全文获取类型
收费全文 | 3621篇 |
免费 | 280篇 |
国内免费 | 846篇 |
专业分类
测绘学 | 202篇 |
大气科学 | 549篇 |
地球物理 | 1223篇 |
地质学 | 1488篇 |
海洋学 | 320篇 |
天文学 | 139篇 |
综合类 | 354篇 |
自然地理 | 472篇 |
出版年
2024年 | 14篇 |
2023年 | 59篇 |
2022年 | 49篇 |
2021年 | 67篇 |
2020年 | 49篇 |
2019年 | 70篇 |
2018年 | 74篇 |
2017年 | 16篇 |
2016年 | 44篇 |
2015年 | 57篇 |
2014年 | 85篇 |
2013年 | 86篇 |
2012年 | 135篇 |
2011年 | 171篇 |
2010年 | 92篇 |
2009年 | 110篇 |
2008年 | 149篇 |
2007年 | 186篇 |
2006年 | 184篇 |
2005年 | 187篇 |
2004年 | 174篇 |
2003年 | 155篇 |
2002年 | 178篇 |
2001年 | 151篇 |
2000年 | 157篇 |
1999年 | 75篇 |
1998年 | 82篇 |
1997年 | 49篇 |
1996年 | 72篇 |
1995年 | 86篇 |
1994年 | 81篇 |
1993年 | 111篇 |
1992年 | 114篇 |
1991年 | 133篇 |
1990年 | 136篇 |
1989年 | 122篇 |
1988年 | 133篇 |
1987年 | 121篇 |
1986年 | 85篇 |
1985年 | 95篇 |
1984年 | 106篇 |
1983年 | 68篇 |
1982年 | 47篇 |
1981年 | 45篇 |
1980年 | 76篇 |
1978年 | 17篇 |
1974年 | 21篇 |
1958年 | 14篇 |
1957年 | 20篇 |
1956年 | 20篇 |
排序方式: 共有4747条查询结果,搜索用时 15 毫秒
11.
Tanlu Fault Zone (TFZ) is a large NE trending deep fracture system in East China and is about 2500 km long. It extends from the south of Lujiang to Tancheng, and passes through the Bohai Sea and continues to the north, where it branches into Yilan ?Shulan Fault and Dunhua ?Mishan Fault. TFZ is a long lasting huge deep - rooted lithospherical fault system with different characteristics in different parts and at different periods of its evolution. TFZ also controls the distribution and occur-rences of many superlarge, large, middle and small sized gold ore deposits, e. g. Jiapigou, Haigou, Xiaoxihancha and Ciwei-gou gold deposits in Northeast China; Linglong, Jiaojia, Sanshandao, Taishang, Xincheng, Rushan, and Pengjiakuang gold deposits in Jiaodong Peninsula of Shandong Province; and Guilaizhuang and Yinan in Western Shandong Province. 相似文献
12.
CHEN Bing-lu ZHANG Yun-ni CHEN Xin-geng WANG Zhi-gang YANG Guang-xing 《中国地理科学(英文版)》2001,11(2):155-162
1 HYDROLOGIC FEATURES Lingdingyang Estuary, located at the middle south of Guangdong Province, is a bell-shaped estuary with a north-south direction. Its area is about 2100km2. The north of Qi′ao Island and Inner-Lingding Island, and the south of Humen are grouped as Neilingdingyang Estuary, having an area of 1041km2. Affected by topography, runoff and tide, its dynamic condition is very complicated. Different water areas have different hydrologic features. The topography under … 相似文献
13.
THE SIMULATED STORAGE CAPACITY OF FLOOD AND WATERLOGGING IN THE TYPICAL AGRICULTURAL REGION IN JIANGHAN PLAIN 总被引:2,自引:0,他引:2
1INTRODUCTIONJianghanPlainisoneoftheimportantbasesofChina′sagriculturalproductivitylocatedinthemiddleChangjiangRivervalleyofcentralChina.TheJianghanplainapproximately6.6×104km2inareaandover30millioninpopulationistherenowned“countryoffishandrice"in… 相似文献
14.
I INTRODUCTIONWetland has very important effect on retainingwater and against drought, regUlating climate, controlling soil erosion and so on ac. Today men often attachimportance to economic effect of wetland reclamation,but neglect and destroy other functions and effectswhich result in blind wetland development, a lot ofwetland degeneration. The area of freshwater wetland inthe 1950s was 134 x 10'ha, but in the 1970s 70% hadchanged into farmland (MITSCH, 1993). The area ofwetland in d… 相似文献
15.
LUO Kai-li LI Bao-sheng ZHU Yi-zhi JIN He-ling ZHANG David Dian YAN Man-cun LI Hou-xin YAO Chun-xia ZHANG Yu-hongf . Department of Geography South China Normal University Guangzhou P. R. China . State Key Labor 《中国地理科学(英文版)》2001,11(4):336-342
About 70years ago,Frenc卜卜alaeohdoglst回LL sc卜dars al卜ome and a卜road卜ave successively con-HARD de Chardin P.et al.Initiated the Quaternary ducted large amount ofwork on the Later Quaternarygeologlcal research In the >alawusu River Basin of strata(TEILHARD,1924; YUAN,1978; LI,1987;desert region of Northern China and established th,ZHENG,1989; SUN et al,1996; LI et al,1993),Salawusu Formation门EILHARD,1924).Sine,then,palaeobiology… 相似文献
16.
In recent years,scholars at home and abroad have method,and that vanous disasters would be analyzed assynthetically studied natural dlsaste‘theoretically and an Integral.SHI Peilun(1991)putforwad a scientificmethodologlcally,as well as its cases analys。s(CND,term—regional disaster system,which Indicates that1987; MA et al,1990; MARBLE,1990; NE et al,the situation of a disaster(calamity loss)results from1999; PATAK et al,1982; SHI,1991;VAN et al,h… 相似文献
17.
1 INTRODUCTIONGlobal change research involves much geo-objectsand geo-process, such as climate and environmentalchange, substance and energy cycling, land-use/land-cover change (LUCC), interactivity between human and nature, etc.. So it need cooperation frommany research communities including international research programs groups such as IGBP (InternationalGeosphere-Biosphere Programme IPCC (Intergovemmental Panel on Climate Change), IHDP (InternationalHuman Dimension Program o… 相似文献
18.
本文报导研究细粒粉尘物质(黄地)在对称丘陵背风区沉降特征的风洞实验。注意力集中于黄土顺风越过丘陵的沉积模式是否具有波动的问题(可与著名的Karman 涡旋尾流相比较)。实验结果表明,虽然再生沉积的最大值出现在紧接丘陵背风坡的下游一带,却未见沉积尾流。 相似文献
19.
在这篇文章里,我研究了十九世纪世界贸易和殖民扩展中的新西兰农业发展,继而研究了导致农业出口依赖于世界贸易、技术和动力平衡所出现的经济过程。我调查了农业(1963—1984年)近期的竞争,以及转向调整和出现二十世纪经济和剩余农业的含意。 相似文献
20.
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