全文获取类型
收费全文 | 2360篇 |
免费 | 125篇 |
国内免费 | 292篇 |
专业分类
安全科学 | 139篇 |
废物处理 | 39篇 |
环保管理 | 472篇 |
综合类 | 932篇 |
基础理论 | 745篇 |
污染及防治 | 65篇 |
评价与监测 | 118篇 |
社会与环境 | 223篇 |
灾害及防治 | 44篇 |
出版年
2024年 | 10篇 |
2023年 | 45篇 |
2022年 | 94篇 |
2021年 | 60篇 |
2020年 | 67篇 |
2019年 | 58篇 |
2018年 | 49篇 |
2017年 | 63篇 |
2016年 | 90篇 |
2015年 | 85篇 |
2014年 | 107篇 |
2013年 | 165篇 |
2012年 | 106篇 |
2011年 | 156篇 |
2010年 | 149篇 |
2009年 | 121篇 |
2008年 | 118篇 |
2007年 | 117篇 |
2006年 | 152篇 |
2005年 | 124篇 |
2004年 | 121篇 |
2003年 | 105篇 |
2002年 | 86篇 |
2001年 | 97篇 |
2000年 | 63篇 |
1999年 | 64篇 |
1998年 | 43篇 |
1997年 | 35篇 |
1996年 | 34篇 |
1995年 | 28篇 |
1994年 | 20篇 |
1993年 | 24篇 |
1992年 | 14篇 |
1991年 | 23篇 |
1990年 | 13篇 |
1989年 | 5篇 |
1988年 | 14篇 |
1987年 | 7篇 |
1986年 | 5篇 |
1985年 | 5篇 |
1984年 | 3篇 |
1983年 | 7篇 |
1982年 | 2篇 |
1981年 | 3篇 |
1980年 | 4篇 |
1979年 | 4篇 |
1978年 | 2篇 |
1977年 | 4篇 |
1972年 | 3篇 |
1970年 | 1篇 |
排序方式: 共有2777条查询结果,搜索用时 31 毫秒
21.
22.
A Simulation of Temporal and Spatial Variations in Carbon at Landscape Level: A Case Study for Lake Abitibi Model Forest in Ontario,Canada 总被引:2,自引:0,他引:2
Xiaolu Zhou Changhui Peng Qing-Lai Dang Jiaxin Chen Sue Parton 《Mitigation and Adaptation Strategies for Global Change》2007,12(4):525-543
Using a case study of the Lake Abitibi Model Forest (LAMF), this study aims to assess the temporal and spatial variability
in carbon storage during 1990–2000, and to present a comprehensive estimation of the carbon budget for LAMF's ecosystems.
As well, it provided the information needed by local forest managers to develop ecological and carbon-based indicators and
monitor the sustainability of forest ecosystems. Temporal and spatial carbon dynamics were simulated at the landscape level
using ecosystem model TRIPLEX1.0 and Geographical Information System (GIS). The simulated net primary productivity (NPP) and
carbon storage in forest biomass and soil were compared with field data and results from other studies for Canada's boreal
forests. The results show that simulated NPP ranged from 3.26 to 3.34 tC ha−1 yr−1 in the 1990s and was consistent with the range measured during the Boreal Ecosystem-Atmosphere Studies (BOREAS) in central
Canada. Modeled NPP was also compared with the estimation from remote sensing data. The density of total above-and belowground
biomass was 125.3, 111.8, and 106.5 tC ha−1 for black spruce, trembling aspen, and jack pine in the LAMF ecosystem, respectively. The total carbon density of forested
land was estimated at 154.4 tC ha−1 with the proportion of 4:6 for total biomass and soil. The analysis of net carbon balance of ecosystem suggested that the
LAMF forest ecosystem was acting as a carbon sink with an allowable harvest in the 1990s. 相似文献
23.
Given the key role of biogenic volatile organic compounds(VOCs) to tropospheric chemistry and regional air quality, it is important to generate accurateVOCs emission inventories. However, only a less fraction of plant species, in temperate grassland of Inner Mongolia, has been characterized by quantitative measurements. A taxonomic methodology, which assigns VOCs measurements to unmeasured species, is an applicable and inexpensive alternation for extensive VOCs emission survey, although data are needed for additional plant families and genera to further validate the taxonomic approach in grassland vegetation. In this experiment, VOCs emission rates of 178 plant species were measured with a portable photoionization detector( PID). The results showed the most of genera and some families have consistent feature of their VOCs emission, especially for isoprene, and provide the basic premise of taxonomic methodology to develop VOCs emission inventories for temperate grassland. Then, the taxonomic methodology was introduced into assigning emission rate to other 96 species, which no measured emission rates available here. A systematical emission inventory of temperate grassland vegetation in Inner Mongolia was provided and further evidence that taxonomy relationship can serve as a useful guide for generalizing the emissions behavior of many, but not all, plant families and genera to grassland vegetation. 相似文献
24.
Vegetation patterns and nature reserve construction in an extremely-arid desert in Anxi,NW China's Gansu Province 总被引:2,自引:0,他引:2
Anxi County is located in the northwestern part of the Hexi Corridor in gansu Province and has the sole national level nature reserve of extremely-arid desert in China.Phytosociological methods (Braun-Blanquet,1964) are used to classify plant community types in this area.Eleven are disting uished,including six of deserts,four of oases and one transitional type between deserts and oases.Direct gradient analysis (DCA) is employed to correlate the distribution of plant communities to physiogeographic conditions.This study makes clear that water is the most important ecological factor for the distribution of plant species and communities in this area.The effects of water have been demonstrated in different ways.A vegetation gradient from lower altitude to higher altitude in the southern part of the reserve is driven by a precipitation gradient.The effects of the depth of ground water table contribute to the differentiation of vegetation from desert to oasis in the flat area.In a finer scale,the washed gullies have obviously higher species richness and also higher vegetation cover than the surround gobi surfaces,possibly caused by the effects of floods.The vegetation patterns demonstrate that the area of Anxi County is a complete landscape unit.The range of the current nature reserve is not large enough for the purpose of conserving the unique biodiversity in this area. 相似文献
25.
Effects of acid deposition on forests in south China 总被引:1,自引:0,他引:1
1IntroductionWiththefastgrowingofmodernindustryandsharplyincreasingofenergyconsumptionprimarilycoal,airpolutionandaciddeposit... 相似文献
26.
Carbon Dioxide Balance of Wood Substitution: Comparing Concrete- and Wood-Framed Buildings 总被引:3,自引:0,他引:3
Leif Gustavsson Kim Pingoud Roger Sathre 《Mitigation and Adaptation Strategies for Global Change》2006,11(3):667-691
In this study a method is suggested to compare the net carbon dioxide (CO2) emission from the construction of concrete- and wood-framed buildings. The method is then applied to two buildings in Sweden
and Finland constructed with wood frames, compared with functionally equivalent buildings constructed with concrete frames.
Carbon accounting includes: emissions due to fossil fuel use in the production of building materials; the replacement of fossil
fuels by biomass residues from logging, wood processing, construction and demolition; carbon stock changes in forests and
buildings; and cement process reactions. The results show that wood-framed construction requires less energy, and emits less
CO2 to the atmosphere, than concrete-framed construction. The lifecycle emission difference between the wood- and concrete-framed
buildings ranges from 30 to 130 kg C per m2 of floor area. Hence, a net reduction of CO2 emission can be obtained by increasing the proportion of wood-based building materials, relative to concrete materials. The
benefits would be greatest if the biomass residues resulting from the production of the wood building materials were fully
used in energy supply systems. The carbon mitigation efficiency, expressed in terms of biomass used per unit of reduced carbon
emission, is considerably better if the wood is used to replace concrete building material than if the wood is used directly
as biofuel. 相似文献
27.
Debra Straussfogel 《Mitigation and Adaptation Strategies for Global Change》2006,11(4):911-931
This paper addresses the combined effects of two sources of disturbance on the boreal forest – climate change and the economic
relations of industrial forestry. It describes a theoretical blueprint constructed of concepts from the theory of dissipative
structures (derived from the discipline of physical chemistry) and world-systems theory (derived from the discipline of sociology)
into a proposed integrated theory pivoting on the concept of social vulnerability. The goal is to examine the key concepts
of this theory – vulnerability, resilience and adaptive capacity – as elements of the complex systems perspective provided
by dissipative structure principles. The focus on social vulnerability provides the means to establish the role of external
economic linkages relevant to industrial forestry – the core/periphery relations of the world-system – as they influence the
social vulnerability of the boreal forest SESs. These systems are posited as embedded peripheries, following world-system
criteria, and as the focal scale of analysis within a larger hierarchically organized dissipative structure. The goal is to
suggest and stimulate ideas for further discussion and exploration, motivated by the premise that any successful climate change
mitigation efforts depend on having sound theoretical foundations on which to stand. 相似文献
28.
29.
Can Forest-protection carbon projects improve rural livelihoods? Analysis of the Noel Kempff Mercado climate action project,Bolivia 总被引:1,自引:0,他引:1
Asquith Nigel M. Vargas Ríos María Teresa Smith Joyotee 《Mitigation and Adaptation Strategies for Global Change》2002,7(4):323-337
We studied the Noel KempffMercado Climate Action Project (NKMCAP),Bolivia, to assess whether forestprotection carbon (C) projects cansignificantly benefit local people. Wehypothesized that forest protection canonly securely deliver C if significantstakeholders are meaningfully andtransparently involved, traditional orcustomary rights are recognized and theirloss compensated for, and there are directlinkages between conservation anddevelopment objective. Our researchfocused on 53 members of the communities ofFlorida, Porvenir and Piso Firme and 36secondary stakeholders. In each of thevillages we held half-day meetings withcommunity leaders, complemented bysemi-structured one-hour interviews with 5,10, and 7 families, representing 20%, 10%and 8% of each community. The long-termimpact of the NKMCAP on the localcommunities may well be positive. However,in the short run, certain sections of thelocal communities are financially poorer. Forest protection projects clearly have thepotential to sequester C, protectbiodiversity and simultaneously contributeto sustainable rural development, but ifthey really are to improve rurallivelihoods, they must be designed andimplemented carefully and participatively. 相似文献
30.