全文获取类型
收费全文 | 14481篇 |
免费 | 1570篇 |
国内免费 | 1820篇 |
专业分类
测绘学 | 5282篇 |
大气科学 | 2031篇 |
地球物理 | 2169篇 |
地质学 | 3047篇 |
海洋学 | 1226篇 |
天文学 | 1229篇 |
综合类 | 1421篇 |
自然地理 | 1466篇 |
出版年
2024年 | 87篇 |
2023年 | 192篇 |
2022年 | 471篇 |
2021年 | 616篇 |
2020年 | 624篇 |
2019年 | 671篇 |
2018年 | 485篇 |
2017年 | 778篇 |
2016年 | 711篇 |
2015年 | 723篇 |
2014年 | 827篇 |
2013年 | 1035篇 |
2012年 | 893篇 |
2011年 | 815篇 |
2010年 | 655篇 |
2009年 | 832篇 |
2008年 | 847篇 |
2007年 | 982篇 |
2006年 | 896篇 |
2005年 | 750篇 |
2004年 | 708篇 |
2003年 | 535篇 |
2002年 | 453篇 |
2001年 | 389篇 |
2000年 | 311篇 |
1999年 | 273篇 |
1998年 | 222篇 |
1997年 | 160篇 |
1996年 | 154篇 |
1995年 | 147篇 |
1994年 | 133篇 |
1993年 | 114篇 |
1992年 | 72篇 |
1991年 | 66篇 |
1990年 | 42篇 |
1989年 | 44篇 |
1988年 | 32篇 |
1987年 | 20篇 |
1986年 | 18篇 |
1985年 | 11篇 |
1984年 | 11篇 |
1982年 | 9篇 |
1981年 | 6篇 |
1980年 | 6篇 |
1979年 | 4篇 |
1977年 | 11篇 |
1973年 | 4篇 |
1972年 | 4篇 |
1971年 | 5篇 |
1954年 | 6篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
51.
Rosa Nappi Giuliana Alessio Giovanni Bronzino Carlo Terranova Giuseppe Vilardo 《Natural Hazards》2008,45(1):73-85
In this article the implementation and potential of the Seismotectonic Information System of the Campania Region (SISCam)
are described, in particular an application of this Web-based GIS system to the seismotectonic analysis of the Sannio area
(Southern Apennines) is performed. WEB-GIS technologies greatly contribute to both the environmental monitoring and the disaster
management of areas affected by high natural risks. Specifically the SISCam system has been developed with the aim of providing
easy access and fast diffusion, through Internet technology, of the most significant geological, geophysical, and territorial
data relative to the Campania Region. The Sannio area has been selected as our application example because it is among the
most active seismic regions in Italy. This portion of the Southern Apennines which was hit by the June 5, 1688 strong earthquake
(M
W = 6.7, CPTI 1999) and by some low- and moderate-energy seismic sequences (1990–1992, 1997), is characterized by a complex
inherited tectonic setting and low-tectonic deformation rates that hide the seismogenic sources position. Since this case
study turned out to be complicated, the use of the SIScam WEB-GIS has become indispensable because it allowed us to visualize,
integrate and analyze all the data available, in order to obtain an accurate and direct picture of the seismotectonic setting
of the area. Moreover, a different approach of data analysis was necessary, due to the lack of up-to-date neotectonic and
structural data; therefore, the operation of this GIS system enabled us to process and generate some original informative
layers, through image analysis, such as new structural lineaments represented on a map of the potential active faults of the
area, which has been the final result of our application, as a contribution to new knowledge about the local seismic risk
parameters. 相似文献
52.
K. Vinod kumar R. C. Lakhera Tapas R. Martha R. S. Chatterjee A. Bhattacharya 《Environmental Geology》2008,55(4):789-799
Mass movements such as landslides in mountainous terrains are natural degradation processes and one of the most important
landscape-building factors. Varunawat Parbat overlooking Uttarkashi town witnessed a series of landslides on 23 September
2003 and the debris slides and rock falls continued for 2 weeks. This landslide complex was triggered due to the incessant
rainfall prior to the event, and its occurrence led to the blockage of the pilgrim route to Gangotri (source of the Ganges
river) and evacuation of thousands of people to safer places. Though there was no loss of lives due to timely evacuation,
heavy losses to the property were reported. High-resolution stereoscopic earth observation data were acquired after the incidence
to study the landslide in detail with emphasis on the cause of the landslide and mode of failure. Areas along the road and
below the Varunawat foothill region are mapped for landslide risk. It was found that the foothill region of the Varunawat
Parbat was highly disturbed by man-made activities and houses are dangerously located below steep slopes. The potential zones
for landslides along with the existing active and old landslides are mapped. These areas are critical and their treatment
with priority is required in order to minimise further landslide occurrences. 相似文献
53.
生基包滑坡监测属于三峡库区奉节县三期地质灾害监测预警项目之一,该滑坡位于长江左岸,临近人口稠密的安坪乡集镇,地理位置重要。三峡水库175 m蓄水后,其变形破坏特征有何表现?对航道安全运营有无潜在威胁?是否会对滑坡体上的重要建筑及村民生产生活构成危害?针对这些问题,首先分析了滑坡的工程地质特征及主要的影响因素;其次,确立以4种监测手段为主、人工巡查为辅的监测方案;通过对大地变形GPS、深部位移、滑坡推力等几种监测方法的运用及对其成果进行分析研究,以实例说明其在滑坡监测中的应用;再次,结合宏观人工巡查进行对照分析,以充分说明大地变形、深部位移和滑坡推力监测在实际运用中的可行性;最后,根据监测结论提出对生基包滑坡防治的建议。 相似文献
54.
Predictability of Interannual Variability in the Kuroshio Transport South of Japan Based on Wind Stress Data over the North Pacific 总被引:1,自引:3,他引:1
It is expected that a roughly two-year forecast of the Kuroshio transport variation can be made from a past record of wind
stress data over the ocean, since it takes nearly ten years for the first-mode baroclinic Rossby wave to traverse the entire
basin in the midlatitude North Pacific (∼30°N). We therefore investigated the predictability using an ocean general circulation
model driven by the wind stress data from the National Centers for Environmental Prediction/National Center for Atmospheric
Research (NCEP/NCAR) reanalysis. Referring to a hindcast experiment as the control run, we carried out fifteen forecast experiments,
the initial conditions of which are taken from the hindcast experiment at intervals of two years during the period from the
end of 1969 to the end of 1997. Each of the forecast experiments is driven only by wind stress in the year preceding each
experiment. The forecasted Kuroshio transport anomaly south of Japan agrees better with the hindcasted one during the first
two years of the forecast in most cases. In some cases, however, significant disagreements occur, most of which are likely
due to larger unpredictable variations caused by wind stress anomalies near Japan. At the end of forecast year 2, the anomaly
correlation coefficient is about 0.7, and rms of the forecast error is smaller than rms of the hindcasted anomaly. These results
indicate that the prediction of the interannual variability in the Kuroshio transport could be made two years in advance at
a statistically significant level.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
55.
GUI Maochang * WU Lingjuan . Institute of Oceanology Chinese Academy of Sciences Qingdao China. Laboratory of Numerical Modeling for Atmospheric Sciences Geophysical Fluid Dynamics Institute of Atmospheric Physics Chine-se Academy of Sciences Beijing China. Graduate School Chinese Academy of Sciences Beijing China 《海洋学报(英文版)》2005,(4)
1 IntroductionIt is well known that interaction between the trop-ical ocean and atmosphere produces the largest inter-annual climate signal, El Nino-Southern Oscillation(ENSO). In past decades many efforts have been madein understanding and predicting ENSO: such as the hy-pothesis of Bjerknes (1969) that ENSO arises as aself-sustained cycle in which SSTA in the Pacific O-cean causes the trade winds to strengthen or slackenand that this in turn drives the ocean circulation changesthat … 相似文献
56.
The Agulhas Ridge is a prominent topographic feature that parallels the Agulhas-Falkland Fracture Zone (AFFZ). Seismic reflection
and wide angle/refraction data have led to the classification of this feature as a transverse ridge. Changes in spreading
rate and direction associated with ridge jumps, combined with asymmetric spreading within the Agulhas Basin, modified the
stress field across the fracture zone. Moreover, passing the Agulhas Ridge’s location between 80 and 69 Ma, the Bouvet and
Shona Hotspots may have supplied excess material to this part of the AFFZ thus altering the ridge’s structure. The low crustal
velocities and overthickened crust of the northern Agulhas Ridge segment indicate a possible continental affinity that suggests
it may be formed by a small continental sliver, which was severed off the Maurice Ewing Bank during the opening of the South
Atlantic. In early Oligocene times the Agulhas Ridge was tectono-magmatically reactivated, as documented by the presence of
basement highs disturbing and disrupting the sedimentary column in the Cape Basin. We consider the Discovery Hotspot, which
distributes plume material southwards across the AAFZ, as a source for the magmatic material. 相似文献
57.
58.
多波束数据的海底数字地形模型构建 总被引:11,自引:0,他引:11
提出大批量多格式原始多波束数据的DTM构建方法,以满足大区域、大比例尺海底地形制图的需要。在多种格式原始多波束数据接口和系统内部标准数据结构的基础上,通过对数据文件、数据种类和数据运算量的有效组织管理,实施边读入、边权重配赋的网格插值,分析了高斯、指数和距离平方反比权重函数的适用性,及最小值、最大值和平均值的实用性。在权重配赋网格插值基础上,提出分形fBM和张力样条配合使用的方程式插值方法,保证DTM数据的有效外延和地形分辨。整套算法效率高,并能有效保证DTM的精度,对存储在外部介质的数据遍历一次即可完成网格插值。 相似文献
59.
Lodolo Emanuele Coren Franco Schreider Anatoly A. Ceccone Giulio 《Marine Geophysical Researches》1997,19(5):439-450
The southwestern part of the Scotia Sea, at the corner of the Shackleton Fracture Zone with the South Scotia Ridge has been investigated, combining marine magnetic profiles, multichannel seismic reflection data, and satellite-derived gravity anomaly data. From the integrated analysis of data, we identified the presence of the oldest part of the crust in this sector, which tentative age is older than anomaly C10 (28.7 Ma). The area is surrounded by structural features clearly imaged by seismic data, which correspond to gravity lows in the satellite-derived map, and presents a rhomboid-shaped geometry. Along its southern boundary, structural features related to convergence and possible incipient subduction beneath the continental South Scotia Ridge have been evidenced from the seismic profile. We interpret this area, now located at the edge of the south-western Scotia Sea, as a relict of ocean-like crust formed during an earlier, possibly diffuse and disorganized episode of spreading at the first onset of the Drake Passage opening. The successive episode of organized seafloor spreading responsible for the opening of the Drake Passage that definitively separated southern South America from the Antarctic Peninsula, instigated ridge-push forces that can account for the subduction-related structures found along the western part of the South Scotia Ridge. This seafloor accretion phase occurred from 27 to about 10 Ma, when spreading stopped in the western Scotia Sea Ridge, as resulted from the identification of the marine magnetic anomalies. 相似文献
60.