全文获取类型
收费全文 | 9095篇 |
免费 | 1887篇 |
国内免费 | 3278篇 |
专业分类
测绘学 | 323篇 |
大气科学 | 2815篇 |
地球物理 | 1889篇 |
地质学 | 4804篇 |
海洋学 | 1690篇 |
天文学 | 126篇 |
综合类 | 608篇 |
自然地理 | 2005篇 |
出版年
2024年 | 78篇 |
2023年 | 193篇 |
2022年 | 317篇 |
2021年 | 405篇 |
2020年 | 384篇 |
2019年 | 454篇 |
2018年 | 397篇 |
2017年 | 471篇 |
2016年 | 436篇 |
2015年 | 466篇 |
2014年 | 577篇 |
2013年 | 631篇 |
2012年 | 636篇 |
2011年 | 628篇 |
2010年 | 556篇 |
2009年 | 648篇 |
2008年 | 633篇 |
2007年 | 698篇 |
2006年 | 718篇 |
2005年 | 565篇 |
2004年 | 592篇 |
2003年 | 474篇 |
2002年 | 451篇 |
2001年 | 389篇 |
2000年 | 379篇 |
1999年 | 359篇 |
1998年 | 294篇 |
1997年 | 256篇 |
1996年 | 216篇 |
1995年 | 186篇 |
1994年 | 191篇 |
1993年 | 150篇 |
1992年 | 115篇 |
1991年 | 80篇 |
1990年 | 51篇 |
1989年 | 78篇 |
1988年 | 35篇 |
1987年 | 25篇 |
1986年 | 6篇 |
1985年 | 9篇 |
1984年 | 5篇 |
1983年 | 8篇 |
1982年 | 3篇 |
1981年 | 1篇 |
1980年 | 2篇 |
1979年 | 4篇 |
1978年 | 3篇 |
1977年 | 3篇 |
1954年 | 4篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
171.
172.
The political turning point in the former GDR and the transformation processes that have been observed since then have significantly
affected economic and social structures in the new Federal States. Gender roles, however, were subjected to even more dramatic
changes. Whilst many women experienced the employment policies of the GDR era as beneficial, social researchers often designate
them as the losers of unification nowadays. This is largely because the abundance of State support measures for employed women
and mothers has been drastically reduced and women as a group have been hit hardest by the crisis on the East German labour
market. Using two cases (Mecklenburg-Westpommerania and Thuringia), this paper aims to illustrate the impact of the transformation
process on the everyday (working) lives of women. We are particularly concerned with a comparative analysis of how women experience
and deal with regional disparities in East Germany.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
173.
Analysis of monthly momentum transport of zonal waves at 850 hPa for the period 1979 to 1993, between ‡S and ‡N for January
to April, using zonal (u) and meridional (v) components of wind taken from the ECMWF reanalysis field, shows a positive correlation (.1% level of significance) between
the Indian summer monsoon rainfall (June through September) and the momentum transport of wave zero TM(0) over latitudinal
belt between 25‡S and 5‡N (LB) during March. Northward (Southward) TM(0) observed in March over LB subsequently leads to a
good (drought) monsoon season over India which is found to be true even when the year is marked with the El-Nino event. Similarly
a strong westerly zone in the Indian Ocean during March, indicates a good monsoon season for the country, even if the year
is marked with El-Nino. The study thus suggests two predictors, TM(0) over LB and the strength of westerly zone in the Indian
Ocean during March. 相似文献
174.
175.
176.
根据华北地区1999年和2001年两期高精度GPS观测结果,通过与1992,1995,1996年和1999年这几期资料的比较,发现近两年的运动与前有所不同,主要表现为:(1)阴山单元和鄂尔多斯单元之间显示为压性运动的性质,但比较微弱,它们之间的边界带上似乎有左旋走滑运动,但从整体上看并不显著。(2)晋冀鲁单元和燕山单元的整体活动性不如以前,各单元内部存在着较明显的差异运动,并山单元和晋冀鲁单元的北部存在着比较显著的东西向挤压,北京地区则表现为南北向挤压。(3)晋冀鲁单元南部与胶辽鲁苏单元的南部的趋势活动呈张性,优势运动方向为东南,这样的结果可能表明,华北目前存在着应力扰动行为,大同与天津之间的区域是受其影响最大的地区,该区有可能成为未来几年中强地震活动的一个主体地区。 相似文献
177.
Based on cross-dating tree rings from the Tianmu Mountain, Zhejiang Province, the tree rings α-cellulose δ 13C time series was measured. By spectrum analysis, the variation of tree-ring δ13C sequence shows a quasi periodicity of 4.4 years, which is coincident with the standard cycle of El Nino. After removing the long-term decrease trend of the δ13C variation related to atmospheric CO2 concentration, the response of the δ13C to climate elements was analyzed using meteorology data from a nearby weather station. The results suggest that there is a distinct relativity between high-frequency variation of tree ring δ 13C series and seasonal climate parameters, e.g. Temperature and precipitation, with a significant time-lag effect. In addition, the high frequency also reflects the strength change of the East Asian Monsoon. The multiple regression method was employed to reconstruct the historical climate, and to analyze the climate change and trend in the last 160 years in the northern Zhejiang Province. 相似文献
178.
E.J. Rohling T.R. CaneS. Cooke M. SprovieriI. Bouloubassi K.C. EmeisR. Schiebel D. KroonF.J. Jorissen A. LorreA.E.S. Kemp 《Earth and Planetary Science Letters》2002,202(1):61-75
Little is known about centennial- to millennial-scale climate variability during interglacial times, other than the Holocene. We here present high-resolution evidence from anoxic (unbioturbated) sediments in the eastern Mediterranean Sea that demonstrates a sustained ∼800-yr climate disturbance in the monsoonal latitudes during the Eemian interglacial maximum (∼125 ka BP). Results imply that before and after this event, the Intertropical Convergence Zone (ITCZ) penetrated sufficiently beyond the central Saharan watershed (∼21°N) during the summer monsoon to fuel flooding into the Mediterranean along the wider North African margin, through fossil river/wadi systems that to date have been considered only within a Holocene context. Relaxation in the ITCZ penetration during the intra-Eemian event curtailed this flux, but flow from the Nile - with its vast catchment area - was not affected. Previous work suggests a concomitant Eurasian cooling event, with intensified impact of the higher-latitude climate on the Mediterranean basin. The combined signals are very similar to those described for the Holocene cooling event around 8 ka BP. The apparent type of concurrent changes in the monsoon and higher-latitude climate may reflect a fundamental mechanism for variability in the transfer of energy (latent heat) between the tropics and higher latitudes. 相似文献
179.
180.