全文获取类型
收费全文 | 2765篇 |
免费 | 507篇 |
国内免费 | 766篇 |
专业分类
测绘学 | 115篇 |
大气科学 | 332篇 |
地球物理 | 1119篇 |
地质学 | 1445篇 |
海洋学 | 397篇 |
天文学 | 33篇 |
综合类 | 151篇 |
自然地理 | 446篇 |
出版年
2024年 | 9篇 |
2023年 | 31篇 |
2022年 | 63篇 |
2021年 | 110篇 |
2020年 | 129篇 |
2019年 | 135篇 |
2018年 | 134篇 |
2017年 | 136篇 |
2016年 | 140篇 |
2015年 | 185篇 |
2014年 | 167篇 |
2013年 | 264篇 |
2012年 | 193篇 |
2011年 | 190篇 |
2010年 | 170篇 |
2009年 | 166篇 |
2008年 | 195篇 |
2007年 | 201篇 |
2006年 | 208篇 |
2005年 | 163篇 |
2004年 | 141篇 |
2003年 | 118篇 |
2002年 | 82篇 |
2001年 | 98篇 |
2000年 | 70篇 |
1999年 | 97篇 |
1998年 | 65篇 |
1997年 | 62篇 |
1996年 | 63篇 |
1995年 | 39篇 |
1994年 | 53篇 |
1993年 | 29篇 |
1992年 | 27篇 |
1991年 | 30篇 |
1990年 | 13篇 |
1989年 | 9篇 |
1988年 | 17篇 |
1987年 | 5篇 |
1986年 | 3篇 |
1985年 | 8篇 |
1984年 | 5篇 |
1983年 | 2篇 |
1982年 | 2篇 |
1981年 | 7篇 |
1978年 | 1篇 |
1977年 | 1篇 |
1973年 | 2篇 |
排序方式: 共有4038条查询结果,搜索用时 500 毫秒
261.
262.
南京红层岩性复杂,桩基持力层承载力难确定。依据南京某工程勘察资料,建立南京红层泥岩、泥质粉砂岩不同互层情况的地质模型,运用FLAC3D软件分析,并与载荷板试验结果进行对比表明:桩基持力层应选择在厚度大于两倍桩径的泥质粉砂岩地层上,避免放置于泥岩地层;载荷板试验结果偏于保守,设计时可以把这部分作为安全储备。 相似文献
263.
264.
第三代浅水波浪数值预报模式及其在黄渤海域的应用 总被引:8,自引:0,他引:8
本文在简单介绍了第三代浅水波浪数值预报SWAN模式的概念、特点、原理等的基础上,着重介绍Mm5模式对风场的模拟,以及利用模拟结果作为SWAN模式中的风场资料,对大连沿海及黄渤海域(36~41°N,117.5~125.5°E)的浪高进行预报。 相似文献
265.
266.
M. J. Best C. S. B. Grimmond Maria Gabriella Villani 《Boundary-Layer Meteorology》2006,118(3):503-525
The UK Met Office has introduced a new scheme for its urban tile in MOSES 2.2 (Met Office Surface Exchange Scheme version 2.2), which is currently implemented within the operational Met Office weather forecasting model. Here, the performance of the urban tile is evaluated in two urban areas: the historic core of downtown Mexico City and a light industrial site in Vancouver, Canada. The sites differ in terms of building structures and mean building heights. In both cases vegetation cover is less than 5%. The evaluation is based on surface energy balance flux measurements conducted at approximately the blending height, which is the location where the surface scheme passes flux data into the atmospheric model. At both sites, MOSES 2.2 correctly simulates the net radiation, but there are discrepancies in the partitioning of turbulent and storage heat fluxes between predicted and observed values. Of the turbulent fluxes, latent heat fluxes were underpredicted by about one order of magnitude. Multiple model runs revealed MOSES 2.2 to be sensitive to changes in the canopy heat storage and in the ratio between the aerodynamic roughness length and that for heat transfer (temperature). Model performance was optimum with heat capacity values smaller than those generally considered for these sites. The results suggest that the current scheme is probably too simple, and that improvements may be obtained by increasing the complexity of the model. 相似文献
267.
268.
269.
数字航空影像辐射信息精处理问题的探讨 总被引:1,自引:0,他引:1
在分析数字航空影像辐射信息的基础上,针对数字航空像片的特点,探讨对数字航空影像进行匀光和匀色处理的技术方法,以及实现批量化处理的方法研究。 相似文献
270.
Much has been written on the apparent urban renaissance in UK cities and the new lifestyle arrangements, working time patterns, economic activities and the more general reordering of work and life that appears to accompany it. Certainly, recent decades have witnessed a range of economic, social and cultural changes in the lives of those living and working in cities and surrounding suburbs. Much of the attention in this work has focused on those groups for whom the changes have appeared most profound: the high-income earners returning to live in the city - the gentrifiers - or those who suffer multiple deprivations as a result of economic restructuring. Seemingly absent from many accounts of urban change are those places where, at first glance, the effects of change have been less pronounced: low-income, working class neighbourhoods where most people continue to get by, albeit in the context of a harsher, and less secure political economic context. In light of this apparent silence, this paper draws on interviews from Wythenshawe in South Manchester, to examine how low-income mothers cope, live and labour, in a rapidly changing city, as they perform paid work at the same time as ensuring the social reproduction of the household. 相似文献