全文获取类型
收费全文 | 959篇 |
免费 | 36篇 |
国内免费 | 41篇 |
专业分类
测绘学 | 12篇 |
大气科学 | 136篇 |
地球物理 | 231篇 |
地质学 | 266篇 |
海洋学 | 264篇 |
天文学 | 71篇 |
综合类 | 27篇 |
自然地理 | 29篇 |
出版年
2023年 | 2篇 |
2022年 | 11篇 |
2021年 | 22篇 |
2020年 | 20篇 |
2019年 | 14篇 |
2018年 | 39篇 |
2017年 | 53篇 |
2016年 | 63篇 |
2015年 | 57篇 |
2014年 | 61篇 |
2013年 | 73篇 |
2012年 | 58篇 |
2011年 | 83篇 |
2010年 | 80篇 |
2009年 | 60篇 |
2008年 | 51篇 |
2007年 | 44篇 |
2006年 | 37篇 |
2005年 | 36篇 |
2004年 | 16篇 |
2003年 | 29篇 |
2002年 | 17篇 |
2001年 | 12篇 |
2000年 | 11篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 2篇 |
1995年 | 2篇 |
1994年 | 2篇 |
1993年 | 4篇 |
1992年 | 6篇 |
1991年 | 3篇 |
1990年 | 4篇 |
1989年 | 2篇 |
1988年 | 3篇 |
1986年 | 3篇 |
1983年 | 2篇 |
1981年 | 3篇 |
1980年 | 3篇 |
1977年 | 3篇 |
1976年 | 2篇 |
1971年 | 1篇 |
1970年 | 1篇 |
1968年 | 1篇 |
1962年 | 2篇 |
1960年 | 1篇 |
1954年 | 3篇 |
1949年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有1036条查询结果,搜索用时 15 毫秒
91.
92.
93.
Hourly outgoing longwave radiation(OLR) from the geostationary satellite Communication Oceanography Meteorological Satellite(COMS) has been retrieved since June 2010. The COMS OLR retrieval algorithms are based on regression analyses of radiative transfer simulations for spectral functions of COMS infrared channels. This study documents the accuracies of OLRs for future climate applications by making an intercomparison of four OLRs from one single-channel algorithm(OLR12.0using the 12.0 μm channel) and three multiple-channel algorithms(OLR10.8+12.0using the 10.8 and 12.0 μm channels; OLR6.7+10.8using the 6.7 and 10.8 μm channels; and OLR All using the 6.7, 10.8, and 12.0 μm channels). The COMS OLRs from these algorithms were validated with direct measurements of OLR from a broadband radiometer of the Clouds and Earth's Radiant Energy System(CERES) over the full COMS field of view [roughly(50°S–50°N, 70°–170°E)] during April 2011.Validation results show that the root-mean-square errors of COMS OLRs are 5–7 W m-2, which indicates good agreement with CERES OLR over the vast domain. OLR6.7+10.8and OLR All have much smaller errors(~ 6 W m-2) than OLR12.0and OLR10.8+12.0(~ 8 W m-2). Moreover, the small errors of OLR6.7+10.8and OLR All are systematic and can be readily reduced through additional mean bias correction and/or radiance calibration. These results indicate a noteworthy role of the6.7 μm water vapor absorption channel in improving the accuracy of the OLRs. The dependence of the accuracy of COMS OLRs on various surface, atmospheric, and observational conditions is also discussed. 相似文献
94.
Climatological features of WRF-simulated tropical cyclones over the western North Pacific 总被引:2,自引:0,他引:2
Dasol Kim Chun-Sil Jin Chang-Hoi Ho Jinwon Kim Joo-Hong Kim 《Climate Dynamics》2015,44(11-12):3223-3235
95.
Distribution of dinoflagellate cysts in Yellow Sea sediments 总被引:1,自引:1,他引:0
To investigate the distribution,abundance,and species composition of dinoflagellate cysts in the Yellow Sea,surface sediment samples were collected at 37 sites,including the Korean dump site.Twenty-one dinoflagellate cyst taxa were identified,with the assemblages dominated mainly by Spiniferites bulloideus,Operculodinium centrocarpum,and cyst of Alexandrium catenella/tamarense type.A high frequency of O.centrocarpum in the Yellow Sea was observed for the first time,and it is likely that this can be attributed to the dynamics of the Yellow Sea Cold Water Mass and the Changjiang(Yangtze) River runoff.Total cyst concentrations ranged from 23 to 48 442 cysts/g dry weight,and high cyst concentrations were recorded adjacent to the dumping site.This result suggests that anthropogenic activities such as ocean dumping stimulate the growth of dinoflagellates in the Yellow Sea,which in turn leads to high levels of dinoflagellate cyst production. 相似文献
96.
97.
Marlon M. Jean John W. Shervais Sung-Hi Choi Samuel B. Mukasa 《Contributions to Mineralogy and Petrology》2010,159(1):113-136
The middle Jurassic Coast Range Ophiolite (CRO) is one of the most important tectonic elements in western California, cropping
out as tectonically dismembered elements that extend 700 km from south to north. The volcanic and plutonic sections are commonly
interpreted to represent a supra-subduction zone (SSZ) ophiolite, but models specifying a mid-ocean ridge origin have also
been proposed. These contrasting interpretations have distinctly different implications for the tectonic evolution of the
western Cordillera in the Jurassic. If an SSZ origin is confirmed, we can use the underlying mantle peridotites to elucidate
melt processes in the mantle wedge above the subduction zone. This study uses laser ablation–inductively coupled plasma–mass
spectrometry (LA–ICP–MS) to study pyroxenes in peridotites from four mantle sections in the CRO. Trace element signatures
of these pyroxenes record magmatic processes characteristic of both mid-ocean ridge and supra-subduction zone settings. Group
A clinopyroxene display enriched REE concentrations [e.g., Gd (0.938–1.663 ppm), Dy (1.79–3.24 ppm), Yb (1.216–2.047 ppm),
and Lu (0.168–0.290 ppm)], compared to Group B and C clinopyroxenes [e.g., Gd (0.048–0.055 ppm), Dy (0.114–0.225 ppm), Yb
(0.128–0.340 ppm), and Lu (0.022–0.05 ppm)]. These patterns are also evident in orthopyroxene. The differences between these
geochemical signatures could be a result of a heterogeneous upper mantle or different degrees of partial melting of the upper
mantle. It will be shown that CRO peridotites were generated through fractional melting. The shapes of REE patterns are consistent
with variable degrees of melting initiated within the garnet stability field. Models call for 3% dry partial melting of MORB-source
asthenosphere in the garnet lherzolite field for abyssal peridotites and 15–20% further partial melting in the spinel lherzolite
field, possibly by hydrous melting for SSZ peridotites. These geochemical variations and occurrence of both styles of melting
regimes within close spatial and temporal association suggest that certain segments of the CRO may represent oceanic lithosphere,
attached to a large-offset transform fault and that east-dipping, proto-Franciscan subduction may have been initiated along
this transform. 相似文献
98.
Y. Thomas He Arthur G. Fitzmaurice Azra Bilgin Sunkyung Choi Peggy O’Day John Horst James Harrington H. James Reisinger David R. Burris Janet G. Hering 《Applied Geochemistry》2010
The behavior of As in the subsurface environment was examined along a transect of groundwater monitoring wells at a Superfund site, where enhanced reductive dechlorination (ERD) is being used for the remediation of groundwater contaminated with chlorinated solvents. The transect was installed parallel to the groundwater flow direction through the treatment area. The ERD technology involves the injection of organic C (OC) to stimulate in situ microbial dechlorination processes. A secondary effect of the ERD treatment at this site, however, is the mobilization of As, as well as Fe and Mn. The concentrations of these elements are low in groundwater collected upgradient of the ERD treatment area, indicating that, in the absence of the injected OC, the As that occurs naturally in the sediment is relatively immobile. Batch experiments conducted using sediments from the site inoculated with an Fe(III)- and As(V)-reducing bacterium and amended with lactate resulted in mobilization of As, Fe and Mn, suggesting that As mobilization in the field is due to microbial processes. 相似文献
99.
This paper investigates the fundamental characteristics of shear strength and deformation of crushed oyster shell–sand mixtures
to stimulate recycling of waste oyster shells. Standard penetration tests (SPT) and large-scale direct-shear tests were carried
out with different kinds of dry unit weight and mixing rate of oyster shell–sand mixture. Correlations between N-value, dry unit weight, and friction angle of mixtures were observed from the results of experimental tests, making it possible
to estimate the in situ strength from SPT, and the coefficient of volume compressibility from the confined direct-shear compression
test. These results also make it possible to compute the settlement of oyster shell–sand mixture when used in soft ground
improvement. 相似文献
100.
Geological and geotechnical aspects of underground coal mining methods within Australia 总被引:1,自引:1,他引:0
B. Scott P. G. Ranjtih S. K. Choi Manoj Khandelwal 《Environmental Earth Sciences》2010,60(5):1007-1019
About one quarter of the coal produced in Australia is by underground mining methods. The most commonly used underground coal
mining methods in Australia are longwall, and room and pillar. This paper provides a detailed review of the two methods, including
their advantages and disadvantages, the major geotechnical and operational issues, and the factors that need to be considered
regarding their choice, including the varying geological and geotechnical conditions suited to a particular method. Factors
and issues such as capital cost, productivity, recovery, versatility and mine safety associated with the two methods are discussed
and compared. The major advantages of the longwall mining method include its suitability for mining at greater depth, higher
recovery, and higher production rate compared to room and pillar. The main disadvantages of the room and pillar method are
the higher risks of roof and pillar collapse, higher capital costs incurred as well as lower recovery rate. 相似文献