全文获取类型
收费全文 | 36029篇 |
免费 | 6509篇 |
国内免费 | 8652篇 |
专业分类
测绘学 | 1691篇 |
大气科学 | 8091篇 |
地球物理 | 9368篇 |
地质学 | 17923篇 |
海洋学 | 4022篇 |
天文学 | 1856篇 |
综合类 | 3995篇 |
自然地理 | 4244篇 |
出版年
2024年 | 110篇 |
2023年 | 496篇 |
2022年 | 1435篇 |
2021年 | 1679篇 |
2020年 | 1446篇 |
2019年 | 1605篇 |
2018年 | 1935篇 |
2017年 | 1753篇 |
2016年 | 2049篇 |
2015年 | 1631篇 |
2014年 | 2110篇 |
2013年 | 1941篇 |
2012年 | 1858篇 |
2011年 | 1987篇 |
2010年 | 2069篇 |
2009年 | 2068篇 |
2008年 | 1786篇 |
2007年 | 1762篇 |
2006年 | 1470篇 |
2005年 | 1300篇 |
2004年 | 1090篇 |
2003年 | 1070篇 |
2002年 | 1072篇 |
2001年 | 1016篇 |
2000年 | 1261篇 |
1999年 | 1793篇 |
1998年 | 1490篇 |
1997年 | 1585篇 |
1996年 | 1310篇 |
1995年 | 1195篇 |
1994年 | 1136篇 |
1993年 | 974篇 |
1992年 | 777篇 |
1991年 | 566篇 |
1990年 | 405篇 |
1989年 | 408篇 |
1988年 | 382篇 |
1987年 | 242篇 |
1986年 | 198篇 |
1985年 | 151篇 |
1984年 | 127篇 |
1983年 | 99篇 |
1982年 | 105篇 |
1981年 | 77篇 |
1980年 | 50篇 |
1979年 | 34篇 |
1978年 | 21篇 |
1977年 | 8篇 |
1976年 | 6篇 |
1958年 | 28篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
131.
《山西地震综合数据处理系统》是遵循《国家地震局数据库技术规范》,以PDP-11/23~+小型机与IBM/PC联机为硬件支撑,以网状型数据库为核心,含前期处理、库管理、数据检索、科学计算、分析会商5个子系统的较大型应用软件系统。具有对数据进行收集、录入、预处理、存储、管理、加工及应用等功能。整个系统通过总控菜单程序实现了异种机间上百个模块的调度,使查询-处理一体化。该系统把地震数据库、日常监测数据处理、专家地震预报系统有机地衔接于一体,可直接服务于地震科研和震情会商。该系统的建设是山西省重大科技攻关项目,也是国家地震局的合同制项目。 相似文献
132.
133.
Gang Zhao Yonggheng Zhao Jtasheng Huang Lonlong Feng Keliang Huang Qiuhe Peng Tan Lu 《Astrophysics and Space Science》1988,141(1):169-176
In this paper, the neutrino mass has been determined from SN1987a observation in a manner that the simultaneity of neutrino emission is not regarded as the starting point, but is itself defined through the analysis by Monte-Carlo simulation. The result is that the neutrino mass lies in 3–4 eV, possiblym
v
3.6 eV. Neutrino luminosity variation and neutrino spectrum are also obtained. Comparison with theories gives further support to the mass determination, and also predicts the mass of progenitor star of SN1987a to be in the range of 12–25M
.The project supported by the National Natural Science Foundation of China. 相似文献
134.
135.
A model of the galactic centre with magnetic monopole has been presented here. The positron can be produced continuously through magnetic monopoles to induce baryon decay (Rubakov catalytic reaction) and a lot of energy can be released as well. The calculation results show that even if the galactic center contains only a few magnetic monopoles (=N
M/NB10–24), this massive object can not collapse into a black hole. This model can explain the observed intensities of the annihilation line and higher energy photons ofE
>511 keV from the galactic centre.Paper presented at the IAU Third Asian-Pacific Regional Meeting, held in Kyoto, Japan, between 30 September–6 October, 1984. 相似文献
136.
Trace and RE element geochemistry and genesis have been studied with respect to ferromanganese nodules from the sediments of the Pacific, Atlantic and Indian oceans. 相似文献
137.
古代西域南道上的若干历史地理问题 总被引:1,自引:0,他引:1
本文探讨塔克拉玛干沙漠南沿、和田以东至若羌间的几个历史地理问题。1,历史时期,塔里木盆地南沿上是否有过一条与北方塔里木河相对应的“南河”?笔者认为是没有的。2,自古以来,和田以东的绿洲数目是在逐期增多或是逐期减少?笔者认为是逐期增多。3,历史时期,和田以东出现过几处绿洲城镇废弃和交通路线改线的现象,笔者就其中的安迪尔、且末、尼雅三地的历史演变作了初步探讨。 相似文献
138.
一万年来白洋淀的扩张与收缩 总被引:5,自引:0,他引:5
本文探讨了一万年来的全新世期间,白洋淀兴起、扩张和收缩的变迁过程,恢复了各个发展阶段的古湖淀范围,论述了相应时期的古环境特征,指出了白洋淀令后的演变趋势。 相似文献
139.
Uranium-series dating of oxygen and carbon isotope records for stalagmite SJ3 collected in Songjia Cave, central China, shows significant variation in past climate and environment during the period 20-10 ka. Stalagmite SJ3 is located more than 1000 km inland of the coastal Hulu Cave in East China and more than 700 km north of the Dongge Cave in Southwest China and, despite minor differences, displays a clear first-order similarity with the Hulu and Dongge records. The coldest climatic phase since the Last Glacial Maximum, which is associated with the Heinrich Event 1 in the North Atlantic region, was clearly recorded in SJ3 between 17.6 and 14.5 ka, in good agreement in timing, duration and extent with the records from Hulu and Dongge caves and the Greenland ice core. The results indicate that there have been synchronous and significant climatic changes across monsoonal China and strong teleconnections between the North Atlantic and East Asia regions during the period 20-10 ka. This is much different from the Holocene Optimum which shows a time shift of more than several thousands years from southeast coastal to inland China. It is likely that temperature change at northern high latitudes during glacial periods exerts stronger influence on the Asian summer monsoon relative to insolation and appears to be capable of perturbing large-scale atmospheric/oceanic circulation patterns in the Northern Hemisphere and thus monsoonal rainfall and paleovegetation in East Asia. Climatic signals in the North Atlantic region propagate rapidly to East Asia during glacial periods by influencing the winter land-sea temperature contrast in the East Asian monsoon region. 相似文献
140.
Decoupling of stalagmite-derived Asian summer monsoon records from North Atlantic temperature change during marine oxygen isotope stage 5d 总被引:2,自引:0,他引:2
Houyun Zhou Jianxin Zhao Chuan-Chou Shen Yuexing Feng Huazheng Guan Chen-Feng You 《Quaternary Research》2008,70(2):315-321
The Asian monsoon is an important component of the global climate system. Seasonal variations in wind, rainfall, and temperature associated with the Asian monsoon systems affect a vast expanse of tropical and subtropical Asia. Speleothem-derived summer monsoon variation in East Asia was previously found to be closely associated with millennial-scale change in temperature in the North Atlantic region between 75 and 10 ka. New evidence recovered from East Asia, however, suggests that the teleconnection between summer monsoon in East Asia and temperature change in the North Atlantic region may have significantly reduced during 120 to ~ 110 ka, a period directly after the full last interglaciation and corresponding roughly to marine oxygen isotope stage 5d. This reduction may be due to the low ice volume in the North Hemisphere at that time, which makes the millennial-scale change in temperature in the North Atlantic region less effective in influencing the Asian summer monsoon. This is important for investigating the mechanisms controlling the Asian summer monsoon and the paleoclimatic teleconnection between East Asia and the North Atlantic region, and for predicting monsoon-associated precipitation in East Asia under a global-warming trend. 相似文献