全文获取类型
收费全文 | 50篇 |
免费 | 3篇 |
国内免费 | 3篇 |
专业分类
测绘学 | 2篇 |
大气科学 | 5篇 |
地球物理 | 11篇 |
地质学 | 23篇 |
海洋学 | 1篇 |
天文学 | 4篇 |
自然地理 | 10篇 |
出版年
2020年 | 2篇 |
2019年 | 2篇 |
2018年 | 1篇 |
2016年 | 2篇 |
2015年 | 2篇 |
2014年 | 2篇 |
2013年 | 4篇 |
2012年 | 2篇 |
2009年 | 5篇 |
2008年 | 1篇 |
2007年 | 5篇 |
2006年 | 3篇 |
2005年 | 3篇 |
2003年 | 2篇 |
2002年 | 4篇 |
2001年 | 1篇 |
2000年 | 3篇 |
1999年 | 1篇 |
1998年 | 3篇 |
1997年 | 1篇 |
1994年 | 1篇 |
1985年 | 1篇 |
1984年 | 1篇 |
1969年 | 1篇 |
1967年 | 1篇 |
1966年 | 1篇 |
1962年 | 1篇 |
排序方式: 共有56条查询结果,搜索用时 15 毫秒
51.
Eric Schlosser Birger Bohn Theo Brauers Hans-Peter Dorn Hendrik Fuchs Rolf Häseler Andreas Hofzumahaus Frank Holland Franz Rohrer Lutz Olaf Rupp Manfred Siese Ralf Tillmann Andreas Wahner 《Journal of Atmospheric Chemistry》2007,56(2):187-205
At the atmosphere simulation chamber SAPHIR in Jülich both Laser-Induced Fluorescence Spectroscopy (LIF) and Long-Path Differential
Optical Laser Absorption Spectroscopy (DOAS) are operational for the detection of OH radicals at tropospheric levels. The
two different spectroscopic techniques were compared within the controlled environment of SAPHIR based on all simultaneous
measurements acquired in 2003 (13 days). Hydroxyl radicals were scavenged by added CO during four of these days in order to
experimentally check the calculated precisions at the detection limit. LIF measurements have a higher precision (σ= 0.88×106 cm–3) and better time resolution (Δt = 60 s), but the DOAS method (σ= 1.24×106 cm–3, Δt = 135 s) is regarded as primary standard for comparisons because of its good accuracy. A high correlation coefficient of
r = 0.95 was found for the whole data set highlighting the advantage of using a simulation chamber. The data set consists of
two groups. The first one includes 3 days, where the LIF measurements yield (1 – 2) ×106 cm–3 higher OH concentrations than observed by the DOAS instrument. The experimental conditions during these days are characterized
by increased NOx concentration and a small dynamic range in OH. Excellent agreement is found within the other group of 6 days. The regression
to the combined data of this large group yields unity slope without a significant offset. 相似文献
52.
ABSTRACTThe United Nations' 2030 Agenda for Sustainable Development sets seventeen Sustainable Development Goals (SDGs) to be achieved by 2030. Earth observation are needed that can support the development and validation of transformation policies to make progress towards the SDGs. A participatory and inclusive goal-based approach (GBA) is introduced that links societal goals, targets and indicators to Essential Transformation Variables (ETVs) of the human and non-human environment. The GBA is complementary to the widely used expert-based approach. The GBA is applied to the SDGs at the goal, target and indicator levels. The high-level conceptual model used for the SDGs is humanity embedded in the Earth's life-support system (ELSS). At the goal level, very few of the SDGs are directly focusing on the ELSS and its physiology. Most of the SDG Targets focus on transformations in society and the built environment. Having targets that explicitly focus on the physiology of the ELSS would be important for sustainability. Most of the current indicator measure the built environment and the embedded social fabric. Sustainable development requires a functioning ELSS, and to ensure this, complementary indicators that bring environmental aspects to the monitoring of SDG targets are needed. 相似文献
53.
Saxicolous species of lichens are able to induce and accelerate weathering of their rock substrate, and effects of lichens
on substrate can be attributed to both physical and chemical causes. This paper is focused on biotic weathering actions of
epilithic and endolithic species on the different rock types (sandstones and volcanogenic rocks) in Antarctica. The patterns,
mechanisms, processes and neoformations of rock-weathering resulting from lichen colonization are expounded in detail. Furthermore,
it is pointed out that, for a better understanding of the impacts of lichens on environments, the studies on the rate of biotic
weathering and the comprehensive involvement of the lichen effects on weathering of natural rocks remain to be carried out
in Antarctica. 相似文献
54.
55.
Recent high-resolution models of past plate motions and their comparison with plate motion models inferred from space geodetic techniques reveal a number of short-term variations in global plate velocities over the past 10 Myrs. Such variations serve as powerful probe into the nature and magnitude of plate boundary forces, because they are unlikely to originate from changes in mantle buoyancy forces, which evolve on longer time scales. Here we explore the constraints of the velocity record using a novel coupled modeling-approach of global neo-tectonic simulations combined with realistic plate driving forces obtained from mantle circulation models (MCMs) to arrive at simple global budgets of mantle, lithosphere and plate boundary forces. We focus on three plate boundary systems along the Nazca/South America plate margin, the Aleutian trench and the India/Australia plate boundary to show that gravitational spreading from high topography in the Andes and Tibet contributes substantially to the global plate tectonic force balance and that this contribution is sufficient to explain some 35% of recent velocity changes over the Earth's surface, including among others the observed 30% convergence reduction between the Nazca/South America plates. Our models make a number of specific predictions such as significant lateral variations in plate coupling forces along a given margin revealed by trench-parallel gravity and bathymetry anomalies and the occurrence of large earthquakes, as well as differences by as much as a factor of five from margin to margin. They also support the notion of a relatively young plate boundary separating the India and Australia plates, which has been previously suggested based on independent observations. Importantly, we find that the modeled Nazca/South America convergence reduction explains recent spreading-rate variations in the South Atlantic and South Pacific, which points to the importance of far field effects on the adjacent continents in explaining the spreading record of oceanic basins. Our numerical results demonstrate (a) that detailed budgets of forces acting upon plates can be obtained and (b) support the notion of strong forcing along weak plate boundaries. 相似文献
56.
由于科学考察活动日益频繁以及旅游业在南极地区的迅速开展 ,人类活动对南极陆地生态系统的影响在最近几十年内一直倍受国际社会的关注。在广泛收集国外有关资料的基础上 ,本文对人类活动引发的南极地区区域性的土壤与植被污染、野生动物受扰、外来物种引进、以及细菌性疾病侵入等方面进行了论述。同时 ,阐述了南极以外地区的人为污染源对南极环境的潜在威胁。最后 ,对“南极条约体系”与国际社会为保护南极环境所作出的不懈努力进行了简要介绍与评价。 相似文献