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51.
山东胶东半岛地区断裂最新活动性研究 总被引:5,自引:2,他引:5
山东胶东半岛地区发育有北北东-北东向和北西西向两组断裂,前者分属蓬莱-栖霞断裂系和即墨-牟平断裂带,为半岛的主体断裂构造;后者分布在半岛北缘及其北侧海域,由多条断裂组成。实地调查表明,断层在第四纪期间是活动的,控制着附近山地和盆地的构造演化与地貌发育,最新活动主要发生在第四纪早期,垂直活动幅度可达百米以上;第四纪晚期,断裂活动性迅速减弱,甚至停止,但依然发现北北东-北东向断裂的多个局部段落还在活动,明显地错断了晚更新世地层,垂直断距最大为10m左右。 相似文献
52.
I. González M. M. Jordán T. Sanfeliu M. Quiroz C. de la Fuente 《Environmental Geology》2007,52(7):1243-1251
In southern Chile, with a mild and rainy climate, high levels of heavy metals have been detected in many gold placer deposits.
Many of the contaminants pose risks to human life, and consequently damage the trofic chain in this environment. The study
zones selected correspond to the handicraft gold-bearing sands of Rio Gato (Los Muermos), Carelmapu and Cucao. These are all
located in the X Region of “Los Lagos” in Chile. The type of methodology used in the characterization of the associated mineralization
consists of testing each representative sample with a grain size distribution, statistical parameter analysis and a mineralogical
analysis, using a binocular magnifying glass, a petrographic microscope, XRD and SEM/EDX. The chemical composition was defined
by means of X ray fluorescence and micro-chemical analysis. The results of the study about sediments in southern Chile are
presented. The major concentrations of heavy minerals are generally located in areas of dynamic river energy. In the samples,
more than 70% of the heavy minerals were distributed among grain sizes corresponding to thin sand with good grain selection
(meshes of 0.25–0.06 mm). The main mineral phases present in the analysed samples were gold, zircon, olivine, ilmenite, hornblende,
hypersthene, hematite, garnet, chromite, chlorite, augite, amphibolitic-epidote, etc. The main heavy metals found as a result
of the study were mercury, lead, cadmium, chrome, tellurium, indium, zinc, cobalt, copper, platinum, gold, etc., and as well
some less common elements like cerium, praseodymium, gadolinium, neodymium, samarium and lanthanum. This research work is
only a starting point for carrying out a risk probability mapping of heavy metals and the mineralogy of the Cucao, Carelmapu
and Rio Gato gold-bearing sands. 相似文献
53.
The multistage concept is explained and illustrated, with particular reference to a bornhardt from the southern Yilgarn Block of southwestern Western Australia. Hyden Rock is a complex inselberg developed on Archaean granite. It probably developed through fracture-controlled differential subsurface weathering in the Cretaceous, followed in the Eocene by erosion of the lateritic regolith and exposure of the massive compartment as an inselberg. But the variations in fracture density to which Hyden Rock owes its origin developed long before the Cretaceous, probably in the latest Archaean or earliest Proterozoic. The relief amplitude of the residual has increased through the Cainozoic.
A rich assemblage of minor forms (basins, runnels, tafoni, pitting, displaced slabs, A-tents) is developed on the bornhardt and, though their mode of development varies, the origin of many can be traced back to magmatic and tectonic events of Late Archaean and earliest Proterozoic times. Others were initiated at the weathering front during the later Mesozoic, and many have developed since exposure, beginning in the Eocene. A few are related to tectonism during the later Quaternary.
The residual is a multistage form. Its development as a major landform can be traced back some 120 million years, and the structures to which the outlines of the bornhardt, and those related to several minor features, originated in later Archaean times. The geomorphological evolution of landforms of the shield lands and cratons extends over vast ages and cannot be regarded as a geologically recent phenomenon. 相似文献
A rich assemblage of minor forms (basins, runnels, tafoni, pitting, displaced slabs, A-tents) is developed on the bornhardt and, though their mode of development varies, the origin of many can be traced back to magmatic and tectonic events of Late Archaean and earliest Proterozoic times. Others were initiated at the weathering front during the later Mesozoic, and many have developed since exposure, beginning in the Eocene. A few are related to tectonism during the later Quaternary.
The residual is a multistage form. Its development as a major landform can be traced back some 120 million years, and the structures to which the outlines of the bornhardt, and those related to several minor features, originated in later Archaean times. The geomorphological evolution of landforms of the shield lands and cratons extends over vast ages and cannot be regarded as a geologically recent phenomenon. 相似文献
54.
55.
新疆火山岩分区及其地质意义 总被引:3,自引:1,他引:2
新疆火山活动强烈 ,火山岩类型多 ,出露广泛。依据火山岩特征和时空分布规律 ,新疆火山岩分布区域可以划分两个较大级别的火山岩分区单元 :第一级为火山岩区 ,第二级为火山岩带。全区共划分出 6个火山岩区和 30个火山岩带。火山岩分区的划分对火山岩、地质构造和矿产的研究具有重要的意义和实用价值 相似文献
56.
Johan G. Borchert 《GeoJournal》1998,45(4):327-336
The retail system is continuously adapting itself to changing demographic conditions, consumer behavior and economic conditions.
Existing retail units, getting larger in order to achieve economics of scale, and new forms of large-scale retailing do not
fit easily in the traditional spatial pattern of retail concentrations. Neverteless the spatial distribution of retailing
in urban areas, as schematized by Berry thirty-five years ago, still has its value. Through an upward hierarchical movement
the retail system has adapted itself to an inflexible spatial system, in which downtown has still a dominant position. Future
developments, however, may weaken the position of central shopping areas in favour of peripheral locations.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
57.
Rolf Monheim 《GeoJournal》1998,45(4):273-287
Counting pedestrians on a street and visitors entering a store is a method used to measure the attractiveness of these places.
Their volumes are governed by daily, weekly, monthly and yearly cycles and are subject to random influences. This must be
taken into account especially where comparison counts reveal changes. When single streets or stores are counted, it must be
ascertained whether this figure is representative of the whole city centre and its retailing. Pedestrian volumes can be used
for adjusting interview samples to the distribution in time and space of the city centre visitors. Counts of the qualitative
characteristics of the pedestrian with respect to composition of groups reveal that surveys among pedestrians are biased in
relation to the size of the group.
Special attention in surveys should be given to the linking of activities. Whereas much emphasis is given to the accessibility
of the city centre from outside, the ‘inner accessibility’ of the city centre is just as important. Long distances are often
walked and many destinations visited. This is best recorded by conducting interviews at public transport stops and car parks.
The attractiveness of the city centre depends not only on its physical structures but very much on the subjective perception
of them; therefore judgements on accessibility, goods and services offered and the urban ambiance should be recorded. Retailer's
attitudes concerning the qualities of the city centre should also be compiled for comparison.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
58.
利用月平均OLR、降水和气温资料,研究了ENSO期间赤道太平洋对流活动与我国夏季降水和气温的关系。结果表明:春季、夏季中、西太平洋对流活动异常与我国夏季江淮地区的降水有密切关系;春季和前一年冬季西太平洋对流活动异常与东北地区夏季降水有显著相关。前一年冬季中、西太平洋对流活动异常与我国降水的显著相关区是不同的,前者为华南、西南地区,后者为东北至内蒙古一带。气温与同期中、西太平洋对流活动的相关不显著。 相似文献
59.
Jing Wu Jian Yin Yonghong Hao Yan Liu Yonghui Fan Xueli Huo Youcun Liu Tian‐Chyi J. Yeh 《水文研究》2015,29(13):2855-2866
The traditional hydrological time series methods tend to focus on the mean of whichever variable is analysed but neglect its time‐varying variance (i.e. assuming the variance remains constant). The variances of hydrological time series vary with time under anthropogenic influence. There is evidence that extensive well drilling and groundwater pumping can intercept groundwater run‐off and consequently induce spring discharge volatility or variance varying with time (i.e. heteroskedasticity). To investigate the time‐varying variance or heteroskedasticity of spring discharge, this paper presents a seasonal autoregressive integrated moving average with general autoregressive conditional heteroskedasticity (SARIMA‐GARCH) model, whose the SARIMA model is used to estimate the mean of hydrological time series, and the GARCH model estimates its time‐varying variance. The SARIMA‐GARCH model was then applied to the Xin'an Springs Basin, China, where extensive groundwater development has occurred since 1978 (e.g. the average annual groundwater pumping rates were less than 0.20 m3/s in the 1970s, reached 1.20 m3/s at the end of the 1980s, surpassed 2.0 m3/s in the 1990s and exceeded 3.0 m3/s by 2007). To identify whether human activities or natural stressors caused the heteroskedasticity of Xin'an Springs discharge, we segmented the spring discharge sequence into two periods: a predevelopment stage (i.e. 1956–1977) and a developed stage (i.e. 1978–2012), and set up the SARIMA‐GARCH model for the two stages, respectively. By comparing the models, we detected the role of human activities in spring discharge volatility. The results showed that human activities caused the heteroskedasticity of the Xin'an Spring discharge. The predicted Xin'an Springs discharge by the SARIMA‐GARCH model showed that the mean monthly spring discharge is predicted to continue to decline to 0.93 m3/s in 2013, 0.67 m3/s in 2014 and 0.73 m3/s in 2015. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
60.
Impact of Human Activities on Depositional Process of Tidal Flat in Quanzhou Bay of China 总被引:2,自引:0,他引:2
WANG Aijun 《中国地理科学(英文版)》2007,17(3):265-269
As a very important component of a coastal system,tidal flats come to be a focus of the studies on land-ocean interaction in the coastal zone because those areas are subjected to intense human activities and are highly sensitive to the global change.The Quanzhou Bay,located along the middle part of Fujian coast of China,covers about 136.4km2,and the area of coastal wetland in the entire bay from intertidal to subtidal with 6m of water depth accounts for 96% of the total area.Seven short cores were collected and divided in situ with the interval of 5cm on the coastal wetlands of Quanzhou Bay on April 19,2006.The sediment samples were scattered and the grain sizes were measured by using Mastersizer 2000.Human beings' activities on tidal flat have disturbed the vertical distribution of sediments in stratigraphic sequence and accelerated the sedimentation rates.Grain size analysis results show that the grain size diameters increase and sediment becomes worse sorted towards the sea under the strong human disturbance;Spartina alterniflora can play a role of trapping the fine sediment;but near the bank,the sediment becomes coarse and there are two peak values on frequency curve influenced by the sandpile.The trough formed by human activities along the coastline changes the transport path of water and suspended sediment.The sediments are transported through the trough and deposit in it during the flood;the ebb flow is retarded by the flow output through the adjacent trough,and the deposited sediment can not be re-suspended;then,the sedimentation rate increases.In situ observation show that the sedimentation rate is about 8-10cm/yr. 相似文献