全文获取类型
收费全文 | 1010篇 |
免费 | 45篇 |
国内免费 | 6篇 |
专业分类
测绘学 | 22篇 |
大气科学 | 127篇 |
地球物理 | 247篇 |
地质学 | 323篇 |
海洋学 | 69篇 |
天文学 | 141篇 |
综合类 | 3篇 |
自然地理 | 129篇 |
出版年
2023年 | 5篇 |
2022年 | 7篇 |
2021年 | 12篇 |
2020年 | 18篇 |
2019年 | 21篇 |
2018年 | 22篇 |
2017年 | 34篇 |
2016年 | 60篇 |
2015年 | 46篇 |
2014年 | 40篇 |
2013年 | 95篇 |
2012年 | 33篇 |
2011年 | 47篇 |
2010年 | 47篇 |
2009年 | 37篇 |
2008年 | 42篇 |
2007年 | 32篇 |
2006年 | 23篇 |
2005年 | 22篇 |
2004年 | 22篇 |
2003年 | 21篇 |
2002年 | 45篇 |
2001年 | 20篇 |
2000年 | 19篇 |
1999年 | 18篇 |
1998年 | 15篇 |
1997年 | 16篇 |
1996年 | 7篇 |
1995年 | 15篇 |
1994年 | 10篇 |
1993年 | 5篇 |
1992年 | 13篇 |
1991年 | 6篇 |
1990年 | 8篇 |
1989年 | 7篇 |
1988年 | 6篇 |
1987年 | 5篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 15篇 |
1983年 | 12篇 |
1982年 | 11篇 |
1981年 | 7篇 |
1980年 | 16篇 |
1979年 | 12篇 |
1978年 | 12篇 |
1977年 | 12篇 |
1976年 | 7篇 |
1975年 | 8篇 |
1973年 | 11篇 |
排序方式: 共有1061条查询结果,搜索用时 15 毫秒
11.
The interrelated use of geological information and other types of geoinformation in local governments 下载免费PDF全文
Elisabeth Häggquist 《Transactions in GIS》2017,21(5):1010-1022
There is a growing interest in the use of geoinformation in government decision‐making. Studies on the usability of geological information, which is one type of geoinformation, have however been scarce in the literature. A system built for an efficient organization may, therefore, not be catering to the needs of the individual user and understanding the perceived barriers to using geological information should be an important goal of geodata implementation. The objectives of this article are to: (1) investigate whether the analyses of user patterns are improved by considering an interrelated estimation with two types of geoinformation, and (2) explore whether there are gender differences in how peer advice affects the use of geoinformation. The data were collected in 2014 through a web survey, and the sample consisted of 390 women and 287 men working in Swedish municipalities. The results indicates a more accurate prediction pattern when a secondary geoinformation decision was included, thus suggesting that different types of geoinformation should be jointly analyzed. The officials tend to use both types of geoinformation, alluding to a demand for combined geoinformation products among the target population. Finally, there is evidence of women's decision to use geoinformation being affected by peer advice. 相似文献
12.
Georg Bergeton Larsen Stig Syndergaard Per Høeg Martin Bjært Sørensen 《GPS Solutions》2005,9(2):144-155
The Global Positioning System (GPS) radio occultation measurements obtained using the TurboRogue GPS receiver on the Danish satellite Ørsted have been processed using the single frequency method. Atmospheric profiles of refractivity and temperature are derived and validated against numerical weather prediction data from the European Centre for Medium-Range Weather Forecast (ECMWF). Results from the Ørsted GPS measurement campaign in February 2000 indicate that the single frequency method can provide retrievals with accuracy comparable to that of using two frequencies. From comparisons between measured dry temperature profiles and corresponding dry temperature profiles derived from ECMWF analysis fields, we find a mean difference of less than 0.5 K and a standard deviation of 2–4 K between 500 and 30 hPa in height. Above 30 hPa the impact of the ionosphere becomes more dominant and more difficult to eliminate using the single frequency method, and the results show degraded accuracy when compared to previous analysis results of occultation data from other missions using the dual frequency method. At latitudes less than 40° (denoted low latitudes), the standard deviation is generally smaller than at latitudes higher than 40° (denoted high latitudes). A small temperature bias is observed centered at 200 hPa for low latitudes and at 300 hPa for high latitudes. This indicates that the ECMWF analyses do not adequately resolve the tropopause temperature minimum. In the lowest part of the troposphere an observed warm bias is thought to be due to erroneous tracking of the GPS signal in cases of atmospheric multipath propagation. 相似文献
13.
Vegard Gundersen Bjørn Petter Kaltenborn Daniel R. Williams 《Norsk geografisk tidsskrift. Norwegian journal of geography》2016,70(4):216-229
Local communities in the Gudbrandsdalen region in Norway are increasingly exposed to climate-induced hazards such as floods and landslides. A core question is how community members respond to climate change and what factors contribute to more resilient communities. The authors used a contextual approach to analyze data from semi-structured interviews along five dimensions. In Gaustad Muncipality they found that individuals’ motivation to adapt to climate change depended largely on subjective values such as identity, place attachment, cultural values, and social networks among individuals, which means it is crucial that strategic plans for adaptation to climate change at different policy levels are experienced as relevant by community members. While the studied community has experienced heavy floods in river systems and streams, little evidence of adaptation was observed. Instead, they appeared to adopt coping strategies. Landowners may have limited incentives to adapt to climate change due to contraproductive policy measures such as economic compensation for direct losses without requiring improved practices. Effective adaptation to climate change on the local level is likely to require making compensation mechanisms contingent upon landowners showing willingness to change from coping to adaptive practices, as well as a contextualized approach integrating local and scientific forms of knowledge. 相似文献
14.
Knut Jørgen Røed Ødegaard 《Astrophysics and Space Science》1996,238(1):107-111
New computations of massive stars follow the evolution up to advanced stages and include: -A large and flexible nuclear network consisting of 174 nuclear species that are linked by 1742 nuclear reactions. -Semiconvection, overshooting and mass loss. -Modern rates for both strong and weak interaction processes as well as the latest rates for the neutrino processes. -Improved grid distribution and a large number of grid points. The nuclear network and the diffusion equation are solved for each time step during the whole evolution. In this way the accuracy of nuclear yields and chemical abundances are mainly limited by uncertainties in the diffusion coefficient found from the convection theories. Several instability mechanisms may affect the mass loss rates of massive stars and thereby the structure and abundances of WR stars. Due to heavy mass loss at the LBV and WR stages, the masses at the pre-SN stage may be less than 5M ⊙. Yields and abundances throughout the stars are discussed together with the amount of all elements expelled. 相似文献
15.
16.
17.
Seasonal dynamics of elemental sulfur in two coastal sediments 总被引:1,自引:0,他引:1
A spectrophotometric method for elemental sulfur (S0) analysis without interference from other reduced sulfur compounds was adapted for the use in reducing sediments. The S0 distribution in two coastal sediments was studied regularly from summer to winter and compared to factors regulating the S0 accumulation, such as redox potentials, the rate of bacterial sulfide production and the general sulfur chemistry. Dense coatings of sulfur bacteria developed on the sediment surface of a sulfuretum which had an S0 concentration of up to 41 μmol S cm?3. The 2·5-mm thick bacterial coating contained 40% of all S0 in the sediment. A more typical marine sediment with a few cm thick oxidized surface layer had an S0 maximum of 1–3 μmol S cm?3 at 2–4 cm depth. The S0 maximum in both sediments increased from summer to winter as the sediments gradually became more oxidized. The deeper layers maintained a low S0 concentration. Most of the S0 in the upper few mm of a laboratory sulfuretum was present inside sulfur bacteria and actively migrated up and down with the bacteria depending upon the changing light and oxygen conditions. 相似文献
18.
Term values for the 1s 2s states of H– are calculated with the use of simple eigenfunction approximations constructed on the basis of available Hartree-type functions for the 1s
2 and 2s
2 states of the ion. The results seem to support a tentative identification of the interstellar diffuse absorption bands at 4890 and 6180 as due to negative hydrogen. 相似文献
19.
A late Pleistocene and Holocene mineral magnetic record from sediments of Lake Aibi,Dzungarian Basin,NW China 总被引:1,自引:0,他引:1
Alina Tudryn Piotr Tucholka Elisabeth Gibert Francoise Gasse Keiquin Wei 《Journal of Paleolimnology》2010,44(1):109-121
We studied mineral magnetic properties of a 6-m-long, late Pleistocene through Holocene sediment sequence from Lake Aibi in
Dzungaria (Zunggary, Junggar), northern Xinjiang, China. Results were used to infer environmental changes and are compared
with previously studied cores from Lake Manas. Both water bodies occupy the deepest parts of the Dzungarian Basin and are
remnants of large Holocene lakes. During the Late Pleistocene, the magnetic mineralogy in both lakes was dominated by detrital,
iron oxide minerals. Oxic conditions, which dominated during sedimentation and early diagenesis, persisted over the Pleistocene–Holocene
transition. Later, during the middle Holocene, lake bottom conditions enabled authigenic formation of iron sulphide minerals
such as pyrite (FeS2) in Lake Aibi, and pyrite and greigite (Fe3S4) in Lake Manas. This iron sulphide mineralogy suggests increased biological activity in stagnant, anoxic bottom waters. Anoxic
bottom conditions started about 9.8 cal kyr BP in Lake Manas and at about 7.2 cal kyr BP in Lake Aibi. A short dry event recorded
in Lake Manas between 6.8 and 5.2 cal kyr BP is not clearly observed in Lake Aibi. In the late Holocene, i.e. the last 2.8 cal
kyr, sediments of both lakes are again characterised by iron oxides, suggesting well-mixed, shallow water bodies. For this
recent period, it seems that the detrital material in the two lakes had a common origin. Magnetic properties of sediments
in Lakes Aibi and Manas show broadly similar environmental evolution during the late Pleistocene and Holocene. Nevertheless,
despite the close proximity of the two lakes (~200 km) in the same basin, they display some different magnetic properties
and record environmental changes at different times. 相似文献
20.
Izabela Golebiowska Tomasz Opach Jan Ketil Rød 《International journal of geographical information science》2017,31(2):237-252
Geographic visualization tools with coordinated and multiple views (CMV) typically provide sets of visualization methods. Such configuration gives users the possibility of investigating data in various visual contexts; however, it can be confusing due to the multiplicity of visual components and interactive functions. We addressed this challenge and conducted an empirical study on how a CMV tool, consisting of a map, a parallel coordinate plot (PCP), and a table, is used to acquire information. We combined a task-based approach with eye-tracking and usability metrics since these methods provide comprehensive insights into users’ behaviour. Our empirical study revealed that the freedom to choose visualization components is appreciated by users. The individuals worked with all the available visualization methods and they often used more than one visualization method when executing tasks. Different views were used in different ways by various individuals, but in a similarly effective way. Even PCP, which is claimed to be problematic, was found to be a handy way of exploring data when accompanied by interactive functions. 相似文献