全文获取类型
收费全文 | 5347篇 |
免费 | 1199篇 |
国内免费 | 2354篇 |
专业分类
测绘学 | 81篇 |
大气科学 | 1822篇 |
地球物理 | 1036篇 |
地质学 | 2905篇 |
海洋学 | 1413篇 |
天文学 | 1094篇 |
综合类 | 255篇 |
自然地理 | 294篇 |
出版年
2024年 | 34篇 |
2023年 | 89篇 |
2022年 | 168篇 |
2021年 | 166篇 |
2020年 | 216篇 |
2019年 | 285篇 |
2018年 | 236篇 |
2017年 | 190篇 |
2016年 | 220篇 |
2015年 | 253篇 |
2014年 | 392篇 |
2013年 | 340篇 |
2012年 | 359篇 |
2011年 | 399篇 |
2010年 | 356篇 |
2009年 | 477篇 |
2008年 | 442篇 |
2007年 | 582篇 |
2006年 | 538篇 |
2005年 | 433篇 |
2004年 | 433篇 |
2003年 | 369篇 |
2002年 | 291篇 |
2001年 | 235篇 |
2000年 | 239篇 |
1999年 | 224篇 |
1998年 | 217篇 |
1997年 | 144篇 |
1996年 | 127篇 |
1995年 | 118篇 |
1994年 | 99篇 |
1993年 | 51篇 |
1992年 | 48篇 |
1991年 | 42篇 |
1990年 | 17篇 |
1989年 | 13篇 |
1988年 | 10篇 |
1987年 | 6篇 |
1986年 | 3篇 |
1985年 | 7篇 |
1984年 | 3篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 6篇 |
1977年 | 2篇 |
1976年 | 7篇 |
1974年 | 1篇 |
1973年 | 4篇 |
1971年 | 2篇 |
1954年 | 3篇 |
排序方式: 共有8900条查询结果,搜索用时 31 毫秒
991.
东亚夏季大气环流和气候对冬季海温异常的邻响应和遥响应 总被引:1,自引:1,他引:0
本文通过IAP-GCM的数值模拟,研究了全球大气环流对黑潮海域和赤道东太平洋冬季SST异常的响应,并着重比较东亚大气环流和气候对黑潮区SSTA的响应(邻响应)和对赤道东太平洋SSTA的响应(遥响应)。首先,无论是黑潮区SSTA引起的邻响应还是赤道东太平洋SSTA所引起的遥响应对东亚大气环流和气候变化的影响都是明显而重要的。由于在大气中低频振荡被激发出来,其响应将持续较长时间。进一步分析表明,东亚大气环流对黑潮区或赤道东太平洋冬季正SSTA的响应都将造成华北地区夏季的多雨,其数值模拟结果与观测相一致。另外,赤道西太平洋地区大气的异常(尤其是对流活动)对于东亚地区大气环流和气候变化有重要作用 相似文献
992.
本文回顾了80年代以来国际上关于岩浆结晶及成矿作用过程的计算机模拟这一领域的研究进展,主要包括镁铁质干岩浆体系、长英质湿岩浆体系的岩浆结晶作用模拟,以及有关的岩浆矿床成矿作用、岩浆热液成矿作用的模拟。基于对这一领域研究现状和发展趋势的分析,笔者首次提出了模拟岩石学的概念。预测在今后5~10年内,模拟岩石学将得到突飞猛进的发展,并将对现代岩石成因理论、实验岩石学与矿物学、实验地球化学、矿床成因理论和矿产预测及勘察理论产生重要影响。 相似文献
993.
本文采用先进的LAGFD风、浪数值模式和POM(PrincetonOceanModel)三维海流模式对自1945~1995年间发生并影响南海东部海域的299个历史最强热带气旋过程进行数值后报,给出了南海东部部分海域(19°~23°N,113°~118°E)中1000m等深线内60个点的多年一遇风、浪、流和水位极值,并简要分析了南海东部(15°~27°N,108°~122°E)的气候特征,为该海域区域性海洋环境研究与工程开发提供了基础参考数据。 相似文献
994.
AnumericalpredictionmodelofstrongthermoclineintheBohaiandtheHuanghaiSeasWangZongshan,XuBochang,JinMeibing,ZouEmei,LiFanhua(Re... 相似文献
995.
Numerical sea ice prediction in China 总被引:5,自引:2,他引:3
NumericalseaicepredictioninChinaWuHuiding,BaiShan,ZhangZhanhai1(ReceivedSeptember12,1996;acceptedJune5,1997)Abstract──Adynami... 相似文献
996.
In this paper the water-taking characteristics of the first,the second and the third stage of theHuanghua Power Plant are studied by numerical model and physical model.The results show that the pres-ent inlet channel only satisfies the supply need of the first stage of the power plant.If the riverbed of the in-let reach is properly dredged,the need of water supply for the third stage of the power plant could be met. 相似文献
997.
In this paper the characteristics of tidal flow and seasonal variation of seidment content in theHangzhou Bay and their affecting factors are studied.Field investigations and data analysis indicate thatthe sediment movement is mainly influenced by the Yangtze estuary and the sediment of the Yangtze estua-ry is induced by wind wave and tidal flow.Owing to the variation of dynamic conditions,the instanta-neous sediment content is controlled by tidal flow,wind wave,depth of water and tidal range synthetically.A sediment content relationship formula is established with related factors.A non-equilibrium2-dimensional numerical model of suspended sediment transportation is set up,and the finite element meth-od is applied.The computation results of the model is in accordance with field data. 相似文献
998.
Zhang Yonggang Li Yucheng Associate Professor Dept. of Mechanic Engineering Shanghai Jiao Tong University Shanghai Professor Dept. of Civil Engineering Dalian University of Technology Dalian 《中国海洋工程》1998,(1)
A nonlinear numerical model has been set up by use of Boussinesq Equation with finite differ-ence method,and has been applied to the simulation of the abnormal change of wave height induced by ex-cavated waterway.Numerical results demonstrate that the abnormal change of wave height is due to theadding of the reflected wave height induced by excavated waterway to the incident wave height.Becausethe angle between the incident wave and the axis of the waterway is smaller than the critical angle,the re-flected wave produced by the waterway may propagate to the breakwater and may be added with the inci-dent wave,then the abnormal change of wave height before the breakwater may be caused.So the wave re-flection caused by the change of water depth cannot be neglected. 相似文献
999.
1997年日本短期降水数值预报效果的检验 总被引:3,自引:0,他引:3
对1997年青岛市降水分布进行了初步统计,并对日本数值预报产品在青岛市天气预报中的应用效果进行了检验分析。结果显示,晴雨和小雨预报在青岛市的短期降水预报中有较好的参考价值。 相似文献
1000.
Oded Navon Anatoly Chekhmir Vladimir Lyakhovsky 《Earth and Planetary Science Letters》1998,160(3-4):763-776
We examine the physics of growth of water bubbles in highly viscous melts. During the initial stages, diffusive mass transfer of water into the bubble keeps the internal pressure in the bubbles close to the initial pressure at nucleation. Growth is controlled by melt viscosity and supersaturation pressure and radial growth under constant pressure is approximately exponential. At later stages, internal pressure falls, radial growth decelerates and follows the square-root of time. At this stage it is controlled by diffusion. The time of transition between the two stages is controlled by the decompression, melt viscosity and the Peclet number of the system. The model closely fit experimental data of bubble growth in viscous melts with low water content. Close fit is also obtained for new experiments at high supersaturation, high Peclet numbers, and high, variable viscosity. Near surface, degassed, silicic melts are viscous enough, so that viscosity-controlled growth may last for very long times. Using the model, we demonstrate that bubbles which nucleate shortly before fragmentation cannot grow fast enough to be important during fragmentation. We suggest that tiny bubbles observed in melt pockets between large bubbles in pumice represent a second nucleation event shortly before or after fragmentation. The presence of such bubbles is an indicator of the conditions at fragmentation. The water content of lavas extruded at lava domes is a key factor in their evolution. Melts of low water content (<0.2 wt%) are too viscid and bubbles nucleated in them will not grow to an appreciable size. Bubbles may grow in melts with 0.4 wt% water. The internal pressure in such bubbles may be preserved for days and the energy stored in the bubbles may be important during the disintegration of dome rocks and the formation of pyroclastic flows. 相似文献