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排序方式: 共有816条查询结果,搜索用时 31 毫秒
1.
Assessment of soil erosion in a monsoon-dominated mountain river basin in India using RUSLE-SDR and AHP 总被引:1,自引:1,他引:0
The long-term average annual soil loss (A) and sediment yield (SY) in a tropical monsoon-dominated river basin in the southern Western Ghats, India (Muthirapuzha River Basin, MRB; area: 271.75 km2), were predicted by coupling the Revised Universal Soil Loss Equation (RUSLE) and sediment delivery ratio (SDR) models. Moreover, the study also delineated soil erosion risk zones based on the soil erosion potential index (SEPI) using the analytic hierarchy process (AHP) technique. Mean A of the basin is 14.36 t ha?1 year?1, while mean SY is only 3.65 t ha?1 year?1. Although the land use/land cover types with human interference show relatively lower A compared to natural vegetation, their higher SDR values reflect the significance of anthropogenic activities in accelerated soil erosion. The soil erosion risk in the MRB is strongly controlled by slope, land use/land cover and relative relief, compared to geomorphology, drainage density, stream frequency and lineament frequency. 相似文献
2.
尼泊尔在地理位置上处于中国和印度包围之中,由于历史原因,其经济、政治、军事等长期受到制约。随着中国“一带一路”倡议的推进和中印近年来领土和国际政治问题的冲突与分歧,尼泊尔正在成为中印新的角力场。本文首先通过构建地缘影响力模型进行演变格局分析与趋势预测,并加入世界环境和区域环境两方面影响因素,运用定性与定量分析结合的方法,预测中、尼、印三国未来战略行动方向。综合以上分析发现:1)2000年—2016年,中国对尼泊尔地缘影响力较于印度对于尼泊尔地缘影响力上升趋势明显,预计在2022年至2023年中、印对尼泊尔地缘影响力达到平衡。2)硬实力是中国对尼泊尔地缘影响力上升的关键因素;软实力和交流互动力是未来中国增强在尼泊尔地缘影响力的发展因素;地理环境是中国对尼泊尔地缘影响力发展的制约因素。3)未来中国将继续实施积极性合作战略,印度形成对中国遏制性防范战略,尼泊尔维持被动性中印平衡战略。 相似文献
3.
Joevivek Vincent Jayaraj Chandrasekar Nainarpandian Jayangondaperumal Ramakrishnan Thakur Vikram Chandr Shree Purniema Krishnan 《海洋学报(英文版)》2019,38(5):151-160
To analyze the grain size and depositional environment of the foreshore sediments, a study was undertaken on wave refraction along the wide sandy beaches of central Tamil Nadu coast. The nearshore waves approach the coast at 45° during the northeast(NE) monsoon, at 135° during the southwest(SW) monsoon and at 90° during the non-monsoon or fair-weather period with a predominant wave period of 8 and 10 s. A computer based wave refraction pattern is constructed to evaluate the trajectories of shoreward propagating waves along the coast in different seasons. The convergent wave rays during NE monsoon, leads to high energy wave condition which conveys a continuous erosion at foreshore region while divergent and inept condition of rays during the SW and non-monsoon, leads to moderate and less energy waves that clearly demarcates the rebuilt beach sediments through littoral sediment transport. The role of wave refraction in foreshore deposits was understood by grain size and depositional environment analysis. The presence of fine grains with the mixed population, during the NE monsoon reveals that the high energy wave condition and sediments were derived from beach and river environment. Conversely, the presence of medium grains with uniform population, during SW and non-monsoon attested less turbulence and sediments were derived from prolong propagation of onshore-offshore wave process.These upshots are apparently correlated with the in situ beach condition. On the whole, from this study it is understood that beaches underwent erosion during the NE monsoon and restored its original condition during the SW and non-monsoon seasons that exposed the stability of the beach and nearshore condition. 相似文献
4.
Nicolas Schlitz 《Singapore journal of tropical geography》2020,41(3):450-467
This article introduces plastic recycling networks in Kolkata, India, as a case to illustrate the contradictory entanglement of economic and environmental change in urban informal contexts of the Global South. In light of the prevailing environmental critique of informal plastic recycling in India, this article discusses plastic recyclers’ environmental impact and contribution as well as the potential to enhance the environmental and economic performance of their business. Network and chain approaches in the emerging field of Environmental Economic Geography are combined with the notion of social metabolism to conceptualize the entanglement of environmental and economic processes as well as socio-environmental inequalities entailed in recycling networks. The analysis reveals the impact that the heterogeneity and fluctuation of plastic waste supply has on the economic organization of recycling networks, giving rise to distinct forms of governance in its intermediate and down-stream segments. Such an integrated perspective also serves to explain why environmental upgrading is hard to achieve under prevailing circumstances by plastic recyclers in Kolkata. Based on an assessment of the social and political conditions of informality under which plastic recyclers operate, the adoption of common assumptions about ecological modernization imbuing parts of Environmental Economic Geography is called into question. 相似文献
5.
GIS‐based modelling of soil erosion processes using the modified‐MMF (MMMF) model in a large watershed having vast agro‐climatological differences 下载免费PDF全文
The present study demonstrates a spatially distributed application of a field‐scale annual soil loss model, the modified‐MMF (MMMF), to a large watershed using hydrological routing techniques, remote sensing data and geospatial technologies. In this study, the MMMF model is implemented after incorporating the corrections suggested in recent literature along with appropriate modifications of the model to suit the agro‐climatological conditions prevailing in most parts of India. Sensitivity analysis carried out through an Average Linear Sensitivity approach indicates that the model outputs are highly sensitive to soil moisture (MS), bulk density (BD), effective hydraulic depth (EHD), ground cover (GC) and settling velocity for clay (VSc). During calibration and validation, the performance evaluation statistics are mostly in the range of very good to satisfactory for both runoff and soil loss at the watershed outlet. Even spatial validation of the results of intermediate processes in the water phase and the sediment phase, although qualitative, seems to be reasonable and rational. Furthermore, the soil erosion severity analysis for different land‐uses existing in the watershed indicates that about 90% of the watershed area, especially that occupied by agricultural lands, is vulnerable to the long‐term effects of soil erosion. Copyright © 2018 John Wiley & Sons, Ltd. 相似文献
6.
《Chemie der Erde / Geochemistry》2020,80(1):125596
Petrographic and geochemical studies characterize lithologies of the Khambal Formation deposited in the Sindreth Basin as arkosic, subarkosic, and quartzarenite. Weathering indices, such as CIA and CIW in conjunction with the ACNK diagram, prescribe mostly moderate chemical weathering with intermittent pulses of extreme weathering in the source area. The discrimination diagrams suggest that these Neoproterozoic clastics were deposited in an active rift basin. Provenance indicators of the detritus components point to a terrane possessing subordinate mafic material in conjunction with large felsic components. A comparison of immobile element ratios with probable source rocks suggest that the Mesoproterozoic Delhi arc situated to the east of the Sindreth Basin could be the possible source. Our mixing calculation defines the proportion of end member components in the Delhi arc. Geodynamic considerations relate the origin of the Sindreth Basin to the processes of disintegration and reassembly of supercontinents. 相似文献
7.
The Linzizong Group (64–44 Ma) of the Lhasa Terrane in Tibet is critically positioned for establishing the paleoposition of the southern leading edge of the Asian continent during Paleogene times and constraining onset of the India–Asia collision. Here we report paleomagnetic results from a collection comprising 384 drill-core samples from 34 sites embracing all three formations of this group. Comprehensive demagnetization and field tests isolate characteristic remanent magnetizations (ChRM) summarized by overall tilt-corrected formation-mean directions of D = 183.6°, I = −12.4° (α95 = 8.1°) for the Dianzhong (64–60 Ma), D = 1.0°, I = 18.1° (α95 = 8.1°) for the Nianbo (60–50 Ma), and D = 12.4°, I = 23.2° (α95 = 7.3°) for the Pana (50–44 Ma). Fold tests are positive in each formation suggesting a pre-folding origin and we interpret the magnetizations as quasi-primary and acquired at, or slightly later than, formation of the Linzizong Group. Revised Paleogene paleopoles with Ar–Ar age constraints for the Lhasa Terrane indicate that onset of the India–Asia collision occurred no later than ∼60.5 ± 1.5 Ma at a low paleolatitude of ∼10°N. Analysis of 60 site-mean observations from a range of studies of the Pana Formation in the higher part of the succession highlight a large dispersion of ChRM directions; a number of possible causes are suggested but further study of this formation over a wider area is required to resolve this issue. 相似文献
8.
《Geoforum》2015
This review offers a critical reading of the November 2014 India–U.S. trade deal that unblocked an impasse in the World Trade Organization’s (WTO) Doha round and considers what it means for the way we govern global trade. It argues that the agreement, rather than being a ‘victory’ for the developing world or a cause for celebration, may simply reinforce an unfair and problematic system of distributing trade opportunities among WTO members. It may also obscure further the need for a fundamental overhaul of the way global trade is governed. In so doing, the review speaks to broader debates about what happens when ‘rising’ powers replace established states in global institutions in the absence of wider processes of reform; and it adds to growing concerns about the increasing precariousness of least developed countries (LDCs) in international economic regimes. 相似文献
9.
《Geoforum》2015
Those of us living in the global north are increasingly urged to divert cast-off clothing from the local waste stream and donate it for reuse and recycling. It is argued that this is the right thing to do, since it is environmentally responsible behaviour, conserves resources, and supports charities via collection systems. Second-hand clothing is thereby culturally framed as waste, as a surplus, and as a morally-charged product that has a powerful redemptive capacity for donors, multiple recyclers and secondary consumers. Two-thirds of collected used clothing is commercially exported for reuse in developing countries, and it is as a freely-traded commodity that it is claimed to grow markets and support livelihoods in the global south, rather than a fairly-traded product. As policy-makers in Northern Europe seek to improve sustainable systems of textile reuse and recycling, ethical issues associated with distant destination markets in the global South are beginning to garner attention. Imported used clothing is ubiquitous in India despite highly restrictive tariff barriers, and the Indian market provides a thought-provoking example since in this case the trade is neither fair nor free. The paper evidences the complexity of the market as vertical hierarchies of dealers negotiate and expand the multiple spaces between legal and illegal commodity flows, and formal and informal economies, to build successful businesses. It reflects upon debates in India around democracy, development and neoliberal economics, and suggests that efforts to introduce ethical interventions in end markets will have to negotiate the nexus of power, politics and corruption. 相似文献
10.
Isolated Archosaur teeth from the green sandstone capping the Coralline Limestone (Bagh Group) of the Narmada valley: Evidence for the presence of pre‐Late to Late Maastrichtian abelisaurids in India 下载免费PDF全文
Guntupalli V.R. Prasad Vishal Verma Pooja Grover Rajkumari Priyadarshini Ashok Sahni Ranjit S. Lourembam 《Island Arc》2016,25(6):410-420
Recent field prospecting in the Cretaceous sequences of the lower Narmada valley has led to the discovery of three isolated archosaur teeth from the upper part of marine Cretaceous rocks of the Bagh Group. The specimens were recovered by surface prospecting from an oyster‐bearing green sandstone bed occurring at the top of the Coralline Limestone (Coniacian) from a site near Phutibawri village, Dhar District, Madhya Pradesh, India. Of the three teeth recovered from this horizon, two are identified with abelisaurid dinosaurs and the third one with an indeterminate crocodile. The abelisaurid teeth conform to the premaxillary and maxillary tooth morphology of Majungasaurus and Indosuchus. Earlier reports of abelisaurid dinosaurs from India are from the Upper Cretaceous (Maastrichtian) Lameta Group of Jabalpur, Pisdura (Central India) and Balasinor (Western India) and Upper Cretaceous (Late Maastrichtian) Kallamedu Formation (South India). As no associated age diagnostic fossils are found, the specimens described here are considered to represent pre‐Late to Late Maastrichtian age based on the known ages of the underlying and overlying formations. The new finds, therefore, document stratigraphically the oldest occurrence of abelisaurid dinosaurs known from the Indian subcontinent. 相似文献