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871.
872.
Analysis of deformation data measured across the faults, regional vertical deformation data and GPS measurements in the Sichuan-Yunnan region made since the 1980s permitted us to conclude that the crustal deformation in the region during this period of time was relatively weak and caused the occurrence of earthquakes (Ms≥6.0), which were not distributed along the major boundary active faults in the region after the 1981 I)awu Ms 6.9 earthquake and that the seismic activity is characterized by quasi-clockwise migration. Thus, it follows that earthquake prediction research should be focused on the central part of the Sichuan-Yunnan region in the coming years. Finally, a concept of temporal division of the region into active blocks is suggested and the preliminary result of the division is given in the paper. 相似文献
873.
环境自净能力是一种宝贵的资源,在我国国民经济高速发展的同时要保护好环境.应充分利用环境自净能力,以防为主,防重于治,在发展规划过程中就应考虑到环境的自净资源的利用和再生。地质地球化学场是决定环境自净能力的重要因素。自净能力可以通过添加催化剂等方式得以提高。对在伊利石存在条件下草酸还原Cr(Ⅵ)的动力学和机制进行研究,对环境自净资源的开发利用进行了讨论。 相似文献
874.
Cenozoic Volcanism in South China Sea and Its Vicinity and South China Sea Spreading 总被引:1,自引:0,他引:1
Zhao Hailing Deng Jinfu Li Kaiming Di Yongjun Yu Junji Zhao Jianhua Li Yonghua 《中国地质大学学报(英文版)》2002,13(3)
The rock series, rock types and Sr-Nd isotopic dating of the Cenozoic volcanic rocks in the South China Sea are similar to those in its vicinity. On the basis of the spreading age of the South China Sea, the Cenozoic volcanic rocks are divided into three stages: the pre-spreading stage, the spreading stage and the post-spreading stage. The deep process characteristics of the asthenosphere and lithosphere may be inferred from the study on primary basaltic magma. The top layers of the asthenosphere both in the spreading stage and in the pre-spreading stage are closer to the earth surface than that in the post-spreading stage. From the pre-spreading stage to the spreading stage, the top layer of the asthenosphere decreased in depth, while the amount of interstitial partial melts increased. The evolution of the primary basaltic magma shows a progressive evolution sequence of the rifting volcanism and a faster lithospheric spreading velocity. From the spreading stage to the post-spreading stage, the top layer of the asthenosphere gradually increased in depth, but the amount of interstitial partial melts decreased. The evolution of primary basaltic magma shows a retrogressive evolution sequence of the rifting volcanism and a gradual decrease in the lithospheric spreading velocity. The depth recognized by the study on the Cenozoic volcanism demonstrates the deep environment for the formation and evolution of the South China Sea. 相似文献
875.
Demarcating the worldwide monsoon 总被引:10,自引:1,他引:10
Summary The monsoon is a global climate phenomenon. This paper addresses the seasonal reversal of atmospheric circulation and the
transition of dry/wet spells in the monsoon regions worldwide. The NCEP/NCAR 850 hPa wind reanalysis data for 1950–1999 and
the upper-tropospheric water vapour (UTWV) band brightness temperature (BT) data observed by NOAA polar orbiting satellites
for 1980–1995 are used. In the tropics, there are three large wet-UTWV centres. The summer monsoon in the subtropics can be
defined as the expansion of these centres associated with the influence of cross-equatorial flows. Specifically, the dry/wet
spell transition is determined by the BT values that are smaller than 244 K. The regions of the South and North African monsoons,
the Asian-northwest Pacific and Australian-Southwest Pacific monsoons, and the North and South American monsoons are examined
with a focus on the dry/wet spell transition and stream field features.
Findings suggest that the summer monsoons over many subtropical regions can be defined by both cross-equatorial flows and
dry/wet spell transitions. In the mid- and low-latitudes, there exist six major dry/wet spell transition regions with a dry
or wet period lasting more than one month. The region of most significant change is located over the subtropical North Africa–Asia–northwest
Pacific. The others appear over subtropical South Africa, Indonesia–Australia, southwest Pacific, the Mexico-Caribbean Sea,
and subtropical South America. In addition, three regions exist where only one of the two indicators (cross-equatorial flow
and dry/wet transition) is satisfied. The first is near the Equator where the directions of cross-equatorial flows alternate
but a dry/wet spell transition is never experienced. The second is over North Africa where only the dry/wet spell transition
can be found but not the cross-equatorial flows. The third is over the mid-latitude regions in North China, South Africa,
and northern North America. These regions are influenced by cross-equatorial flows but the upper-tropospheric water vapour
content is not as high as that in tropical regions.
Received June 29, 2000 Revised May 15, 2001 相似文献
876.
877.
城市共享汽车分布的时空演变及影响因素研究——以北京市主城区为例 总被引:1,自引:0,他引:1
城市交通可持续发展的本质在于空间资源合理配置,共享汽车作为一种新型交通方式,探究其时空分布规律及影响因素,能支撑交通资源空间配置并优化城市功能布局。以供需理论为基础,运用核密度分析、空间自相关、标准差椭圆等方法反映时空特征,通过地理探测器从供给和需求2个维度,分别选取停车场、人口密度以及居住空间、就业空间、公共服务与活动空间等5方面,共14个代理变量探究时空格局形成的影响因素。结果表明:① 共享汽车分布具有显著的时空异质性,根据时空特征可分为“早晚”型、“日间”型、和“均匀”型3类集聚中心;② 出行需求是影响共享汽车空间分布的主要因素,其中购物场所、科教文化场所、医疗保健场所等公共服务和活动空间是共享汽车的主要目的地;③ 政府应进一步做到精准投放,将资源重点布局于“日间”型集聚中心、居住空间和公共服务与活动空间等,以此促进共享汽车可持续发展和城市空间布局优化。 相似文献
878.
On 10th Oct.and 3rd Nov.2018,two successive landslides occurred in the Jinsha River catchment at Baige Village,Tibet Autonomous Region,China.The landslides blocked the major river and formed the barrier lake,which finally caused the huge flood disaster loss.The hillslope at Baige landslide site has been still deforming after the 2018 slidings,which is likely to fail and block the Jinsha River again in the future.Therefore the investigation of 2018 flood disaster at the Baige landslide is of a great significance to provide a classic case for flood assessment and early warning for the future disaster.The detailed survey revealed that the outstanding inundations induced bank collapse disasters upstream the Baige landslide dams,and the field investigations and hydrological simulation suggested that the downstream of the Baige landslide were seriously flooded due to the two periods of the outburst floods.On these bases,the early warning process of potential outburst floods at the Baige landslide was advised,which contains four stages:Outburst Flood Simulating Stage,Outburst Flood Fore-casting Stage,Emergency Plan and Emergency Evacuation Stage.The study offers a con-ceptual model for the mitigation of landslides and flood disasters in the high-relief mountain-ous region in Tibet. 相似文献
879.
Identification and alleviation pathways of multidimensional poverty and relative poverty in counties of China 总被引:1,自引:1,他引:0
To realize efficient and sustainable poverty alleviation,this study firstly investigated the identification of multidimensional poverty and relative poverty,and then explored relevant poverty alleviation pathways.Poverty levels in 31 provinces including the autonomous re-gions and municipalities of China were identified at the county level using the average nighttime light index (ANLI),county multidimensional development index (CMDI),and a method combining multidimensional poverty index and relative poverty standards.Poverty alleviation pathways for poverty-stricken counties were explored from the aspects of industry,education,tourism and agriculture.The results revealed that nearly 60% of counties in China were primarily under relative poverty,most of which were corresponded to light relative pov-erty.In terms of ANLI and CMDI,63% and 79% of the national poverty-stricken counties,as of 2018,could be identified,suggesting that CMDI had a higher performance for identifying poverty at the county level.In terms of poverty alleviation pathways,414,172,442,and 298 poverty-stricken counties were receptive to industry poverty alleviation,education poverty alleviation,tourism poverty alleviation,and agriculture poverty alleviation,and 61% of coun-ties had more poverty-causing factors,implying that multidimensional poverty alleviation is suitable in most of the counties. 相似文献
880.
Natural Resources Research - Identifying lithology from well logs is an important step in deep prospecting and resource estimation. Various machine learning algorithms have been adopted to identify... 相似文献