全文获取类型
收费全文 | 1473篇 |
免费 | 265篇 |
国内免费 | 258篇 |
专业分类
测绘学 | 81篇 |
大气科学 | 240篇 |
地球物理 | 401篇 |
地质学 | 762篇 |
海洋学 | 140篇 |
天文学 | 55篇 |
综合类 | 153篇 |
自然地理 | 164篇 |
出版年
2024年 | 5篇 |
2023年 | 25篇 |
2022年 | 51篇 |
2021年 | 63篇 |
2020年 | 56篇 |
2019年 | 64篇 |
2018年 | 72篇 |
2017年 | 64篇 |
2016年 | 88篇 |
2015年 | 80篇 |
2014年 | 94篇 |
2013年 | 87篇 |
2012年 | 79篇 |
2011年 | 80篇 |
2010年 | 84篇 |
2009年 | 71篇 |
2008年 | 64篇 |
2007年 | 53篇 |
2006年 | 56篇 |
2005年 | 40篇 |
2004年 | 36篇 |
2003年 | 57篇 |
2002年 | 89篇 |
2001年 | 73篇 |
2000年 | 68篇 |
1999年 | 63篇 |
1998年 | 46篇 |
1997年 | 38篇 |
1996年 | 45篇 |
1995年 | 42篇 |
1994年 | 36篇 |
1993年 | 24篇 |
1992年 | 21篇 |
1991年 | 17篇 |
1990年 | 11篇 |
1989年 | 11篇 |
1988年 | 14篇 |
1987年 | 10篇 |
1986年 | 4篇 |
1985年 | 1篇 |
1984年 | 4篇 |
1983年 | 2篇 |
1982年 | 1篇 |
1981年 | 3篇 |
1980年 | 1篇 |
1978年 | 2篇 |
1958年 | 1篇 |
排序方式: 共有1996条查询结果,搜索用时 531 毫秒
291.
292.
<正>In the original article, the name of the fourth author is incorrect. The correct one is Kyoung Ho Kang, in which "Kang" is the family name. The publishing companies apologize to the author. 相似文献
293.
294.
Estimation and spatial interpolation of rainfall intensity distribution from the effective rate of precipitation 总被引:1,自引:0,他引:1
Ming Li Quanxi Shao Luigi Renzullo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(1):117-130
Great emphasis is being placed on the use of rainfall intensity data at short time intervals to accurately model the dynamics
of modern cropping systems, runoff, erosion and pollutant transport. However, rainfall data are often readily available at
more aggregated level of time scale and measurements of rainfall intensity at higher resolution are available only at limited
stations. A distribution approach is a good compromise between fine-scale (e.g. sub-daily) models and coarse-scale (e.g. daily)
rainfall data, because the use of rainfall intensity distribution could substantially improve hydrological models. In the
distribution approach, the cumulative distribution function of rainfall intensity is employed to represent the effect of the
within-day temporal variability of rainfall and a disaggregation model (i.e. a model disaggregates time series into sets of
higher solution) is used to estimate distribution parameters from the daily average effective precipitation. Scaling problems
in hydrologic applications often occur at both space and time dimensions and temporal scaling effects on hydrologic responses
may exhibit great spatial variability. Transferring disaggregation model parameter values from one station to an arbitrary
position is prone to error, thus a satisfactory alternative is to employ spatial interpolation between stations. This study
investigates the spatial interpolation of the probability-based disaggregation model. Rainfall intensity observations are
represented as a two-parameter lognormal distribution and methods are developed to estimate distribution parameters from either
high-resolution rainfall data or coarse-scale precipitation information such as effective intensity rates. Model parameters
are spatially interpolated by kriging to obtain the rainfall intensity distribution when only daily totals are available.
The method was applied to 56 pluviometer stations in Western Australia. Two goodness-of-fit statistics were used to evaluate
the skill—daily and quantile coefficient of efficiency between simulations and observations. Simulations based on cross-validation
show that kriging performed better than other two spatial interpolation approaches (B-splines and thin-plate splines). 相似文献
295.
HCHO is ubiquitous and important chemical constitutes in the troposphere. The concentrations of the HCHO (aq) in the rainwater were measured in the Guiyang city, southeastern of China from May 2006 to April 2007 and 153 discrete samples were collected. Rainwater (N = 151) HCHO (aq) concentrations ranged from lower than method detection limit (MDL) to 40.2 µmol/L with a volume weighted mean value of 7.4 ± 8.8 µmol/L. The strong correlations between HCHO (aq) and HCOO? (r = 0.69, n = 137), HCHO (aq) and nss‐ (r = 0.74, n = 137), HCHO (aq) and (r = 0.67, n = 137), HCHO (aq) and (r = 0.74, n = 133) suggest the significant influence of the anthropogenic input for the HCHO (aq) levels. The concentration levels of rainwater HCHO (aq) was inversely proportional to the amount of rainfall, indicating the below‐cloud process is the most important mechanism for rainwater HCHO (aq) scavenging processes. More than 70% of the HCHO (aq) wet deposition took place during the early stage of the rainfall. According to the air mass back‐trajectory analysis, the rainwater with industrial back‐trajectories coming from the north had the highest levels of HCHO (aq) while the rainwater with the green‐covered or marine back‐trajectories from the southeast had the lowest concentrations, and this indicate the HCHO (aq) originated from urban or industrial regions served as an important source of the rainwater. The annual HCHO (aq) wet deposition flux was calculated as 6.96 mmol/m2 per year and the total deposition flux was estimated as 24.35 mmol/m2 per year, 71.4% of which was dominated by dry deposition. 相似文献
296.
Development of a hybrid simulation controller for full‐scale experimental investigation of seismic retrofits for soft‐story woodframe buildings
下载免费PDF全文
![点击此处可从《地震工程与结构动力学》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Xiaoyun Shao Weichiang Pang Chelsea Griffith Ershad Ziaei John van de Lindt 《地震工程与结构动力学》2016,45(8):1233-1249
Hybrid simulations of a full‐scale soft‐story woodframe building specimen with various retrofits were carried out as part of the Network for Earthquake Engineering Simulation Research project – NEES‐Soft: seismic risk reduction for soft‐story woodframe buildings. The test structure in the hybrid simulation was a three‐story woodframe building that was divided into a numerical substructure of the first story with various retrofits and a full‐scale physical substructure of the upper two stories. Four long‐stroke actuators, two at the second floor and two at the roof diaphragm, were attached to the physical substructure to impose the simulated seismic responses including both translation and in‐plane rotation. Challenges associated with this first implementation of a full‐scale hybrid simulation on a woodframe building were identified. This paper presents the development and validation of a scalable and robust hybrid simulation controller for efficient test site deployment. The development consisted of three incremental validation phases ranging from small‐scale, mid‐scale, to full‐scale tests conducted at three laboratories. Experimental setup, procedure, and results of each phase of the controller development are discussed, demonstrating the effectiveness and efficiency of the incremental controller development approach for large‐scale hybrid simulation programs with complex test setup. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
297.
298.
Study of a comprehensive assessment method of the environmental quality of soil in industrial and mining gathering areas 总被引:1,自引:0,他引:1
Yang Guan Chaofeng Shao Qingbao Gu Meiting Ju Xueju Huang 《Stochastic Environmental Research and Risk Assessment (SERRA)》2016,30(1):91-102
Industrial and mining activities have been recognized as major sources of heavy metal contamination in soil. Here, we developed a comprehensive assessment method for the soil environment in industrial and mining gathering areas based on the pressure–state–response model. Using this method, we assessed the environmental quality of soil in a typical industrial and mining gathering area in Tianjin City, China. The results are as follows: (1) The comprehensive environmental quality index of the soil in the study area was 0.532, which corresponds to an alert state and shows that the soil environment is generally poor. (2) The pressure, state, and response indexes were 0.609, 0.634, and 0.163, respectively, which suggests that the pressure in the soil environment of the study area is barely acceptable, and the state is merely passable. Furthermore, the response measures are not ideal. (3) The low response index scores indicate poor production processes, low pollutant treatment level, and unsatisfactory level of management by the enterprises in the study area. (4) The distribution of soil risks was found to be inseparably related to that of contamination sources and land use types. Furthermore, the distribution was uneven to a certain degree. Finally, we propose recommendations for the optimization, adjustment, and management of typical industrial and mining gathering areas with petrochemical, metallurgy, and other heavily polluting enterprises. 相似文献
299.
Shale needs to contain a sufficient amount of gas to make it viable for exploitation. The continental heterogeneous shale formation in the Yan-chang (YC) area is investigated by firstly measuring the shale gas content in a laboratory and then investigating use of a theoretical prediction model. Key factors controlling the shale gas content are determined, and a prediction model for free gas content is established according to the equation of gas state and a new petrophysical volume model. Application of the Langmuir volume constant and pressure constant obtained from results of adsorption isotherms is found to be limited because these constants are greatly affected by experimental temperature and pressures. Therefore, using measurements of adsorption isotherms and thermodynamic theory, the influence of temperature, total organic carbon (TOC), and mineralogy on Langmuir volume constants and pressure constants are investigated in detail. A prediction model for the Langmuir pressure constant with a correction of temperatures is then established, and a prediction model for the Langmuir volume constant with correction of temperature, TOC, and quartz contents is also proposed. Using these corrected Langmuir constants, application of the Langmuir model determined using experimental adsorption isotherms is extrapolated to reservoir temperature, pressure, and lithological conditions, and a method for the prediction of shale gas content using well logs is established. Finally, this method is successfully applied to predict the shale gas content of the continental shale formation in the YC area, and practical application is shown to deliver good results with high precision. 相似文献
300.