全文获取类型
收费全文 | 231篇 |
免费 | 32篇 |
国内免费 | 67篇 |
专业分类
测绘学 | 8篇 |
大气科学 | 41篇 |
地球物理 | 43篇 |
地质学 | 154篇 |
海洋学 | 25篇 |
综合类 | 27篇 |
自然地理 | 32篇 |
出版年
2015年 | 3篇 |
2013年 | 2篇 |
2011年 | 43篇 |
2010年 | 34篇 |
2009年 | 34篇 |
2008年 | 5篇 |
2007年 | 7篇 |
2006年 | 12篇 |
2005年 | 21篇 |
2004年 | 65篇 |
2003年 | 30篇 |
2002年 | 18篇 |
2001年 | 14篇 |
2000年 | 6篇 |
1999年 | 4篇 |
1998年 | 6篇 |
1997年 | 7篇 |
1996年 | 3篇 |
1994年 | 2篇 |
1993年 | 1篇 |
1992年 | 3篇 |
1991年 | 5篇 |
1990年 | 3篇 |
1989年 | 1篇 |
1980年 | 1篇 |
排序方式: 共有330条查询结果,搜索用时 203 毫秒
91.
Fabric and crystal characteristics of Bohai and Arctic sea ice 总被引:1,自引:0,他引:1
1 IntroductionBohaione yeariceandAntarcticonehavethesimilarsurface featuresandcorre spondingfabricandcrystalcharacteristics (Allison 1 997;Lietal.1 997;Qin 1 991 ) .DuringtheChinaFirstArcticExpedition ,theresultsinthestudyofone yearicefromBohaiandAntarcticwereusedfo… 相似文献
92.
Paul A. Mayewski 《中国科学D辑(英文版)》2005,(2)
The δ18O variations in an 80.36 m ice core retrieved in the accumulation zone of the East Rongbuk Glacier, Mount Qomolangma (Everest), is not consistent with changes of air temperature from both southern and northern slopes of Himalayas, as well as these of the temperature anomalies over the Northern Hemisphere. The negative relationship between the δ18O and the net accumulation records of the ice core suggests the "amount effect" of summer precipitation on the δ18O values in the region. Therefore, the δ18O records of the East Rongbuk ice core should be a proxy of Indian Summer Monsoon intensity, which shows lower δ18O values during strong monsoon phases and higher values during weak phases. 相似文献
93.
1 IntroductionForthepast 1 5years,muchattentionofoceanographershasbeenfocusedontheroleofironinlimiting phytoplankton productivityinthehigh nutrient ,low chlorophyll(HNLC)regions.OnboardshipironenrichmentincubationshavebeencarriedoutinthethreewellknownHNLCregions :notablyequatorialPacificOcean ,subarcticPacificO ceanandSouthernOcean (seereferencesinTable 1 ) .Theinsituironenrichmentexper imentshavebeenaccomplishedintheequatorialPacific (IronEx1in 1 993 (Wells 1 994)andIronEx2in 1 996(… 相似文献
94.
Protective and treatment measures against major harmful organisms in cotton-growing belt of Xinjiang
Received date: -- Foundation item: Supported by Light of Western Regions Project Key Project of CAS Integrated Demonstration Project for Sustainable Development of Cotton in Xinjiang with High Quality High Yield Technique LU Zhaozhi CHEN 《地理学报(英文版)》2000,(3)
1 Harmful Organisms in Xinjiang Cotton-Growing BeltThe harmful organisms in Xinjiang cotton-growing belt are mainly diseases, insects and weeds. The diseases include Verticillium albo-atrum, cotton-root decaying disease and cotton-boll decaying disease, while the harmful insects include cotton aphids (Aphis gosspii), cotton mites, cotton boll-worms (Heliothis armigera), cotton thrips (Thrips. sp), Lygus pratersis and cutworms. Their harmful effects vary in different places but all of them … 相似文献
95.
WANG Shilu WAN Guojiang State Key Laboratory of Environmental Geochemistry Institute of Geochemistry CAS Guiyang 《《地质学报》英文版》2000,74(2):301-305
The comparison between the carbon isotope and the index of ring width of a pine disc from the Tuomuer Peak region in Xinjiang shows that the effects of climate changes on the tree-ring growth and carbon iso-topic fractionation varies with time. The reason is probably relative to the characters of climate changes and adaptability of the tree-ring growth to climate changes. The relationships between the atmospheric CO2 level and the revised δ13Cair by the tree-ring carbon isotope indicate that the carbon cycle is not in a steady state, but under a stage-change condition in this area. It also can be concluded that the ratio of CO2 from the terrestrial eco-system has increased, and the flux of CO2 exchange between the atmosphere and the biosphere was gradually increasing over the past century. In addition, the results also confirm the validity and superiority of the carbon isotope to the research of the water-use efficiency. 相似文献
96.
Autumn intensification of the Ryukyu Current during 2003-2007 总被引:2,自引:0,他引:2
ZHU Xiao-Hua HUANG DaJi & GUO XinYu State Key Laboratory of Satellite Ocean Environment Dynamics Second Institute of Oceanography State Oceanic Administration Hangzhou China Center for Marine Environmental Study Ehime University - Bunkyo-cho Matsuyama - Japan 《中国科学:地球科学(英文版)》2010,(4)
Inverse calculations using data from 16 repeat hydrographic transects collected from April 2003 to June 2007 have yielded velocity structures and volume transports(VTs) of the Ryukyu Current in the region east of the northern Ryukyu Islands.The inverse calculation results show that the Ryukyu Current is dominated by a subsurface velocity core with maximum velocities from 15.1 to 80.0 cm/s,whose positions vary between 110 and 600 dbar and 27.2°-28.2°N along the transect.The mean velocity exhibits a subsurface velocity core with a maximum value of 24.6 cm/s at 326 dbar depth,a VT of 14.0 Sv(1 Sv≡106 m3/s),a vertical dimension of 800 m,and a horizontal dimension of 60 km.The seasonal mean velocities show that the Ryukyu Current is stronger in autumn than in other seasons.It is suggested that this seasonal variation is coincident with the intensification of the anticyclonic eddy south of Shikoku,Japan. 相似文献
97.
98.
喜马拉雅山佩枯岗日冰川地貌的年代学、平衡线高度和气候研究 总被引:8,自引:6,他引:2
喜马拉雅山珠穆朗玛峰-希夏邦马峰地区是青藏高原南部现代冰川集中发育区之一,古冰川遗迹亦十分丰富,是研究第四纪青藏高原冰川形成和演化的关键区,一直备受地貌和第四纪环境研究者的关注.应用原地宇宙核素10Be暴露年龄测试技术,对采自希夏邦马峰西北佩枯岗日拉曲谷地冰碛垄上的冰川漂砾进行年代学研究;结合冰川地貌分析方法,对古冰川... 相似文献
99.
To investigate the seasonal variability and potential environmental significance of trace elements in mountain glaciers, the surface snow and snow pit samples were collected at Urumqi Glacier No. 1 (43o06'N, 86o49'E, 4 130 m a.s.l.), eastern Tianshan (天山), from September 2002 to September 2003, and analyzed for Li, V, Cr, Mn, Co, Cu, and Ba. The samples were acidified (leached) in a manner intended to reasonably approximate the extent to which the natural hydrologic and weathering cycles would liberate elem... 相似文献
100.
During the past five decades, fluctuations of glaciers were reconstructed from historical documents, aerial photographs, and remote sensing data. From 1956 to 2003, 910 glaciers investigated had reduced in area by 21.7% of the 1956 value, with a mean reduction for the individual glacier of 0.10 km2. The relative area reductions of small glaciers were usually higher than those of large ones, which exhibited larger absolute loss, indicating that the small glaciers were more sensitive to climate change than la... 相似文献