全文获取类型
收费全文 | 571篇 |
免费 | 13篇 |
国内免费 | 19篇 |
专业分类
测绘学 | 9篇 |
大气科学 | 95篇 |
地球物理 | 119篇 |
地质学 | 157篇 |
海洋学 | 173篇 |
天文学 | 27篇 |
综合类 | 9篇 |
自然地理 | 14篇 |
出版年
2023年 | 2篇 |
2022年 | 6篇 |
2021年 | 15篇 |
2020年 | 12篇 |
2019年 | 8篇 |
2018年 | 29篇 |
2017年 | 34篇 |
2016年 | 43篇 |
2015年 | 41篇 |
2014年 | 36篇 |
2013年 | 37篇 |
2012年 | 34篇 |
2011年 | 53篇 |
2010年 | 43篇 |
2009年 | 35篇 |
2008年 | 26篇 |
2007年 | 24篇 |
2006年 | 25篇 |
2005年 | 20篇 |
2004年 | 12篇 |
2003年 | 18篇 |
2002年 | 9篇 |
2001年 | 8篇 |
2000年 | 5篇 |
1999年 | 8篇 |
1998年 | 2篇 |
1997年 | 6篇 |
1994年 | 1篇 |
1993年 | 3篇 |
1992年 | 2篇 |
1988年 | 1篇 |
1986年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1981年 | 1篇 |
1973年 | 1篇 |
排序方式: 共有603条查询结果,搜索用时 15 毫秒
511.
Supra-subduction and abyssal mantle peridotites of the Coast Range ophiolite,California 总被引:6,自引:0,他引:6
Sung Hi Choi John W. Shervais Samuel B. Mukasa 《Contributions to Mineralogy and Petrology》2008,156(5):551-576
The Coast Range ophiolite (CRO) of California is one of the most extensive tracts of oceanic crust preserved in the North
American Cordillera, but its origin has long remained controversial. We present here new data on mineral compositions in mantle
peridotites that underlie crustal sections of the ophiolite, and show that these are dominantly refractory harzburgites related
to high apparent melting in a supra-subduction zone (SSZ) setting. Abyssal peridotite (characterized by high-Al spinels and
relatively high Ti, Na, Nd, Sm, Lu, and Hf in pyroxene) occurs at one location where it is associated with SSZ mantle peridotite
and volcanic rocks with both oceanic and arc-like geochemistry. SSZ mantle peridotites (characterized by intermediate-Cr/Al
or high-Cr spinels, and by extremely low Ti, Na, Nd, Sm, Lu, and Hf in pyroxenes) are associated with crustal sections containing
arc-related volcanic rocks, including boninites. This convergence between conclusions based on crustal lithologies and their
underlying mantle sections confirms previous proposals that link the CRO to SSZ processes, and seriously undermines hypotheses
that invoke formation of the ophiolite at a mid-ocean ridge spreading center. 相似文献
512.
Hyunwook Choo Jaewook Hwang Youngmin Choi Changho Lee 《Marine Georesources & Geotechnology》2016,34(6):571-580
One of the distinguishing features of volcanic beach sand compared to typical silica sand can be found in its relatively high iron content; however, studies on the effect of iron content on the engineering properties of volcanic beach sand have been very limited until now. Consequently, this experimental investigation quantifies the effect of iron content on the engineering properties of Ulleung volcanic beach sands, including small strain stiffness, compressibility, friction angle, and cone tip resistance. Various geotechnical experiments were performed, and test results demonstrate that the small strain stiffness increases with an increase in iron content because of the increased interparticle contact stiffness. In addition, the elastic deformation of soil particles decreases with an increase in iron content because of the greater elastic modulus of iron compared to that of silica. In contrast, the effects of iron content on the intermediate strain constrained modulus and on the large strain friction angle are insignificant, and these properties are mainly determined by state variables. The relationship between the stress-normalized cone tip resistance and the state parameter of tested Ulleung sand is very similar to that on silica sands, reflecting that the effect of iron contents on the cone tip resistance is minimal. 相似文献
513.
This study investigated the simulations of three months of seasonal tropical cyclone (TC) activity over the western North Pacific using the Advanced Research WRF Model. In the control experiment (CTL), the TC frequency was considerably overestimated. Additionally, the tracks of some TCs tended to have larger radii of curvature and were shifted eastward. The large-scale environments of westerly monsoon flows and subtropical Pacific highs were unreasonably simulated. The overestimated frequency of TC formation was attributed to a strengthened westerly wind field in the southern quadrants of the TC center. In comparison with the experiment with the spectral nudging method, the strengthened wind speed was mainly modulated by large-scale flow that was greater than approximately 1000 km in the model domain. The spurious formation and undesirable tracks of TCs in the CTL were considerably improved by reproducing realistic large-scale atmospheric monsoon circulation with substantial adjustment between large-scale flow in the model domain and large-scale boundary forcing modified by the spectral nudging method. The realistic monsoon circulation took a vital role in simulating realistic TCs. It revealed that, in the downscaling from large-scale fields for regional climate simulations, scale interaction between model-generated regional features and forced large-scale fields should be considered, and spectral nudging is a desirable method in the downscaling method. 相似文献
514.
515.
Adaptive GPS/INS integration for relative navigation 总被引:1,自引:0,他引:1
Je Young Lee Hee Sung Kim Kwang Ho Choi Joonhoo Lim Sebum Chun Hyung Keun Lee 《GPS Solutions》2016,20(1):63-75
Relative navigation based on GPS receivers and inertial measurement units is required in many applications including formation flying, collision avoidance, cooperative positioning, and accident monitoring. Since sensors are mounted on different vehicles which are moving independently, sensor errors are more variable in relative navigation than in single-vehicle navigation due to different vehicle dynamics and signal environments. In order to improve the robustness against sensor error variability in relative navigation, we present an efficient adaptive GPS/INS integration method. In the proposed method, the covariances of GPS and inertial measurements are estimated separately by the innovations of two fundamentally different filters. One is the position-domain carrier-smoothed-code filter and the other is the velocity-aided Kalman filter. By the proposed two-filter adaptive estimation method, the covariance estimation of the two sensors can be isolated effectively since each filter estimates its own measurement noise. Simulation and experimental results demonstrate that the proposed method improves relative navigation accuracy by appropriate noise covariance estimation. 相似文献
516.
517.
518.
Chang-Hoi Ho Woosuk Choi Jinwon Kim Maeng-Ki Kim Hee-Dong Yoo 《Asia-Pacific Journal of Atmospheric Sciences》2016,52(4):395-403
A number of studies in the past two decades have attempted to find the relationship between the precipitation in Korea and the El Niño-Southern Oscillation (ENSO) on various time scales. Comprehensive analyses of station precipitation data in Korea for the 61-year period, 1954-2014, in this study show that the effects of ENSO on the seasonal precipitation in Korea are practically negligible. The correlation between summer precipitation and ENSO is insignificant regardless of the intensity, type (e.g., eastern-Pacific or central-Pacific), and stage (e.g., developing, mature, or decaying) of ENSO. Somewhat meaningful correlation between ENSO and precipitation in Korea occurs only in the ENSO-developing fall. Because summer rainfall accounts for over half of the annual total and fall is a dry season in Korea, the overall effects of ENSO on precipitation in Korea are practically nonexistent. 相似文献
519.
Shao-Chen Liu Qun-Ke Xia Sung Hi Choi Etienne Deloule Pei Li Jia Liu 《Contributions to Mineralogy and Petrology》2016,171(12):100
Various enriched recycled oceanic components in the source of Cenozoic intra-plate alkaline basalts from eastern China were identified by previous studies. Due to the existence of a stagnant subducted Pacific slab in the mantle transition zone beneath eastern China, it is logical to connect the stagnant slab to the recycled oceanic materials. However, the recycled oceanic materials could also result from ancient subduction events (e.g., Paleo-Tethyan, Paleo-Asian or Izanagi plate subduction) because enriched geochemical signatures of a recycled slab can be preserved in the mantle for longer than 1 Gyr. Investigating the temporal variations of the recycled oceanic materials in the mantle source is a useful way to trace the origin of the basalts. In this article, we have conducted a detailed geochemical study, including major and trace elements and Sr–Nd–Pb isotopes, on two alkaline basalt groups from Zhejiang, SE China, which erupted 26–17 Ma and after 11 Ma, respectively. In particular, we recovered the H2O content of the initial magmas based on the H2O content of the clinopyroxene (cpx) phenocrysts and the partition coefficients of H2O between cpx and basaltic melts. The H2O contents of the Zhejiang basalts range from 1.3 to 2.6 (wt.%), which fall within the range of back-arc basin or island arc basalts. The older basalts are more alkaline and have lower Si and Al contents; higher trace element concentrations; higher La/Yb, Ce/Pb and Nb/La ratios; lower H2O/Ce and Ba/Th ratios; and stronger negative K, Pb, Hf and Ti anomalies than the younger ones. The co-relationships between Ba/La, H2O/Ce, Nb/La, Ce/Pb and Ba/Th in the two groups of the Zhejiang basalts indicate that a recycled dehydrated oceanic alkaline basalt component is needed in the source of the older rocks, along with a depleted mantle component. Meanwhile, an additional recycled dehydrated sediment component was required in the source of the younger rocks. The temporal change in the recycled oceanic materials in the mantle sources of Zhejiang Cenozoic basalts demonstrates that the recycled components can only originate in the stagnant Pacific slab that is the only plate subducted since 100 Ma in this area. 相似文献
520.
Smartphones can be utilized in the field of geosciences for various purposes due to their multifaceted abilities that combine both hard- and software features. The unique abilities of smartphones allow new methodologies for the collection and visualization of data that rarely become available in traditional computing platforms. In this study, commercially available smartphone applications (apps) that have been released in geoscience (e.g., geology/soil, minerals and rocks, petroleum and gas) so far were investigated. The apps were categorized based on the extent of smartphone feature usage into (a) basic, standard-feature apps; (b) calculator and referencing apps; and (c) sensing and communication apps. Furthermore, each of these categories was divided into several app groups based on specific features. Representative apps of each specific app group were selected and their characteristics and applicability were examined. Lastly, major limitations regarding smartphone app development and implementation in geoscience and implications for future improvements were discussed. 相似文献