-203
Sources and pathways of supply of polycyclic aromatic hydrocarbons (PAH) in the surface sediments of the Laptev and East Siberian seas were identified based on an analysis of the lithological-geochemical characteristics and distribution of organic matter (OM). The distribution of organic carbon, humic acids, bitumoids, and hydrocarbons demonstrates the determining role of the riverine runoff in the formation of the recent sediments. The total average content of PAH in the sediments of this region approximates 37 ng/g, not exceeding 80 ng/g of dry sediment. The biogenic components of the PAH (alkylphenanthrenes, alkylchrysenes, perylene) dominate in the estuarine-shelf and coastal-shelf sediments enriched with plant detritus and significantly decrease in the pelagic zone. The anthropogenic influence is observed in sediments of the port of Tiksi, where the total content of PAH with dominant pyrogenic components is two orders of magnitude higher as compared with the background values in the study region. 相似文献
44.
Isometamorphous samples of gagate and vitrain from Balkan coal-bearing formations were investigated. Quantitative spectrophotometric, chemical and reflectance measurements were performed. The data obtained from quantitative IR-analysis indicate great differences in the functional composition and structure of the organic matter of the two coal lithotypes. This explains the different properties of the gagate, e.g. lower reflectance, high volatile matter and hydrogene contents, etc. In the case of gagate the aliphatic part predominates in a naphthenic form and hybrid structures bonded to benzene rings as hydroaromatic cycles. Therefore, the number of benzene rings is several times lower than in vitrain, the elemental composition remaining the same. This is why under identical thermobatic conditions and through geological time, the coal molecule of gagate has a lower degree of aromatization. 相似文献
45.
Diana Petrova Kjurkchieva Velimir Angelov Popov Doroteya Lyubenova Vasileva Nikola Ivanov Petrov 《天文和天体物理学研究(英文版)》2018,(4)
Photometric observations in Sloan g′and i′ bands of W UMa binaries NSVS 4340949,T-Dra0–00959,GSC 03950–00707,NSVS 4665041,NSVS 4803568,MM Peg,MM Com and NSVS4751449 are presented.The light curve solutions revealed that the components of each target are of G and K spectral types.The binaries of the sample have middle-contact configurations whose fillout factors are within the range 0.2–0.4.The only exception is NSVS 4751449 which is in deeper contact(fillout factor of 0.55).It precisely obeys the relation between mass ratio and fillout factor for deep,low mass ratio overcontact binaries.One of the eclipses of almost all targets(except MM Peg)is an occultation and their photometric mass ratios and solutions could be accepted with confidence.We found that the target components have almost equal temperatures but differ considerably in size and mass.The components of the partially-eclipsed MM Peg have close parameters.Our solutions reveal that NSVS 4340949,T-Dra0–00959,NSVS 4803568 and MM Com are of W subtype while GSC 03950–00707,NSVS 4665041,MM Peg and NSVS 4751449 are of A subtype.This subclassification is well-determined for all totallyeclipsed binaries.The targets confirm the trends in which W-subtype systems have smaller periods and lower temperatures than A subtype binaries. 相似文献
46.
47.
S. G. Skolotnev N. N. Turko S. Yu. Sokolov A. A. Peyve N. V. Tsukanov S. Yu. Kolodyazhnyi N. P. Chamov Yu. E. Baramykov A. S. Ponomarev V. N. Efimov A. E. Eskin V. V. Petrova L. A. Golovina V. Yu. Lavrushin E. A. Letyagina E. P. Shevchenko K. V. Krivosheya L. V. Zotov 《Doklady Earth Sciences》2007,416(1):1037-1041
48.
Victor Vladimirovich Orlov Anna V. Petrova Kiyotaka Tanikawa Masaya M. Saito Alija I. Martynova 《Celestial Mechanics and Dynamical Astronomy》2008,100(2):93-120
The rectilinear equal-mass and unequal-mass three-body problems are considered. The first part of the paper is a review that
covers the following items: regularization of the equations of motion, integrable cases, triple collisions and their vicinities,
escapes, periodic orbits and their stability, chaos and regularity of motions. The second part contains the results of our
numerical simulations in this problem. A classification of orbits in correspondence with the following evolution scenarios
is suggested: ejections, escapes, conditional escapes (long ejections), periodic orbits, quasi-stable long-lived systems in
the vicinity of stable periodic orbits, and triple collisions. Homothetic solutions ending by triple collisions and their
dependence on initial parameters are found. We study how the ejection length changes in response to the variation of the triple
approach parameters. Regions of initial conditions are outlined in which escapes occur after a definite number of triple approaches
or a definite time. In the vicinity of a stable Schubart periodic orbit, we reveal a region of initial parameters that corresponds
to trajectories with finite motions. The regular and chaotic structure of the manifold of orbits is mostly defined by this
periodic orbit. We have studied the phase space structure via Poincaré sections. Using these sections and symbolic dynamics,
we study the fine structure of the region of initial conditions, in particular the chaotic scattering region. 相似文献
49.
Stukalova I. E. Petrova V. V. Sakharov B. A. Pokrovskaya E. V. 《Lithology and Mineral Resources》2001,36(3):243-254
The rare mineral, potassium tobelite being the NH4-bearing mica, was first described in Lower Carboniferous coal-bearing rocks of the Egorshin–Kamensk district on the eastern slope of the Urals. It was formed from kaolinite and pyrophyllite at temperature less than 500°C and pressure about 2000 atm. The formation of tobelite was probably favored by postsedimentary stresses. Owing to sharp increase in pressure, gases were released from organic matter of the coal-bearing sequence and transformed into ammonia, which was subsequently incorporated as NH+
4in the structure of clay minerals. The potassium tobelite is an indicator of high-grade metamorphism (up to anthracite rank) of the organic matter in coal-bearing sequences. 相似文献
50.
V. A. Rashidov O. V. Pilipenko V. V. Petrova 《Izvestiya Physics of the Solid Earth》2016,52(4):550-571
The rock magnetic properties of the samples of dredged rocks composing the submarine volcanic edifices within the Sea-of-Okhotsk slope of the northern part of the Kuril Island Arc are studied. The measurements of the standard rock magnetic parameters, thermomagnetic analysis, petrographical studies, and microprobe investigations have been carried out. The magnetization of the studied rocks is mainly carried by the pseudo-single domain and multidomain titanomagnetite and low-Ti titanomagnetite grains. The high values of the natural remanent magnetization are due to the pseudo-single-domain structure of the titanomagnetite grains, whereas the high values of magnetic susceptibility are associated with the high concentration of ferrimagnetic grains. The highest Curie points are observed in the titanomagnetite grains of the igneous rocks composing the edifices of the Smirnov, Edelshtein, and 1.4 submarine volcanoes. 相似文献