全文获取类型
| 收费全文 | 114篇 |
| 免费 | 2篇 |
| 国内免费 | 1篇 |
专业分类
| 测绘学 | 2篇 |
| 大气科学 | 5篇 |
| 地球物理 | 23篇 |
| 地质学 | 39篇 |
| 海洋学 | 31篇 |
| 天文学 | 12篇 |
| 综合类 | 1篇 |
| 自然地理 | 4篇 |
出版年
| 2023年 | 1篇 |
| 2022年 | 1篇 |
| 2021年 | 2篇 |
| 2020年 | 4篇 |
| 2019年 | 3篇 |
| 2018年 | 7篇 |
| 2017年 | 8篇 |
| 2016年 | 4篇 |
| 2015年 | 1篇 |
| 2014年 | 9篇 |
| 2013年 | 13篇 |
| 2012年 | 5篇 |
| 2011年 | 6篇 |
| 2010年 | 12篇 |
| 2009年 | 10篇 |
| 2008年 | 10篇 |
| 2007年 | 4篇 |
| 2006年 | 5篇 |
| 2005年 | 3篇 |
| 2004年 | 2篇 |
| 2003年 | 2篇 |
| 2002年 | 1篇 |
| 2001年 | 1篇 |
| 1999年 | 1篇 |
| 1983年 | 2篇 |
排序方式： 共有117条查询结果，搜索用时 31 毫秒
1.
Ya. A. Virolainen Yu. M. Timofeev A. V. Polyakov H. Steele M. Newchurch 《Izvestiya Atmospheric and Oceanic Physics》2006,42(6):752-764
A statistical ensemble of microphysical parameters of the background stratospheric aerosol at altitudes of 15 to 30 km is modeled on the basis of experimental data. The aerosol attenuation coefficients (AACs) in the wavelength range 0.38–16.3 μm are calculated for all realizations of the ensemble by algorithms of the Mie theory. Analysis of correlations between the AACs and the microphysical parameters indicate that the AAC correlates most strongly with the total volume V and area S of all particles. The errors of determining the microphysical parameters from AAC measurements are analyzed via the method of linear regression. It is shown that, if the AAC is measured with an error of 5%, the errors of determining both the particle size distribution (PSD) for particles with sizes of 0.4 to 4 μm and the parameter S are an order of magnitude smaller than the prior uncertainty, whereas the error of determining V is two orders of magnitude smaller than the prior uncertainty. Schemes of AAC measurements with the SAGE III, ISAMS, CLAES, HALOE instruments and an IR interferometer in the visible and IR regions are discussed. It is shown that combining the schemes makes it possible to extend the range of particle sizes for which the PSD is retrieved with a satisfactory accuracy and to increase the accuracy of determining S and V substantially and the accuracy of determining the total number of particles N opt to a lesser extent. Examples of interpreting AAC measurements carried out simultaneously with the SAGE III and HALOE instruments within the same spatial region are presented. A systematic discrepancy between vertical profiles of S and V obtained from SAGE III and HALOE measurements is revealed. 相似文献
2.
3.
4.
5.
V. N. Frolov Yu. K. Ananjevskaja D. L. Gorshanov E. V. Polyakov 《Astronomy Letters》2010,36(5):338-348
We present the results of our comprehensive study of the Galactic open star cluster NGC 6866. The positions of stars in the
investigated region have been obtained with the “Fantasy” automatic measuring machine from 10 plates of the normal astrograph
at the Pulkovo Astronomical Observatory. The size of the investigated field is 40′ × 40′, the limiting magnitude is B ∼ 16·
m
6, and the maximum epoch difference is 79 yr. For 1202 field stars, we have determined the relative proper motions with an
rms error of 2.5 mas yr−1. Out of them, 423 stars may be considered cluster members with a probability P > 70% according to the astrometric criterion. Photometric diagrams have been used as an additional criterion. We have performed
two-color BV CCD photometry of stars with the Pulkovo ZA-320M mirror astrograph. The U magnitudes from the literature have also been used to construct the two-color diagrams. A total of 267 stars have turned
out to be members of NGC 6866 according to the two criteria. We present refined physical parameters of the cluster and its
age estimate (5.6 × 108 yr). The cluster membership of red and blue giants, variable, double, and multiple stars is considered. We have found an
almost complete coincidence of the positions of one of the stars in the region (a cluster nonmember) and a soft X-ray source
in the ROSAT catalog. The “Fantasy” automatic measuring machine is described in the Appendix. 相似文献
6.
Polyakov A. S. Roslyakov A. G. Lobkovskii L. I. Levchenko O. V. Putans V. A. Ambrosimov A. K. Merklin L. R. Anan’ev R. A. Dmitrevskii N. N. Libina N. V. 《Doklady Earth Sciences》2010,431(1):376-379
By means of mathematical modeling, the parameters of flows forming sedimentary waves on the western slope of the Derbent basin
were estimated. The height of these flows depends on the slope steepness and varies from 25 to 170 m to reach its maximum
values at gentler slope areas. However, the flow rate is independent of the slope steepness and depends only on the concentration
of sediment matter supplied by the flow. At the upper part of the slope (the flow starting), the rate amounts to 0.4–1.4 m/s,
being almost halved at the depths where the sedimentary waves are damped. The present rates of near-bottom currents show pronounced
seasonal differences, and their values are close to flow rates obtained by numerical modeling. 相似文献
7.
P.A. Balykin G.V. Polyakov A.E. Izokh Tran Trong Hoa Ngo Thi Phuong Tran Quoc Hung T.E. Petrova 《Russian Geology and Geophysics》2010,51(6):611-624
The Jinping–Song Da rift structure in the Emeishan Large Igneous Province is composed of Permian high- and low-Ti volcanic and volcanoplutonic ultramafic-mafic associations of different compositions and genesis. High-Ti picrites, picrobasalts, basalts, and dolerites are enriched in LREE and depleted in HREE and show low Al2O3/TiO2 ratios (~4), commensurate εNd(T) values (+0.5 to +1.1), and low (Th/Nb)PM ratios similar to those of OIB-enriched mantle source. The established geochemical characteristics evidence that the parental melts of these rocks were generated from garnet lherzolite at the depths of garnet stability (~200 to 400 km). Later, high-Mg low-Ti volcanics (komatiites, komatiitic basalts, and basalts) and associating small peridotite-gabbro massifs and komatiite-basalt dikes were produced as a result of ~20% partial melting of depleted water-poor (≤0.03 wt.% H2O) peridotite substratum from the hottest upper part of mantle plume at relatively shallow depths (100–120 km). The LREE-depleted komatiites and komatiitic basalts are characterized by low (Ce/Yb)CH values, 187Re/188Os = 0.05–1.2, 87Sr/86Sr = 0.704–0.706, positive εNd(T) values (+3 to +8), γOs = –0.5 to +0.9, and strong negative anomalies of Ba, K, and Sr on the spidergrams. The scarcer LREE-enriched komatiites, komatiitic basalts, and basalts vary greatly in chemical composition and values of εNd(t) (+6.4 to –10.2), 87Sr/86Sr (0.706–0.712), and γOs (+14.8 to +56), which is due to the different degrees of crustal contamination of parental magmas. The Rb-Sr isotopic age of basaltic komatiite is 257 ± 24 Ma. The Re-Os age determined by analysis of 12 komatiite samples is 270 ± 21 Ma. These data agree with the age of flood basalts of the Emeishan Large Igneous Province. The komatiite-basalt complex of the Song Da rift is still the only Phanerozoic PGE-Cu-Ni-complex of this composition. The geochemistry of accompanying Cu-Ni-PGE-ores confirms their relationship with komatiite-basaltic magmatism. 相似文献
8.
D. M. Polyakov A. V. Mozherovskii A. A. Mar’yash 《Russian Meteorology and Hydrology》2014,39(10):697-704
The concentration of Si, Al, Mg, K, Ca, Na, Sr, and Ba in the subcolloidal fraction of sediments at the Razdol’naya River-Amur Bay cross-section is determined using the atomic emission spectroscopy method. Computed is the mean content of studied elements in the soil and river bottom sediments (to the mixing zone). Revealed are river bottom sediments with the high concentration of macroelements corresponding to the zone of mixing of fresh river water and salt sea water. It is demonstrated that the additional accumulation of macroelements (Ca, Na, and Sr) in these sediments is associated with the formation of hydroxides of Fe and Mn and processes of sorption (Mg, Ca, Na, K, Sr, and Ba) on clay minerals (hydromica and smectites). 相似文献
9.
V.B. Polyakov S.D. Mineev G. Hu D.A. Khramov V.E. Gorbunov 《Geochimica et cosmochimica acta》2005,69(5):1287-1300
Oxygen isotope equilibrium fractionation constants (β18O-factors) of cassiterite were evaluated on the basis of heat capacity and X-ray resonant (Mössbauer spectroscopy and X-ray inelastic scattering) data.The low-temperature heat capacity of cassiterite was measured in the range from 13 to 340 K using an adiabatic calorimeter. Results of measurements of two samples agree very closely but deviate more than 5% from previous heat capacity data used for calculation of thermodynamic functions. The temperature dependence of heat capacity was treated using the modern version of the Thirring expansion, and the appropriate temperature dependence of the vibrational kinetic energy was found.Measurements of temperature-dependent Mössbauer parameters of cassiterite were conducted in the range from 300 to 900 K. The attempt to describe Mössbauer fraction and the second order Doppler (SOD) shift on the basis of the Debye model failed. The first term of the Thirring expansion of the Mössbauer SOD shift agrees with that calculated from the Sn sublattice vibration density of states (VDOS) obtained via synchrotron X-ray scattering. Based on this agreement we calculated the kinetic energy of the cassiterite Sn sublattice from VDOS.From the kinetic energy of the total cassiterite crystalline lattice and its Sn sublattice, β18O-factors of cassiterite were computed in the temperature range 300-1500 K by the method of Polyakov and Mineev (2000). Appropriate polynomials, which are valid at temperatures above 400 K, are the following:
10.
The results of a comprehensive study of the Galactic open cluster NGC 2323 (M50) are presented. The positions of stars to
a limiting magnitude {ie74-1} in a {ie74-2} area centered on the cluster were measured on six plates from the Pulkovo normal
astrograph with a maximum epoch difference of 60 yr. The measurements were performed with the Pulkovo “Fantasy” automated
measuring system upgraded in 2010. The corresponding areas from the USNO-A2.0, USNO-B1, and 2MASS catalogues were used as
additional plates. As a result, the relative proper motions of stars were obtained with a root-mean-square error of 5.85 mas
yr−1. A catalogue of UBV and JHK magnitudes for objects in the investigated area was compiled from available published resources. The astrometric selection
of cluster members was made by the maximum likelihood method. A high individual cluster membership probability of a star (P ≥ 80%) served as the first selection criterion. The position of a star on the photometric color-magnitude (V ∝ (B-V), J ∝ (J-K)) diagrams of the cluster was considered as the second criterion. The position of an object on the color-color ((U-B)-(B-V), (J-H)-(J-K)) diagrams served as the third criterion. On the basis of these criteria, it was established that 508 stars are members of
NGC 2323. These data were used to refine the physical parameters of the cluster: the mean reddening {ie74-3}, the true distance
modulus {ie74-4}, and the cluster age of about 140 Myr from the grid of isochrones computed by the Padova group for solar
chemical composition. Two tables contain the catalogues of proper motions and photometry for stars in the area. The luminosity
and mass functions were constructed. The cluster membership of red and blue giants, variable, double, and multiple stars was
considered. The position of the cluster center was improved: {ie74-5}, δ = −08°20′16″(2000.0). 相似文献