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辽东湾海冰晶体结构及其内部叶绿素的初步研究 总被引:6,自引:0,他引:6
本文介绍了1996年冬季首次辽东湾生态环境调查中的海洋背景条件。扼要地阐述了辽东湾海冰一般概况,分析辽东湾冰样晶体结构、存储条件及其与冰内和冰下海水叶绿素之间的关系。辽东湾冰内叶绿素符合其它结冰海区的一般规律。根据辽东湾冰层底部实测盐度变化规律阐明海冰对冰下海水营养盐的贡献。最后对深入开展结冰海区生态环境调查工作的技术、侧重点和意义做了讨论。 相似文献
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Lee H. Macdonald Donald M. Anderson William E. Dietrich 《Environmental management》1997,21(6):851-863
2 /yr, respectively. Geomorphic evidence indicates that plantation agriculture during the 18th and 19th centuries did not cause
severe erosion. Since about 1950 there has been rapid growth in roads and development due to increasing tourism and second-home
development. Our field investigations identified the approximately 50 km of unpaved roads as the primary source of anthropogenic
sediment. Field measurements of the road network in two catchments led to the development of a vector-based GIS model to predict
road surface erosion and sediment delivery. We estimate that road erosion has caused at least a fourfold increase in island-wide
sediment yields and that current sedimentation rates are unprecedented. Paving the dirt roads and implementing standard sediment
control practices can greatly reduce current sediment yields and possible adverse effects on the marine ecosystems surrounding
St. John. 相似文献
5.
Christopher R. Ellis Jerry Champlin Heinz G. Stefan 《Journal of the American Water Resources Association》1997,33(6):1363-1374
ABSTRACT: Evidence is presented that snowmelt runoff from an urban watershed can produce density current intrusions (underflows) in a lake. Several episodes of density current intrusions are documented. Water temperatures and salinities measured near the bottom of a 10 m deep Minneapolis lake during the late winter warming periods in 1989, 1990, 1991, and 1995 show significant rapid changes which are correlated with observed higher air temperatures and snowmelt runoff. The snowmelt runoff entering this particular lake (Ryan Lake) has increased electrical conductivity, salinity, and density. The source of the salinity is the salt spread on urban streets in the winter. Heating of littoral waters in spring may also contribute to the occurrence of the sinking flows, but is clearly not the only cause. 相似文献
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To overcome the shortcomings of phosphorus-containing compounds (PCCs, not widely used) in fire suppression, the dry water powder containing phosphoric acid was analyzed for a new fire suppressant (SiO2-P). First, the fine conditions (solid-to-liquid ratio, stirring time and stirring speed) were determined to prepare the new powder. The particle size distributions and XPS of SiO2-P powder were analyzed. The TG tests were conducted to study the decomposition of powder, and there was a major decomposition peak. Second, the extinguishing time of SiO2-P powder was tested, which showed that the SiO2-P powder containing phosphorus species could significantly improve the fire suppression ability. In addition, the kinetic parameters of powder decomposition reaction were determined by genetic algorithm based on TG results. Last, based on the decomposition products and kinetic parameters, the burning velocity and mass fraction of free radicals of CH4/air flame with SiO2-P powder addition were studied theoretically. The results indicated that SiO2-P powder had great ability of reducing the burning velocity and scavenging free radicals. Furthermore, the suppression effects were analyzed, which indicated that the cooperation of H2O and P suppression effect dominated the suppression mechanism and resulted in the good suppression efficiency. 相似文献
8.
Reza Kashiry Fard Reza Azar Afza Reza Teimouri 《Journal of Manufacturing Processes》2013,15(4):483-494
Dry wire electrical discharge machining (WEDM) is an environmentally friendly modification of the oil WEDM process in which liquid dielectric is replaced by a gaseous medium. In the present work, parametric analysis has been fulfilled while dry WEDM of Al–SiC metal matrix composite. Experiments were designed and conducted based on L27 Taguchi's orthogonal array to study the effect of pulse on time, pulse off time, gap voltage, discharge current, wire tension and wire feed on cutting velocity (CV) and surface roughness (SR). Firstly, a series of exploratory experiments has been conducted to identify appropriate gas and wire material based on the values of cutting velocity. After selection of best gas and best wire, they were used for later stage of experiments. Analysis of variances (ANOVA) has been performed to identify significant factors. In order to correlate relationship between process inputs and responses, an adaptive neuro-fuzzy inference system (ANFIS) has been employed to predict the process characteristics based on experimental observation. At the end, an artificial bee colony (ABC) algorithm has been associated with ANFIS models to maximize CV and minimize SR, simultaneously. Then the optimal solutions that obtained through ANFIS-ABC technique have been compared with numbers of confirmatory experiments. Results indicated that oxygen gas and brass wire guarantee superior cutting velocity. Also, according to ANOVA, pulse on time and discharge current were found to have significant effect on CV and SR. In modeling of CV and SR by ANFIS, it was resulted that the proposed method has superiority in prediction of them in the ranges of factors beyond the training condition. Also, association of ANFIS with ABC can find the optimal combination of process parameters accurately according to the confirmatory experiments. 相似文献
9.
Hole LR Brunner SH Hanssen JE Zhang L 《Environmental pollution (Barking, Essex : 1987)》2008,154(3):473-481
The conditional time averaged gradient method was used to measure air-surface exchange of nitrogen and sulphur compounds at a semi-alpine site in Southern Norway. Dry deposition velocities were then obtained from the bi-weekly concentration gradient measurements. Annual deposition velocities were found to be 1.4, 11.8 and 4.0 mm s(-1) for NH3, HNO3 and SO2, respectively, if all data were included, and to be 10.8, 11.8 and 13.0 mm s(-1), respectively, if only positive values were included. Measured deposition velocities were compared to two sets of values estimated from a big-leaf dry deposition module applying to two different land types (short grass and forbs, and tundra), driven by measured micrometeorological parameters. The deposition module gives reasonable values for this site throughout the year, but does not reproduce the large variability as shown in the measured data. No apparent seasonal variations were found from either measurements or module estimates due to the very low productivity of the studied area. 相似文献
10.
Karley Campbell Ilkka Matero Christopher Bellas Thomas Turpin-Jelfs Philipp Anhaus Martin Graeve Francois Fripiat Martyn Tranter Jack Christopher Landy Patricia Sanchez-Baracaldo Eva Leu Christian Katlein C. J Mundy Sren Rysgaard Letizia Tedesco Christian Haas Marcel Nicolaus 《Ambio》2022,51(2):318
Sea ice continues to decline across many regions of the Arctic, with remaining ice becoming increasingly younger and more dynamic. These changes alter the habitats of microbial life that live within the sea ice, which support healthy functioning of the marine ecosystem and provision of resources for human-consumption, in addition to influencing biogeochemical cycles (e.g. air–sea CO2 exchange). With the susceptibility of sea ice ecosystems to climate change, there is a pressing need to fill knowledge gaps surrounding sea ice habitats and their microbial communities. Of fundamental importance to this goal is the development of new methodologies that permit effective study of them. Based on outcomes from the DiatomARCTIC project, this paper integrates existing knowledge with case studies to provide insight on how to best document sea ice microbial communities, which contributes to the sustainable use and protection of Arctic marine and coastal ecosystems in a time of environmental change.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01658-z. 相似文献