全文获取类型
收费全文 | 293篇 |
免费 | 19篇 |
国内免费 | 4篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 9篇 |
地球物理 | 112篇 |
地质学 | 98篇 |
海洋学 | 26篇 |
天文学 | 43篇 |
综合类 | 1篇 |
自然地理 | 16篇 |
出版年
2023年 | 6篇 |
2022年 | 4篇 |
2021年 | 9篇 |
2020年 | 12篇 |
2019年 | 11篇 |
2018年 | 10篇 |
2017年 | 12篇 |
2016年 | 26篇 |
2015年 | 12篇 |
2014年 | 12篇 |
2013年 | 12篇 |
2012年 | 18篇 |
2011年 | 15篇 |
2010年 | 17篇 |
2009年 | 15篇 |
2008年 | 17篇 |
2007年 | 18篇 |
2006年 | 10篇 |
2005年 | 5篇 |
2004年 | 14篇 |
2003年 | 8篇 |
2002年 | 5篇 |
2001年 | 3篇 |
2000年 | 2篇 |
1999年 | 2篇 |
1998年 | 1篇 |
1997年 | 7篇 |
1996年 | 6篇 |
1995年 | 6篇 |
1994年 | 1篇 |
1992年 | 2篇 |
1991年 | 3篇 |
1990年 | 1篇 |
1989年 | 2篇 |
1988年 | 1篇 |
1987年 | 2篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1983年 | 1篇 |
1979年 | 2篇 |
1975年 | 1篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
排序方式: 共有316条查询结果,搜索用时 250 毫秒
161.
Carmen Pilar Padilla-Torres Carlos M. Gutiérrez Rafael Rebolo Ricardo Génova-Santos José Alberto Rubiño-Martin 《Monthly notices of the Royal Astronomical Society》2009,396(1):53-60
We study the spatial distribution and colours of galaxies within the region covered by the cold spot in the cosmic microwave background recently detected by the Very Small Array interpherometer (VSA) towards the Corona Borealis supercluster (CrB-SC). The spot is in the northern part of a region with a radius ∼1° (∼5 Mpc at the redshift of CrB-SC) enclosing the clusters Abell 2056, 2065, 2059 and 2073, and where the density of galaxies, excluding the contribution from those clusters, is approximately two times higher than the mean value in typical intercluster regions of the CrB-SC. Two of such clusters (Abell 2056 and 2065) are members of the CrB-SC, while the other two are in the background. This high-density intercluster region is quite inhomogeneous, being the most remarkable feature a large concentration of galaxies in a narrow filament running from Abell 2065 with a length of ∼35 arcmin ( ∼3 Mpc at the redshift of CrB-SC) in the SW–NE direction. This intercluster population of galaxies probably results from the interaction of clusters Abell 2065 and 2056. The area subtended by the VSA cold spot shows an excess of faint (21 < r < 22) and red (1.1 < r − i < 1.3) galaxies as compared with typical values within the CrB-SC intercluster regions. This overdensity of galaxies shows a radial dependence and extends out to ∼15 arcmin. This could be the signature of a previously unnoted cluster in the background. 相似文献
162.
163.
It is generally assumed that the magnetic fields of millisecond pulsars (MSPs) are ~108 G. We argue that this may not be true and the fields may be appreciably greater. We present six evidences for this: (1) The ~108G field estimate is based on magnetic dipole emission losses which is shown to be questionable; (2) The MSPs in low mass X-ray binaries (LMXBs) are claimed to have <1011 G on the basis of a Rayleygh-Taylor instability accretion argument. We show that the accretion argument is questionable and the upper limit 1011 G may be much higher; (3) Low magnetic field neutron stars have difficulty being produced in LMXBs; (4) MSPs may still be accreting indicating a much higher magnetic field; (5) The data that predict ~108 G for MSPs also predict ages on the order of, and greater than, ten billion years, which is much greater than normal pulsars. If the predicted ages are wrong, most likely the predicted ~108 G fields of MSPs are wrong; (6) When magnetic fields are measured directly with cyclotron lines in X-ray binaries, fields ?108 G are indicated. Other scenarios should be investigated. One such scenario is the following. Over 85% of MSPs are confirmed members of a binary. It is possible that all MSPs are in large separation binaries having magnetic fields >108 G with their magnetic dipole emission being balanced by low level accretion from their companions. 相似文献
164.
165.
Antonio M. Álvarez-Valero Reinaldo Sáez Rafael Pérez-López Joaquín Delgado José M. Nieto 《Journal of Geochemical Exploration》2009
The beginning of polymetallic sulphide ore exploitation at Almagrera, Iberian Pyrite Belt, SW Spain, has been dated back to pre-Roman times; mining activity lasted until 2001 when it was definitely halted. The Almagrera sulphide tailings dam was built at the Sotiel–Coronada mine, where Cu, Zn and Pb concentrates were obtained by flotation processes, and sulphide (mainly pyrite) wastes formed. The dam was built as a water-reservoir, on a tectonic fault; its hazard is currently documented by the released wastes after a strong storm in the region, then, its stability is not monitored by the owner. 相似文献
166.
Natural Hazards - There has been an increase in drownings over recent decades in Australia, particularly among rock fishers swept from the edge of rock platforms. Platform morphology is central to... 相似文献
167.
168.
A strong-motion accelerograph array in Santiago, Chile has been installed. One of the sites is located on rock and the other six sites are on soil ground with different surface geology, so that local site effects on ground motions can be studied. As a preliminary evaluation of the site effects, the spectral ratios of weak-motion records at soil sites with respect to the rock site are calculated. The spectral ratios show that the amplification of ground motions with respect to the rock site is approximately 1.25 on dense gravel deposits, 2.5 on stiff pumice ground and 3.5 on soft silt ground. 相似文献
169.
170.
A method for evaluating the reliability of ceramic structural members subjected to earthquake-induced vibrations is presented. The method uses the Weibull distribution to represent the probability of failure of the brittle ceramic material and includes the effects of stress concentrations introduced by flaws and the volume of material subjected to stress. The stress concentration introduced by the complex form of insulators and at the mounting interfaces is considered. A numerical example is given to illustrate the application of the method. 相似文献