全文获取类型
收费全文 | 1008篇 |
免费 | 119篇 |
国内免费 | 226篇 |
专业分类
测绘学 | 117篇 |
大气科学 | 113篇 |
地球物理 | 127篇 |
地质学 | 423篇 |
海洋学 | 86篇 |
天文学 | 9篇 |
综合类 | 82篇 |
自然地理 | 396篇 |
出版年
2024年 | 3篇 |
2023年 | 12篇 |
2022年 | 33篇 |
2021年 | 38篇 |
2020年 | 48篇 |
2019年 | 55篇 |
2018年 | 38篇 |
2017年 | 49篇 |
2016年 | 38篇 |
2015年 | 49篇 |
2014年 | 59篇 |
2013年 | 92篇 |
2012年 | 69篇 |
2011年 | 58篇 |
2010年 | 53篇 |
2009年 | 75篇 |
2008年 | 56篇 |
2007年 | 44篇 |
2006年 | 55篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 45篇 |
2002年 | 36篇 |
2001年 | 36篇 |
2000年 | 33篇 |
1999年 | 32篇 |
1998年 | 22篇 |
1997年 | 22篇 |
1996年 | 22篇 |
1995年 | 17篇 |
1994年 | 12篇 |
1993年 | 9篇 |
1992年 | 10篇 |
1991年 | 6篇 |
1990年 | 5篇 |
1989年 | 5篇 |
1988年 | 1篇 |
1987年 | 6篇 |
1985年 | 3篇 |
1983年 | 2篇 |
1976年 | 1篇 |
排序方式: 共有1353条查询结果,搜索用时 15 毫秒
91.
Julie Rozenberg Stéphane Hallegatte Baptiste Perrissin-Fabert Jean-Charles Hourcade 《Climate Policy》2013,13(1):134-141
Introducing a carbon tax is difficult, partly because it suggests that current generations have to make sacrifices for the benefit of future generations. However, the climate change externality could be corrected without such a sacrifice. It is possible to set a carbon value, and use it to create ‘carbon certificates’ that can be accepted as part of commercial banks’ legal reserves. These certificates can be distributed to low-carbon projects, and be exchanged by investors against concessional loans, reducing capital costs for low-carbon projects. As the issuance of carbon certificates would increase the quantity of money, it will either lead to accelerated inflation or induce the Central Bank to raise interest rates. Low-carbon projects will thus have access to cheaper loans at the expense of either ‘regular’ investors (in case of higher interest rates) or of lenders and depositors (in case of accelerated inflation). Within this scheme, mitigation expenditures are compensated by a reduction in regular investments, so that immediate consumption is maintained. It uses future generation wealth to pay for a hedge against climate change. This framework is not as efficient as a carbon tax but is politically easier to implement and represents an interesting step in the trajectory towards a low-carbon economy. 相似文献
92.
There are compelling reasons for policy makers to be interested in the low-carbon agenda. More than half of the world's population lives in, and more than half of the world's economic output comes from, cities. Up to 70% of global carbon emissions can also be attributed to consumption that takes place in cities. Recent research has shown that cost-effective investments in low-carbon options could deliver a 40% reduction in GHG emissions from cities by 2020, while also providing wider economic benefits such as enhanced competitiveness and increased employment. As yet, however, investments in low-carbon cities have not been made at scale due mainly to the scale of the finance required, local government budgetary constraints, and perceptions about their costs and benefits. With a focus on the UK, a contemporary account is provided of what local authorities see as the major financial risks associated with funding low-carbon cities. Practical proposals – which also have more general relevance to the future financing of low-carbon cities around the world – are offered on how local authorities, in conjunction with central government, the private sector, and institutional investors, can effectively manage these risks. Policy relevance Cities house more than half of the world's population, generate more than half of the world's economic output, and produce between 40% and 70% of all anthropogenic GHG emissions. In the UK, 70% of such emissions are under the influence of its local authorities. Thus, one of the key public policy challenges for the low-carbon transition is how it should be financed. There are several obstacles and related risks to this transition, including financial and legal obstacles and the differing views and perceptions of stakeholders. These can be attenuated, somewhat, by national government support at scale, local authority leadership, and cooperation between other authorities and the private sector, and the development of tools and guidance to reduce transaction costs. 相似文献
93.
José I. Muñoz 《Climate Policy》2013,13(2):87-105
How does financial performance risk affect investments in low-carbon electricity-generating technologies to achieve climate policy targets? A detailed risk simulation of price formation in the Great Britain wholesale power market is used to show that the increasing replacement of fossil facilities with wind, ceteris paribus, may cause a deterioration of the financial risk–return performance metrics for incremental investments. Low-carbon investments appear to be high risk, low return, and as such may require a progressively higher level of support over time than envisaged by the conventional degression trajectories. The increasing riskiness of the wholesale market will to some extent offset the benefits of lower capital costs and operational efficiencies if investors need to satisfy cautious debt coverage ratios alongside positive expected returns. This increased risk is additional to the well-known ‘merit order effect’ of low-carbon investments progressively depressing wholesale prices and hence their expected investment returns. Policy relevance Policy support for renewable technologies such as wind is usually based upon levelized costs and is expected to reduce over time as capital costs and operational efficiencies improve. However, levelized costs do not take full account of the risk aversion that investors may have in practice. Expected policy support reductions may be moderated to some extent by the increased financial performance risk that intermittent technologies bring to the power market. The annual risk-return profiles for incremental investments deteriorate for all technologies as wind replaces fossil fuels. This extra risk premium will need to be incorporated into evaluating policy incentives for new investments in a decarbonizing power market. 相似文献
94.
《Climate Policy》2013,13(1):9-21
Governments willing to commit themselves to maintain carbon prices at or above a certain level face the challenge that their commitments need to be credible both for investors in low-carbon technology and for foreign governments. This article argues that governments can make such commitments by issuing long-term put option contracts on the price of CO2 allowances. This mechanism gives investors the right, but not the obligation, to sell allowances to the government at the strike price. From the investors' point of view, a government is therefore fully committed to a price floor for allowances in the future. This proposed approach alters the incentives that a government faces when considering noncompliance and serves to prevent non-compliance. The proposal fares well when assessed against criteria to determine its suitability in legitimacy, enforcement, proportionality, lack of interference from other contracting States, and transparency. It also allows for fine-tuning through the number and duration of issued options and the strike price. A robust contract structure is proposed to protect against government interference that might threaten the credibility of commitments. 相似文献
95.
96.
本文对四川省巴中县莲花山,从1954年开始,在调查研究和规划的基础上,根据造林地条件,提出马尾松栽培技术,取得明显成效。该经验对类似山区有借鉴参考价值。 相似文献
97.
Kang-tsung Chang 《The Professional geographer》1989,41(3):314-328
Japan is the most important foreign investor in the United States. Japanese companies are trade-oriented and have ownership-specific advantages in select industries; their US investment is aimed at protecting their market share. The distribution of Japanese plants correlates well with US manufacturing, except that the West Coast and states that aggressively sought Japanese investment have more employees in Japanese plants. Japanese presence in US manufacturing is most prominent in consumer electronics, steel, automobiles, and high-technology industries. 相似文献
98.
The Meixner functions are utilized to relate the effective rainfall, the direct runoff and the unit hydrograph through linkage equations. The linkage equations are then employed to derive the unit hydrograph for given rainfall-runoff data on a small agricultural watershed. These functions are tested with regard to their ability to reproduce and predict the direct runoff hydrograph. The Meixner functions are found to be an effective analytical tool for hydrograph synthesis. Further, they compare well with the least squares and linear programming methods of the unit hydrograph derivation. 相似文献
99.
100.
陈姝 《测绘与空间地理信息》2012,(3):85-88
由于通用传感器模型与具体的传感器无关,因而更能适应传感器成像方式多样化的发展要求,所以通用传感器模型的研究已成为当前摄影测量与遥感领域的一个重要研究方向。在对包括多项式模型、直接线性变换模型和有理函数模型在内的通用传感器模型的定义,参数解算和模型定位进行系统归纳的基础上,对基于通用传感器模型的高分辨率遥感影像的立体像对定位方法进行了理论和实验研究,并对实验结果进行了比较和分析。 相似文献