全文获取类型
| 收费全文 | 14964篇 |
| 免费 | 569篇 |
| 国内免费 | 764篇 |
专业分类
| 测绘学 | 616篇 |
| 大气科学 | 709篇 |
| 地球物理 | 599篇 |
| 地质学 | 1638篇 |
| 海洋学 | 407篇 |
| 天文学 | 11435篇 |
| 综合类 | 381篇 |
| 自然地理 | 512篇 |
出版年
| 2024年 | 24篇 |
| 2023年 | 52篇 |
| 2022年 | 120篇 |
| 2021年 | 111篇 |
| 2020年 | 122篇 |
| 2019年 | 146篇 |
| 2018年 | 88篇 |
| 2017年 | 95篇 |
| 2016年 | 114篇 |
| 2015年 | 226篇 |
| 2014年 | 585篇 |
| 2013年 | 425篇 |
| 2012年 | 547篇 |
| 2011年 | 371篇 |
| 2010年 | 427篇 |
| 2009年 | 1131篇 |
| 2008年 | 972篇 |
| 2007年 | 1176篇 |
| 2006年 | 1195篇 |
| 2005年 | 1262篇 |
| 2004年 | 1104篇 |
| 2003年 | 1108篇 |
| 2002年 | 927篇 |
| 2001年 | 793篇 |
| 2000年 | 688篇 |
| 1999年 | 698篇 |
| 1998年 | 791篇 |
| 1997年 | 126篇 |
| 1996年 | 114篇 |
| 1995年 | 180篇 |
| 1994年 | 111篇 |
| 1993年 | 84篇 |
| 1992年 | 68篇 |
| 1991年 | 52篇 |
| 1990年 | 52篇 |
| 1989年 | 51篇 |
| 1988年 | 31篇 |
| 1987年 | 30篇 |
| 1986年 | 22篇 |
| 1985年 | 16篇 |
| 1984年 | 9篇 |
| 1983年 | 9篇 |
| 1982年 | 12篇 |
| 1981年 | 12篇 |
| 1980年 | 4篇 |
| 1977年 | 3篇 |
| 1975年 | 1篇 |
| 1973年 | 5篇 |
| 1972年 | 4篇 |
| 1971年 | 2篇 |
排序方式： 共有10000条查询结果，搜索用时 171 毫秒
1.
Monitoring of the fluctuations of groundwater storage is particularly important in arid and semi-arid regions where water scarcity brings about various challenges. Remote sensing data and techniques play a preponderant role in developing solutions to environmental problems. The launch of Gravity Recovery and Climate Experiment (GRACE) satellites has eased the remote monitoring and evaluation of groundwater resources with an unprecedented precision over large scales. Within the scope of the current study, the latest release (RL06) of GRACE mass concentrations (Mascons) from Jet Propulsion Laboratory (JPL) dataset as well as Global Land Data Assimilation System (GLDAS) models of Noah and Catchment Land Surface Model (CLSM) were used to provide Groundwater Storage Anomalies (GWSA) over Turkey. The temporal interactions of the estimated GWSA with the climatic variables of precipitation and temperature (derived from the reanalysis datasets of CHELSA [Climatologies at High resolution for the Earth's Land Surface Areas] and FLDAS [the Famine Early Warning Systems Network Land Data Assimilation System], respectively) were investigated statistically. The results suggest that there is a descending trend (from 2003 to 2016) for Terrestrial Water Storage Anomalies (TWSA) and GWSA over Turkey with a total loss of 11 and 6 cm of water, respectively. The statistical analysis results also indicate that the monthly variations of GWSA over Turkey are highly correlated with precipitation and temperature at 2-month lag. The analysis of the climatology (long-term) values of monthly GWSA, precipitation and temperature also revealed high agreement between the variables. 相似文献
2.
Microbial degradation technologies have been developed to restore ground water quality in aquifers polluted by organic contaminants effectively in recent years. However, in course of the degradation, the formation of biofilms in ground water remediation technology can be detrimental to the effectiveness of a ground water remediation project. Several alternatives are available to a remedial design engineer, such as Permeable Reactive Barriers (PRBs) and in -situ bioremediation, Hydrogen Releasing Compounds (HRCs) barrier, Oxygen Releasing Compounds (ORCs) barrier etc. which are efficient and cost- effective technologies. Excessive biomass formation renders a barrier ineffective in degrading the contaminants, Efforts are made to develop kinetics models which accurately determine bio - fouling and bio - filn formation and to control excessive biomass formation. 相似文献
3.
4.
5.
6.
7.
8.
9.
10.
Neill Reid 《Monthly notices of the Royal Astronomical Society》2003,342(3):837-850
We present high-resolution echelle spectroscopy of 20 stars in 16 systems catalogued as members of the TW Hydrae association, and 16 stars identified as possible new members. We have calibrated the range of coronal and chromospheric activity expected for such young stars as a function of spectral type by combining our observations with literature data for field and open cluster stars. We also compute space motions for TWA members and candidate members with proper motion measurements, using two techniques to estimate distances to stars lacking direct trigonometric parallax measurements. The mean space motion of the four TWA members with known parallaxes is ( U , V , W : −10.0, −17.8, −4.6) km s−1 . 14 of the candidates have properties inconsistent with cluster membership; the remaining two are potential new members, although further observations are required to confirm this possibility. 相似文献