全文获取类型
收费全文 | 1866篇 |
免费 | 32篇 |
国内免费 | 5篇 |
专业分类
测绘学 | 57篇 |
大气科学 | 43篇 |
地球物理 | 883篇 |
地质学 | 431篇 |
海洋学 | 17篇 |
天文学 | 382篇 |
综合类 | 4篇 |
自然地理 | 86篇 |
出版年
2018年 | 41篇 |
2017年 | 37篇 |
2016年 | 55篇 |
2015年 | 42篇 |
2014年 | 41篇 |
2013年 | 60篇 |
2012年 | 62篇 |
2011年 | 51篇 |
2010年 | 57篇 |
2009年 | 51篇 |
2008年 | 44篇 |
2007年 | 58篇 |
2006年 | 41篇 |
2005年 | 38篇 |
2004年 | 38篇 |
2003年 | 45篇 |
2002年 | 39篇 |
2001年 | 28篇 |
2000年 | 33篇 |
1999年 | 24篇 |
1998年 | 20篇 |
1997年 | 23篇 |
1996年 | 26篇 |
1995年 | 28篇 |
1994年 | 26篇 |
1993年 | 32篇 |
1992年 | 22篇 |
1991年 | 24篇 |
1989年 | 27篇 |
1988年 | 25篇 |
1987年 | 30篇 |
1986年 | 29篇 |
1985年 | 32篇 |
1984年 | 32篇 |
1983年 | 32篇 |
1982年 | 36篇 |
1981年 | 32篇 |
1980年 | 33篇 |
1979年 | 30篇 |
1978年 | 34篇 |
1977年 | 31篇 |
1976年 | 24篇 |
1975年 | 29篇 |
1974年 | 21篇 |
1973年 | 22篇 |
1972年 | 26篇 |
1971年 | 41篇 |
1970年 | 20篇 |
1969年 | 21篇 |
1968年 | 25篇 |
排序方式: 共有1903条查询结果,搜索用时 0 毫秒
21.
The analysis of the time and space distribution of specular (reflecting) points in bistatic altimetry between GPS and CHAMP
satellites or SAC-C (taken as examples) is extended from Wagner and Klokočník (2003 J. Geod 77: 128–138). We demonstrate a
significantly higher number and density of reflecting points in bistatic altimetry in comparison with traditional monostatic
altimetry. After an outline of our older accuracy assessment for the vertical position of the reflecting point, we add a new
independent derivation and compare both approaches. We account for orbit errors of both the transmitters (GPS) and receiver
(CHAMP) satellites, and the measurement (delay) error. We found that the accuracy of the vertical position of the reflecting
point decreases only slowly with increasing off-nadir angle and that the orbit errors must be accounted for if decimeter and
better accuracy is required. In this paper, we do not study errors such as state of the ocean, technical parameters of the
receiving system, and atmospheric corrections. 相似文献
22.
23.
John E. Gordon Igor J. Dvorák Christer Jonasson Melanie Josefsson Milena Kociánová & Des B.A. Thompson 《Geografiska Annaler: Series A, Physical Geography》2002,84(3&4):193-203
Montane (alpine) areas are generally of high value for nature conservation. Such environments and the habitats they support are dynamic and often fragile. They are vulnerable to disturbance from a range of human activities and are responsive to climate changes over short and long timescales. Biodiversity and conservation values are closely linked to geological history, geomorphological processes and soils, and it is crucial that management systems are based on understanding these links.
There are many similarities between the Cairngorm Mountains (Scotland), the Giant Mountains (Czech Republic) and Abisko Mountains (Sweden) in terms of geology, geomorphology, ecology, links with biodiversity and high conservation importance. Comparable pressures and management issues involve, to varying degrees, a history of human use and impacts from deforestation, pasturing, grazing, recreation and atmospheric pollution. Landscape change therefore involves a complex interplay between natural and anthropogenic factors. Managing such change requires better understanding of the geo–ecological processes involved and the factors that determine landscape sensitivity. This is illustrated through a simple framework and examples from the three areas. Comparison of landscape sensitivity between similar montane areas, but in different geographic locations and climatic environments, should allow more informed management planning and a precautionary approach in advance of further changes in human activity and from predicted global warming scenarios. 相似文献
There are many similarities between the Cairngorm Mountains (Scotland), the Giant Mountains (Czech Republic) and Abisko Mountains (Sweden) in terms of geology, geomorphology, ecology, links with biodiversity and high conservation importance. Comparable pressures and management issues involve, to varying degrees, a history of human use and impacts from deforestation, pasturing, grazing, recreation and atmospheric pollution. Landscape change therefore involves a complex interplay between natural and anthropogenic factors. Managing such change requires better understanding of the geo–ecological processes involved and the factors that determine landscape sensitivity. This is illustrated through a simple framework and examples from the three areas. Comparison of landscape sensitivity between similar montane areas, but in different geographic locations and climatic environments, should allow more informed management planning and a precautionary approach in advance of further changes in human activity and from predicted global warming scenarios. 相似文献
24.
25.
Andesitic pillow lavas containing biogenic, solid bitumen (SB) are a constituent of a Neoproterozoic volcanosedimentary sequence (Teplá-Barrandian unit, Bohemian Massif) in the Mítov area of the Czech Republic. A black shale formation that is crosscut by these andesitic basalts is 565 Ma old. Carbon disulfide extracts of two powdered samples of SB contain 0.2 and 0.3 ppm of C60, respectively, as determined by high-pressure liquid chromatography. The peak assignment based on retention time is fully supported by high-resolution electron ionization mass spectrometry (EI-MS). No C70 was detected, nor was C60 found in two other SB samples from this locality. Other investigated carbonaceous samples from Bohemia (coals and anthracites of Upper Paleozoic age and anthraxolite, graphitoids, and graphite of Upper Proterozoic age) did not contain fullerenes at concentrations above the detection limit of 0.01 ppm. The absence of C60 in these samples was confirmed by EI-MS. The proposed mechanism of fullerene formation involves a primary algal phase, generation of a hydrocarbonaceous mixture in the course of thermal evolution of the sedimentary series, and their high-temperature transformation related to the extrusion of basalt. An important feature for fullerene conservation was the enclosure of fullerenes in SB with a structure similar to glasslike carbon, where the fullerene was protected against oxidation. 相似文献
26.
27.
28.
J. Keder M. Střižík P. Berger A. Černý P. Engst I. Němcová 《Meteorology and Atmospheric Physics》2004,85(1-3):155-164
Summary Air pollution problem in the Czech Republic is very complex due to large number of factors as turbulent dispersion and chemical reactions concurring in the status of the PBL. For this 3D distribution of pollutants is a key information that cannot be given by conventional monitoring stations. Combined use of DIAL lidar and sodar can give access to such information. Case studies of air pollutants transport are presented using 3D concentration fields of NO2 and ozone measured by lidar and meteorological conditions monitored by Doppler Sodar. 相似文献
29.
Alessandro Beghini Zdeněk P. Bažant R. Chambon D. Kolymbas I. Herle 《国际地质力学数值与分析法杂志》2004,28(4):365-372
30.