全文获取类型
收费全文 | 19700篇 |
免费 | 2663篇 |
国内免费 | 5300篇 |
专业分类
测绘学 | 372篇 |
大气科学 | 1397篇 |
地球物理 | 2613篇 |
地质学 | 8898篇 |
海洋学 | 7079篇 |
天文学 | 5159篇 |
综合类 | 949篇 |
自然地理 | 1196篇 |
出版年
2024年 | 51篇 |
2023年 | 189篇 |
2022年 | 552篇 |
2021年 | 531篇 |
2020年 | 627篇 |
2019年 | 709篇 |
2018年 | 649篇 |
2017年 | 626篇 |
2016年 | 661篇 |
2015年 | 760篇 |
2014年 | 1215篇 |
2013年 | 1271篇 |
2012年 | 1110篇 |
2011年 | 1416篇 |
2010年 | 1300篇 |
2009年 | 1849篇 |
2008年 | 1700篇 |
2007年 | 1632篇 |
2006年 | 1504篇 |
2005年 | 1385篇 |
2004年 | 1148篇 |
2003年 | 1042篇 |
2002年 | 907篇 |
2001年 | 783篇 |
2000年 | 705篇 |
1999年 | 627篇 |
1998年 | 493篇 |
1997年 | 347篇 |
1996年 | 312篇 |
1995年 | 270篇 |
1994年 | 259篇 |
1993年 | 231篇 |
1992年 | 152篇 |
1991年 | 119篇 |
1990年 | 96篇 |
1989年 | 95篇 |
1988年 | 54篇 |
1987年 | 30篇 |
1986年 | 33篇 |
1985年 | 46篇 |
1984年 | 45篇 |
1983年 | 30篇 |
1982年 | 27篇 |
1981年 | 23篇 |
1980年 | 11篇 |
1979年 | 2篇 |
1978年 | 11篇 |
1977年 | 17篇 |
1954年 | 4篇 |
1875年 | 1篇 |
排序方式: 共有10000条查询结果,搜索用时 31 毫秒
101.
102.
R. F. Griffin 《Journal of Astrophysics and Astronomy》1990,11(4):533-540
Photoelectric radial-velocity measurements show that HD 118670 is a double-lined spectroscopic binary in an orbit which is
not quite circular and whose period is about 48 days. Spectral types of K0 V and K7 V would satisfy the photometry and the
mass ratio; the mass function would then suggest the possibility of eclipses. However, actual spectral classification indicates
a luminosity somewhat above the main sequence 相似文献
103.
Simulation of double cold cores of the 35°N section in the Yellow Sea with a wave-tide-circulation coupled model 总被引:1,自引:0,他引:1
Based on the MASNUM wave-tide-circulation coupled numerical model, the temperature structure along 35°N in the Yellow Sea
was simulated and compared with the observations. One of the notable features of the temperature structure along 35°N section
is the double cold cores phenomena during spring and summer. The double cold cores refer to the two cold water centers located
near 122°E and 125°E from the depth of 30m to bottom. The formation, maintenance and disappearance of the double cold cores
are discussed. At least two reasons make the temperature in the center (near 123°E) of the section higher than that near the
west and east shores in winter. One reason is that the water there is deeper than the west and east sides so its heat content
is higher. The other is invasion of the warm water brought by the Yellow Sea Warm Current (YSWC) during winter. This temperature
pattern of the lower layer (from 30m to bottom) is maintained through spring and summer when the upper layer (0 to 30m) is
heated and strong thermocline is formed. Large zonal span of the 35°N section (about 600 km) makes the cold cores have more
opportunity to survive. The double cold cores phenomena disappears in early autumn when the west cold core vanishes first
with the dropping of the thermocline position.
Supported by the National Basic Research Program of China (No. G1999043809) and the National Science Foundation of China (No.
49736190). 相似文献
104.
WANG Yachun 《东北亚地学研究》2002,(1)
The paper deals with the methods of formation pressure evaluation for a single well by using the very common ac-cepted parameters, such as drilling exponent , and flowline temperature , etc. which is part of compiling the end well report. 相似文献
105.
106.
107.
108.
109.
110.