全文获取类型
收费全文 | 5602篇 |
免费 | 1015篇 |
国内免费 | 1310篇 |
专业分类
测绘学 | 332篇 |
大气科学 | 1180篇 |
地球物理 | 1526篇 |
地质学 | 2709篇 |
海洋学 | 674篇 |
天文学 | 293篇 |
综合类 | 653篇 |
自然地理 | 560篇 |
出版年
2024年 | 31篇 |
2023年 | 81篇 |
2022年 | 247篇 |
2021年 | 279篇 |
2020年 | 217篇 |
2019年 | 257篇 |
2018年 | 288篇 |
2017年 | 265篇 |
2016年 | 328篇 |
2015年 | 288篇 |
2014年 | 327篇 |
2013年 | 298篇 |
2012年 | 283篇 |
2011年 | 318篇 |
2010年 | 297篇 |
2009年 | 362篇 |
2008年 | 324篇 |
2007年 | 302篇 |
2006年 | 222篇 |
2005年 | 242篇 |
2004年 | 172篇 |
2003年 | 169篇 |
2002年 | 179篇 |
2001年 | 182篇 |
2000年 | 186篇 |
1999年 | 260篇 |
1998年 | 230篇 |
1997年 | 186篇 |
1996年 | 205篇 |
1995年 | 149篇 |
1994年 | 153篇 |
1993年 | 153篇 |
1992年 | 125篇 |
1991年 | 70篇 |
1990年 | 57篇 |
1989年 | 49篇 |
1988年 | 42篇 |
1987年 | 21篇 |
1986年 | 24篇 |
1985年 | 11篇 |
1984年 | 10篇 |
1983年 | 8篇 |
1982年 | 9篇 |
1981年 | 8篇 |
1980年 | 3篇 |
1978年 | 2篇 |
1977年 | 1篇 |
1976年 | 1篇 |
1975年 | 1篇 |
1958年 | 4篇 |
排序方式: 共有7927条查询结果,搜索用时 522 毫秒
871.
Huang Yuhuan Sun Chengjun Yang Guipeng Yue Xinan Jiang Fenghua Cao Wei Yin Xiaofei Guo Chaonan Niu Jiaohong Ding Haibing 《中国海洋湖沼学报》2020,38(3):650-664
Journal of Oceanology and Limnology - Two sediment cores were retrieved in the hadal zone of the Yap Trench, and their concentrations of six major elements Mg, Al, Ca, Ti, Mn and Fe and nine trace... 相似文献
872.
局限于仅有观测数据的情况下,利用模拟手段研究土壤风蚀引起的粉尘释放是非常必要的,有助于评估区域土壤风蚀及大气环境质量和气候效应。本文通过分析塔克拉玛干沙漠观测站不同高度层风速及计算平均摩阻风速,利用DPM模型计算粉尘释放通量,综合分析了摩阻风速与粉尘释放通量的相互关系。结果表明:1)不同观测日不同高度层的风速变化各不相同,2m高度层风速的变化范围是0.05~7.73 m·s-1,4m高度层风速的变化范围是0.09~7.19 m·s-1,10m高度层风速的变化范围是0.5~8.09 m·s-1。2)4月1日~4月30日各个观测日24小时内平均摩阻风速分别为0.423 m·s-1、0.344 m·s-1、0.271 m·s-1、0.343 m·s-1、0.161 m·s-1、0.315 m·s-1,其变化范围为0.16~0.42 m·s-1。3)DPM模型研究发现实测跃移通量约为模拟值的122%,模拟值与实测值相关性较好,R2为0.91。上述研究结果对定量评估区域乃至全疆的土壤风蚀对粉尘释放通量的影响具有重要意义。 相似文献
873.
Lijing CHENG John ABRAHAM Kevin E.TRENBERTH John FASULLO Tim BOYER Michael E.MANN Jiang ZHU Fan WANG Ricardo LOCARNINI Yuanlong LI Bin ZHANG Fujiang YU Liying WAN Xingrong CHEN Licheng Feng Xiangzhou SONG Yulong LIU Franco RESEGHETTI Simona SIMONCELLI Viktor GOURETSKI Gengxin CHEN Alexey MISHONOV Jim REAGAN Guancheng LI 《大气科学进展》2023,40(6):963-974
Changes in ocean heat content(OHC), salinity, and stratification provide critical indicators for changes in Earth’s energy and water cycles. These cycles have been profoundly altered due to the emission of greenhouse gasses and other anthropogenic substances by human activities, driving pervasive changes in Earth’s climate system. In 2022, the world’s oceans, as given by OHC, were again the hottest in the historical record and exceeded the previous 2021 record maximum.According to IAP/CAS data, ... 相似文献
874.
Xuechun LUO Xiao TANG Haoyue WANG Lei KONG Huangjian WU Weiguo WANG Yating SONG Hongyan LUO Yao WANG Jiang ZHU Zifa WANG 《大气科学进展》2023,40(4):601-618
In recent years, China has implemented several measures to improve air quality. The Beijing-Tianjin-Hebei(BTH)region is one area that has suffered from the most serious air pollution in China and has undergone huge changes in air quality in the past few years. How to scientifically assess these change processes remain the key issue in further improving the air quality over this region in the future. To evaluate the changes in major air pollutant emissions over this region, this paper employs ens... 相似文献
875.
局限于仅有观测数据的情况下,利用模拟手段研究土壤风蚀引起的粉尘释放是非常必要的,有助于评估区域土壤风蚀及大气环境质量和气候效应。本文通过分析塔克拉玛干沙漠观测站不同高度层风速及计算平均摩阻风速,利用DPM模型计算粉尘释放通量,综合分析了摩阻风速与粉尘释放通量的相互关系。结果表明:1)不同观测日不同高度层的风速变化各不相同,2m高度层风速的变化范围是0.05~7.73 m·s-1,4m高度层风速的变化范围是0.09~7.19 m·s-1,10m高度层风速的变化范围是0.5~8.09 m·s-1。2)4月1日~4月30日各个观测日24小时内平均摩阻风速分别为0.423 m·s-1、0.344 m·s-1、0.271 m·s-1、0.343 m·s-1、0.161 m·s-1、0.315 m·s-1,其变化范围为0.16~0.42 m·s-1。3)DPM模型研究发现实测跃移通量约为模拟值的122%,模拟值与实测值相关性较好,R2为0.91。上述研究结果对定量评估区域乃至全疆的土壤风蚀对粉尘释放通量的影响具有重要意义。 相似文献
876.
本文对SpacEyes3D平台下的三维可视化技术进行了探讨,研究了在SpacEyes3D平台下建立矿山三维GIS平台的方法,并基于c#开发语言应用插件编程建立了矿山三维GIS平台。 相似文献
877.
GPS Solutions - The Chinese BeiDou Navigation Satellite System (BDS) has completed its first milestone by providing coverage of the Asia–Pacific area navigation service since December 27,... 相似文献
878.
GPS Solutions - Frequency division multiplexing of GLONASS signals causes inter-frequency bias (IFB) in receiving equipment. IFB significantly increases the difficulties of fixing GLONASS... 相似文献
879.
Yitong Jiang 《地理信息系统科学与遥感》2017,54(1):95-117
Surface moisture is important to link land surface temperature (LST) to people’s thermal comfort. In urban areas, the surface roughness from buildings and urban trees impacts wind speed, and consequently surface moisture. To find the role of surface roughness in surface moisture estimation, we developed methods to estimate daily and hourly evapotranspiration (ET) and soil moisture, based on a case study of Indianapolis, Indiana, USA. In order to capture the spatial and temporal variations of LST, hourly and daily LST was produced by downscaling techniques. Given the heterogeneity in urban areas, fractions of vegetation, soil, and impervious surfaces were calculated. To describe the urban morphology, surface roughness parameters were calculated from digital elevation model (DEM), digital surface model (DSM), and Terrestrial Light Detection and Ranging (LiDAR). Two source energy balance (TSEB) model was employed to generate ET, and the temperature vegetation index (TVX) method was used to calculate soil moisture. Stable hourly soil moisture fluctuated from 15% to 20%, and daily soil moisture increased due to precipitation and decreased due to seasonal temperature change. ET over soil, vegetation, and impervious surface in the urban areas yielded different patterns in response to precipitation. The surface roughness from high-rise has bigger influence on ET in central urban areas. 相似文献
880.
Jiang Xu 《Urban geography》2017,38(5):687-707
ABSTRACTIn much of the contemporary academic inquiry and political discourse on Chinese cities, urban entrepreneurialism and environmentalism often appear to be analyzed disjointedly and unreflectively. They are portrayed as two conflicting interests. Commentators also view urban planners as a homogenous group of professionals and/or state agents being forced to give up environmental goals to pursue economic value of space. Using the case of Tianjin Eco-City planning, this article interrogates the bargaining process between the “ecological value” and “commodity narrative”. It offers three major arguments. First, even though the discourse of environmental sustainability has been used to legitimize economic transformation, ecological demands are creating new pressures on entrepreneurial urban governance. Second, rather than treating Chinese planners as a fully constituted, internally coherent, organizationally-fixed, and operationally-consistent group, they should be viewed as hybrid, and diverse entities that represent divergent and sometimes contentious state interests. Third, planners, though still under tremendous pressure from landed interests, can become active players to positively influence urban transformation toward more environmental care. 相似文献