全文获取类型
收费全文 | 10162篇 |
免费 | 2篇 |
专业分类
安全科学 | 4篇 |
废物处理 | 774篇 |
环保管理 | 1252篇 |
综合类 | 1242篇 |
基础理论 | 3183篇 |
环境理论 | 1篇 |
污染及防治 | 1794篇 |
评价与监测 | 1011篇 |
社会与环境 | 902篇 |
灾害及防治 | 1篇 |
出版年
2018年 | 1475篇 |
2017年 | 1379篇 |
2016年 | 1195篇 |
2015年 | 129篇 |
2014年 | 21篇 |
2013年 | 28篇 |
2012年 | 471篇 |
2011年 | 1341篇 |
2010年 | 697篇 |
2009年 | 604篇 |
2008年 | 891篇 |
2007年 | 1237篇 |
2006年 | 9篇 |
2005年 | 23篇 |
2004年 | 40篇 |
2003年 | 66篇 |
2002年 | 102篇 |
2001年 | 20篇 |
2000年 | 14篇 |
1999年 | 11篇 |
1998年 | 14篇 |
1997年 | 9篇 |
1994年 | 6篇 |
1993年 | 7篇 |
1992年 | 8篇 |
1991年 | 9篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1984年 | 12篇 |
1983年 | 10篇 |
1963年 | 11篇 |
1962年 | 6篇 |
1959年 | 8篇 |
1958年 | 7篇 |
1956年 | 6篇 |
1955年 | 6篇 |
1954年 | 6篇 |
1941年 | 6篇 |
1939年 | 6篇 |
1935年 | 9篇 |
1934年 | 7篇 |
1930年 | 9篇 |
1929年 | 10篇 |
1928年 | 8篇 |
1927年 | 11篇 |
1926年 | 15篇 |
1925年 | 12篇 |
1924年 | 6篇 |
1923年 | 6篇 |
1921年 | 9篇 |
排序方式: 共有10000条查询结果,搜索用时 265 毫秒
21.
Application of a checklist for quality assistance in environmental modelling to an energy model 总被引:2,自引:0,他引:2
James Risbey Jeroen van der Sluijs Penny Kloprogge Jerry Ravetz Silvio Funtowicz Serafin Corral Quintana 《Environmental Modeling and Assessment》2005,10(1):63-79
Large, complex energy models present considerable challenges to develop and test. Uncertainty assessments of such models provide only partial guidance on the quality of the results. We have developed a model quality assistance checklist to aid in this purpose. The model checklist provides diagnostic output in the form of a set of pitfalls for the model application. The checklist is applied here to an energy model for the problem of assessing energy use and greenhouse gas emissions. Use of the checklist suggests that results on this issue are contingent on a number of assumptions that are highly value-laden. When these assumptions are held fixed, the model is deemed capable of producing moderately robust results of relevance to climate policy over the longer term. Checklist responses also indicate that a number of details critical to policy choices or outcomes on this issue are not captured in the model, and model results should therefore be supplemented with alternative analyses. 相似文献
22.
23.
24.
25.
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
26.
In angiosperms, archesporial cells in the anther primordium undergo meiosis to form haploid pollen, the sole occupants of anther sacs. Anther sacs are held together by a matrix of parenchyma cells, the connective tissue. Cells of the connective tissue are not known to differentiate. We report the differentiation of parenchyma cells in the connective tissue of two Gordonia species into pollen-like structures (described as pseudopollen), which migrate into the anther sacs before dehiscence. Pollen and pseudopollen were distinguishable by morphology and staining. Pollen were tricolpate to spherical while pseudopollen were less rigid and transparent with a ribbed surface. Both types were different in size, shape, staining and surface architecture. The ratio of the number of pseudopollen to pollen was 1:3. During ontogeny in the connective tissue, neither cell division nor tetrad formation was observed and hence pseudopollen were presumed to be diploid. Only normal pollen germinated on a germination medium. Fixed preparations in time seemed to indicate that pseudopollen migrate from the connective tissue into the anther sac. 相似文献
27.
28.
29.
Bosch J 《Die Naturwissenschaften》2002,89(12):575-578
Female midwife toads (genus Alytes) emit highly variable reciprocal calls of unclear function prior to and during courtship. In some species, female-female competition, expressed as physical fighting, has been reported. Males of Majorcan midwife toads (Alytes muletensis) show phonotactic response to female calls, and females of Iberian midwife toads (Alytes cisternasii) respond differently according to the male call characteristics. In this study, I test the hypothesis of female-female acoustic competition as an additional function of female reciprocal calls. Playback tests indicate that female calls are not clearly involved in female acoustic competition in the Iberian midwife toad, therefore female calls could be directed at males rather than towards competitive females. 相似文献
30.
Otto Kandler 《Die Naturwissenschaften》1981,68(4):183-192
The determination of the sequence similarity of the ribosomal 16S RNA of many bacteria and a few higher organisms has shown that the methanogenic, halophilic, and acido-thermophilic organisms are phylogenetically separated from the kingdoms of the Eubacteria and Eukaryotes thus representing a third kingdom called "Archaebacteria". Many biochemical and molecular biological features support this conclusion. 相似文献