全文获取类型
收费全文 | 4016篇 |
免费 | 702篇 |
国内免费 | 106篇 |
专业分类
测绘学 | 49篇 |
大气科学 | 91篇 |
地球物理 | 3864篇 |
地质学 | 536篇 |
海洋学 | 29篇 |
天文学 | 16篇 |
综合类 | 52篇 |
自然地理 | 187篇 |
出版年
2024年 | 11篇 |
2023年 | 26篇 |
2022年 | 58篇 |
2021年 | 67篇 |
2020年 | 80篇 |
2019年 | 98篇 |
2018年 | 107篇 |
2017年 | 112篇 |
2016年 | 105篇 |
2015年 | 143篇 |
2014年 | 194篇 |
2013年 | 192篇 |
2012年 | 180篇 |
2011年 | 193篇 |
2010年 | 179篇 |
2009年 | 231篇 |
2008年 | 271篇 |
2007年 | 191篇 |
2006年 | 232篇 |
2005年 | 197篇 |
2004年 | 178篇 |
2003年 | 137篇 |
2002年 | 149篇 |
2001年 | 133篇 |
2000年 | 144篇 |
1999年 | 152篇 |
1998年 | 172篇 |
1997年 | 136篇 |
1996年 | 149篇 |
1995年 | 157篇 |
1994年 | 83篇 |
1993年 | 84篇 |
1992年 | 54篇 |
1991年 | 43篇 |
1990年 | 37篇 |
1989年 | 26篇 |
1988年 | 47篇 |
1987年 | 7篇 |
1986年 | 3篇 |
1985年 | 2篇 |
1984年 | 21篇 |
1983年 | 3篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1980年 | 4篇 |
1979年 | 11篇 |
1978年 | 6篇 |
1977年 | 10篇 |
1954年 | 6篇 |
排序方式: 共有4824条查询结果,搜索用时 875 毫秒
1.
Journal of Geographical Sciences - The border areas of the Tibetan Plateau and the neighboring mountainous areas have a high incidence of earthquakes with a magnitude greater than Ms 5.0, as well... 相似文献
2.
ENVIRONMENTAL SUSTAINABILITY AND SCENARIOS OF URBANIZATION IN ARID AREA——A Case Study in Wuwei City of Gansu Province 总被引:1,自引:0,他引:1
YOUFei LIYu DONGSuo-cheng 《中国地理科学(英文版)》2005,15(2):120-130
1IN T R O D U C T IO N The western China isfacinggrowing problems of eco- logicaland economic development. The disparitiebse- tween the socio-economy of the western and eastern China were enlarging, and the major ecologicalprob- lems stilelvolve as past(H… 相似文献
3.
Chen Zhangli 《中国地震研究》2001,15(4):329-345
In the article the author looks back the hard development course and great progress in earth quake science and technology in China during the last near a half of century and expounds the following 3 aspects: (1) The strong desire of the whole society to mitigate seismic disasters and reduce the effect of earthquakes on social-economic live is a great driving force to push forward the development of earthquake science and technology in China; (2) To better ensure people‘ s life and property, sustainable economic development, and social stability is an essential purpose to drive the development of earthquake science and technology in China; and (3) To insist on the dialectical connection of setup of technical system for seismic monitoring with the scientific research of earthquakes and to better handle the relation between crucial task, current scientif ic level, and the feasibility are the important principles to advance the earthquake science and technology in China. Some success and many setbacks in earthquake disaster mitigation consistently enrich our knowledge regarding the complexity of the conditions for earthquake occurrence and the process of earthquake preparation, promote the reconstruction and modernization of technical system for earthquake monitoring, and deepen the scientific research of earthquakes. During the last 5 years, the improvement and modernization of technical system for earthquake monitoring have clearly provided the technical support to study and practice of earthquake prediction and pre caution, give prominence to key problems and broaden the field of scientific research of earth quakes. These have enabled us to get some new recognition of the conditions for earthquake oc currence and process of earthquake preparation, characteristics of seismic disaster, and mecha nism for earthquake generation in China‘s continent. The progress we have made not only en courages us to enhance the effectiveness of earthquake disaster mitigation, but also provides a basis for accelerating further development of earthquake science and technology in China in the new century, especially in the 10th five-year plan. Based on the history reviewed, the author sets forth a general requirement for develop ment of earthquake science and technology in China and brings out 10 aspects to be stressed and strengthened at present and in the future. These are: upgrade and setup of the network of digitized seismic observation; upgrade and setup of the network for observation of seismic pre cursors; setup of the network for observation of strong motion; setup of the laboratories for ex periment on seismic regime; establishment of technical system for seismic information, emer gency command and urgent rescue; research on short-term and imminent earthquake predic tion; research on intermediate- and long-term earthquake prediction; research on attenuation of seismic ground motion, mechanism for seismic disaster, and control on seismic disaster; ba sic research fields related to seismology and geoscience. We expect that these efforts will signifi cantly elevate the level of earthquake science and technology in China to the advanced interna tional level, improve theories, techniques, and methods for earthquake precaution and predic tion, and enhance the effectiveness of earthquake disaster mitigation. 相似文献
4.
Age estimates of coastal terraces in the Andaman and Nicobar Islands and their tectonic implications
Kusala Rajendran C.P. Rajendran Anil Earnest G.V. Ravi Prasad K. Dutta D.K. Ray R. Anu 《Tectonophysics》2008,455(1-4):53-60
The great Indian Ocean earthquake of December 26, 2004 caused significant vertical changes in its rupture zone. About 800 km of the rupture is along the Andaman and Nicobar Islands, which forms the outer arc ridge of the subduction zone. Coseismic deformation along the exposed land could be observed as uplift/subsidence. Here we analyze the morphological features along the coast of the Andaman and Nicobar Islands, in an effort to reconstruct the past tectonics, taking cues from the coseismic effects. We obtained radiocarbon dates from coastal terraces of the island belt and used them to compute uplift rates, which vary from 1.33 mm yr− 1 in the Little Andaman to 2.80 mm yr− 1 in South Andaman and 2.45 mm yr− 1 in the North Andaman. Our radiocarbon dates converge on 600 yr and 1000 yr old coastal uplifts, which we attribute to the level changes due to two major previous subduction earthquakes in the region. 相似文献
5.
In this study, dynamic behavior and earthquake resistance of Alibey earth dam was investigated. The dam was modeled with four
node plane-strain finite elements (FE) and displacement-pore pressure coupled FE analyses were performed. Nonlinear material
models such as pressure dependent and independent multi yield materials were implemented during the analyses. Transient dynamic
FE analyses were performed with Newmark method. The Newton-Raphson solution scheme was adopted to solve the equations. Liquefaction
and/or cyclic mobility effects were considered during the analysis. For the FE analyses, OpenSees (Open System for Earthquake
Engineering Simulation) framework was adopted. 相似文献
6.
H. M. Hussein K. M. Abou Elenean I. A. Marzouk A. Peresan I. M. Korrat E. Abu El-Nader G. F. Panza M. N. El-Gabry 《Natural Hazards》2008,47(3):525-546
The aim of the present work is to compile and update a catalogue of the instrumentally recorded earthquakes in Egypt, with
uniform and homogeneous source parameters as required for the analysis of seismicity and seismic hazard assessment. This in
turn requires a detailed analysis and comparison of the properties of different available sources, including the distribution
of events with time, the magnitude completeness, and the scaling relations between different kinds of magnitude reported by
different agencies. The observational data cover the time interval 1900–2004 and an area between 22°–33.5° N and 25°–36° E.
The linear regressions between various magnitude types have been evaluated for different magnitude ranges. Using the best
linear relationship determined for each available pair of magnitudes, as well as those identified between the magnitudes and
the seismic moment, we convert the different magnitude types into moment magnitudes M
W, through a multi-step conversion process. Analysis of the catalogue completeness, based on the M
W thus estimated, allows us to identify two different time intervals with homogeneous properties. The first one (1900–1984)
appears to be complete for M
W ≥ 4.5, while the second one (1985–2004) can be considered complete for magnitudes M
W ≥ 3. 相似文献
7.
本文运用福建省沿海气象要素的异常变化,作台湾省的中、短期地震预报,取得了成功的效果。采用长乐历年各月14时最低气压的距平值,作台湾省未来4~7个月内出现强震的预报依据,并采用热异常进行短临跟踪。当秋冬季节连续4d 长乐、福州、台北的气温均比广州累计高出10℃时,预报未来1~5d 台湾省出现7级强震。又根据近百年来台湾发生的强震,统计其活动季节,得到近20年来7级地震发生的时间,绝大部分在9~12月。 相似文献
8.
Recovery of thermohaline circulation under CO2 stabilization and overshoot scenarios 总被引:1,自引:0,他引:1
Norikazu. Nakashiki Dong-Hoon Kim Frank O. Bryan Yoshikatsu Yoshida Daisuke Tsumune Koki Maruyama Hideyuki Kitabata 《Ocean Modelling》2006,15(3-4):200
In this study we examine the behavior of the thermohaline circulation, as simulated by the Community Climate System Model version 3 (CCSM3), for several centuries following CO2 stabilization for the SRES B1 and A1B scenarios and for an “overshoot” scenario in which CO2 levels temporarily reach the same level as in the A1B scenario before declining to an ultimate stabilization level that is identical to the B1 case. While we find no evidence for irreversible changes of the thermohaline circulation in the overshoot experiment, the interplay of the different timescales of the temperature response of the surface and interior ocean does lead to a number of differences in the long-term response of the ocean between it and the B1 stabilization scenario where the same GHG levels are approached by different paths. The stronger initial warming and its slow penetration into the deeper ocean, followed by a transient surface cooling in the overshoot scenario leads to lower static stability, deeper mixing, and a more rapid recovery of the thermohaline circulation than in the B1 stabilization scenario. While the overshoot scenario recovers surface conditions (e.g. SST, sea ice extent) very similar to the B1 scenario shortly after reaching the same GHG levels, the additional accumulation of heat in the interior ocean during the period of higher forcing causes the global mean ocean temperature and steric sea level to remain higher than in the B1 stabilization scenario for at least another several centuries. 相似文献
9.
A Santa Marta JG Ferreira GC Pitcher J Lencart e Silva 《African Journal of Marine Science》2020,42(2):151-166
The carrying capacity for bivalve shellfish culture in Saldanha Bay, South Africa, was analysed through the application of the well-tested EcoWin ecological model, in order to simulate key ecosystem variables. The model was set up using: (i) oceanographic and water-quality data collected from Saldanha Bay, and (ii) culture-practice information provided by local shellfish farmers. EcoWin successfully reproduced key ecological processes, simulating an annual mean phytoplankton biomass of 7.5 µg Chl a l–1 and an annual harvested shellfish biomass of about 3 000 tonnes (t) y–1, in good agreement with reported yield. The maximum annual carrying capacity of Small Bay was estimated as 20 000 t live weight (LW) of oysters Crassostrea gigas, or alternatively 5 100 t LW of mussels Mytilus galloprovincialis, and for Big Bay as 100 000 t LW of oysters. Two production scenarios were investigated for Small Bay: a production of 4 000 t LW y–1 of mussels, and the most profitable scenario for oysters of 19 700 t LW y–1. The main conclusions of this work are: (i) in 2015–2016, both Small Bay and Big Bay were below their maximum production capacity; (ii) the current production of shellfish potentially removes 85% of the human nitrogen inputs; (iii) a maximum-production scenario in both Big Bay and Small Bay would result in phytoplankton depletion in the farmed area; (iv) increasing the production intensity in Big Bay would probably impact the existing cultures in Small Bay; and (v) the production in Small Bay could be increased, resulting in higher income for farmers. 相似文献
10.
在5.12汶川特大地震抗震救灾中,国家测绘部门设计和组织实施了以数据成果服务、专用系统服务和专题制图服务为核心的基础地理信息综合应急服务。其是针对汶川震区地形特点和抗震救灾主体工作需求,快速整合和提供震区已有的基础测绘成果和最新遥感影像资料;快速搭建集震区海量数据集成管理为一体并具备3维影像浏览、对比分析等功能的专用地理信息系统,为灾情评估分析和重建规划研究提供地理空间数据集成展示和分析平台;应需地制作反映受灾范围、受灾程度、救灾响应、规划思路等的各类专题地图和地图集,有效地表达地震灾害的时空分布、重建规划布局等。 相似文献