全文获取类型
| 收费全文 | 1979篇 |
| 免费 | 389篇 |
| 国内免费 | 260篇 |
专业分类
| 测绘学 | 24篇 |
| 大气科学 | 99篇 |
| 地球物理 | 428篇 |
| 地质学 | 477篇 |
| 海洋学 | 1319篇 |
| 天文学 | 1篇 |
| 综合类 | 77篇 |
| 自然地理 | 203篇 |
出版年
| 2024年 | 6篇 |
| 2023年 | 39篇 |
| 2022年 | 59篇 |
| 2021年 | 78篇 |
| 2020年 | 75篇 |
| 2019年 | 84篇 |
| 2018年 | 74篇 |
| 2017年 | 190篇 |
| 2016年 | 105篇 |
| 2015年 | 105篇 |
| 2014年 | 188篇 |
| 2013年 | 115篇 |
| 2012年 | 90篇 |
| 2011年 | 142篇 |
| 2010年 | 137篇 |
| 2009年 | 136篇 |
| 2008年 | 130篇 |
| 2007年 | 111篇 |
| 2006年 | 85篇 |
| 2005年 | 70篇 |
| 2004年 | 57篇 |
| 2003年 | 70篇 |
| 2002年 | 107篇 |
| 2001年 | 36篇 |
| 2000年 | 46篇 |
| 1999年 | 49篇 |
| 1998年 | 49篇 |
| 1997年 | 29篇 |
| 1996年 | 29篇 |
| 1995年 | 20篇 |
| 1994年 | 11篇 |
| 1993年 | 30篇 |
| 1992年 | 9篇 |
| 1991年 | 19篇 |
| 1990年 | 10篇 |
| 1989年 | 6篇 |
| 1988年 | 5篇 |
| 1987年 | 1篇 |
| 1986年 | 3篇 |
| 1985年 | 7篇 |
| 1984年 | 6篇 |
| 1983年 | 7篇 |
| 1982年 | 2篇 |
| 1978年 | 1篇 |
排序方式： 共有2628条查询结果，搜索用时 15 毫秒
1.
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
2.
UV-B辐射对海洋微藻抗氧化系统的影响 总被引：4，自引：1，他引：4
研究了UV－B辐射对两种海洋微藻－小新月菱形藻（Ntzschia closterlum)和亚心形扁藻（Platymonas subcordiforming)的抗氧化系统的影响。结果表明：在本实验的辐射剂量范围内，随着UV－B辐射剂量的增强，两种藻的抗氧化防御系统的非酶性组分还原型谷胱甘肽（GSH）和类胡萝卜素（CAR）的含量随之下降；抗氧化防御系统的酶性组分超氧化歧化酶（SOD）和过氧化氢酶（CAT）的活性逐渐降低。加入外源性抗氧化剂GSH可减轻UV－B辐射对藻的伤害。分析表明海洋微藻的UV－B伤害是由于抗氧化防御系统遭到破坏而导致活性氧积累的结果。 相似文献
3.
1986年11月—1987年5月,在中国第三次南极考察和环球科学考察期间,收集了58个海洋气溶胶样品,采用中子活化法分析了Al,V,Mn,I,Br,Mg,Na,Cl等元素。应用因子分析、回归分析和富集因子分析对气溶胶中元素进行分类、定量评估和来源判别,讨论不同来源元素的特征,计算各主要来源的贡献分量。结果表明,海洋气溶胶中Al的99.99％是来自陆源地壳风化物,Na的99.2％。和Cl的99.99％是来自海水,V的91.4％。来自陆源污染物。因此,Al可作为海洋气溶胶中陆源地壳风化物的示踪元素,Na和Cl可作为海水源示踪元素,非地壳源的V则可选择为陆源污染物的示踪元素。 相似文献
4.
The expansion of offshore activities and the increasing need to meet international and national commitments to biodiversity conservation have led to an enhanced interest in marine spatial planning (MSP) as a tool for sea use management. Several European countries, on their own initiative or driven by European legislation and policy, have taken global leadership in implementing MSP. This article will discuss the Belgian experiences with MSP. It will give a short historical overview based on legal developments and review the implementation process of a ‘Master Plan’ as a spatial management policy for the Belgian Part of the North Sea. Additionally, this article will reflect on the research that has been done in Belgium to apply a land-use planning approach to the marine environment. The MSP process in Belgium shows that a spatial approach to sea use management is possible despite the lack of a legal zoning framework. However, it concludes that a legal basis for MSP, in addition to the current permit system, would provide a more strategic and integrated framework for ecosystem-based, sea use management. 相似文献
5.
6.
Information systems developed for different applications within the environmental domain have common characteristics, which can potentially be abstracted for sharing and reuse of design and software modules. This article presents an approach to designing for reuse by abstracting commonalities in the design of a Marine Information System (MIS), facilitating data management in a prototype operational monitoring, forecasting, and management system for the North Atlantic and the Nordic Seas. A detailed study of the requirements and data analysis was carried out, and Object-Oriented Technology (OOT) is employed to encapsulate abstractions and to promote reuse of code and design. This article identifies the Object-Oriented Frameworks (OOFW) required to build the MIS. It also provides guidelines to environmental scientists for restructuring legacy software and employing modern programming techniques. 相似文献
7.
8.
This paper is part of a comprehensive review of the oceanography of the eastern tropical Pacific, the oceanic region centered on the eastern Pacific warm pool, but also including the equatorial cold tongue and equatorial current system, and summarizes what is known about oceanographic influences on seabirds and cetaceans there. The eastern tropical Pacific supports on the order of 50 species of seabirds and 30 species of cetaceans as regular residents; these include four endemic species, the world’s largest populations for several others, three endemic sub-species, and a multi-species community that is relatively unique to this ecosystem. Three of the meso-scale physical features of the region are particularly significant to seabirds and cetaceans: the Costa Rica Dome for blue whales and short-beaked common dolphins, the Equatorial Front for planktivorous seabirds, and the countercurrent thermocline ridge for flocking seabirds that associate with mixed-species schools of spotted and spinner dolphins and yellowfin tuna. A few qualitative studies of meso- to macro-scale distribution patterns have indicated that some seabirds and cetaceans have species-specific preferences for surface currents. More common are associations with distinct water masses; these relationships have been quantified for a number of species using several different analytical methods. The mechanisms underlying tropical species–habitat relationships are not well understood, in contrast to a number of higher-latitude systems. This may be due to the fact that physical variables have been used as proxies for prey abundance and distribution in species–habitat research in the eastern tropical Pacific.Though seasonal and interannual patterns tend to be complex, species–habitat relationships appear to remain relatively stable over time, and distribution patterns co-vary with patterns of preferred habitat for a number of species. The interactions between seasonal and interannual variation in oceanographic conditions with seasonal patterns in the biology of seabirds and cetaceans may account for some of the complexity in species–habitat relationship patterns.Little work has been done to investigate effects of El Niño-Southern Oscillation cycles on cetaceans, and results of the few studies focusing on oceanic seabirds are complex and not easy to interpret. Although much has been made of the detrimental effects of El Niño events on apex predators, more research is needed to understand the magnitude, and even direction, of these effects on seabirds and cetaceans in space and time. 相似文献
9.
10.