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991.
政和-大埔深(大)断裂带中段地质构造特征及其演化探讨 总被引:4,自引:0,他引:4
政和—大埔深(大)断裂带为划分福建省内一级构造单元的断裂带,通过各类资料综合分析,初步认为该断裂带自中晚元古代形成以来,持续活动至今,是一条深(大)断裂带,其活动位置不断迁移,各期的构造特征也不尽相同。该断裂带的活动对其两侧地质构造格局有较大的影响,在控岩、控矿等方面具有明显的表现。 相似文献
992.
993.
Through analysis of natural and social attributes of earthquake forecasting, the relationship between the natural and social attributes of earthquake forecasting (early warning) has been discussed. Regarding the natural attributes of earthquake forecasting, it only attempts to forecast the magnitude, location and occurrence time of future earthquake based on the analysis of observational data and relevant theories and taking into consideration the present understanding of seismogeny and earthquake generation. It need not consider the consequences an earthquake forecast involves, and its purpose is to check out the level of scientific understanding of earthquakes. In respect of the social aspect of earthquake forecasting, people also focus on the consequence that the forecasting involves, in addition to its natural aspect, such as the uncertainty of earthquake prediction itself, the impact of earthquake prediction, and the earthquake resistant capability of structures (buildings), lifeline works, etc. In a word, it highlights the risk of earthquake forecasting and tries to mitigate the earthquake hazard as much as possible. In this paper, the authors also discuss the scientific and social challenges faced in earthquake prediction and analyze preliminarily the meanings and content of earthquake early warning. 相似文献
994.
Most of the present earthquake early warning systems are based on broadband or strong motion recordings. How-ever, the short-period instruments are still deployed. It is well-known that short-period recordings have saturation problems for large earthquakes when estimating the size of an earthquake. Thus, it is necessary to make clear the magnitude at which saturation starts to occur for the commonly used τc and Pd measurements, respectively. To investigate the possibility of using short-period seismic recordings for earthquake early warning, we conducted a simulated experiment using the strong motion data of the 1999 Chi-Chi earthquake sequence including its main shock and 31 aftershocks, with magnitude span from 4 to 7.6. The strong motion acceleration recordings were convolved with the instrument response of short-period seismographs in northern China to simulate short-period seismograms. Parameters τc and Pd from the first-three-second seismograms were calculated for the simulated short-period recordings and compared with that obtained by the original strong ground motion recordings. The result showed that to some extent, short-period recordings can be used for threshold earthquake early warning, while the magnitude saturation of Pd estimation can be up to 6.5, better than τc estimation. 相似文献
995.
Chemocline instability and isotope variations of the Ediacaran Doushantuo basin in South China 总被引:4,自引:1,他引:3
Stable isotope analyses in sections across a shelf to basinal transect of the Ediacaran Doushantuo basin show substantial isotope variabilities. In Songlin section where sediments were deposited in an intrashelf basin, δ 13C values are persistently negative (_3‰ to _5‰, VPDB) through the entire Doushantuo Formation, similar to those obtained from the slope section in Wuhe (_5‰ to _10‰, VPDB). Shallow water sections in Weng'an and Duoding show two broad δ 13C anomalies overprinted with significant meter-scale variations, but none of the curves has similar absolute δ 13C values compared to the Yangtze Gorges areas in South China and other sections globally. Such isotope variations, if partially recording ancient seawater signature, imply spatial and temporal chemocline instability in the Doushantuo basin. In combination with available δ 13C records from other Ediacaran successions globally, the data from the Doushantuo basin are consistent, in first order, with the existence and oxidation of a large dissolved organic carbon (DOC) reservoir in Ediacaran oceans, but imply local environmental controls on Neoproterozoic isotope values and call attentions for using δ 13C anomalies as time lines in stratigraphic correlation. 相似文献
996.
通过新型岩土固化剂(ESC)搅拌桩体与水泥土搅拌桩体的对比试验以及ESC固化土作用机理的论述,说明了搅拌桩具有较高的侧摩阻力,同时证明了用ESC固化剂替代水泥能使搅拌桩固结土的强度大幅度得到提高,从而解决了搅拌桩因桩体强度低而存在的侧摩阻力难以发挥、单桩承载力低的问题。 相似文献
997.
分布式基坑监测信息管理与预警系统的研制 总被引:3,自引:0,他引:3
针对基坑监测的信息化、集成化、共享化要求,开发了基于GIS的分布式基坑监测信息管理与预警系统。介绍了系统的结构框架,着重介绍了系统实现的功能。在GIS图形可视化技术基础上,系统地实现了区域内多个基坑地质勘察、设计、施工等资料及测点信息、监测仪器、监测数据、周边建筑物等相关资料的全面采集,并在此基础上实现了信息的存储、处理、分析、查询、预测、预警以及成果输出的自动化。系统采用C/S结构实现信息共享与多人协作,在网络环境下可高效运行,为基坑监测提供了一个功能强大的信息平台。 相似文献
998.
999.
研究了在人工条件下,鲻鱼MugilcephalusLinnaeus幼体各部分形态、器官的发育时间、行为、营养和变态特点,划分了发育期。仔鱼在生长过程常因畸形、损伤和消化不良而死亡;生长差异则存在于整个发育期,并且差异随时间延长而增大。同时,对鲻鱼早期发育的生物学特点、疾病、变态危险期和生长差异等进行了讨论,指出鲻鱼与环境和饲育条件之间的生态生理关系,以及这种关系对鲻鱼生长和存活的影响。 相似文献
1000.