全文获取类型
收费全文 | 282篇 |
免费 | 15篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 11篇 |
大气科学 | 33篇 |
地球物理 | 85篇 |
地质学 | 85篇 |
海洋学 | 39篇 |
天文学 | 27篇 |
综合类 | 1篇 |
自然地理 | 19篇 |
出版年
2024年 | 1篇 |
2023年 | 1篇 |
2022年 | 1篇 |
2021年 | 2篇 |
2020年 | 7篇 |
2019年 | 9篇 |
2018年 | 8篇 |
2017年 | 10篇 |
2016年 | 11篇 |
2015年 | 12篇 |
2014年 | 20篇 |
2013年 | 12篇 |
2012年 | 12篇 |
2011年 | 15篇 |
2010年 | 20篇 |
2009年 | 22篇 |
2008年 | 13篇 |
2007年 | 13篇 |
2006年 | 14篇 |
2005年 | 14篇 |
2004年 | 10篇 |
2003年 | 6篇 |
2002年 | 8篇 |
2001年 | 4篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 4篇 |
1993年 | 1篇 |
1992年 | 5篇 |
1990年 | 1篇 |
1989年 | 3篇 |
1986年 | 1篇 |
1985年 | 4篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 1篇 |
1971年 | 1篇 |
1969年 | 2篇 |
1965年 | 2篇 |
1963年 | 2篇 |
1962年 | 2篇 |
排序方式: 共有300条查询结果,搜索用时 26 毫秒
81.
An incentive mechanism for reducing emissions from conversion of intact and non-intact forests 总被引:1,自引:0,他引:1
Danilo Mollicone Frédéric Achard Sandro Federici Hugh D. Eva Giacomo Grassi Alan Belward Frank Raes Günther Seufert Hans-Jürgen Stibig Giorgio Matteucci Ernst-Detlef Schulze 《Climatic change》2007,83(4):477-493
This paper presents a new accounting mechanism in the context of the UNFCCC issue on reducing emissions from deforestation
in developing countries, including technical options for determining baselines of forest conversions. This proposal builds
on the recent scientific achievements related to the estimation of tropical deforestation rates and to the assessment of ‘intact’
forest areas. The distinction between ‘intact’ and ‘non intact’ forests used here arises from experience with satellite-based
deforestation measurements and allows accounting for carbon losses from forest degradation. The proposed accounting system
would use forest area conversion rates as input data. An optimal technical solution to set baselines would be to use historical
average figures during the time period from 1990 to 2005. The system introduces two different schemes to account for preserved
carbon: one for countries with high forest conversion rates where the desired outcome would be a reduction in their rates,
and another for countries with low rates. A ‘global’ baseline rate would be used to discriminate between these two country
categories (high and low rates). For the hypothetical accounting period 2013–2017 and considering 72% of the total tropical
forest domain for which data are available, the scenario of a 10% reduction of the high rates and of the preservation of low
rates would result in approximately 1.6 billion tCO2 of avoided emissions. The resulting benefits of this reduction would be shared between those high-rate countries which reduced
deforestation and those low-rate countries which did not increase their deforestation over an agreed threshold (e.g., half
of “global” baseline rate). 相似文献
82.
Eva Maria Walitzi 《Mineralogy and Petrology》1965,10(1-4):241-255
Zusammenfassung Denningit, (Mn, Ca, Zn) Te2O5 ist tetragonal mit der Raumgruppe P 42/n bc und den Gitterkonstanten a=8,82, c=13,04; Z=8. Die Struktur wurde mit Patterson-, Fourier- und (Fo-Fc)-Projektionen parallel [100], [110] und [001] bestimmt und verfeinert. Abschließend konnte eine least-squares-Verfeinerung durchgeführt werden. Je zwei trigonale TeO3-Pyramiden (Te–O=1,84–2,04 ) sind zu isolierten Te2O5-Gruppen verbunden. Mn, Ca und Zn in 8- und in [4+2]-Koordination bilden längs [001] Ketten, die durch Te2O5-Gruppen miteinander verknüpft sind.
Mit 3 Textabbildungen
Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet 相似文献
Summary Denningite, (Mn, Ca, Zn) Te2O5 is tetragonal with spacegroup P 42/n bc and unit-cell dimensions a=8,82, c=13,04; Z=8. The structure has been determined and refined by Patterson, Fourier and (Fo-Fc) projections along [100], [110] and [001]. Finally a least-squares refinement has been carried out. Pairs of trigonal TeO3 pyramids (Te–O=1,84–2,04) are connected to isolated Te2O5 groups. Mn, Ca and Zn in 8 coordination and in [4+2] coordination form chains along [001] connected by Te2O5 groups.
Mit 3 Textabbildungen
Herrn Professor Dr.F. Machatschki zum 70. Geburtstag gewidmet 相似文献
83.
84.
The concept of climate impact response function is introduced and placed into the context of integrated assessment models to analyze policy options under climate change constraints. An example of developing such response functions is presented that entails a global model of potential natural vegetation driven by a climate change pattern derived from a general circulation model. A large array of strenuous issues are introduced that will be addressed by the set of papers included in this Special Issue. 相似文献
85.
Eva Kiss 《GeoJournal》2000,51(3):221-233
Rural settlements in Hungary account for 93% of all settlements and 37% of the country's population. Since 1989 they are scenes of spectacular changes. Based on some case studies of less developed villages this paper considers the most important characteristics of the post-socialist rural transformation by examining the local economy and living conditions. The main issues are how local actors (for example, economic corporations, households and individuals) have been affected by the interaction of supralocal and local factors and how they responded to them. Such responses can be considered to be manifestations of survival strategy. 相似文献
86.
Eva Thorborg Mørk Lise Lotte Sørensen Bjarne Jensen Mikael K. Sejr 《Boundary-Layer Meteorology》2014,151(1):119-138
The air–sea transfer velocity of $\mathrm{CO}_{2}\, (k_{\mathrm{CO}_{2}})$ was investigated in a shallow estuary in March to July 2012, using eddy-covariance measurements of $\mathrm{CO}_{2}$ fluxes and measured air–sea $\mathrm{CO}_{2}$ partial-pressure differences. A data evaluation method that eliminates data by nine rejection criteria in order to heighten parametrization certainty is proposed. We tested the data evaluation method by comparing two datasets: one derived using quality criteria related solely to the eddy-covariance method, and the other derived using quality criteria based on both eddy-covariance and cospectral peak methods. The best parametrization of transfer velocity normalized to a Schmidt number of 600 $(k_{600})$ was determined to be: $k_{600} = 0.3\,{U_{10}}^{2.5}$ where $U_{10}$ is the wind speed in m $\mathrm{s}^{-1}$ at 10 m; $k_{600}$ is based on $\mathrm{CO}_{2}$ fluxes calculated by the eddy-covariance method and including the cospectral peak method criteria. At low wind speeds, the transfer velocity in the shallow water estuary was lower than in other coastal waters, possibly a symptom of low tidal amplitude leading to low intensity water turbulence. High transfer velocities were recorded above wind speeds of 5 m $\mathrm{s}^{-1}$ , believed to be caused by early-breaking waves and the large fetch (6.5 km) of the estuary. These findings indicate that turbulence in both air and water influences the transfer velocity. 相似文献
87.
Zoltan Siklosy Zoltan Kern Attila Demeny Sebastian Pilet Szabolcs Leel-Ossy Ke Lin Chuan-Chou Shen Eva Szeles Daniel Breitner 《Applied Geochemistry》2011,26(5):666-678
Four decades of U ore production in Hungary provides an opportunity to study the possible environmental effects of mining. The study reveals significant changes in chemical composition of a stalagmite (cave deposit). The good fit between U content changes in the studied deposit and the U ore production rate support the assumption of the relationship with mining activity. An independent chemoenviromental archive, living pine (Pinus sylvestis) trees were also investigated. Data on pine tree cores collected from the same region show different levels of pollution (Cu, Zn, Mn, U) after the 1950s and 1960s, linked to the opening of mines and subsequent dust fallout around the site. Elevated concentrations of detritally derived elements (Si, Al, Th) coupled with a rise in U concentration and change in δ234U values of the stalagmite suggest increasing amounts of mine-derived dust from 1 to 3 km distance that settled and washed into the karst system. The combined usage of different proxies not only provides historic records for the anthropogenic impact in the environment, but also allows the timing of U concentration increases within the stalagmite and the identification of elemental behavior from the pollution. This study shows that complementary geochemical archives such as stalagmites and tree rings used together can enhance understanding of past environmental contamination. 相似文献
88.
The study deals with changes in large-scale atmospheric circulation (represented by circulation types) and associated surface air temperatures as projected in an ensemble of regional climate models (RCMs) from the ENSEMBLES project. We examine changes of circulation type frequencies and means of daily maximum and minimum temperatures within circulation types in individual seasons for two time slices of transient runs under the SRES A1B scenario (2021–2050 and 2071–2100) with respect to the control period (1961–1990). To study the influence of driving data, simulations of the driving general circulation models (GCMs) also are evaluated. We find that all models project changes of atmospheric circulation that are statistically significant for both future time slices. The models tend to project strengthening of the westerly circulation in winter and its weakening in summer. We show that increases of daily maximum and minimum temperatures in all seasons differ for individual circulation types. There are, however, only few features of the projected changes in the future circulation–temperature links that are common among the models, in particular relatively smaller warming for westerly types. Only in winter, projected changes in circulation types tend to contribute to the projected overall warming. This effect is negligible and mostly opposite in the other seasons. We also detect a strong influence of driving data on RCMs’ simulation of atmospheric circulation and temperature changes. 相似文献
89.
Ágnes Kóspál Péter Ábrahám Mária Kun Szilárd Csizmadia Eva Verdugo 《Astrophysics and Space Science》2004,292(1-4):547-551
We investigated the brightness evolution of 5 FU Ori systems in the 1–200 μm wavelength range using observations from the Infrared Space Observatory, 2MASS and MSX data. The SEDs were compared with earlier ones derived from the IRAS photometry and ground-based observations around the epoch 1983. In three cases no difference was seen, in one object the near- and mid-infrared part of the spectrum became fainter by a factor of 2, and in the fifth case a marginal fading was observed. We study in detail the case of V1057 Cyg. 相似文献
90.
Vladislav Chrastný Jan Rohovec Eva Čadková Jan Pašava Juraj Farkaš Martin Novák 《Geostandards and Geoanalytical Research》2014,38(1):103-110
In recent years, routine application of the stable isotope determination of chromium (Cr) in environmental and health protection research has led to the search for simpler chromite decomposition techniques. As the range of Cr isotope abundance ratios in nature is very narrow, conventional chromite decomposition techniques are no longer suitable, due to the relatively high risk of contamination during laboratory procedures. We have developed a protocol for the decomposition of chromites based on oxidation by bromic acid at room temperature. The procedure takes 15 d and requires two doses of bromic acid during the reaction period (day 1 and 8), due to the limited stability of the reagent. Chromium extracted by alkaline oxidative fusion and by bromic acid decomposition yielded statistically indistinguishable δ53Cr values, measured by multi‐collector inductively coupled plasma‐mass spectrometry following addition of a 50Cr‐54Cr double‐spike. 相似文献