全文获取类型
收费全文 | 2054篇 |
免费 | 417篇 |
国内免费 | 428篇 |
专业分类
测绘学 | 111篇 |
大气科学 | 353篇 |
地球物理 | 481篇 |
地质学 | 1137篇 |
海洋学 | 161篇 |
天文学 | 219篇 |
综合类 | 229篇 |
自然地理 | 208篇 |
出版年
2024年 | 10篇 |
2023年 | 35篇 |
2022年 | 105篇 |
2021年 | 122篇 |
2020年 | 70篇 |
2019年 | 97篇 |
2018年 | 124篇 |
2017年 | 92篇 |
2016年 | 93篇 |
2015年 | 104篇 |
2014年 | 116篇 |
2013年 | 139篇 |
2012年 | 117篇 |
2011年 | 104篇 |
2010年 | 95篇 |
2009年 | 110篇 |
2008年 | 85篇 |
2007年 | 98篇 |
2006年 | 74篇 |
2005年 | 79篇 |
2004年 | 52篇 |
2003年 | 48篇 |
2002年 | 57篇 |
2001年 | 75篇 |
2000年 | 94篇 |
1999年 | 104篇 |
1998年 | 90篇 |
1997年 | 86篇 |
1996年 | 66篇 |
1995年 | 58篇 |
1994年 | 48篇 |
1993年 | 54篇 |
1992年 | 29篇 |
1991年 | 31篇 |
1990年 | 29篇 |
1989年 | 18篇 |
1988年 | 17篇 |
1987年 | 18篇 |
1986年 | 19篇 |
1985年 | 13篇 |
1984年 | 6篇 |
1983年 | 3篇 |
1982年 | 5篇 |
1981年 | 2篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1976年 | 2篇 |
1958年 | 4篇 |
排序方式: 共有2899条查询结果,搜索用时 937 毫秒
971.
?о???????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????????? 相似文献
972.
A dipole wind curl pattern induced by Taiwan Island and its effect on upper stratification in the northeastern South China Sea 总被引:1,自引:0,他引:1
Using hydrographic data sampled during four successive late summer-early autumn cruises in 2004-2007, vertical stratification along transects in the lee of Taiwan Island was analyzed to investigate upper ocean responses to orographically induced dipole wind stress curl (WSC). Results indicate that mixed-layer depth (MLD) and its relationship with thermocline depth varied under different local wind forcings. Average MLD along the transects from the 2004 to 2007 cruises were 18.5,30.7,39.2 and 24.5m, respectively. The MLD along the transects deepened remarkably and resulted in thermocline ventilation in 2005 and 2006, whereas ventilation did not occur in 2004 and 2007. Estimates indicate that frictional wind speed was the major factor in MLD variations. To a large degree, the combined effects of frictional wind speed and Ekman pumping are responsible for the spatial pattern of MLD during the cruises. 相似文献
973.
??????????θ??????????????????????????У???????????????????ж????????????????????????????????????????ó??????????????????????????????????????????????????8 m?????????????????????ó????????????????????????????????????????????·??????·????????????????????????????к??????????????????????вο???? 相似文献
974.
����GPS��InSAR�����ӳ�У�������о� 总被引:1,自引:0,他引:1
????GPS??InSAR????????????????????????????PSO(Particle Swarm Optimization)?????????LSSVM (Least Square Support Vector Machine)????????????GPS?????????в?????????GPS??InSAR????????????????????????????,????GPS????????InSAR??????????30 mm,?????????InSAR????????? 相似文献
975.
分析襄阳万山井数字化水位对苏门答腊M9.0、汶川M8.0和日本M9.0地震的同震效应,结合井台所在地的地质构造背景,总结出井水位同震响应和震后效应等特征.研究结果表明:该井水位同震响应均表现为水位同震下降型阶变,井与井之间的同震效应差别的原因与井所处构造位置、含水层系统的自身特性、地震震级和震中构造位置等有关. 相似文献
976.
根据野外调查获得的第一手资料,结合前人有关雾渡河断裂的研究成果,论述了雾渡河断裂的区域地质背景、构造应力场、深部构造特征、地貌水系样式,其中重点解决了雾渡河断裂的运动学特征和断裂活动时代.根据所采断裂上覆第四纪沉积物样品的TL测年数据(76.43±6.49 ka),确定雾渡河断裂晚更新世以来活动不明显. 相似文献
977.
????????????????SAR??????????????????????????????????????????????????????????????????????????????????????????????????????????????仯?????????????????????????仯????????????????????????????????????????EM????????????????в????????????????????С????????б仯????????????????????????仯????????б?????????????????????????????????仯??????????????????????????????С?????и??????Ч???? 相似文献
978.
Slope seismic response monitoring on the aftershocks of the Wenchuan earthquake in the Mianzhu section 总被引:1,自引:0,他引:1
Previous investigations have shown that the seismic response of slopes during the Wenchuan earthquake was highly variable.The present study tries to give an answer to the question:Which are the main factors affecting the seismic response degree of slopes? With the support of the China Geological Survey Bureau,we set 3 monitoring sections in Jiulong slope,Mianzhu city,China with the aim to record the site response of the slope during the aftershocks of the Wenchuan earthquake.After the Wenchuan earthquake,which happened on 12 May 2008,30 aftershocks have been recorded in these monitoring points.We analyzed 11 records,with magnitudes ranging from ML = 4.6 to ML = 3.1.The amplification factors of the horizontal compound PGA and 3D compound PGA have been determined for the 3 points at different elevations on the slope.Results showed that the dynamic response of the slope on the earthquake was controlled by factors such as topography and the thickness of the Quaternary overburden. 相似文献
979.
Shuo Wang Yuanyong Deng Rajmal Jain Vasyl Yurchyshyn Haimin Wang Yuanyuan Liu Zhiliang Yang 《Journal of Astrophysics and Astronomy》2008,29(1-2):57-61
In this paper, we study the evolution of vector magnetic field of AR 10656 by using the observations of Huairou Solar Observing Station (HSOS, China) and Big Bear Solar Observatory (BBSO, USA). The magnetic flux emergence and cancellation, and thus, magnetic nonpotential changes, are associated with the major flares in this active region. Compared with some other super-active regions, the evolution of magnetic morphologies and non-potentialities are relatively gradual, and thus the energy transportation and release are relatively slow. This gradual process may result in the recurrent flares of AR 10656. 相似文献
980.
Two-dimensional bulge/disk light decomposition with GIM2D in both the r-and g-bands has been applied to a sample of 129 early-type galaxies brighter than 13.5 magnitude in the r-band,selected from the Sloan Digital Sky Survey Data Release 2.Intensity-weighted Fourier coefficient (a4/a) was also derived for each sample galaxy.Our analysis shows that and between bulge and disk scale sizes.Isophotal shape parameter (a4/a) is not correlated with BIT and nB.Both bulge and disk components satisfy a color-magnitude relation.The k space Fundamental Plane analysis shows that galaxies with larger B/T tend to lie tighter and closer to the line of k1 k2=8 (the so-called "zone of avoidance") than the galaxies with smaller B/T.It indicates that existence of the disk component may lead to scatter of the distribution on the Fundamental Plane.Our analysis also shows that k1 k2 correlates with (y-r) color and B/T,but does not correlate with (a4/a) for early-type galaxies.The fitted parameters and other retrieved parameters used in this paper for all sample galaxies are available online. 相似文献