全文获取类型
收费全文 | 1212篇 |
免费 | 129篇 |
国内免费 | 152篇 |
专业分类
安全科学 | 622篇 |
废物处理 | 22篇 |
环保管理 | 80篇 |
综合类 | 525篇 |
基础理论 | 98篇 |
污染及防治 | 60篇 |
评价与监测 | 41篇 |
社会与环境 | 25篇 |
灾害及防治 | 20篇 |
出版年
2024年 | 2篇 |
2023年 | 20篇 |
2022年 | 45篇 |
2021年 | 35篇 |
2020年 | 29篇 |
2019年 | 34篇 |
2018年 | 26篇 |
2017年 | 48篇 |
2016年 | 40篇 |
2015年 | 77篇 |
2014年 | 62篇 |
2013年 | 52篇 |
2012年 | 135篇 |
2011年 | 118篇 |
2010年 | 69篇 |
2009年 | 87篇 |
2008年 | 54篇 |
2007年 | 75篇 |
2006年 | 84篇 |
2005年 | 60篇 |
2004年 | 44篇 |
2003年 | 47篇 |
2002年 | 42篇 |
2001年 | 37篇 |
2000年 | 41篇 |
1999年 | 34篇 |
1998年 | 34篇 |
1997年 | 21篇 |
1996年 | 10篇 |
1995年 | 3篇 |
1994年 | 5篇 |
1993年 | 6篇 |
1992年 | 3篇 |
1991年 | 1篇 |
1990年 | 1篇 |
1985年 | 2篇 |
1984年 | 1篇 |
1983年 | 1篇 |
1982年 | 2篇 |
1981年 | 1篇 |
1979年 | 1篇 |
1978年 | 1篇 |
1977年 | 2篇 |
1973年 | 1篇 |
排序方式: 共有1493条查询结果,搜索用时 218 毫秒
991.
煤矿安全评价若干问题的研究与探讨 总被引:1,自引:0,他引:1
笔者结合煤矿安全评价工作的经验,就煤矿安全评价工作若干问题进行研讨,主要内容包括:资料收集及分析处理,法律、法规引用,危险辨识,确定评价范围和划分评价单元,选择评价方法及确定评价深度,提高对策措施针对性,完善风险判别指标体系,正确得出评价结论,规避评价风险等9个方面。通过对煤矿安全评价工作若干问题的研讨和提出的对策,为安全评价机构提高煤矿安全评价水平,促进安全评价工作健康发展,有重要参考价值。 相似文献
992.
将工业废弃物锰矿尾渣与壳聚糖混合制得一种高效吸附斛,并应用扫描电镜、X射线衍射对其结构进行了表征。采用正交表设计试验,分别考察了pH值、吸附时间、温度、复合吸附剂的投加量等4个影响因素对Pb^2+吸附的影响,最佳吸附条件为:pH值为7,吸附时问为40mjn,温度为20℃,复合吸附剂的投加量为0.10g。处理后的水符合国家污水综合排放标准(GB8978.1996)中的一级标准。复合吸附剂对Pb^2+的吸附符合Langmuir和Freundlich吸附等温方程。 相似文献
993.
Niyogi Dev K. Mcknight Diane M. Lewis William M. 《Water, Air, & Soil Pollution: Focus》2002,2(2):329-341
Rates of aspen litter breakdown were measured at 40 sites in streams of the Rocky Mountains of Colorado, U.S.A. The sites encompassed a range of effects of mine drainage, from pristine (no effects) to highly stressed. The pH, concentrations of dissolved zinc, and deposition rates of metal oxides (the three main stresses from mine drainage) were measured in each stream. Rates of litter breakdown were estimated from changes in mass of aspen leaves in litterbags. The biological communities associated with litter breakdown also were evaluated by measuring the biomass of shredding invertebrates in litterbags and the rate of microbial respiration on litter. Of the stresses from mine drainage, concentration of zinc and deposition rate of metal oxides were most closely related (negatively) to rate of litter breakdown. Biomass of shredding invertebrates was also negatively related to concentration of dissolved zinc and deposition of metal oxides. Microbial respiration was negatively related to deposition rate of metal oxides and positively related to concentration of nutrients. Both shredder biomass and microbial respiration were positively related to litter breakdown rate and, together, accounted for 79% of its variation. Recovery of litter breakdown in streams affected by mine drainage requires remediation that limits both dissolved and deposited metals. 相似文献
994.
针对新桥矿通风系统存在的问题,结合矿山当前生产实际,提出并实施了降低风阻和提高风量率等优化改造措施。 相似文献
995.
996.
Lloyd R. Stark Robert P Brooks Frederick M. Williams S. Edward. Stevens Luise K Davis 《Journal of the American Water Resources Association》1994,30(4):639-650
ABSTRACT: Flow rates, pH, iron concentration, and manganese concentration were measured during several storm events at two constructed wetlands receiving mine water. During a substantial rain event, flow rates at both the wetland outlets surpassed flow rates at the wetland inlets, reflecting incident rainfall and differences in wetland area at the two sites. A significant positive correlation existed between local rainfall and outflow rates at the larger wetland, but not between rainfall and inflow rates. During storm events, outlet pH, relative to inlet pH, was slightly elevated at the larger wetland, and depressed at the smaller wetland. However, over the course of one year, rainfall was uncorrelated to outlet pH in the larger wetland. A substantial rain event at the smaller wetland resulted in a temporary elevation in outlet iron concentrations, with treatment efficiency reduced to near zero. However, in the larger wetland, outlet iron concentrations were not significantly affected by storm events. Although rainfall and outlet iron concentration were not significant correlates at the larger wetland, flow rate was positively correlated to outlet iron concentration. A normal manganese treatment efficiency of 50 percent at the smaller wetland was reduced to zero during a heavy rain. 相似文献
997.
Robert C. Hoehn Dallas R. Sizemore 《Journal of the American Water Resources Association》1977,13(1):153-160
ABSTRACT: A study was conducted to 1) chemically characterize three AMD streams entering Chestnut Creek in southwestern Virginia below the town of Galax, Virginia, and 2) to assess the biological and chemical alterations in the creek. Over a six mile reach, the benthic macroinvertebrate population was reduced to zero, the naturally low alkalinity (~25mg/1) of the stream was reduced to less than 5 mg/1, and the pH was reduced from 7.2 to 6.3. Increased concentration of iron from less than 0.01 mg/I to more than 4.0 mg/1 were accompanied by the deposition of a coating of iron hydroxide up to 0.25 in. thick in the stream bed, a phenomenon most likely responsible for the absence of benethic macroinvertebrates. In situ bioassays with bluegill sunfish and one snail species showed that the creek water, after confluence with all the AMD streams, was not toxic in 192 hours to fish, and snails survived 96 hours before they began to die. The undiluted AMD itself was highly toxic. 相似文献
998.
999.
Dennis R. Helsel 《Journal of the American Water Resources Association》1983,19(6):881-888
ABSTRACT: Stream water during fair weather (base flow) is largely ground water discharge, which has been in contact with minerals of the underlying aquifer. Base flow water quality should therefore reflect aquifer mineralogy as well as upstream land use. Three upstream mining categories (unmined lands, abandoned coal mines, and reclaimed coal mines) differed in pH, specific conductance, sulfate, iron, aluminum, and alkalinity for 122 streams in eastern Ohio. Aquifer rock type influenced pH, specific conductance, sulfate, iron, and alkalinity. Reclamation returned many components of acid mine drainage to near unmined levels, although sulfate and specific conductance were not improved. Acid mine drainage problems were less severe in watersheds underlain by the calcareous Monogahela Formation. These results should ayply to other Appalachian coal regions having similar rock units. The water quality data distributions were neither consistently normal nor lognormal. Statistical tests utilizing ranks of the water quality data, instead of the data themselves, proved useful in analyzing the influences of mining category and rock type. 相似文献
1000.
James E. Crews 《Journal of the American Water Resources Association》1973,9(3):567-576
ABSTRACT Twenty-seven watersheds in the Susquehanna River Basin are severely degraded by acid mine drainage pollution. Approximately 620 miles of significant tributaries as well as 230 miles of principal rivers are either sterile or intermittently degraded by acid slugs. As a result of the acid discharges, many uses of the streams, such as water supply and recreation, are precluded. In the past, acid mine drainage abatement programs did not look beyond the immediate problem area. No considerations were given to the blending effect of natural alkalinity in other streams. Since the abatement of acid mine drainage pollution is extremely costly, a method of minimizing these costs was needed. The systematic, cost-effectiveness approach, discussed in this paper presents such a method. This system allows the water resources planners to control the allocation of funds for maximizing the abatement of acid mine drainage. 相似文献