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821.
以空间相关性和空间异质性为基础,构建SLM-STIRPAT、SEM-STIRPAT和GWR-STIRPAT模型,对京津冀地区汽车运输碳排放进行测算和影响因素分析.结果表明:京津冀地区汽车运输碳排放存在显著空间相关性和空间异质性.人口对汽车运输碳排放呈正向影响;人均GDP对货运碳排放和总量碳排放呈正向影响,对客运碳排放呈负向影响,城镇化水平对汽车运输碳排放呈负向影响.第三产业增加值对客运碳排放和总量碳排放呈正向影响,对货运碳排放呈负向影响,人口对张家口市汽车运输碳排放影响最为显著;人均GDP对秦皇岛市和沧州市的汽车运输碳排放影响最为显著;城镇化水平对秦皇岛市的汽车运输碳排放影响最为显著;第三产业增加值对秦皇岛市的汽车运输碳排放影响最为显著. 相似文献
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青藏铁路临界翻车风速研究 总被引:3,自引:0,他引:3
分析了青藏铁路沿线不同季节大风平均风速、最大风速和超过8级风天数。由于空气密度随海拔上升而减小,大风对铁路运输安全的影响与低海拔地区差异较大。笔者利用车辆动力学原理建立了列车的临界翻车风速模型,研究了高寒铁路不同海拔地区和冻土地区的临界翻车风速。研究结果表明:青藏高寒铁路临界翻车风速随海拔升高而增大,而随冻土路基病害出现而降低的规律。参考英、日等国大风标准,结合青藏高原的特点,根据危险翻车风速和临界翻车风速,首次提出青藏高原铁路海拔4000m地区安全行车标准。 相似文献
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Peter D. Lattin Parker J. Wigington Thomas J. Moser Barbara E. Peniston Dale R. Lindeman Doug R. Getter 《Journal of the American Water Resources Association》2004,40(1):215-227
ABSTRACT: This paper compares approaches to quantifying land cover/land use (LCLU) in riparian corridors of 23 watersheds in Oregon's Willamette Valley using color infrared aerial photography (AP) and Thematic Mapper (TM) imagery. For each imagery source, LCLU adjacent to stream networks were quantified across a range of lateral and longitudinal scales. Single‐date AP data had higher LCLU class accuracies than the multi‐date TM data, except for row crops. Correlations among LCLU classes for the two imagery sources increased with increased spatial extent. In general, LCLU proportions for AP and TM differed, but lateral/longitudinal patterns were similar. An aggregated vegetation class comprised of forest, shrub/scrub, and grass/forb was strongly associated with a fish index of biotic integrity (IBI) for both AP and TM data, although AP correlations were higher. Highest fish IBI correlations for both data sources were with the aggregated vegetation class close to the stream and for the longest longitudinal scales. The row crop class was strongly associated with stream nitrate for both data sources, although correlations for the TM data were higher. Stream nitrate correlations were strongest for the widest lateral and longest longitudinal scales. Overall, both single‐date AP and multi‐date TM imagery appear to have potential for use in estimating indicators of stream ecological condition. 相似文献
825.
The US National Park Service must map forest cover types over extensive areas in order to fulfill its goal of maintaining or reconstructing presettlement vegetation within national parks and monuments. Furthermore, such cover type maps must be updated on a regular basis to document vegetation changes. Computer-aided classification of small scale aerial photography is a promising technique for generating forest cover type maps efficiently and inexpensively. In this study, seven cover types were classified with an overall accuracy of 62 percent from a reproduction of a 1120,000 color infrared transparency of a conifer-hardwood forest. The results were encouraging, given the degraded quality of the photograph and the fact that features were not centered, as well as the lack of information on lens vignetting characteristics to make corrections. Suggestions are made for resolving these problems in future research and applications. In addition, it is hypothesized that the overall accuracy is artificially low because the computer-aided classification more accurately portrayed the intermixing of cover types than the hand-drawn maps to which it was compared. 相似文献
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Air pollution and its control in China 总被引:2,自引:0,他引:2
Hao Jiming He Kebin Duan Lei Li Junhua Wang Litao 《Frontiers of Environmental Science & Engineering in China》2007,1(2):129-142
The rapid growth of China’s economy has led to severe air pollution characterized by acid rain, severe pollution in cities,
and regional air pollution. High concentrations are found for various pollutants such as sulfur dioxides (SO2), nitrogen oxides (NOx), and fine particulates. Great efforts have thus been undertaken for the control of air pollution in the country. This paper
discusses the development and application of appropriate technologies for reducing the major pollutants produced by coal and
vehicles, and investigates air quality modeling as an important support for policy-making. 相似文献
830.
Chen Hongfeng Li Fen Li Xiangling . School of Environment Natural Resources Renmin University of China Beijing China . School of Natural Resources Environment Hefei University of Technology Hefei Anhui China 《中国人口.资源与环境(英文版)》2007,5(2):41-48
As a megacity with thriving economy, Shanghai is experiencing rapid motorisation and confronted with traffic congestion problems despite its low car ownership. It is of value to look into the policies on emission control of motor vehicle and congestion reduction in such a city to explore how to reconcile mobility enhancement with the environment. Results of a dynamic simulation displayed time paths of emissions from motor vehicles in Shanghai over the period from 2000 to 2020. The simulation results showed that early policies on emission control of motor vehicle could bring about far-reaching effects on emission reduc- tion, and take advantage of available low-polluting technologies and technical innovation over time. Travel demand management would play an important role in curbing congestion and reducing motor vehicle pollution by calming down car ownership rise and deterring inefficient trips as well as reducing fuel waste caused by congestion. 相似文献