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741.
Ryan T. Bailey Abedalrazq Khalil Vansa Chatikavanij 《Journal of the American Water Resources Association》2015,51(1):112-122
The water resources of the atolls of the Republic of Maldives are under continual threat from climatic and anthropogenic stresses, including land surface pollution, increasing population, drought, and sea‐level rise (SLR). These threats are particularly acute for groundwater resources due to the small land surface area and low elevation of each island. In this study, the groundwater resources, in terms of freshwater lens thickness, total volume of fresh groundwater, and safe yield are estimated for the 52 most populous islands of the Maldives for current conditions and for the year 2030, with the latter accounting for projected SLR and associated shoreline recession. An algebraic model, designed in previous studies to estimate the lens thickness of atoll islands, is expanded in this study to also estimate volume of groundwater. Results indicate that average current lens thickness, groundwater volume, and per capita safe yield are approximately 4.6 m, 1,300 million liters, and 300 l/day, and that these values will decrease by approximately 10, 11, and 34%, respectively, by the year 2030. Based on results, it is demonstrated that groundwater, in terms of quantity, is a viable source of water for the islands of the Maldives both now and in coming decades, particularly for islands with large surface area and low population. Study results can provide water resource managers and government officials with valuable data for consideration in water security measures. 相似文献
742.
Climate Trends but Little Net Water Supply Shift in One of Canada's Most Water‐Stressed Regions over the Last Century
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The southern interior ecoprovince (SIE) of British Columbia, Canada represents the northernmost extent of the great western North American deserts, it is experiencing some of the nation's fastest economic and population growth making it one of Canada's most water‐stressed regions, and it includes two headwater basins of the transboundary (Canada‐US) Columbia River. Statistical trend analyses were performed on 90‐year regional indicator time series for annual conditions in observed temperature, precipitation, and streamflow reflecting the three major SIE river basins: the Thompson, and transboundary Okanagan and Similkameen. Results suggest that regional climate has grown warmer and wetter, but with little net impact on total water supply availability. The outcome might reflect mutual cancellation of increases in precipitation inputs vs. evapotranspiration losses. Conclusions appeared largely insensitive to low‐pass data filtering, Pacific Decadal Oscillation effects, or solar output variability. Ensemble historical global climate model runs over the same time interval support this absence of appreciable trend in regionally integrated annual runoff volume, but a possible mismatch in precipitation results suggests a direction for further study. Overall, while important changes in hydrologic timing and extremes are likely occurring here, there is limited evidence for a net change in overall water supply availability over the last century. 相似文献
743.
An extended hazard and operability (HAZOP) analysis approach with dynamic fault tree is proposed to identify potential hazards in chemical plants. First, the conventional HAZOP analysis is used to identify the possible fault causes and consequences of abnormal conditions, which are called deviations. Based on HAZOP analysis results, hazard scenario models are built to explicitly represent the propagation pathway of faults. With the quantitative analysis requirements of HAZOP analysis and the time-dependent behavior of real failure events considered, the dynamic fault tree (DFT) analysis approach is then introduced to extend HAZOP analysis. To simplify the quantitative calculation, the DFT model is solved with modularization approach in which a binary decision diagram (BDD) and Markov chain approach are applied to solve static and dynamic subtrees, respectively. Subsequently, the occurrence probability of the top event and the probability importance of each basic event with respect to the top event are determined. Finally, a case study is performed to verify the effectiveness of the approach. Results indicate that compared with the conventional HAZOP approach, the proposed approach does not only identify effectively possible fault root causes but also quantitatively determines occurrence probability of the top event and the most likely fault causes. The approach can provide a reliable basis to improve process safety. 相似文献
744.
745.
针对现有填埋场渗漏检测系统在检测大面积填埋场时存在的检测成本高、电极铺设困难和定位不精确的实际问题,设计了一种新型填埋场实时渗漏检测系统,该系统采用分区检测、多点供电的方式采集检测电极电势,并通过定位算法定位漏洞。该系统在大大降低了大面积填埋场渗漏检测成本的同时,也提高了定位精度。通过在中国环境科学研究院内小型填埋场做模拟实验验证,在膜上供电电流400 mA、膜下电极栅格间距10 m、膜下媒质电阻率50Ω·m的情况下,系统的定位精度可达到20 cm。该系统为垃圾填埋场的科学管理和减少环境污染提供了新的科学技术手段。 相似文献
746.
管线渗漏诱发地铁工程事故的安全控制技术研究 总被引:1,自引:0,他引:1
在分析管线渗漏诱发地铁工程事故原因的基础上,建立一整套技术措施体系。在这个措施体系中,共包括给排水管线现状调查、给排水管线安全评估、管线渗漏地层饱和范围分析、监控量测、管线保护综合技术措施和工程应急预案建设6个方面的内容。其中,给排水管线现状调查、安全评估和管线周围饱和地层范围分析是做好此项工作的基础。管线变形和地层变形监控量测是管线保护和地层坍塌预防的必不可少的保证手段。应依据不同施工方法,从主动控制和被动控制两方面采取管线保护技术措施及地层坍塌预防和处理措施。而工程应急预案建设是工程安全控制的重要补充。 相似文献
747.
748.
微生物分子生态学进展[综述] 总被引:2,自引:2,他引:0
现代分子生物学技术在生态学研究中的应用大大推动了微生物生态学的发展,导致了微生物分子生态学的产生.微生物分子生态学方法弥补了传统的微生物生态学方法的不足,使人们可以避开传统的分离培养过程而直接探讨自然界中微生物的种群结构及其与环境的关系.微生物生态学研究中采用的分子生物学方法主要有核酸探针技术、PCR扩增技术、rRNA序列同源性分析方法、剃度凝胶电泳方法等.这些技术方法的采用,取得了一系列重要的成果和微生物生态学研究中的突破[1~6],使得对某些微生物的研究成为可能,并在分子水平上阐述了生态问题… 相似文献
749.
微生物分子生态学进展 总被引:2,自引:0,他引:2
《应用与环境生物学报》1999,5(Z1):1000
This paper summarizes some molecular
techniques applied in the studies on microbial ecology,such as hybridization of nucleic
acid probes,ampification of polymerase chain reaction,denaturing gradient gel
electrophoresis and analyses of ribosomal RNA gene sequences,and the progress,performance,achievements
and advances made from the researches of microbial ecology in recent years by using these
molecular techniques. 相似文献
750.