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261.
Organic aerosols in the Miami area, USA: temporal variability of atmospheric particles and wet/dry deposition 总被引:1,自引:0,他引:1
Atmospheric particulate matter and both wet and dry deposition was collected over a period of nine months at one location in the metropolitan area of Miami, Florida. Molecular distributions and concentrations of n-alkanes, fatty acids, polycyclic aromatic hydrocarbons (PAHs) and hopanes were determined using weekly composite samples over this time period in order to determine temporal variability, and their possible dependence on climatic parameters such as temperature, rainfall and wind direction and frequency. Based on molecular distributions of the compounds studied, potential emission sources for the atmospheric particles were assessed and suggested to be mainly derived from automobile exhaust and natural sources. Although wet and dry deposition processes were observed to remove about equal amounts of organic aerosols from the Miami atmosphere, dry deposition was dominant in the removal of anthropogenically derived compounds such as PAHs and hopanes. Only very limited seasonal trends were observed, while wind direction and frequency was found to be the most important meteorological parameter controlling the temporal variability of the organic aerosols. This is the first detailed report of this nature for the Miami area. 相似文献
262.
Ten years of atmospheric methane observations at a high elevation site in Western China 总被引:3,自引:0,他引:3
L.X. Zhou D.E.J. Worthy P.M. Lang M.K. Ernst X.C. Zhang Y.P. Wen J.L. Li 《Atmospheric environment (Oxford, England : 1994)》2004,38(40):7041-7054
In this paper, the continuous (1994–2001) and discrete air sample (1991–2001) measurements of atmospheric CH4 from the Waliguan Baseline Observatory located in western China (36°17′N, 100°54′E, 3816 m asl) are presented and characterized. The CH4 time series show large episodic events on the order of 100 ppb throughout the year. During spring, a diurnal cycle with average amplitude of 7 ppb and a morning maximum and late afternoon minimum is observed. In winter, a diurnal cycle with average amplitude of 14 ppb is observed with an afternoon maximum and morning minimum. Unlike most terrestrial observational sites, no obvious diurnal patterns are present during the summer or autumn. A background data selection procedure was developed based on local horizontal and vertical winds. A selected hourly data set representative of “baseline” conditions was derived with approximately 50% of the valid hourly data. The range of CH4 mixing ratios, annual means, annual increases and mean annual cycle at Waliguan during the 1992–2001 were derived from discrete and continuous data representative of “baseline” conditions and compared to air samples collected at other Northern Hemisphere sites. The range of CH4 monthly means of 1746–1822 ppb, average annual means of 1786.7±10.8 ppb and mean annual increase of 4.5±4.2 ppb yr−1 at Waliguan were inline with measurements from sites located between 30° and 60°N. There were variations observed in the CH4 annual increase patterns at Waliguan that were slightly different from the global pattern. The mean CH4 annual cycle at Waliguan shows an unusual pattern of two gentle peaks in summer and February along with two small valleys in early winter and spring and a mean peak-to-peak amplitude of 11 ppb, much smaller than amplitudes observed at most other mid- and high-northern latitude sites. The Waliguan CH4 data are strongly influenced by continental Asian CH4 emissions and provide key information for global atmospheric CH4 models. 相似文献
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265.
改进型升流式固体反应器处理猪粪污新工艺研究 总被引:6,自引:1,他引:5
对传统升流式固体反应器(USR)进行改进,反应器内设置专用搅拌器,搅拌器间歇开启,在保留USR各项优势的前提下,使料液与厌氧微生物接触更充分,反应温度更均匀,提高产气率,同时还解决了传统USR的“结壳”问题,提高了反应器的传质效率、甲烷产气率和COD去除效果。进料含固量在12.1%时,水利停留时间为17 d,反应器最高容积负荷达到4.9 kg COD/(m3·d),产气速率为2.55 m3/(m3·d),产气率达到0.359 m3/kg干猪粪。 相似文献
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267.
Christopher Luederitz David J. Abson René Audet Daniel J. Lang 《Sustainability Science》2017,12(3):393-407
Sustainability transitions aim to comprehensively address key challenges of today’s societies through harmonizing ecological integrity and social viability. During the last decades, increasing attention has focused on the conceptual development and identification of trajectories that navigate societies toward sustainability. While a broad agreement exists with regard to the need for mainstreaming sustainability into the core of decision-making and everyday practices, different transition pathway narratives are advocated to foster urgently needed structural and societal changes. In this article, we describe four archetypes of present transition narratives, examining the system properties (from underpinning intent to mechanistic parameters) that each narrative seeks to transform. We review the articulated critiques of, and provide exemplary case studies for, each narrative. The four transition narratives are (1) the green economy, (2) low-carbon transformation, (3) ecotopian solutions and (4) transition movements. Based on our analysis, we argue that despite the assumption that these narratives represent competing pathways, there is considerable complementarity between them regarding where in a given system they seek to intervene. An integrative approach could potentially help bridge these intervention types and connect fragmented actors at multiple levels and across multiple phases of transition processes. Effectively mainstreaming sustainability will ultimately require sustainability scientists to navigate between, and learn from, multiple transition narratives. 相似文献
268.
Hu Jian Liu Congqiang Guo Qingjun Yang Junxin Okoli Chukwunonso Peter Lang Yunchao Zhao Zhiqi Li Siliang Liu Baojian Song Guangwei 《Environmental science and pollution research international》2017,24(20):17090-17102
Environmental Science and Pollution Research - The concentration characteristics, sources, and potential ecological risk assessment of 16 PAHs were investigated in the surface water from the... 相似文献
269.
F. M. Black L. E. High J. M. Lang 《Journal of the Air & Waste Management Association (1995)》2013,63(11):1216-1220
Mathematical modeling of ambient air photochemistry requires comprehensive mobile source hydrocarbon emission speciation. Passenger car tailpipe and evaporative hydrocarbon emissions have been examined using procedures described in the Federal Register for emissions certification. Hydrocarbon emission rates and compositions were determined for four passenger cars: a 1963 Chevrolet, a 1977 Ford Mustang II, a 1978 Mercury Monarch, and a 1979 Ford LTD-II. These vehicles are representative of a wide range of exhaust and evaporative emissions control configurations. Both emission rates and compositions were dependent on the emissions control devices used with the vehicles, and the fuel composition and vapor pressure. In agreement with the literature, tailpipe catalyst control systems removed unsaturated olefinic, aromatic, and acetylenic hydrocarbons to a greater extent than saturated paraffinic hydrocarbons. The impact of evaporative control devices on composition was not well defined, however the limited data suggested a sensitivity to fuel aromatic content. The emission rate of benzene, emphasized because of its potential carcinogenicity, was sensitive to both fuel benzene and total aromatic content. 相似文献
270.
Jinxia Yan Jingling Liu Yi Li Sisi Lang 《Environmental science and pollution research international》2014,21(20):12050-12061
The pollution loads continuously increased in Haihe estuary, of Tianjin, China, due to intensive human activities, especially the construction of the Haihe Gate and Lingang Industrial Area. In 2011, hydrological variability in Haihe estuary was investigated and sediments were collected. Total organic carbon (TOC), particle size, total polycyclic aromatic hydrocarbons (ΣPAHs), heavy metals (Cd, Cr, Cu, Ni, Pb, and Zn), and benthic diatom community were analyzed. The highest concentrations of ΣPAHs and heavy metals were found near the Haihe Gate. The Shannon diversity index and the relative abundance of Coscinodiscus perforatus (RC) indicated a decreasing trend seaward. Results of Pearson correlation analysis illustrated significant relations between water current velocity and ΣPAHs (p?0.01), Cr (p?0.05), and RC (p?0.05). Path analysis further indicated that water current played an important role in the distribution of PAH, Cr, and RC. 相似文献