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991.
GUO FuxiangResearch Centre of Prediction of Hidden Ore Deposits Guilin Institute of Technology Guilin Guangxi Wang Yi Fei Zhenbi 《《地质学报》英文版》1998,72(1):121-126
The Meso-Cenozoic tectonic attribute of southern China is a continental tridirectional orogenic belt formed by subsynchronous interaction among the Tethys, Northwest Pacific and Kunlun-Qinling tectonic domains. It was created by superimposition of repeated orogenies since the Late Permian. The Indosinian folds therein are gentle and localized. 相似文献
992.
O. W. Archibold A. Paterson E. A. Ripley J. Kort 《Applied geography (Sevenoaks, England)》1998,18(4):375-395
North American ginseng is native to the deciduous forest region of eastern North America but is now cultivated in areas well beyond its natural range. In recent years an expanding market has attracted growers in climatically less suitable regions, including the Canadian prairies. The ginseng root requires at least four years to reach marketable size and is sensitive to injury when the temperature drops below about −4°C. Such temperatures are not unusual in the prairies; thus winter kill is a hazard that may limit ginseng production in this region of Canada. This study analyses the risks of winter soil temperatures falling below levels critical for the survival of ginseng in Saskatchewan. It appears that winter conditions may be too severe for reliable production of this lucrative crop, although application of straw mulch and additional benefits of trapped snow could reduce the risk of winter kill. 相似文献
993.
USGCRP土地覆被研究的最新动向 总被引:12,自引:1,他引:11
本文根据美国全球变化研究委员会提出的“美国全球变化研究计划”(USGCRP),概要介绍了土地覆被研究的目标、内容和设想。由于美国在这一领域研究中的领先地位,因此本文基本反映了国际上的最新趋势。 相似文献
994.
Cover systems are widely used to safeguard landfills and contaminated sites. The evaluation of the water balance is crucial
for the design of landfill covers. The Hydrologic Evaluation of Landfill Performance (HELP) model of the US Environmental
Protection Agency was developed for this purpose. This paper discusses some limitations of version 2 of this model and some
operational difficulties for the use of this model in Germany, which has been developed for the United States. The model results
are tested against field data of the water balance, measured on test fields on the Georgswerder landfill in Hamburg. Theoretically,
HELP considers gravitational forces as driving forces of water flow only. Therefore capillary barriers cannot be simulated.
Furthermore, the formation of and the flow through macropores are not considered, a main critical process that the diminishes
the effectiveness of compacted soil liners. In the output comparison, the matching of measured and simulated data is quite
good for lateral drainage, but failed for surface runoff and liner leakage through compacted soil liners. A further validation
study is planned for HELP version 3 using a broader range of test field data.
Received: 10 January 1995 · Accepted: 14 November 1995 相似文献
995.
996.
分析了1995-1996年冬季我国高原东部地区形成雪灾的降水和平均环流异常的关系,以及雪灾与高原地我冬季降水气候振动及其背景关系。结果表明,高原雪灾和冬季降水从60、70年代至80、90年代有增多的趋势。 相似文献
997.
AN EXPERIMENTAL STUDY OF INFILTRATION AND EROSION UNDER SLOPE GRADIENTS AND VEGETAL COVERS 总被引:1,自引:0,他引:1
I.llltr0dtlch0n~studyhasshowedU1atiI1filtrationdePa1dsnot0nIyOnsoiIpIDpeIty,alndatln0iStLle,lainfallproPeltiesbutalsoonSu1facel1liclDtopographicprope1ties,sud1assudecesloPegradia1t,vopalcoverandlandtItiIization.n1etheofh1efonnerelelna1tsol1infiltrationhas… 相似文献
998.
In this paper, hydroclimatic fluctuations of the Upper Narmada catchment (upto Narmadasagar damsite) have been studied by
examining the time series (1901–80) of (i) 1-to 10-day annual extreme rainfall; (ii) seasonal total rainfall between May and
October; (iii) the precipitation concentration index (PCI); (iv) a modified version of PCI(MPCI); and (v) parameters of the
periods contributing specified percentages of rainfall to annual total. Most of these parameters followed the normal distribution
and did not show any significant long-term trend. However, some dominant long period oscillations have been noticed in extreme
rainfall, seasonal rainfall, PCI and MPCI series. Influence of break-monsoon days over India during July and August on the
rainfall activities of the Upper Narmada catchment has also been investigated and salient findings discussed. 相似文献
999.
冬季青藏高原地面辐射平衡 总被引:4,自引:1,他引:4
本文根据实测资料建立了冬季青藏高原上地面辐射平衡与日照百分率、地面反射率之间的经验公式,并用此公式试验了纬度、时间、地面反射率和日照百分率对地面辐射平衡的影响。试验结果表明:冬季高原地面辐射能收支的盈亏状况是由地理纬度和地面反射率决定的。天空遮蔽状况(本文用日照百分率表示)仅影响其盈亏值的大小。亦即地面辐射平衡的地理分布形式由地理纬度和地面反射率所决定,但正、负中心的数值还受天空遮蔽状况的影响。冬季青藏高原地面辐射平衡场是一个由地理因子(地理纬度和自然地理带)作用下形成的基本场叠加上一个地面积雪区形成的扰动场。长江和黄河源区的巴颜喀拉山和藏北草原是冬季高原地面加热场最可能出现异常的关键区。 相似文献
1000.