全文获取类型
收费全文 | 517篇 |
免费 | 82篇 |
国内免费 | 144篇 |
专业分类
测绘学 | 16篇 |
大气科学 | 140篇 |
地球物理 | 100篇 |
地质学 | 256篇 |
海洋学 | 83篇 |
天文学 | 59篇 |
综合类 | 48篇 |
自然地理 | 41篇 |
出版年
2023年 | 9篇 |
2022年 | 24篇 |
2021年 | 34篇 |
2020年 | 20篇 |
2019年 | 22篇 |
2018年 | 31篇 |
2017年 | 25篇 |
2016年 | 41篇 |
2015年 | 27篇 |
2014年 | 29篇 |
2013年 | 33篇 |
2012年 | 25篇 |
2011年 | 40篇 |
2010年 | 25篇 |
2009年 | 20篇 |
2008年 | 27篇 |
2007年 | 16篇 |
2006年 | 15篇 |
2005年 | 14篇 |
2004年 | 15篇 |
2003年 | 15篇 |
2002年 | 11篇 |
2001年 | 18篇 |
2000年 | 22篇 |
1999年 | 24篇 |
1998年 | 22篇 |
1997年 | 27篇 |
1996年 | 24篇 |
1995年 | 13篇 |
1994年 | 11篇 |
1993年 | 13篇 |
1992年 | 6篇 |
1991年 | 6篇 |
1990年 | 6篇 |
1989年 | 5篇 |
1988年 | 4篇 |
1987年 | 5篇 |
1986年 | 2篇 |
1985年 | 2篇 |
1984年 | 3篇 |
1982年 | 1篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1974年 | 1篇 |
1973年 | 1篇 |
1958年 | 1篇 |
排序方式: 共有743条查询结果,搜索用时 312 毫秒
181.
182.
We present an analysis of a multidecadal simulation of present-day climate (1961–1990) over Europe with the regional climate model RegCM nested within the global atmospheric model HadAMH. Climatic means, interannual variability and trends are examined, with focus on surface air temperature and precipitation. The RegCM driven by HadAMH fields is able to reproduce the basic features of the observed mean surface climate over Europe, its seasonal evolution and the regional detail due to topographic forcing. Surface air temperature biases are mostly less than 1–2 °C and precipitation biases mostly within 10–20%. The RegCM has more intense vertical transport of temperature and water vapor than HadAMH, which results in lower surface air temperatures and greater precipitation than found in the HadAMH simulation. In some cases this is in the direction of greater agreement with observations, while in others it is in the opposite direction. The simulation shows a tendency to overestimate interannual variability of temperature and precipitation compared to observations, particularly during summer and over the Mediterranean regions. It is shown that in DJF, MAM and SON the RegCM interannual variability is primarily determined by the boundary forcing from HadAMH, while in JJA the internal model physics and resolution effects dominate over many subregions of the domain, and the RegCM has higher interannual variability than HadAMH. The precipitation trends simulated by the nested modeling system for the period 1961–1990 capture some features of the observed trends, in particular the cold season drying over the Mediterranean regions. Ensembles of simulations are, however, needed for a more robust assessment of the models capability to simulate climatic trends. Overall, this simulation is of good quality compared with previous nested RegCM experiments and will constitute the basis for the generation of climate change scenarios over the European region to be reported in future work. 相似文献
183.
地基GPS遥感观测安徽地区水汽特征 总被引:9,自引:3,他引:9
对2002年6~7月安徽地区肥西、桐城、寿县、无为、芜湖、滁州6个GPS观测站的数据,结合相应的地面温度、气压等气象数据反演了时间间隔为30min连续变化的水汽总量。这一解算结果由解算方法分析达到1~2mm量级精度,达到了数值天气预报和气候研究的要求。利用这些资料,分析了上述地区水汽变化特征。单站水汽的持续积累和源源不断的水汽输送是强降水系统发生发展的必要条件,为了研究水汽来源及水汽量的大小,结合NCEP资料计算了一次强降雨过程中水汽通量值。 相似文献
184.
Summary We use the regional climate model RegCM nested within time-slice atmospheric general circulation model experiments to investigate
the possible changes of intense and extreme precipitation over the French Maritime Alps in response to global climate change.
This is a region with complex orography where heavy and/or extended precipitation episodes induced catastrophic floods during
the last decades. Output from a 30-year simulation of present-day climate (1961–1990) is first analysed and compared with
NCEP reanalysed 700 hPa geopotential heights (Z700) and daily precipitation observations from the Alpine Precipitation Climatology
(1966–1999). Two simulations under forcing from the A2 and B2 IPCC emission scenarios for the period 2071–2100 are used to
investigate projected changes in extreme precipitation for our region of interest. In general, the model overestimates the
annual cycle of precipitation. The climate change projections show some increase of precipitation, mostly outside the warm
period for the B2 scenario, and some increase in the variability of the annual precipitation totals for the A2 scenario. The
model reproduces the main observed patterns of the spatial leading EOFs in the Z700 field over the Atlantic-European domain.
The simulated large scale circulation (LSC) variability does not differ significantly from that of the reanalysis data provided
the EOFs are computed on the same domain. Two similar clusters of LSC corresponding to heavy precipitation days were identified
for both simulated and observed data and their patterns do not change significantly in the climate change scenarios. The analysis
of frequency histograms of extreme indices shows that the control simulation systematically underestimates the observed heavy
precipitation expressed as the 90th percentile of rainday amounts in all seasons except summer and better reproduces the greatest 5-day precipitation accumulation.
The main hydrological changes projected for the Maritime Alps consist of an increase of most intense wet spell precipitation
during winters for both scenarios and during autumn for the B2 scenario. Case studies of heavy precipitation events show that
the RegCM is capable to reproduce the physical mechanisms responsible for heavy precipitation over our region of interest. 相似文献
185.
The study results of He and Ar isotopes from fluid inclusions in pyrites formed during mineralization stage of Jinding superlarge
Pb-Zn deposit in west Yunnan, China are reported. The data show that the40Ar/36Ar and3He/4He ratios of fluid inclusions are respectively in the range of 301. 7–385. 7 and 0. 03–0.06Ra, suggesting the oreforming fluid
is a kind of air saturated meteoric groundwater. On the basis of research on coupled relationships among He, Ar, S and Pb
isotopes, the evolution history of ore-forming fluid of the deposit can be summarized as (i) air saturated meteogenic groundwater
infiltrated down and was heated→ (ii) leached S, C and radiogenic He, Ar from the basinal strata → (iii) leached Pb and Zn
from mantle-derived igneous rocks located in the bottom of the basin→ (iv) ore-forming fluid ascended and formed the deposit.
Due to this process, the isotope signatures of crustal radiogenic He, atmospheric Ar (with partial radiogenic40Ar), crustal S and mantle-derived Pb remained in the ore-forming fluid.
Project supported by A30 Project of the National Climbing Program of China and University of Manchester. 相似文献
186.
哀牢山金矿带成矿流体稀土元素地球化学 总被引:24,自引:2,他引:22
本项研究测定了矿石、蚀变围岩和相应未蚀变岩石的稀土元素组成。通过对这些地质体稀土元素地球化学特征的对比研究发现,在成矿流体的演化过程中,镇沅和墨江两个金矿床成矿流体的稀土模式具明显的变化,而大坪金矿成矿流体的稀土模式则保持相对不变。因此,大坪金矿的稀土模式(轻稀土高度富集、弱负Eu异常和较强负Ce异常)可以代表初始成矿流体的稀土模式。研究表明,具有这种稀土模式的流式,可能是由地幔去气作用产生的地幔 相似文献
187.
庐山运动 总被引:1,自引:0,他引:1
本文简述了庐山隆-滑构造的基本特征。在中元古代双桥山群底部的顺层韧变带中,把前人的断层构造砾或沉积成因的巨厚层状变质复成分砾岩,自上而下分离出三层砾:上部砾、中部砾、下部砾。其中上部砾为断层构造砾;中部砾不是砾,而是构造分泌物;下部砾为沉积底砾。在此基础上,同时参考研究区早元古代星子群与中元古代双桥山群构造、岩浆活动、变质作用等方面的差异,建立了“庐山运动”,其活动时间为2200~1800Ma,这可以与华北及华南其它地区同时期的构造运动相对比,但庐山运动的强度相对较弱,表现为以垂直隆升为特色的造陆运动,它曾使研究区早元古代晚期至少遭受过长达200Ma(1800~1600Ma)的风化、剥蚀作用。 相似文献
188.
189.
中期暴雨预报系统实现了从信息采集、预报制作到服务全过程自动化。中期暴雨预报方法主要有:环流分型相似预报、暴雨个例相似预报和中期暴雨预报专家系统,采用层次分析动态决策方法进行预报集成。该系统在业务预报中取得显著效果。 相似文献
190.
The East Asian Monsoon Simulation with IAP AGCMs-A Composite StudyWangHuijunandBiXunqiang(InstituteofAtmosphericPhysics(IAP),... 相似文献