全文获取类型
收费全文 | 324篇 |
免费 | 11篇 |
国内免费 | 10篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 13篇 |
地球物理 | 68篇 |
地质学 | 200篇 |
海洋学 | 13篇 |
天文学 | 19篇 |
综合类 | 4篇 |
自然地理 | 19篇 |
出版年
2023年 | 1篇 |
2022年 | 5篇 |
2021年 | 9篇 |
2020年 | 13篇 |
2019年 | 13篇 |
2018年 | 23篇 |
2017年 | 25篇 |
2016年 | 25篇 |
2015年 | 15篇 |
2014年 | 23篇 |
2013年 | 27篇 |
2012年 | 16篇 |
2011年 | 15篇 |
2010年 | 8篇 |
2009年 | 11篇 |
2008年 | 8篇 |
2007年 | 10篇 |
2006年 | 5篇 |
2005年 | 3篇 |
2004年 | 6篇 |
2003年 | 3篇 |
2002年 | 3篇 |
2001年 | 5篇 |
1999年 | 2篇 |
1998年 | 6篇 |
1997年 | 4篇 |
1996年 | 4篇 |
1995年 | 7篇 |
1994年 | 3篇 |
1993年 | 2篇 |
1991年 | 2篇 |
1990年 | 1篇 |
1988年 | 2篇 |
1987年 | 3篇 |
1986年 | 3篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 4篇 |
1982年 | 6篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1978年 | 3篇 |
1975年 | 1篇 |
1973年 | 1篇 |
1972年 | 2篇 |
1971年 | 2篇 |
1966年 | 1篇 |
1959年 | 1篇 |
1957年 | 1篇 |
排序方式: 共有345条查询结果,搜索用时 15 毫秒
341.
Mohammed A. Jasim Helmi Zulhaidi Mohd Shafri Alireza Hamedianfar Maher Ibrahim Sameen 《Arabian Journal of Geosciences》2016,9(15):667
Human activities and climate changes significantly affect our environment, altering hydrologic cycles. Several environmental, social, political, and economical factors contribute to land transformation as well as environmental changes. This study first identified the most critical factors that affect the environment in Al-Anbar city including population growth, urbanization expansion, bare land expansion, and reduction in vegetation cover. The combination of remote sensing data and fuzzy analytic hierarch process (Fuzzy AHP) enabled exploration of land transformations and environmental changes in the study area during 2001 to 2013 in terms of long and short-term changes. Results of land transformation showed that the major changes in water bodies increased radically (94 %) from the long-term change in 2001 to 2013 because of water policies. In addition, the urban class expanded in two short-term periods (2001–2007 and 2007–2013), representing net changes of 46 and 60 %, respectively. Finally, barren land showed 25 % reduction in the first period because of the huge expansion of water in the lake; a small percentage of growth gain was observed in the second period. Based on the land transformation results, the environmental degradation assessment showed that the study area generally had high level of environmental degradation. The degradation was mostly in the center and the north part of the study area. This study suggested for further studies to include other factors that also responsible for environmental degradation such as water quality and desertification threatening. 相似文献
342.
Abdel-Galil A. Hewaidy Medhat M. M. Mandur Sherif Farouk Ibrahim S. El Agroudy 《Arabian Journal of Geosciences》2016,9(2):159
Lower to Middle Miocene successions in three offshore wells named GS 160-2, QQ-89, and Ras Elush-2 located in the central and southern parts of the Gulf of Suez were examined for their planktonic foraminifera, calcareous nannofossil assemblages, and paleoenvironments. These successions are subdivided from older to younger into Aquitanian Nukhul, Burdigalian-Langhian Rudeis, Langhian Kareem, and Serravallian Belayim formations. The identified foraminifera includes 54 benthic species belonging to 25 genera and 47 planktonic species belonging to 11 genera, in addition to 64 calcareous nannofossil species belonging to 21 genera. The stratigraphic distribution of these assemblages suggests classifying the studied successions into seven planktonic foraminiferal and six calcareous nannoplankton biozones. The planktonic foraminiferal and calcareous nannoplankton biozones are integrated. Different environments ranging from shallow inner to outer shelf are recognized. This is based on quantitative analyses of foraminifera including benthic biofacies, planktonic/benthonic ratio, and diversity. Syn-rift tectonics played an important role in configuration of the Miocene depositional history in the Gulf of Suez region. 相似文献
343.
The bottom of the magnetized crust determined from the spectral analysis of magnetic anomaly is interpreted as a level of the Curie point isotherm. A spectral analysis technique was used to estimate the depth of the magnetic anomalies sources (Curie point depth analysis) of the eastern shore of the Gulf of Suez, Egypt. The depth to the tops and centers of the magnetic anomalies are calculated by azimuthally averaged power spectrum method for the whole area. The results obtained suggests from this study showed that the average depth to the top of the crustal block ranges between 1.15 and 1.9 km, whereas the average depth to the center of the deepest crustal block ranges between 9.1 and 12.7 km. Curie point depths in the study area range between 14.5 km in the northwestern part of the study area and 26 km in the southeastern part of the study area. The results imply a high geothermal gradient (34.7 °C/km) and corresponding high heat flow value (72.87 mW/m2) in the northwestern part of the study area. The southeastern part of the study area displays a low geothermal gradient (24.26 °C/km) and low heat flow value (50.9 mW/m2). These results are consistent with the existence of the possible promising geothermal reservoir in the eastern shore of the Gulf of Suez especially at Hammam Faraun area. 相似文献
344.
Ibrahim Sel Hacer Bilir Ozhan Recep Cibik Esra Buyukcangaz 《Marine Georesources & Geotechnology》2013,31(5):403-407
Several conventional methods for treatment of soil are available for engineers. The most widely used method includes solution/grout, but they alter the ground pH level and could be toxic. In order to avoid the potential environmental harms and make use of naturally occurring microorganisms, biological methods to improve the engineering properties of soils have been intensely studied. This article presents the results of a research project in which Sporosarcina pasteurii (formerly known as Bacillus pasteurii) was used to induce biological cementation in loose sand medium. The bacteria was injected into sand, which led to the development of cementation (calcium carbonate crystal) between sand grains. The calcification was observed using a scanning electron microscope (SEM). 相似文献
345.
Apip Kaoru Takara Yosuke Yamashiki Kyoji Sassa Agung Bagiawan Ibrahim Hiroshi Fukuoka 《Landslides》2010,7(3):237-258
This paper describes the potential applicability of a hydrological–geotechnical modeling system using satellite-based rainfall
estimates for a shallow landslide prediction system. The physically based distributed model has been developed by integrating
a grid-based distributed kinematic wave rainfall-runoff model with an infinite slope stability approach. The model was forced
by the satellite-based near real-time half-hourly CMORPH global rainfall product prepared by NOAA-CPC. The method combines
the following two model outputs necessary for identifying where and when shallow landslides may potentially occur in the catchment:
(1) the time-invariant spatial distribution of areas susceptible to slope instability map, for which the river catchment is
divided into stability classes according to the critical relative soil saturation; this output is designed to portray the
effect of quasi-static land surface variables and soil strength properties on slope instability and (2) a produced map linked
with spatiotemporally varying hydrologic properties to provide a time-varying estimate of susceptibility to slope movement
in response to rainfall. The proposed hydrological model predicts the dynamic of soil saturation in each grid element. The
stored water in each grid element is then used for updating the relative soil saturation and analyzing the slope stability.
A grid of slope is defined to be unstable when the relative soil saturation becomes higher than the critical level and is
the basis for issuing a shallow landslide warning. The method was applied to past landslides in the upper Citarum River catchment
(2,310 km2), Indonesia; the resulting time-invariant landslide susceptibility map shows good agreement with the spatial patterns of
documented historical landslides (1985–2008). Application of the model to two recent shallow landslides shows that the model
can successfully predict the effect of rainfall movement and intensity on the spatiotemporal dynamic of hydrological variables
that trigger shallow landslides. Several hours before the landslides, the model predicted unstable conditions in some grids
over and near the grids at which the actual shallow landslides occurred. Overall, the results demonstrate the potential applicability
of the modeling system for shallow landslide disaster predictions and warnings. 相似文献