全文获取类型
收费全文 | 3569篇 |
免费 | 648篇 |
国内免费 | 803篇 |
专业分类
测绘学 | 207篇 |
大气科学 | 669篇 |
地球物理 | 1125篇 |
地质学 | 1821篇 |
海洋学 | 338篇 |
天文学 | 134篇 |
综合类 | 327篇 |
自然地理 | 399篇 |
出版年
2024年 | 12篇 |
2023年 | 49篇 |
2022年 | 151篇 |
2021年 | 183篇 |
2020年 | 158篇 |
2019年 | 168篇 |
2018年 | 228篇 |
2017年 | 204篇 |
2016年 | 174篇 |
2015年 | 189篇 |
2014年 | 223篇 |
2013年 | 252篇 |
2012年 | 210篇 |
2011年 | 227篇 |
2010年 | 220篇 |
2009年 | 216篇 |
2008年 | 182篇 |
2007年 | 184篇 |
2006年 | 125篇 |
2005年 | 107篇 |
2004年 | 129篇 |
2003年 | 105篇 |
2002年 | 116篇 |
2001年 | 121篇 |
2000年 | 142篇 |
1999年 | 128篇 |
1998年 | 103篇 |
1997年 | 99篇 |
1996年 | 117篇 |
1995年 | 72篇 |
1994年 | 96篇 |
1993年 | 74篇 |
1992年 | 49篇 |
1991年 | 33篇 |
1990年 | 33篇 |
1989年 | 28篇 |
1988年 | 25篇 |
1987年 | 21篇 |
1986年 | 8篇 |
1985年 | 10篇 |
1984年 | 9篇 |
1983年 | 2篇 |
1982年 | 12篇 |
1981年 | 5篇 |
1980年 | 7篇 |
1976年 | 2篇 |
1975年 | 2篇 |
1949年 | 1篇 |
1936年 | 1篇 |
1933年 | 1篇 |
排序方式: 共有5020条查询结果,搜索用时 46 毫秒
991.
Matlab与高级编程语言在科学计算中的联合运用 总被引:2,自引:1,他引:1
在数字地震观测、地震预报及地震工程研究中,Matlab作为一套功能强大的科学计算及数学分析软件,得到广泛的应用.本文介绍如何将Matlab高效的数值计算和分析能力与高级编程语言结合的方法. 相似文献
992.
CBMD是一款针对CB-3模拟磁照图进行数字化处理的软件,利用专业图像处理技术,对模拟磁照图进行数字化,由于模拟仪器调试及存放因素造成了图纸状况不尽相同,使用者在数字化处理过程中,根据不同的图,纸采用相应的方法进行处理,才能保证数字化结果精确度.本文就主要的几种影响处理精度的情况展开讨论,并提出具体的解决方法. 相似文献
993.
利用常规观测资料、区域自动站资料和“葵花8号”气象卫星资料,对2016年4—9月甘肃省陇东南地区出现的43次强对流天气过程进行分析,确立了强对流云团识别指标、追踪方法及预报指标,并对2018年部分个例进行效果检验。结果表明:(1)利用卫星B13通道(10.4μm)亮温值TBB≤238 K或B08通道(6.2μm)与B13通道亮温差△TBB<0 K双阈值作为强对流云团识别指标,可以准确识别出陇东南地区的强对流天气云团;(2)利用“逆向搜索法”、“面积重叠法”及对云团重心的计算,可以对强对流云团进行准确定位、追踪及移动路径外推预报;(3)建立的强对流天气落区判别指标对该地区短时强降水及冰雹落区具有一定的预报能力。 相似文献
994.
在区分地方饮食与传统饮食概念的基础上,选择宏村传统饮食臭鳜鱼作为研究对象,通过对就餐环境、服务、食物3个原真性维度和满意度与行为意向2个维度,构建Amos结构方程模型,探究游客对传统饮食文化的原真性感知及其对旅游地就餐满意度和行为意向的影响。结果显示,3个维度的原真性均对满意度呈显著、直接、正向影响,对行为意向呈显著、间接、正向影响;其中,环境原真性对就餐满意度影响最大,其次为服务原真性,最后为食物原真性。研究认为,即使体验对象是与原真性关联紧密的传统饮食,大众游客仍更关注整体就餐环境和服务氛围,食物本身对满意度的影响最低。游客需求引发传统饮食文化舞台化重塑,并呈现“去传统化”与“去地方化”特征,旅游地饮食文化塑造对环境的关注大于食物,但当地居民更加关注食物本身的口味,主客关注差异和食物生产过程的游客需求导向引发当地居民对舞台化饮食的认同度降低。未来旅游地要充分考虑传统饮食的特殊性,重塑让游客与本地居民更加满意的饮食文化。 相似文献
995.
Xiushu QIE Shanfeng YUAN Zhixiong CHEN Dongfeng WANG Dongxia LIU Mengyu SUN Zhuling SUN Abhay SRIVASTAVA Hongbo ZHANG Jingyu LU Hui XIAO Yongheng BI Liang FENG Ye TIAN Yan XU Rubin JIANG Mingyuan LIU Xian XIAO Shu DUAN Debin SU Chengyun SUN Wenjing XU Yijun ZHANG Gaopeng LU Da-Lin ZHANG Yan YIN Ye YU 《中国科学:地球科学(英文版)》2021,64(1):10-26
The Dynamical-microphysical-electrical Processes in Severe Thunderstorms and Lightning Hazards(STORM973)project conducted coordinated comprehensive field observations of thunderstorms in the Beijing metropolitan region(BMR)during the warm season from 2014 to 2018.The aim of the project was to understand how dynamical,microphysical and electrical processes interact in severe thunderstorms in the BMR,and how to assimilate lightning data in numerical weather prediction models to improve severe thunderstorm forecasts.The platforms used in the field campaign included the Beijing Lightning Network(BLNET,consisting of 16 stations),2 X-band dual linear polarimetric Doppler radars,and 4 laser raindrop spectrometers.The collaboration also made use of the China Meteorological Administration’s mesoscale meteorological observation network in the Beijing-Tianjin-Hebei region.Although diverse thunderstorm types were documented,it was found that squall lines and multicell storms were the two major categories of severe thunderstorms with frequent lightning activity and extreme rainfall or unexpected local short-duration heavy rainfall resulting in inundations in the central urban area,influenced by the terrain and environmental conditions.The flash density maximums were found in eastern Changping District,central and eastern Shunyi District,and the central urban area of Beijing,suggesting that the urban heat island effect has a crucial role in the intensification of thunderstorms over Beijing.In addition,the flash rate associated with super thunderstorms can reach hundreds of flashes per minute in the central city regions.The super(5%of the total),strong(35%),and weak(60%)thunderstorms contributed about 37%,56%,and 7%to the total flashes in the BMR,respectively.Owing to the close connection between lightning activity and the thermodynamic and microphysical characteristics of the thunderstorms,the lightning flash rate can be used as an indicator of severe weather events,such as hail and short-duration heavy rainfall.Lightning data can also be assimilated into numerical weather prediction models to help improve the forecasting of severe convection and precipitation at the cloud-resolved scale,through adjusting or correcting the thermodynamic and microphysical parameters of the model. 相似文献
996.
Yuqing Zhang Fengqi Zhang Xiaogan Cheng Xiubin Lin Hanlin Chen Karl‐Heinz Wyrwoll Lei Wu Jie Chen Bryan Krape Yanchou Lu Weiwei Ding Kaixuan An Yaguang Chen Chunyang Li 《地学学报》2021,33(1):1-11
The Altyn Tagh Fault (ATF) serves as a key continental‐scale controlling structural element of the Tibetan Plateau. However, its eastward extent remains controversial. Here we use high‐resolution seismic reflection profiles to investigate the subsurface structures of the easternmost ATF and use these to delimit the easternmost extent of the fault. The structural analyses show an eastward geometric change from transpressional positive flower structures to compressional thrusts, with transpression‐induced shortening magnitudes decreasing eastwards from a maximum of ~5.3 km to being absent. Stratigraphic controls indicate that the deformation took place over the last ~<1.2 Ma. Our wider findings lead us to: (a) reject the suggestion that the ATF previously extended beyond the Kuantan Shan‐Hei Shan to link with the Alxa‐East Mongolia Fault; and (b) propose that the rigid block model used to describe the Tibetan Plateau crust is not consistent with the extent and structural details of the easternmost ATF. 相似文献
997.
Acta Geotechnica - The site formation for the construction of a new airport in a mountainous region is typically performed by cutting and filling a hill section. The fill materials are subjected to... 相似文献
998.
Das Samiran Zhu Dehua Yin Yixing 《Stochastic Environmental Research and Risk Assessment (SERRA)》2020,34(8):1175-1196
Stochastic Environmental Research and Risk Assessment - Reliable estimation of return period values of extreme precipitation at ungauged locations is considered to be a key exercise in... 相似文献
999.
Currently, numerical studies at the real scale of an entire engineering structure considering internal erosion are still rare. This paper presents a three-dimensional (3D) numerical simulation of the effects of internal erosion within a linear dike located on a foundation. A two-dimensional (2D) finite element code has been extended to 3D in order to analyze the impact of internal erosion under more realistic hydromechanical conditions. The saturated soil has been considered as a mixture of four interacting constituents: soil skeleton, erodible fines, fluidized fine particles, and fluid. The detachment and transport of the fine particles have been modeled with a mass exchange model between the solid and the fluid phases. An elastoplastic constitutive model for sand-silt mixtures has been developed to monitor the effect of the evolution of both the porosity and the fines content induced by internal erosion upon the behavior of the soil skeleton. An unsaturated flow condition has been implemented into this coupled hydromechanical model to describe more accurately the seepage within the dike and the foundation. A stabilized finite element method was used to eliminate spurious numerical oscillations in solving the convection-dominated transport of fluidized particles. This numerical tool was then applied to a specific dike-on-foundation case subjected to internal erosion induced by a leakage located at the bottom of the foundation. Different failure modes were observed and analyzed for different boundary conditions, including the significant influence of the leakage cavity size and the elevation of the water level at the upstream and downstream sides of the dike. 相似文献
1000.
本文根据第四纪沉积物化学分析资料,研究各种元素在不同沉积时期分布、迁移和累积的规律,探讨冀东平原地球化学环境的形成特征以及与古地理环境的关系。 相似文献