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161.
162.
163.
影响淀山湖水质变化的因素分析 总被引:4,自引:0,他引:4
就1996-1998年淀册湖全湖水质均值变化情况作了评述,对影响淀山湖水质变化的因素进行了分析和探讨。针对淀山湖水质受到太湖来水水质影响的情况,提出了在今后的工作中进一步加大保护淀册湖水质的建议和措施。 相似文献
164.
K. Bruce Jones Daniel T. Heggem Timothy G. Wade Anne C. Neale Donald W. Ebert Maliha S. Nash Megan H. Mehaffey Karl A. Hermann Anthony R. Selle Scott Augustine Iris A. Goodman Joel Pedersen David Bolgrien J. Max Viger Dean Chiang Cindy J. Lin Yehong Zhong Joan Baker Rick D. Van Remortel 《Environmental monitoring and assessment》2000,64(1):227-245
The Environmental Monitoring and Assessment Program (EMAP) is proposing an ambitious agenda to assess the status of streams and estuaries in a 12-State area of the western United States by the end of 2003. Additionally, EMAP is proposing to access landscape conditions as they relate to stream and estuary conditions across the west. The goal of this landscape project is to develop a landscape model that can be used to identify the relative risks of streams and estuaries to potential declines due to watershed-scale, landscape conditions across the west. To do so, requires an understanding of quantitative relationships between landscape composition and pattern metrics and parameters of stream and estuary conditions. This paper describes a strategic approach for evaluating the degree to which landscape composition and pattern influence stream and estuary condition, and the development and implementation of a spatially-distributed, landscape analysis approach. 相似文献
165.
选用配备了2种不同检测器(电导检测器和直流安培检测器)的离子色谱仪对稀释后过0.22μm滤膜的水样进行分析。配备有直流安培检测器的离子色谱仪测定水中碘化物的方法在0.100~20.0μg/L范围内线性关系良好,相关系数(r)=0.9999,方法检出限为0.030μg/L,测定下限为0.120μg/L,样品加标回收率为95.0%~104%,相对标准偏差为1.06%~1.64%;配备有电导检测器的离子色谱仪测定水中碘化物的方法在20.0~2.00×105μg/L范围内线性关系良好,相关系数(r)=0.9995,方法检出限为2.00μg/L,测定下限为8.00μg/L,样品加标回收率为99.0%~110%,相对标准偏差为0.71%~3.12%。离子色谱-直流安培检测器法测定水中碘化物的方法准确度高、灵敏度高、精密度好,检出限相对较低,适用于测定ρ(碘化物)≤20.0μg/L的清洁水样;离子色谱-电导检测器法主要适用于测定ρ(碘化物)≥20.0μg/L的水样。 相似文献
166.
水体富营养化的渐进性和灾难性 总被引:8,自引:2,他引:8
水体富营养化是全球范围内的普遍现象,他的危害性已越来越引起全人类的关注.本文从生态学、地球化学循环和全球气候变迁的角度,结合人类的社会活动,讨论了水体富营养化发生的机制、危害,并从全球角度提出人类面对富营养化应有的态度和应采取的对策. 相似文献
167.
研究了几种典型的城市给水管网优化设计数学模型,并给出了求解方法,指出在给水管网系统的优化设计中进一步完善广义简约(GRG)算法的必要性. 相似文献
168.
Securing sustainable livelihood conditions and reducing the risk of outmigration in savanna ecosystems hosted in the tropical semiarid regions is of fundamental importance for the future of humanity in general. Although precipitation in tropical drylands, or savannas, is generally more significant than one might expect, these regions are subject to considerable rainfall variability which causes frequent periods of water deficiency. This paper addresses the twin problems of “drought and desertification” from a water perspective, focusing on the soil moisture (green water) and plant water uptake deficiencies. It makes a clear distinction between long‐term climate change, meteorological drought, and agricultural droughts and dry spells caused by rainfall variability and land degradation. It then formulates recommendations to better cope with and to build resilience to droughts and dry spells. Coping with desertification requires a new conceptual framework based on green‐blue water resources to identify hydrological opportunities in a sea of constraints. This paper proposes an integrated land/water approach to desertification where ecosystem management supports agricultural development to build social‐ecological resilience to droughts and dry spells. This approach is based on the premise that to combat desertification, focus should shift from reducing trends of land degradation in agricultural systems to water resource management in savannas and to landscape‐wide ecosystem management. 相似文献
169.
Olanike O. Aladenola Ayodele E. Ajayi Ayorinde A. Olufayo Babatunde Ajayi 《The Environmentalist》2008,28(2):123-127
The performance of a mixture of a forest bye product and cement for the production of storage structure for harvested rainwater
was assessed. Three mix ratios of Cement: Gmelina arborea sawdust 3.0:1.0 (specimen A), 2.5:1.0 (specimen B) and 2.0:1.0 (specimen C) were considered. Engineering properties and dimensional
stability of the different mix-ratios were monitored from prototypes cylindrical pots and test billet specimens. Possible
change in quality of stored rainwater, with time was monitored in all the three cases. Water quality parameters monitored
include pH, hardness, total suspended solids, alkalinity, acidity and total dissolved CO2. The tensile stress obtained were 110, 104, and 95 N/mm2, while the compressive strength were 5,000, 3,000, and 2,000 kN for specimens A, B and C respectively. Accelerated aging
test showed that sample A were more resistant to deformation, while specimen C were more susceptible to change in structure
over time. Similarly, the values of tensile and compressive strength after accelerated aging test increased in the order of
specimen A > B > C. Except in specimen C where significant differences in alkalinity and acidity were observed, there were
no significant differences in quality of the water stored in the pots after 2 months of storage. The results indicate the
suitability of the Gmelina arborea waste as an alternative in constructing water storage structures in rural communities. 相似文献
170.
Guoyi Zhou Ge Sun Xu Wang Chuanyan Zhou Steven G. McNulty James M. Vose Devendra M. Amatya 《Journal of the American Water Resources Association》2008,44(1):208-221
Abstract: It is critical that evapotranspiration (ET) be quantified accurately so that scientists can evaluate the effects of land management and global change on water availability, streamflow, nutrient and sediment loading, and ecosystem productivity in watersheds. The objective of this study was to derive a new semi‐empirical ET modeled using a dimension analysis method that could be used to estimate forest ET effectively at multiple temporal scales. The model developed describes ET as a function of water availability for evaporation and transpiration, potential ET demand, air humidity, and land surface characteristics. The model was tested with long‐term hydrometeorological data from five research sites with distinct forest hydrology in the United States and China. Averaged simulation error for daily ET was within 0.5 mm/day. The annual ET at each of the five study sites were within 7% of measured values. Results suggest that the model can accurately capture the temporal dynamics of ET in forest ecosystems at daily, monthly, and annual scales. The model is climate‐driven and is sensitive to topography and vegetation characteristics and thus has potential to be used to examine the compounding hydrologic responses to land cover and climate changes at multiple temporal scales. 相似文献