全文获取类型
收费全文 | 1806篇 |
免费 | 71篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 77篇 |
大气科学 | 282篇 |
地球物理 | 442篇 |
地质学 | 664篇 |
海洋学 | 59篇 |
天文学 | 272篇 |
综合类 | 2篇 |
自然地理 | 85篇 |
出版年
2021年 | 26篇 |
2020年 | 23篇 |
2019年 | 17篇 |
2018年 | 56篇 |
2017年 | 54篇 |
2016年 | 85篇 |
2015年 | 66篇 |
2014年 | 76篇 |
2013年 | 122篇 |
2012年 | 62篇 |
2011年 | 57篇 |
2010年 | 69篇 |
2009年 | 81篇 |
2008年 | 56篇 |
2007年 | 60篇 |
2006年 | 62篇 |
2005年 | 31篇 |
2004年 | 19篇 |
2003年 | 43篇 |
2002年 | 36篇 |
2001年 | 36篇 |
2000年 | 39篇 |
1999年 | 26篇 |
1998年 | 22篇 |
1997年 | 40篇 |
1996年 | 25篇 |
1995年 | 33篇 |
1994年 | 30篇 |
1993年 | 18篇 |
1991年 | 23篇 |
1990年 | 19篇 |
1988年 | 13篇 |
1987年 | 22篇 |
1986年 | 13篇 |
1984年 | 18篇 |
1983年 | 27篇 |
1982年 | 15篇 |
1981年 | 15篇 |
1980年 | 16篇 |
1979年 | 15篇 |
1978年 | 21篇 |
1976年 | 16篇 |
1975年 | 15篇 |
1974年 | 19篇 |
1973年 | 20篇 |
1972年 | 14篇 |
1970年 | 12篇 |
1969年 | 12篇 |
1968年 | 12篇 |
1965年 | 14篇 |
排序方式: 共有1883条查询结果,搜索用时 765 毫秒
211.
This study investigated the association of flood/stagnant water (FSW) with various health outcomes among respondents living in urban slums of Dhaka and adjacent rural areas. We also assessed the differences of individual-, household- and area-level characteristics between the FSW-affected and non-affected areas. Bangladesh as a whole and slums in the megacity of Dhaka in particular are severely affected by the FSW. Data were collected from 3,207 subjects (aged 10+ years) through baseline surveys conducted in March 2008 and 2009. Twelve big slums in Dhaka and three adjacent villages were selected as study areas. Face-to-face interviews using a multidimensional pre-tested questionnaire were conducted by the trained university graduates. We performed various types of analyses ranging from the simple frequency analysis to the multivariable-adjusted logistic regression modelling. Our empirical findings suggest that slums were more affected by the FSW as compared to the rural areas. People living in the FSW-affected areas were more vulnerable in terms of individual-, household- and area-level characteristics than non-affected people. Age was also significantly associated with various health outcomes. According to multivariable analyses controlled for various factors, the FSW-affected people reported significantly higher likelihoods of health symptoms (namely fever, cold/cough, weakness), communicable diseases (namely diarrhoea and gastric disease) and poor mental well-being as compared to the non-affected people. Only the burden of non-communicable diseases was lower in the FSW-affected areas than the non-affected areas. Our findings lead us to conclude that the FSW-affected area is an independent risk factor for various physical and mental health problems. Urban slums are more affected than rural areas by the FSW. Therefore, we underscore the necessities of well-designed and comprehensive public health interventions focusing on individual, community and higher levels of interventions to reduce the FSW-related health and other consequences among the people living in the FSW-affected areas and urban slums in the rapidly growing city of Dhaka, Bangladesh. 相似文献
212.
W. Curdt D. Germerott K. Wilhelm U. Schühle L. Teriaca D. Innes K. Bocchialini P. Lemaire 《Solar physics》2014,289(6):2345-2376
We have released an archive of all observational data of the VUV spectrometer Solar Ultraviolet Measurements of Emitted Radiation (SUMER) on SOHO that have been acquired until now. The operational phase started with ‘first light’ observations on 27 January 1996 and will end in 2014. Future data will be added to the archive when they become available. The archive consists of a set of raw data (Level 0) and a set of data that are processed and calibrated to the best knowledge we have today (Level 1). This communication describes step by step the data acquisition and processing that has been applied in an automated manner to build the archive. It summarizes the expertise and insights into the scientific use of SUMER spectra that has accumulated over the years. It also indicates possibilities for further enhancement of the data quality. With this article we intend to convey our own understanding of the instrument performance to the scientific community and to introduce the new, standard FITS-format database. 相似文献
213.
214.
The magnetic flux tubes that rise across the convection zone to produce active regions are shown to develop a difference in inclination between their preceding and follower sides. This asymmetry is such that the follower wing is more vertical (i.e., closer to the radial direction) than the preceding side. An asymmetry of this kind can be obtained as a natural consequence of the conservation of angular momentum along the rise. This process may explain a number of the observed asymmetries in morphology and behavior of the preceding and follower parts of the active regions. We present results of numerical simulations showing this effect and discuss possible observational consequences. 相似文献
215.
Time variable Earth’s gravity field from SLR satellites 总被引:4,自引:4,他引:0
216.
217.
218.
N. V. Chukanov S. M. Aksenov R. K. Rastsvetaeva K. V. Van D. I. Belakovskiy I. V. Pekov V. V. Gurzhiy W. Schüller B. Ternes 《Geology of Ore Deposits》2015,57(8):721-731
A new mineral, mendigite (IMA no. 2014-007), isostructural with bustamite, has been found in the In den Dellen pumice quarry near Mendig, Laacher Lake area, Eifel Mountains, Rhineland-Palatinate (Rheinland-Pfalz), Germany. Associated minerals are sanidine, nosean, rhodonite, tephroite, magnetite, and a pyrochlore-group mineral. Mendigite occurs as clusters of long-prismatic crystals (up to 0.1 × 0.2 × 2.5 mm in size) in cavities within sanidinite. The color is dark brown with a brown streak. Perfect cleavage is parallel to (001). D calc = 3.56 g/cm3. The IR spectrum shows the absence of H2O and OH groups. Mendigite is biaxial (–), α = 1.722 (calc), β = 1.782(5), γ = 1.796(5), 2V meas = 50(10)°. The chemical composition (electron microprobe, mean of 4 point analyses, the Mn2+/Mn3+ ratio determined from structural data and charge-balance constraints) is as follows (wt %): 0.36 MgO, 10.78 CaO, 37.47 MnO, 2.91 Mn2O3, 4.42 Fe2O3, 1.08 Al2O3, 43.80 SiO2, total 100.82. The empirical formula is Mn2.00(Mn1.33Ca0.67) (Mn0.50 2+ Mn0.28 3+ Fe0.15 3+ Mg0.07)(Ca0.80 (Mn0.20 2+)(Si5.57 Fe0.27 3+ Al0.16O18). The idealized formula is Mn2Mn2MnCa(Si3O9)2. The crystal structure has been refined for a single crystal. Mendigite is triclinic, space group \(P\bar 1\); the unit-cell parameters are a = 7.0993(4), b = 7.6370(5), c = 7.7037(4) Å, α = 79.58(1)°, β = 62.62(1)°, γ = 76.47(1)°; V = 359.29(4) Å3, Z = 1. The strongest reflections on the X-ray powder diffraction pattern [d, Å (I, %) (hkl)] are: 3.72 (32) (020), 3.40 (20) (002, 021), 3.199 (25) (012), 3.000 (26), (\(01\bar 2\), \(1\bar 20\)), 2.885 (100) (221, \(2\bar 11\), \(1\bar 21\)), 2.691 (21) (222, \(2\bar 10\)), 2.397 (21) (\(02\bar 2\), \(21\bar 1\), 203, 031), 1.774 (37) (412, \(3\bar 21\)). The type specimen is deposited in the Fersman Mineralogical Museum, Russian Academy of Sciences, Moscow, registration number 4420/1. 相似文献
219.
220.